How Big Is It?

The Polaris is 792.6 tons of propellant and 396.3 tons of everything else. How big is this, exactly?

When comparing the spacecraft to other vehicles, just use the "everything else" value, ignore the propellant mass. This is because few earthly vehicles have total masses dominated by fuel mass as much as rockets are. How does 396.3 tons stack up?

Rick Robinson notes that is pretty small compared to "wet-navy" vessels. It's under the size of a coastal corvette. But compared to aircraft, it's huge. A Boeing 747 is only 180 tons empty. If you want to get an idea of other sizes, go check out Jeff Russell's huge Starship Dimensions website and Florian Käferböck's impressive Rockets and Space Ships Size Comparison.

0Human Being1.77 meters/5.8 feet
1Giraffe6 meters/20 feet
2City Bus12 meters/40 feet long
3Small Orion Drive ship21 meters/70 feet
4Millennium Falcon35 meters/115 feetStar Wars
5Polaris43 meters/140 feetTom Corbett, Space Cadet
6Moonship44 meters/144 feetChesley Bonestell,
Conquest of Space
7Luna46 meters/150 feetDestination Moon
8Arc De Triomphe50 meters/164 feet
9Orion Drive Mars
Exploration Vehicle
50 meters/165 feet
10United Planets Star
Cruiser C-57D
51 meters/170 feet wideForbidden Planet
11Nautilus51 meters/170 feet long
12Space Shuttle stack56 meters/180 feet
13Absyrtis60 meters/197 feetG. Harry Stine,
Contraband Rocket
14Boeing74771 meters/231 feet
16Ferry Rocket81 meters/265 feetCollier's Magazine,
22 March, 1952
17Statue of Liberty93 meters/300 feet
18DE-51 Destroyer Buckley93 meters/306 feet
19Saturn V111 meters/363 feet
20DY-100 Botany Bay92 meters/302 feetStar Trek
21California Redwood112 meters/367 feet
15RS-10128 meters/420 feetAndre Norton Star Born
22Discovery140 meters/459 feet2001, A Space Odyssey
23Romulan Bird of Prey131 meters/430 feetStar Trek
24Great Pyramid of Cheops139 meters/455 feet
25Oscar class submarine155 meters/509 feet
26Galactic Cruiser Leif Ericson168 meters/551 feetLeif Ericson Model
27Washington Monument169 meters/555 feet
28Klingon D7 battlecruiser228 meters/750 feetStar Trek
29LZ-129 Passenger
Airship Hindenburg
245 meters/804 feet
30BB-62 Battleship New Jersey270 meters/887 feet
31NCC 1701 Starship Enterprise289 meters/950 feetStar Trek
32Eiffel Tower300 meters/984 feet
33CVN-65 Carrier Enterprise342 meters/1,123 feet
34Empire State Building443 meters/1,454 feet
35Al Rafik102 meters/335 feetAttack Vector: Tactical
36Tachi/Rocinante46 meters/151 feetThe Expanse
3710 Story Building30 meters/98 feet
38International Space Station109 meters/358 feet
39X-Wing Fighter13 meters/41 feetStar Wars
40Eagle Transporter31 meters/100 feetSpace 1999
41Shuttle Orbiter37 meters/122 feet
42Type S Scout39 meters/128 feetTraveller RPG
43Serenity58 meters/190 feetFirefly
44DDG-90 Destroyer Chafee155 meters/510 feet
45ISV Venture Star1,646 meters/5,400 feetAvatar
46CVN-68 Aircraft Carrier Nimitz333 meters/1,092 feet
47Imperial Star Destroyer1,600 meters/5,249 feetStar Wars
48Scoutship Vega20 meters/66 feetLeif Ericson Model
49Michael Battleship132 meters/433 feetFootfall
50Orion Battleship78 meters/256 feet
51ANNIC NOVA78 meters/256 feetTraveller RPG
52Valley Forge1,600 meters/5,249 feetSilent Running
53Klingon K't'inga class
Battle Cruiser
349.54 meters/1,147 feetStar Trek

Note: according to the blueprints the Michael Battleship (49) is 408 feet tall. However, this would make the Shuttle Orbiters mounted on the battleship too small. I scaled the blueprint so the Orbiters were at their official length, which made the Michael 433 feet tall.

Credits for the computer meshes used in the images below:

  • 10 Story Building: KG
  • ANNIC NOVA: Winchell Chung (me)
  • Al Rafik: Charles Oines
  • Boeing 747: Jay
  • CVN-68 Aircraft Carrier Nimitz: Toby
  • DDG-90 Destroyer Chafee
  • Eagle Transporter: James Murphy
  • Galactic Cruiser Leif Ericson: Winchell Chung (me)
  • Giraffe: BMS
  • Human: ?
  • ISV Venture Star: krabz
  • Imperial Star Destroyer: Blenderwars
  • International Space Station: ?
  • Klingon K't'inga Battle Cruiser: ?
  • Michael Battleship: Winchell Chung (me)
  • Millennium Falcon: Blenderwars
  • NCC 1701 Starship Enterprise: William P. "Tallguy" Thomas
  • Ogre Mark V: Winchell Chung (me)
  • Orion Battleship: Winchell Chung (me)
  • Polaris: Winchell Chung (me)
  • Saturn V: Tesler
  • School Bus: tamias6
  • Scoutship Vega: Winchell Chung (me)
  • Serenity: JayThurman (Cyberia23)
  • Space Shuttle Orbiter: NASA
  • Space Shuttle Stack: ?
  • Statue of Liberty: Damo
  • Tachi/Rocinante: Chris Kuhn
  • Type S Scout: Winchell Chung (me)
  • Valley Forge: ?
  • X-Wing Fighter: Blenderwars
Maiden Flight, SDSD Freudian Nightmare
Imperial Weapons Development Center, Coruscant
To Whom it May Concern:

Gentlemen, let me start by saying that I am greatly honored to be chosen for command of such a magnificent vessel. That said, our insystem shakedown cruise has turned up a few minor issues that I would like to see remedied as soon as possible.

1) We understand your desire to continue the classical stylized lines of the first star destroyer class vessels, and we appreciate your asthetic sense in that regard. However, strictly speaking, was it absolutely necessary to scale up the bridge tower directly? I must confess the foreward bridge window is a great distraction. Militarily, we feel that as is, the three kilometer tall window pane may provide too tempting a target for enemy forces we may engage. We've lost four helmsmen so far to vertigo as well, and we don't think this is in the best interests of the vessel's well-being.

2) The sheer size of our vessel, while a glorious symbol of the mighty Emperor, which we all appreciate completely, has become apparent to us all. My initial briefing tour of the vessel took six days to complete, and the travel tubes were based on the design in use aboard the slightly smaller Executor-class vessels. Travel time being prohibitive, we were forced to camp out in the corridors of the major sectors when we stopped for the night. Furthermore, since our crew quarters sections are located entirely within the aft dorsal sectors, both our Engineering crew and ground forces complements have built tent cities within their own sections, and are living there. Fire hazard has become nearly intolerable and the hydroponics department has sent me six hundred messages insisting that the smoke from the camp-fires is ruining their crop, and that we have enough food left aboard for only another three weeks.

2) Our vessel's own gravity is not being handled as well as could be done, with some minor problematical consequences. Our plumbers called my attention to the fact that the sewage from our 6 million-man crew backwashed through the air vents in Sections 42 to 78, decks 258 through 532. Malaria and dysentary broke out in those sections, and we were forced to cordon it off to prevent an epidemic. Our first Chief Medical Officer unfortunately was killed when he requested the paperwork on those affected, and upon receiving e-mailed reports from all 739 of his senior doctors, the computer screen in his quarters self-destructed, propelling shrapnel throughout his quarters. All droids who enter the area have failed to return, and a remote camera probe sent in, recorded images of the survivors in the affected area where they were flinging their own feces at each other, warring with sharpened pieces of metal, and attempting to eat the dismembered limbs of the aforementioned droids.

3) On a similar note, regarding the unfortunate loss of our last CMO, we have finally decided that the staff requirements of this vessel are creating further problems. For instance, our Chief Engineer has begun the habit of signing his reports, "Chief Marshal, Sovereign Nation of Ree'Ak'tor." He has since sealed off those decks, and started a war. The war in question is against his apparent rival, the commander of our ground forces near the main flightdeck, who has taken to calling himself "Bringer of the Apocalypse." Surveillance records indicate that they have since stopped wearing their armor, and have begun smearing their bodies with industrial cleaning fluid and lubricants before launching raids upon the Engineering department. We believe that they have begun ritualistically sacrificing one of our TIE-fighter pilots before each attack to bring them luck.

Aside from a minor note that some of our turbolaser turret gunners may have starved to death when their food shipments were cut off by the warzone, there is little else to remark on, save that in our first tactical drill, during the course of a two-hour right turn, we failed to halt our rotation with the result of the subsequent and very unfortunate destruction of the entire Coruscant 4th Defensive Fleet. I've made a note to send out letters of regret the moment we reacquire contact with our communications room at the bow of the vessel. That of course is the reason why this message had to be sent to your offices via pen, paper, and one of our probe droids. I beg forgivness for the clerical difficulties that may cause.

Grand Admiral
SDSD Freudian Nightmare
unknown author (2013)

“Finally, let us turn to the biggest megaships of them all, the fleet carriers. Including them in this work is a choice which I expect to be somewhat controversial – many would argue that a fleet carrier is a formation, not a vessel – but with respect to those readers who may hold that position, since the Imperial Navy treats fleet carriers as a single vessel for asset accounting and command designation purposes, so in turn shall I.

“Let us begin with a look at the history of the type. Fleet carriers were not known before the Exterminomachy (5782-5901). While before that time lighthuggers had met with occasional hostility, they had proven more than capable of defending themselves against local system defense forces, in particular with the Perreinar Wheel1 – and in those cases where they were not, it was because they had encountered a Power not readily opposed by pure military force. This changed with the arrival of the skrandar berserker probes, whose numbers and willingness to embrace suicide tactics made them a serious threat to even well-defended vessels, and eliminating breeding site for which required the transport of full task forces to their host systems.

“The first fleet carriers, then, were improvisations; lighthuggers pressed into service under the right of angary. Stripped down by removing all cargo capacity, much crew space, and all other less-than-essential facilities, and enhancing their fuel capacity with multiple drop tanks, it became possible to clamp a small number of light units – overstocked with fuel and supplies – to the spine of such a vessel, and have it haul them slowly and painfully to a target system.

“Such crude improvisations were fraught with problems, from wear and tear on ships and crew during the slow transit, to the risk of interception before the transported units could free themselves from the carrier – both due to the inefficiency of the mechanical clamps, and the need to cut clamps frozen in transit or actual hard welds used where clamps would not suffice, to even entire vessels lost from the carrier in transit. (The last of these to be recovered, CS Bloodwashed3, was salvaged with all hands in 6722.)

“Fortunately, by the third year of the Exterminomachy, new designs were emerging from the cageworks at Ashen Planitia and Armory. The second-generation fleet carriers were custom-built starships, or rather, the specialized elements (the “propulsion head” and “collier module”) were, since the second generation eschewed the rigid designs of the first in exchange for dispersed tensegrity structures.

“In effect, the starships transported by the fleet carrier, along with the specialized elements, formed the floating compression struts of the overall structure, while being linked by braided cables (derived from orbital elevator technology) into a unified structure. The majority of the propulsive thrust is provided by the dedicated propulsion heads, while specialized fleet mediator software enables the use of the drives of the various carried ships to balance the structure and correct attitude. Meanwhile, supplies carried in the collier modules, distributed by rigged flexpipe and by cable-crawling logistics robots, eliminated the need to overload any individual ship with supplies, and indeed enabled the transportation of greater volumes of fuel and replenishment. Moreover, such fleet carriers could separate instantly if intercepted by simply blowing the explosive cable-couplers and engaging their drives independently, the dispersed tensegrity structure providing adequate safety separation for this.

“Such dispersed-design fleet carriers served with distinction throughout the remainder of the Exterminomachy, and have remained a key element of IN subluminal doctrine since. While there exist a third generation of fleet carrier designs, these merely reflect the evolution in technological reliability that allows the physical cables of the second generation to be replaced with vector-control tractor-pressor beams, and does not reflect any change in fundamental design or doctrine.

“As ad hoc structures, of course, it would be incorrect to say that fleet carriers have classes, in the strictest sense. However, the individual propulsion heads and collier modules, the former full starships in themselves, do. Thus, we shall begin our examination of fleet carriers with a look at the most common propulsion head in Imperial service, the Legends-class…”

– Megaships of the Imperium, Lorvis Maric, pub. 7290

  1. Perreinar2 Wheel: a fight-and-flight maneuver in which a lighthugger puts its stern towards the battle and engages its interstellar drive, thus retreating from the engagement while simultaneously treating the enemy to the close-range efflux of a pion drive – a situation which is very rarely survivable for anything larger than a baryon.
  2. From the eponymous horse archers who had perfected the “Perreinar shot” centuries before.
  3. Lost in the wreck of CS Cúlíän Daphnotarthius, which suffered a structural collapse of the spine while outward bound to IGS 31238 in the second year of the war.
From OUTSIZE by Alistair Young (2019)

Calculating Volume and Mass

The Easy Way 1

If you just want something really quick and dirty:

Estimate somehow the volume (m3) of your spacecraft. Calculate the mass by multiplying the volume by the average density (kg/m3) of a spacecraft.

Estimating Volume

  1. There are equations to calculate the volume of simple geometric objects such as cubes, spheres, cylinders, and cones. Approximate the spacecraft as an assemblage of such objects, calculate the volumes, then add them all up. Example: here.
  2. Create a scale model inside a 3D modeling package, and use the included tools to calculate the internal volume. Example: On my mesh model of the Galactic Cruiser Leif Ericson, the AreaVol script informs me the ship has an internal volumeof 68,784.87 cubic meters.
  3. See if somebody else has already calculated the volume. Example: According to ST-v-SW.Net the internal volume of the TOS Starship Enterprise is 211,248 cubic meters.
  4. Use the known volume of a comparable existing object. Example: a Russian Oscar submarine has a volume of 15,400 cubic meters. It is a good size for a spaceship.
  5. If the spacecraft is approximately a sphere or approximately a cylinder, just use the ship's average radius and height to calculate an approximate volume using the sphere or cylinder volume formulae. Close enough for government work.
  6. Make it up out of your imagination.

Of course there is some differences of opinion on the exact value of the average density of a spacecraft.

One easy figure I've seen in various SF role playing games is a density of 0.1 to 0.2 metric tons per cubic meter (100 to 200 kilograms). That corresponds to average pressure compartments being cubes 10 meters on a side, with pressure bulkheads averaging 17 to 33 kg/m2.

Ken Burnside did some research when he designed his game Attack Vector: Tactical. He found that jet airliners have an average density of about 0.28 metric tons per cubic meter, fighter aircraft 0.35 tons/m3, wet navy warships from 0.5 to 0.6 tons/m3, WWII battleships 0.7 tons/m3 (it don't take much excess mass to send them straight to Davy Jones locker), and submarines 0.9 tons/m3. For the combat spacecraft in AV:T, Ken chose a density of 0.25 tons/m3.

Ship Densities
Attack Vector: Tactical0.25 ton/m3
Jet Airliners0.28 ton/m3
Fighter Aircraft0.35 ton/m3
Wet Navy Warships0.5 to 0.6 ton/m3
WWII Battleships0.7 ton/m3
Submarines0.9 ton/m3

A student of the game Orbiter (who goes by the handle T. Neo) used the 3D models in the game to figure the volume of various space constructions. Dividing by their known masses yielded the densities.

Spacecraft Densities
Space Shuttle External Tank0.011 ton/m3*
Long Duration Exposure Facility0.049 ton/m3
S-IC0.050 ton/m3*
Leonardo Multi-Purpose Logistics Modules0.058 ton/m3
Hubble Space Telescope0.061 ton/m3
International Space Station0.074 ton/m3
Space Shuttle Orbiter0.088 ton/m3
Space Station Mir0.175 ton/m3
Space Shuttle Solid Rocket Booster0.206 ton/m3*

* Large portion of volume is dedicated to propellant

Fans of the Traveller role playing game have to do a bit of work. Starships in Traveller are rated in terms of "displacement tons" or "dtons". This is a measure of volume, not mass. 1 dton is 14 cubic meters, which is approximately the volume taken up by one metric ton of liquid hydrogen (actually closer to 14.12 m3). Liquid hydrogen is starship fusion fuel.

So if you assume a Traveller starship has an average density of 0.2 tonnes/m3, then given dtons the starship mass in metric tons is:

starshipMass = dtons * 14 * 0.2


starshipMass = mass of starship (metric tons)
dtons = displacement of starship (displacement tons or dtons)
0.2 = average density of starships (tonnes/m3)

Example: a Broadsword class mercenary cruiser has a volume of 800 dtons (or 1200 depending on where you read it). This means its mass is 800 * 14 * 0.2 = 2,230 metric tons.

Traveller deck plans are confusing as well. If they are ruled off in a square grid, chances are the squares are 1.5 meters on a side. The space between the floor and the ceiling of a deck is assumed to be 3 meters. Bottom line is that on a Traveller deck plan 1 dton is represented by two grid squares.


(ed note: This is from a tabletop starship wargame called Voidstriker. In the game one can custom design one's combat starships using a ship construction system. The different classifications of starship internals is somewhat interesting, but I found UDST to be hilarious.)

Ships are made of multiple sections called hulls. These hulls represent an unspecified amount of volume, and come in five types: Undifferentiated Starship Tissue (UDST), Containment, Magazines, Systems, and Hangars.

UDST hulls hold the ship's drives, power plants, hardpoints, crew quarters and access areas, command decks, and everything else that a ship requires to function at a minimal level. Containment hulls hold reaction mass, cargo and troops. Magazines hold internally-stored bombs, missiles and torpedoes. Hangars hold small craft (fighters, shuttles and the like). Systems hulls hold short and long range scanners.

Up to 80% (round down) of the ships hulls may be containment hulls, magazines, systems or hangars. The rest must be UDST hulls.

From VOIDSTRIKER by Charles Oines (2007)

The Easy Way 2

The second quick and dirty method:

Estimate the mass (kg) of each major component. Divide the mass of each major component by its density (kg/m3) to find the volume of each major component. Total the masses to get the spacecraft mass, total the volume to get the spacecraft volume.

Estimating Mass

Often you have the total mass, and the propellant mass. The dry mass is the total mass less the propellant.

If you have the mass ratio, you can figure your dry mass by totaling up the various components, then use the mass ratio to calculate the propellant mass and total mass.

remember that average NASA spacecraft dry mass (i.e., sans propellant) divides up to include:

Percentage of Dry Mass
Power Systems28.0%
Thermal (heat radiators)3.4%
Guidance, Navigation, and Control8.0%
Everything Else26.7%

Keep in mind that this is for NASA style spacecraft. The percentages for, say, the Starship Enterprise will be totally different and anybody's guess.

Now all you need are some figures on the average density of these various items and you can calculate quick and dirty ship volumes. I'm looking into it but it's hard.

The Hard Way

The following is a method to calculate the spacecraft's structural mass. It is derived from a document at Christopher Thrash's web site. He bases his analysis on data from the book all the pros in astronautics use, Space Mission Analysis and Design. There is some additional information here.

Lucky you, Eric Rozier has implemented the algorithm below as an on-line calculator.

Assumptions: as a first approximation, the spacecraft is modeled as a free standing column resting upon the engines. The column is "thin-walled", that is, the column radius divided by the hull thickness is less than 0.1. The column is only supported by its walls (monocoque construction). The column has its mass uniformly distributed along its length. The ratio of column's length to its diameter is 3.2 : 1.0. The hull is assumed to be capable of withstanding forces equal to its mass times gs of acceleration on any axis: axial, lateral, or bending.

This means that the following formula only work for a cigar-shaped rocket, not a spherical one.

Decide upon the volume, or total displacement of the hull in cubic meters (m3). This will boil down to volume for reaction mass plus volume for the crew and cargo. Calculate the volume for your reaction mass by

Vpt = Mpt / Dpt


  • Mpt = mass of propellant (kg)
  • Dpt = density of propellant (kg/m3) = 71 for liquid hydrogen, 423 for methane, 682 for ammonia, and 1000 for water
  • Vpt = volume of propellant (m3)

If you don't know the mass of the propellant, it can be calculated from the dry mass and the mass ratio:

Mpt = (R * Me) - Me


  • R = mass ratio (dimensionless number)
  • Mpt = mass of propellant (kg)
  • Me = mass of rocket with empty propellant tanks (kg)

Add the volume of the reaction mass to the desired living space volume to get the spacecraft's volume. Later you can figure the approximate spacecraft dimensions by using the formula for the volume of a cylinder ( v = π r 2h ), keeping in mind that it should be about 3.2 times as high as it is wide (although you can get away with larger values).

Now comes the fun part. This is going to be what they call an "iterative process". This means you do the calculations, take the results and do the calculations again on the results.

Step 1: Find Mass

M = M~st + Mst


  • M = mass of spacecraft (kg)
  • M~st = sum of mass of all spacecraft components except structure (kg)
  • Mst = spacecraft's structural mass (kg)

Since this is an iterative process to calculate Mst, the first time through Mst will be equal to zero.

Step 2: Find Density

D = (M/1000) / V


  • D = density of spacecraft (ton/m3)
  • M = mass of spacecraft (kg)
  • V = volume of spacecraft (m3)

Note that here density is in tons, not kilograms per cubic meter

Step 3: Find Structural Support Volume

Vsr = (V4/3 * Apg0 * D) / (1000 * Thm)


  • Vsr = volume of structural mass needed to support spacecraft (m3)
  • V = volume of spacecraft (m3)
  • Apg0 = maximum acceleration of spacecraft (Terra gs)
  • D = density of spacecraft (ton/m3)
  • Thm = "toughness" of hull material. Hard steel = 2.86.
Step 4: Find Anti-Buckling Structural Volume

Vsb = (V1.15 * (Apg0 * D)0.453) / 300


  • Vsb = volume of structural mass needed avoid buckling (m3)
Step 5: Find Actual Volume

The actual volume Vs is equal to the larger of Vsr and Vsb.

(Note: Mr. Thrash informs me that an aeronautical engineer of his acquaintance is of the opinion that while the equation in step 4 works fine for a small rocket with a ten ton payload, the equation does not scale well if used for a larger rocket. The engineer is sure that Vsr will almost always be enough to resist buckling as well. In other words, just use Vsb = Vsr).

Step 6: Find Structural Mass

Mst = Vs * Dhm


  • Mst = spacecraft's structural mass (kg)
  • Vs = volume of structural mass (m3)
  • Dhm = density of hull material (kg/m3) (7,850 for steel, 4,507 for titanium, 1,738 for magnesium)
Step 7: Start Over from Step 1

Use the new value for Mst and start over. Repeat until the value for Mst stops changing (or you get tired).

When you have your final value for Mst, and M, use M to check and see if the spacecraft's mass ratio is still acceptable. If not, reduce the value for M~st and do some more iterations.

Now you know why rocket scientists use computers to do all the grunt work.

Remember that the mass of the propellant tanks will be approximately equal to full propellant mass times 0.15. The tank mass will be included in the structural mass, if the ship designer is not totally incompetent.

The shortcut is to stop at step seven, reduce M~st by Mst, and everything will add up.

Calculating Volume Of Existing Model

Figuring the hull volume of an existing design is a bit more tricky.

By way of example, a Russian Oscar-II submarine is an oval cylinder about 18 meters wide by 9 meters tall by 154 meters long. It has an internal volume of about 15,400 cubic meters. It has a density of about 0.9 metric tons per cubic meter, so it has a mass of about 15,400 x 0.9 = 13,900 metric tons.

There are equations for calculating the internal volume of various geometric shapes. What you have to do is approximate your spacecraft design using only these shapes. A sphere is easy. A classic cigar shape is sort of a cylinder with a cone on each end. You'll find a crude example of that here.

If your spacecraft is a complicated shape like the Starship Enterprise, you have a real problem.

If you have a physical model of your spacecraft, you can try estimating its displacement by caulking it water-tight, immersing it in a container of water, and measuring the water it displaces. Alternatively, fill a box with sand, dump the sand into measuring cups to measure the volume of sand, put the model in the box and fill it with sand, dump the sand out into measuring cups, and finally subtract the two volumes to discover the volume of the model.

Designing with CGI Modeling

Finally, you can hire a computer artist to use your blueprints to create a computer model in Lightwave then use the AreaVolume plug-in to determine the volume of the model.

Alternatively, you can proceed like graphic artist Myn.pheos, creating your mesh in the amazing free program Blender and using the 3D Printing Toolbox to calculate the volumes. Myn.pheos also has some techniques to find the center of gravity of various components, and to discover optimal placement of heat radiators.

The following tips are specific to the Blender software, but an artist skilled with another 3D computer modeling program could adapt the tips to their software. Myn.pheos is a native of Slovakia, and English is his second language. Myn.pheos:

Area and Volume

Guessing the volume of spacecraft isn't accurate in most cases. Boxy shapes aren't the most pleasing, and computing volume or area of curved surface by hand is tedious and hard. So the best approach is to let the computer [do the] work for you. In Blender, there is no build-in way to compute volume of objects. But there exist scripts than can do this. One of the is Quantities Bill by Yorik. It computes length, area or volume depending on the topology of mesh. If you have the shape of the spacecraft in your mind, let it pass the test. Roughly model the hull, propellant tank or crew compartment (it must be one object, with no holes in it) so you can get the volume. If you want to know the area of hull, simply remove the smallest face from the mesh and run the script. The figures aren't exact (this depends on how precisely you modelled the hull), but they are obtained fast, and it's easy to [re-calculate the figures if you alter the shape of the hull].

Where is the Center of Gravity?

This is easy to guess in case of homogeneous objects. But spaceships aren't that case. When you know the mass of spacecraft, rough location of components and their estimated weight, you can try to search for the center of gravity (COG). In Blender, it is possible to find the COG easily, just place vertexes in COG of each component. Decide the weight of each vertex, and then add as many as you'll need. Logically, the sum of them should be equal to total mass of ship. To get the COG, simply select all vertexes and make sure the pivot is set to Median point.

(ed note: in Blender, if the pivot control is set to "Median", when you select a group of vertexes the pivot control will automatically appear at the mathematical median point. Myn.pheos is saying that at the center of gravity of each component, place a number of vertexes proportional to that component's relative mass. Select all the COG vertexes of all the components, and the pivot control will indicate the COG of the spaceship as a whole. Keep in mind that the ship's axis of thrust must pass through the COG)

Where to place radiators?

That depends on the shape of the ship. If you have several spots where they look good, you can test the placement. This involves rendering the image and then using histogram to interpret the rendered result. First create two materials. For hull, create fully transparent material (Alpha = 0.0), with no specularity (Spec=0.0), don't forget to check the Ztransp button on. For radiator, use total white material (Col = R 1.00, G 1.00, B 1.00), with again without specularity (Spec=0). Make sure both receive all ambient colour (Amb = 1.0). Now to the environment settings. As background, use total black color (HoR = 0.0, HoG = 0.0, HoB = 0.0, ZoR = 0.0, ZoG = 0.0, ZoB = 0.0), and ambient perfect white (AoR = 1.0, AoG = 1.0, AoB = 1.0). Turn on Ambient Occlusion, make the Sub button pushed (so it darkens occluded spots), ensure that Energy is 1.0 and Plain button pushed.

Now only to set the camera (the best to be perpendicular to the radiator) and render.

Open the rendered image in an image editor. I use GIMP, but only the histogram is important. Now set the lower value in histogram to the lowest non-zero number (remember the pitch black background?), and read the statistical data. The most important is Mean value, this is the average value of all pixels on radiator. Divide this number by 255 to get the percentage of unoccluded area. There rest is probably heating up the ship, so change try with another radiator position.

This method has some weak points, but it is good enough for some decisions. The fully occluded pixels aren't taken into account, the precision increases with samples, the edges aren't treated well (they are not full white, if antialiasing is on).


I must say that I am very impressed with Myn.pheos' technique. I am reasonably skilled with Blender, but it never occurred to me that it could be used to find centers of gravity and optimal heat radiator placement. Myn.pheos is a genius.

Radiation Backscatter

A gentleman who goes by the handle Dogmatic Pyrrhonist (and TiktaalikDreaming) is a noted crafter of spacecraft mods for the simulation game Kerbal Space Program.

He decided to make a Gaseous-core Open-cycle nuclear thermal rocket mod for KSP. He is using Blender 3D as his modeling program.

He wanted to add some heat radiators (because GCR need lots of them), when he became aware of the dangers of neutron embrittlement, neutron activation, and radiation scattering. It seems that William Black was working on a similar project.

Dogmatic Pyrrhonist Backscatter 1

Dogmatic Pyrrhonist
     After shadow shields were brought up in William Black's feed regarding his work on a Gas Core Rocket, I had a good read about various things (mostly from Winchell Chung's Atomic Rocket pages, see
     Turns out my prior plan of wide-short expanding radiator panels would result in radiation scattering, eventual enbrittlement of the radiators, and basically cooking the crew with neutrons, and gamma rays. The radiator free, high thrust, low ISP edition had no such issue, and has a simple shadow shield in line now. But the high ISP needed a radiator rethink.
     I have a plan for the radiators, much like one of the pre-movie sketches of the Martian's Hermes on Atomic Rockets ( Basically a triangle type arrangement made from staggered rectangular panels that all fold away.
     That means a much longer frame to hold all that radiator. All of it, forward of the shadow shield.
     Anyway, WIP, this is the rocket, edition one of the shadow shield, and the frame structure. I'll be adding a final frame at the end to spread load onto a wider area. I'll be wanting that as a separate piece, as the KSP heat transfer systems don't include cooling fluid pumping, so the frame, rocket and radiators will all have extremely heat conductive values to mimic the working fluid. Which means I'll need one extra piece to be an insulator, to protect the rest of the craft from those 1390C radiators.

William Black
     This is looking great! I recall we had that conversation early on, when I described why the rectangular radiators arrayed around the nozzle would reflect radiation forward onto crew and vehicle, and so would definitely need to be forward of a radiation shadow shield, or did I have that discussion with Winchell Chung?
     The propulsion bus for my version is definitely an in-space assembly. I gathered (from yours or Winchell Chung's comments) that for KSP purposes it would need to be segmented and fold-away. 
     Oh, BTW, data sheet for 5% Borated Polyethylene here

Dogmatic Pyrrhonist
     William Black Yep, I remember all the reasons why you'd gone for the triangular shape. At first I was going to just dismiss the idea under the category of "Kerbals don't care". But then, I thought, I'd still like the thing to be real-world-sane, esp as I'm looking at doing some Realism-Overhaul conversions for some of the mods. So, while there's no mechanism in game to handle it, I have come around to thinking it should be arranged to at least mostly shield payload/crew.
     I roughed in a truncated triangle to get the surface area right for the radiators, and adjusted the shadow shield to match. I might need more than 51.5m of frame. :-/
     That's quite the shadow shield.
William Black
     Dogmatic Pyrrhonist, yeah, that's pretty much how I did it. I needed a 6.7 meter diameter shadow shield and wound up adding an additional 9.1 meters to my truss, two 3.0 meter sections between the shadow shield and the aft edge of the radiator and one 3.0 meter section between the forward edge and propellant tank. With the 29.8 by 10.01 meter propellant tanks for the 80 day Mars mission spacecraft that puts my crew module 12.4 meters past the 100 meter minimum separation between crew and nozzle.

(Then noted virtual production engineer Ron Fischer made a quiet but brilliant suggestion:)

Ron Fischer
     You can use lighting and shadows in your CG rendering program to analyze the shadowing of the shield. In fact, this is where the original math for lighting simulation came from: radiation studies on tanks in the 60s. Might as well go "Back to the Future" on that one! 

(You could almost see the light bulbs lighting up over each person's head.)

Dogmatic Pyrrhonist
     Ron Fischer I had not thought of that.

Winchell Chung
     Yes, what Ron Fischer said.
     I just remembered about somebody was using Blender to calculate spillover from heat radiators in their design
     Actually, some scientists did something similar to resolve the Pioneer Anomaly.

Dogmatic Pyrrhonist
     Dammit Winchell Chung , I've got enough tabs open in my browser already. :-)
     Initial ray casting adjustments, although I haven't checked yet if that's enough radiator. Nor whether it's still in shadow when rotated 45 or 90 degrees.

Winchell Chung
     Dogmatic Pyrrhonist You might have to simplify the model. First approximation with a light at the reaction chamber, the shadow shield, and the radiator.
     If you want to get into actually modeling the scatter, be my guest.

Dogmatic Pyrrhonist
     Winchell Chung Scatter is easy. Just place light sources at the outside edges of things that might scatter. I should disable rendering of things that would be basically transparent to neutrons or gammas, etc.
     oooo.... transparency. :-)

Dogmatic Pyrrhonist
     Oh dear, emissive, transparent, reflective shaders.

Winchell Chung
     Dogmatic Pyrrhonist Yes! That's the ticket! Radiation design by CGI mesh modeling. Hot stuff!

Ron Fischer
     Very cool Dogmatic Pyrrhonist Also, Winchell Chung I recommend requesting use of those for Atomic Rockets! Should illustrate the point nicely!
     Hey! I should suggest this to the good people making Kerbal. Could be a cool part of the design experience for nuclear spacecraft. 
     It is interesting to note that the cylinders which (I guess) are used to gimbal the engine get quite a strong dose. 

William Black
     Dogmatic Pyrrhonist and Winchell Chung I've found that you can optimize the shadow shield using this technique. I've found that a smaller shadow shield diameter is possible by adding truss segments between the shadow shield and the aft end of the radiator panels. Because the truss is lighter than the shadow shield, you realize a mass savings. 

From a thread on Google Plus (2015)
Dogmatic Pyrrhonist Backscatter 2

      I've been checking my rework of my gas core NTR for Kerbal Space Program regarding the shadow shield. Using 3d ray casting as it was originally intended.

     Each radiation emitter gets its own colour, so I can see what might be the cause of anything getting past the shield. Which is important, as there's a world of difference between active fission cores and a bit of stored uranium. Most of the non emitting structure uses a rough translucent blender material so it can scatter, emulating, well, scatter, and re-emission. The shadow shield itself I did as a reflective opaque, although that isn't quite true. It's reflective to high energy electromagnetic (gamma), but absorbent to neutrons. Above the shadow shield though, are the uranium tanks. And although they themselves are emitting neutrons and other things, you really really don't want them getting hit with bonus neutrons. There's also the tungsten dust tanks, and as that exists to absorb, I used an opaque material for them, although the radiation they're collecting, it didn't make a big difference.

     Looking up past the plume (volume emitter material) there's a faint blue tinge for the plume's emission on the structural ring around the top. I'm mostly ok with that because from last time I did this it became apparent there's absolutely no way to prevent all the radiation from the plume. You can minimise, but not remove. And why am I checking the radiation from the plume? This is a model of an open cycle gas core reactor nuclear thermal rocket, so the exhaust has fission fuel and products in it. As little as you can engineer, but likely something like 1%

     Anyway, now almost a Kerbal Space Program mod. Still needs a better plume and several square km of radiator (slight exaggeration)

From a thread on Twitter (2019)

Meanwhile William Black was already hard at work on a GCR. He is also using Blender 3D.

When William Black read Ron Fischer's brilliant suggestion, he quote "found this to be a compelling proposition, an opportunity to test out the validity of my design" unquote.

William Black Backscatter 1

      I found this to be a compelling proposition, an opportunity to test out the validity of my design.
     Dogmatic Pyrrhonist and I both set about individually setting up a radiation simulation by CG lighting; his results are to be found at links in this thread November 6, 2015
     Initially, for purposes of approximation, I used a cone, which you strip out of the scene once it has served its purpose, this is used to insure the radiators panels (and everything else forward of the shadow shield) are completely within the shadow region. It is a matter of placing the cone so to intersect the aft-most edge of the radiation shadow shield, if all components forward of the shadow shield are properly placed nothing should protrude through the surface of the cone.
     I realized the technique can be used not only to optimize the shadow shield in terms of placement, but also in terms of diameter. Previously, using the cone I had realized that increasing the distance between the aft edge of the radiator panels and shadow shield allows a smaller diameter shadow shield. Using this technique allowed me to test that theory, and it in fact worked exactly as anticipated. Truss segments mass less than the 5% Borated Polyethylene of the shadow shield, so there is a savings on structural mass, which is important because, as we all know, every gram counts.
     I rendered the scene against a gray background, then a second time against a completely black background.
     I made an attempt (which may be laughable) to model the plume. I used a bright blue emission shader. I was curious in regards to how much blue emission, representing radiation from the plume, would show up on the structure of the vehicle. Lacking data on the physical characteristics of plume expansion immediately after leaving the nozzle, this may be an insufficient test, so I’m not sure this adds anything, but darn, it looks nifty.
     Ron Fischer suggested I attempt this again with volumetric lighting, and I intend to do so at a future date.

From William Black (2015)

Physicist Luke Campbell had some additional suggestions:

     You might want to check for radiation scatter from the rocket bell to the radiators. You could make the entire structure aft of the shadow shield glow, make the shadow shield 100% black, make the spacecraft fore of the shadow shield white, and then look at the craft from the back to see if the edges of the radiators are illuminated. If they are, neutrons and gamma rays emitted from the reactor can scatter off the rocket bell (say), bypass the shadow shield, scatter off the radiator, and make their way to the payload/crew/control electronics/whatever. Just eyeballing it, it looks like that could happen.
     Also, from the linked post describing the design — you probably will want a few centimeters of lead fore of the borated polyethylene, for sopping up the gamma rays. The set of materials that are good at stopping neutrons seems to be orthogonal to the set of materials that are good at stopping gamma rays. By putting the poly between the reactor and the lead, you arrange it so that gamma rays produced by neutron interactions in the poly are also blocked by the lead part of the shield.

From Luke Campbell (2015)

     Physicist Luke Campbell examined my Blender radiation simulation and suggested some modifications which might test the model more rigorously.
     Following his suggestion I applied emission shaders to everything on the “hot” side of the shadow shield, so, rather than just the gas core reactor, this now includes all structure (truss, engine gimbals and supports) and all LH2, Helium coolant lines, and turbine pumps and associated plumbing including the turbine exhaust, and of course the expansion nozzle.
     I applied a flat non-reflective black shader to the shadow shield, and applied a white shader to all structure on the “safe” side of the shadow shield (truss, radiator panels and heat exchanger housings, tensioning cable, cable rigging, LH2 and Helium coolant lines).
     Changes in place, I ran the radiation simulation again. As you can see from the top image the simulation revealed that radiation was in fact impinging on the aft outer corners of the radiator panels and the tensioning cables, a fact not visible in my previous simulation.
     This means radiation would travel along these parts of the vehicle, turning them into additional sources of radiation, damaging the radiator system and vehicle structure via radiation embrittlement, damaging control and electrical systems, and it means radiation would scatter from these points onto the rest of the vehicle posing a hazard to the crew.
     I added truss segments and increased the diameter of the radiation shadow shield, running the simulation after each configuration change, till I arrived at a good result, which you can see in the second image down.
     The lower two images are non-rendered screen captures of the same area of the model, the aft-most portion of the propulsion bus. Before structural modifications on the Left, and the final optimized configuration, on the Right.

From William Black (2015)

Pioneer Anomaly

Something like Myn.pheos technique for placing heat radiators was used to solve the mystery of the Pioneer Anomaly. The trajectory of space probes in general and the Pioneer probes in particular should follow precisely Newton's Laws of Motion. Once you've accounted for all the extra factors, of course. So scientists were quite upset when the probes started to gradually diverge from their calculated trajectory. There are all sorts of proposed explanations, ranging from observational errors to new laws of physics.

Dr. Frederico Francisco (Instituto Superior Técnico, Lisbon) and colleagues believe they have the answer. Others have tried and found wanting the hypothesis that heat radiated from the probes could be the culprit. But Dr. Francisco et al submit that this is because the radiation mathematical models are too simplistic. Using the 3D CGI rendering technique known as "Phong shading", they have shown this will account for the Pioneer Anomaly. Phong shading takes into account not just the heat radiated, but the heat that hits parts of the probe's structure and is reflected from it.

As you can see, this is very similar to the technique used by Myn.pheos.


Figuring the surface area of a spacecraft is about the same level of difficulty as figuring the internal volume. The same techniques apply: approximate the spacecraft as a series of easy to calculate shapes, or use a CGI package that can calculate it for you.

Usually it isn't worth the bother unless you are trying to figure the mass of the armor required for a warship. Or you worry if there is enough space on the hull to place all the stuff you want to put.

Some other bits of dynamic tension for you.

Surface area goes up at a square function, volume at a cubic function. Everything fights for surface area on the hull of the ship — if you want more weapons, you need surface area to mount them. If you want sensors or radiators, ditto. Don't forget docking ports, fuel tank hookups, and everything else you'll want. If you're using plausible engines with thrusts rated in double digit milligees (as opposed to the over-the-top engines I use for Attack Vector: Tactical), it's more and more likely that your ship will look like a fusion torch with a christmas tree that's been well and truly loved by a cat on top of it. :)

The lesser your surface area for a given volume, the less armor you need for a given rate of protection. For a generalized case, most internal components can, as Rick likes to point out, be approximated by aircraft parts for unit density. (Surface naval ships range from average density of 0.35 to 0.65 for some of the fully loaded WWII battleships, aircraft range from 0.2 to about 0.4).

Perhaps, to minimize the hazards of radiation, they use structural osmium for the hull? :)

One side effect of this wide range of masses for hulls is that for a given constant K (drive output in terawatts), the frigate is going to have 1/5 the thrust of the corvette, and the cruiser will have 1/25th the thrust of the corvette. (if two ships have the same engine output, the one with more mass will have a lower acceleration) That's a wide enough disparity that the setup is probably ungameable, and may prove problematic for novels. (This sort of disparity is why freighters in the Ten Worlds aren't sitting ducks. They're sitting ducks with two broken wings and both feet stapled to a stump, painted bright flourescent orange.)

When dealing with kinetics, that disparity of thrust really changes the available defenses and offensive capabilities. Fuel on the launch platform is a weapon, and the target's evasion parameter is set by how much thrust it can generate in a unit of time.

From Ken Burnside (2008)



The traveling-public gripes at the lack of direct Earth-to-Moon service, but it takes three types of rocket ships and two space-station changes to make a fiddling quarter-million-mile jump for a good reason: Money. The Commerce Commission has set the charges for the present three-stage lift from here to the Moon at thirty dollars a pound. Would direct service be cheaper?

A ship designed to blast off from Earth, make an airless landing on the Moon, return and make an atmosphere landing, would be so cluttered up with heavy special equipment used only once in the trip that it could not show a profit at a thousand dollars a pound! Imagine combining a ferry boat, a subway train, and an express elevator.

So Trans-Lunar uses rockets braced for catapulting, and winged for landing on return to Earth to make the terrific lift from Earth to our satellite station Supra-New York.

The long middle lap, from there to where Space Terminal circles the Moon, calls for comfort—but no landing gear. The Flying Dutchman and the Philip Nolan never land; they were even assembled in space, and they resemble winged rockets like the Skysprite and the Firefly as little as a Pullman train resembles a parachute.

The Moonbat and the Gremlin are good only for the jump from Space Terminal down to Luna . . . no wings, cocoon-like acceleration-and-crash hammocks, fractional controls on their enormous jets.

From SPACE JOCKEY by Robert Heinlein (1947)

The British Interplanetary Society (BIS) in general, and Sir Arthur C. Clarke in particular figured that there were three main types of spacecraft needed for the exploration of space: Space Ferry, Orbit-to-Orbit, and Airless Lander. Each is optimized for their own particular area of use.

More recently, orbital propellant depots and their related tanker ships also seem like a good piece of infrastructure. There are some sample realistic designs here, here, here, here and here. Not to mention here and here.

However, space warships are an entirely different kettle of fish.

More facetiously:


Warfare in the densely-populated Gilgamesh Cluster is almost incessant, and befitting their way of life. Gilgamite civilization has developed inexpensive and highly efficient spaceships. Vector One ships convey materials from planetary surfaces to orbit. Vector Two ships transport material between planets of a stellar system. And Vector Three ships range through the interstellar lanes.

Vector Three ships, comprising a central cylinder and detachable cargo and cabin pods, are more than simple transports, however. When war threatens, the merchant marine is recalled, the cargo pods are removed, and weapon pods are installed. Within months, an interstellar fleet can be converted from merchant-men to men-of-war.

(ed note:
Vector One ships travel in one dimension: the altitude from the planetary surface.
Vector Two ships travel in two dimensions: the two dimensional plane of the stellar system's ecliptic.
Vector Three ships travel in three dimensions: the three dimensional volume of interstellar space.)
From VECTOR 3 tabletop wargame by Greg Costikyan (1979)

“Since the days of Charan Rashuri, commander of Pride of Earth, it has been the ship commander’s obligation to recognize a moment of transition for those among his crew new to the Survey branch,” Neale began.

“I have no doubt that some among you have invested the outcrossing with far more meaning than it deserves. It is an occasion for the exchange of theater insignia. You give up the blue Orbital or yellow System ellipse you now wear. You receive the black Intersystem ellipse. But the difference in color is meaningless in itself.”

Then why do you vets call us lessers? Thackery wondered, fingering his own System insignia absently.

“Contrary to what many of you believe, this is not a promotion. The Service does not honor you by doing this. All we do here today is to mark the beginning of an opportunity for honor—honor you will have to bring to yourself in the months and years ahead. You wear the black ellipse, but you have not yet earned it.”

From ENIGMA by Michael Kube-McDowell (1986)

Type: Space Ferry

The space ferry concept is what evolved into the NASA space shuttle. Its function is to boost payload into orbit, though you can think of it as an "atmospheric lander." Refer to the section on Surface To Orbit.

These are sometimes called "interface vehicles" because their function is to transport payload through the interface boundary between Terra's atmosphere and airless space.

The idea was to re-use as much of the rocket as possible, which is why the upper section has wings and the lower stages had parachutes. In Robert Heinlein's Space Cadet, the rocket is launched from a rocket sled going up the side of Pike's Peak. Nuclear powered rockets could boost more massive payloads, but a space elevator could boost so much more cheaply and efficiently.

Hop Davis estimates that space ferries launching from Terra will require a delta-V budget of around 10 kilometers per second (with orbital propellant depot) and require a thick atmosphere for aerobraking. It will require a bit more if there is no orbital depot, but not much more because coming down it uses aerobraking instead of propellant. The delta-V budget means they will probably have to be multi-stage if they are chemical rockets (good luck getting permission to use nuclear rockets). They will require a propulsion system with a thrust-to-weight ratio above 1.0.

Type: Orbit-to-Orbit

Orbit-to-orbit spacecraft never land on any planet, moon, or asteroid.

Therefore they are free to use efficient propulsion systems with a thrust-to-weight ratio below 1.0, such as ion drives or VASIMR. They require no landing gear or parachutes. If there ain't no landing gear, it is an orbit-to-orbit. No streamlining is required either. They require no ablative heat shields unless they are designed to perform aerobraking to burn off delta-V without requiring propellant (like the Leonov in the movie 2010 The Year We Make Contact).

Hop Davis estimates that a orbit-to-orbit spacecraft will require a delta-V budget of only 3 to 4 kilometers per second, if orbital propellant depot are available. Otherwise it will be twice that, with along with a dramatic reduction in payload capacity. 4 km/s is well within the capabilities of a chemical rocket, but any higher and you will probably need staging or a propulsion system with more exhaust velocity.

The old image of orbit-to-orbit ships look like dumb-bells, the front ball is the cargo and habitat module, the rear is the propellant and radioactive atomic drive. The stick in between is a way to substitute distance for lead radiation shielding.

The Basic Solid Core NTR or Reusable Nuclear Shuttle would make admirable backbones for an orbit-to-orbit spacecraft. Liquid hydrogen propellant and fissionables for fuel.


A ferry service of chemically-fuelled rockets linked the station to the planet beneath, for by law no atomic drive unit was allowed to operate within a thousand kilometres of the Earth’s surface. Even this safety margin was felt by many to be inadequate, for the radioactive blast of a nuclear propulsion unit could cover that distance in less than a minute.

(ed note: this implies an exhaust velocity of about 16,000 meters per second. This could be done by a liquid or gas core nuclear thermal rocket with molecular hydrogen propellant, or a solid-core nuclear thermal rocket using atomic hydrogen as propellant.)

And the third, of course, was the Ares, almost dazzling in the splendour of her new aluminium paint.

Gibson had never become reconciled to the loss of the sleek, steamlined spaceships which had been the dream of the early twentieth century. The glittering dumb-bell hanging against the stars was not his idea of a space-liner; though the world had accepted it, he had not. Of course, he knew the familiar arguments——there was no need for streamlining in a ship that never entered an atmosphere, and therefore the design was dictated purely by structural and power-plant considerations. Since the violently radioactive drive-unit had to be as far away from the crew quarters as possible, the double-sphere and long connecting tube was the simplest solution.

It was also, Gibson thought, the ugliest; but that hardly mattered since the Ares would spend practically all her life in deep space where the only spectators were the stars. Presumably she was already fuelled and merely waiting for the precisely calculated moment when her motors would burst into life, and she would pull away out of the orbit in which she was circling and had hitherto spent all her existence, to swing into the long hyperbola that led to Mars.

(ed note: the Ares can travel from Terra to Mars in three months flat.)

“Five seconds, four, three, two, one”

Very gently, something took hold of Gibson and slid him down the curving side of the porthole-studded wall on to what had suddenly become the floor. It was hard to realise that up and down had returned once more, harder still to connect their reappearance with that distant, attenuated thunder that had broken in upon the silence of the ship. Far away in the second sphere that was the other half of the Ares, in that mysterious, forbidden world of dying atoms and automatic machines which no man could ever enter and live, the forces that powered the stars themselves were being unleashed. Yet there was none of that sense of mounting, pitiless acceleration that always accompanies the take-off of a chemically propelled rocket.

The Ares had unlimited space in which to manoeuvre; she could take as long as she pleased to break free from her present orbit and crawl slowly out into the transfer hyperbola that would lead her to Mars. In any case, the utmost power of the atomic drive could move her two-thousand-ton mass with an acceleration of only a tenth of a gravity; at the moment it was throttled back to less than half of this small value.

(ed note: implies thrust of 1.962×106 Newtons, about 2 megaNewtons)

When Space Station One had vanished completely, Gibson went round to the day side of the ship to take some photographs of the receding Earth. It was a huge, thin crescent when he first saw it, far too large for the eye to take in at a single glance. As he watched, he could see that it was slowly waxing, for the Ares must make at least one more circuit before she could break away and spiral out towards Mars.

Gibson was still watching at the observation post when, more than an hour later, the Ares finally reached escape velocity and was free from Earth. There was no way of telling that this moment had come and passed, for Earth still dominated the sky and the motors still maintained their muffled, distant thunder. Another ten hours of continuous operation would be needed before they had completed their task and could be closed down for the rest of the voyage.

(ed note: one-half of a tenth of a gravity of acceleration is 0.4905 m/s2
One hour is 3,600 seconds.
0.4905×3,600 = 1,765 m/s, which is about Low Earth Orbit escape velocity of 1,800 m/s.
1+10 hours = 39,600 seconds.
0.4905×39,600 = 19,423 m/s, which is very short of solar escape velocity of 525,000 m/s
but which is impressively larger than the Terra-Mars Hohmann delta V of 5,590 m/s.
Terra-Mars Hohmann takes about 8 months, 26,000 m/s will get you to Mars in 1 month, so I guess 19,423 m/s getting you to Mars in three months sounds reasonable.
Delta V of 19,423 m/s and exhaust velocity of 16,000 m/s implies a mass ratio of 3.4, which is large but not unreasonable.
Keeping in mind that more delta V will be required for Mars capture.)

It was impossible to believe that the Ares was now racing out from the Earth’s orbit at a speed so great that even the Sun could never hold her back.

As the ship was spherical, it had been divided into zones of latitude like the Earth. The resulting nomenclature was very useful, since it at once gave a mental picture of the liner’s geography. To go “North” meant that one was heading for the control cabin and the crew’s quarters. A trip to the Equator suggested that one was visiting either the great dining-hall occupying most of the central plane of the ship, or the observation gallery which completely encircled the liner. The Southern hemisphere was almost entirely fuel tank, with a few storage holds and miscellaneous machinery. Now that the Ares was no longer using her motors, she had been swung round in space so that the Northern Hemisphere was in perpetual sunlight and the “uninhabited” Southern one in darkness. At the South Pole itself was a small metal door bearing a set of impressive official seals and the notice: “To be Opened only under the Express Orders of the Captain or his Deputy.” Behind it lay the long, narrow tube connecting the main body of the ship with the smaller sphere, a hundred metres away, which held the power plant and drive units. Gibson wondered what was the point of having a door at all if no one could ever go through it; then he remembered that there must be some provision to enable the servicing robots of the Atomic Energy Commission to reach their work.

Strangely enough, Gibson received one of his strongest impressions not from the scientific and technical wonders of the ship, which he had expected to see in any case, but from the empty passenger quarters— — a honeycomb of closely packed cells that occupied most of the North Temperate Zone.

From THE SANDS OF MARS by Sir Arthur C. Clarke (1951)

The hold was a large hemispherical room with a thick central column which carried the controls and cabling to the other half of the dumb-bell-shaped spaceship a hundred metres away. It was packed with crates and boxes arranged in a surrealistic three-dimensional array that made very few concessions to gravity.

Anything more unlike the early-twentieth-century idea of a spaceship than the Star Queen would be hard to imagine. She consisted of two spheres, one fifty and the other twenty metres in diameter, joined by a cylinder about a hundred metres long. The whole structure looked like a matchstick-and-plasticine model of a hydrogen atom. Crew, cargo and controls were in the larger sphere, while the smaller one held the atomic motors and was — to put it mildly — out of bounds to living matter.

The Star Queen had been built in space and could never have lifted herself even from the surface of the Moon. Under full power her ion drive could produce an acceleration of a twentieth of a gravity, which in an hour would give her all the velocity she needed to change from a satellite of the Earth to one of Venus.

Hauling cargo up from the planets was the job of the powerful little chemical rockets. In a month the tugs would be climbing up from Venus to meet her

From "BREAKING STRAIN" by Arthur C. Clarke (1949)

Space travel had never been inexpensive, but early in the century an economic watershed had been crossed, like a saddle in low hills that nevertheless marks a continental divide. Nuclear technology moved into its most appropriate sphere, outer space; the principles were sufficiently simple and the techniques sufficiently easy to master that private companies could afford to enter the interplanetary shipping market. With the shippers came the yards, the drydocks, the outfitters.

The Falaron shipyards, one of the originals, orbited Earth two hundred and fifty miles up. Presently the only vessel in the yards was an old atomic freighter, getting an overhaul and a face lift—a new reactor core, new main engine nozzles, refurbished life-support systems, new paint inside and out. When all the work was done the ship was to be recommissioned and given a new, rather grand, name: Star Queen.

The huge atomic engines had been mounted and tested. Spacesuited workers wielding plasma torches were fitting new holds, big cylinders that fastened to the thin central shaft of the ship below the spherical crew module.

Star Queen, though of a standard freighter design, was a spacecraft quite unlike anything that had been imagined at the dawn of modern rocketry—which is to say it looked nothing like an artillery shell with fins or the hood ornament of a gasoline-burning automobile. The basic configuration was two clusters of spheres and cylinders separated from each other by a cylindrical strut a hundred meters long. The whole thing somewhat resembled a Tinkertoy model of a simple molecule. The forward cluster included the crew module, a sphere over five meters in diameter. A hemispherical cage of superconducting wires looped over the crew module, partially shielding the crew against cosmic rays and other charged particles in the interplanetary medium—which included the exhaust of other atomic ships. Snugged against the crew module's base were the four cylindrical holds, each seven meters across and twenty meters long, grouped around the central strut. Like the sea-land cargo containers of the previous century, the holds were detachable and could be parked in orbit or picked up as needed; each was attached to Star Queen's central shaft by its own airlock and was also accessible through outside pressure hatches. Each hold was divided into compartments which could be pressurized or left in vacuum, depending on the nature of the cargo.

At the other end of the ship's central strut were bulbous tanks of liquid hydrogen, surrounding the bulky cylinder of the atomic motor's reactor core. Despite massive radiation shielding, the aft of the ship was not a place for casual visits by living creatures—robot systems did what work needed to be done there.

For all its ad hoc practicality. Star Queen had an air of elegance, the elegance of form following function. Apart from the occasional horn of a maneuvering rocket or the spike or dish of a communications antenna, the shapes from which she had been assem­bled shared a geometric purity, and all alike shone dazzling white under their fresh coats of electro-bonded paint.

Two days later heavy tugs moved Star Queen into launch orbit, beyond the Van Allen belts. The atomic motor erupted in a stream of white light. Under steady acceleration the ship began a five-week hyperbolic dive toward Venus.

Still, things might have been worse. Star Queen was fourteen days into her trajectory and had twenty-one days still to go to reach Port Hesperus. Thanks to her upgraded engines she was travelling much faster than the slow freighters, the tramp steamers of the space-ways who were restricted to Hohmann ellipses, those long tangential flight paths that expended minimum energy by just kissing the orbits of Earth and Venus on opposite sides of the sun. Passenger ships equipped with even more powerful gaseous-core reactors, or fast cutters using the still-new fusion drives, could slice across from planet to planet in as little as a fortnight (2 weeks), given favorable planetary alignments—and given a profit margin that allowed them to spend an order of magnitude more on fuel—but Star Queen was stuck in the middle of the equation. Her optimal acceleration and deceleration determined both her launch window and her time of arrival.

Type: Airless Lander

These are designed for landing on bodies that have no atmosphere, but you probably could get away with using them on Mars. They evolved into NASA's Apollo Lunar Module. So they will require some sort of landing gear. But no streamlining. They will require a propulsion system with a thrust-to-weight ratio near 1.0, depending on the surface gravity of the bodies they are designed to land on. This probably means chemical propulsion, maybe a solid-core NTR. Hop Davis estimates that airless lander spacecraft will require a delta-V budget of around 5 kilometers per second if orbital and surface propellant depots are available. Otherwise it will be twice that, with along with a dramatic reduction in payload capacity.

For sample designs, go to the Lander page.

Type: Shuttlecraft

So the smart way to design is to use an orbit-to-orbit spacecraft to travel between planets, and at a planetary destination use locally based surface-to-orbit services: either a space ferry, airless lander or surface-to-orbit installation at a spaceport.

But what if there are no locally available surface-to-orbit services? If NASA dispatches a Mars mission, there ain't no Martian space shuttles to ferry the crew down to the surface.

Making the entire spacecraft land-able is often a bad idea. For one, optimizing a spacecraft for both orbit-to-orbit and surface-to-orbit operations will probably result in an inefficient ship with the disadvantages of both and the advantages of neither. If you are designing with a weak propulsion system, it might not even be possible. And even if your propulsion system is up to the task, often it is better to park your ticket home in orbit where it is safe while other means are used to send crew into a possibly dangerous situation.

The standard solution is for the main spacecraft to carry small auxiliary spacecraft as landers, either aerodynamic space ferries or airless landers. The popular term from Star Trek is "Shuttlecraft".

A large space ferry shuttlescraft on modestly sized orbit-to-orbit spacecraft can make the ship look like an arrow.

The traveling-public gripes at the lack of direct Earth-to-Moon service, but it takes three types of rocket ships and two space-station changes to make a fiddling quarter-million-mile jump for a good reason: Money.

The Commerce Commission has set the charges for the present three-stage lift from here to the Moon at thirty dollars a pound. Would direct service be cheaper? A ship designed to blast off from Earth, make an airless landing on the Moon, return and make an atmosphere landing, would be so cluttered up with heavy special equipment used only once in the trip that it could not show a profit at a thousand dollars a pound! Imagine combining a ferry boat, a subway train, and an express elevator. So Trans-Lunar uses rockets braced for catapulting, and winged for landing on return to Earth to make the terrific lift from Earth to our satellite station Supra-New York. The long middle lap, from there to where Space Terminal circles the Moon, calls for comfort-but no landing gear. The Flying Dutchman and the Philip Nolan never land; they were even assembled in space, and they resemble winged rockets like the Skysprite and the Firefly as little as a Pullman train resembles a parachute.

The Moonbat and the Gremlin are good only for the jump from Space Terminal down to Luna . . . no wings, cocoon-like acceleration-and-crash hammocks, fractional controls on their enormous jets.

From SPACE JOCKEY by Robert Heinlein (1947)

Type: Tanker

Many aerospace engineers have pointed out that all of these spacecraft can be far more cheap and efficient if there were orbital depots of propellant and/or fuel established in various strategic locations where space travel is desired. This will necessitate some sort of tanker-type spacecraft to keep the depots supplied. They will be a species of orbit-to-orbit spacecraft optimized to carry huge amounts of propellant, and hopefully be unmanned drones or robot controlled. They can use an efficient propulsion system with thrust-to-weight ration below 1.0, ion or VASIMR. Like standard orbit-to-orbit, probably a delta-V budget of 4 km/sec, unless they are in a real hurry.

There will also be a species of airless lander optimized to carry propellant to planetary based depots, this is called a "lighter". As all landers the propulsion thrust to weight ratio will have to be near 1.0, probably chemical propulsion. As standard airless lander, probably a delta-V budget of 5 km/sec. The lighter will probably be designed to land a single modular tank from the cluster carried by the tanker.

Examples of tankers include Dr. Parkinson's Lighter and Tanker, Kuck Mosquitos, Zuppero Water Ships, and Zuppero Lunar Water Trucks.

Type: Tug

Space Taxis, Space Pods, and Space Tugs are covered in the Spacesuit section.

Type: Cargo Ship

(ed note: The Cargo ship section is quite long, click the Hide button if you want to skip over this section)

If spacecraft actually lands on a planet it may be a belly-lander instead of a tail-sitter, for ease of cargo loading/unloading. Otherwise it is like unloading cargo from the 25th floor window of a skyscraper.

Conventional cargo spacecraft have a conventional ship arrangement: a rocket engine aft of a cargo hold. You know, like pretty much every rocket you've ever seen: engines on the bottom.

The hold is an enclosed area to store cargo in, sections of which may or may not be pressurized. Unpressurized sections are for cheaper storage of inert durable cargo, e.g., raw ore. Pressurized sections are more expensive storage for delicate cargo that can be easily ruined by temperature and pressure extremes, e.g., produce and live animals.

The cargo hold may be rigged with attachment points for cargo containers. The hatches may be such to allow accessing individual containers. Alternatively the hold might be basically a huge tank. This is used for bulk cargo: liquids, gases, asteroid ore dust or gravel, grain, etc.

Cargo spacecraft might not bother with an enclosed area at all. Instead cargo containers are carried on the outside of spacecraft, attached to the ship's spine.

Unconventional cargo spacecraft have the rocket engine before the cargo hold. The engines are on the top.

This uses a waterskiing arrangement, with the engine and everything acting like a waterbound motorboat, dragging the cargo behind like a water skier. The rocket exhaust is angled such that it doesn't incinerate the cargo (but angled just barely enough to minimize thrust cosine loss). If the spacecraft carries relatively few cargo cans it is a Space Truck. If it carries long strings of cargo cans it is a Space Train. Yes, the boundary between a truck and a train is totally arbitrary.

Conventional cargo spacecraft may or may not be capable of landing on a planet (airless or with atmosphere). If the cargo ship cannot land and the local infrastructure is primitive, the cargo ship may have to carry landing shuttles to ferry cargo to and from the surface. If the local infrastructure is advanced, the ship can rent shuttle services from the local spaceport.

Unconventional cargo spacecraft are highly unlikely to be capable of landing at all. Certainly not if the planet has an atmosphere.

Cargo Containers

For transporting huge amounts of cargo, a safe bet is that the space industries will settle on a standard cargo container size. Because in the real world this lead to the miracle of Containerization. Which transformed global trade and built, nay even changed the world.

They would allow standardized design of cargo holds, they work well with space trucks and space trains, heck they work well as inert cargo vessels. Surface to Orbit services would probably be optimized to accommodate standard cargo container form factors.

Each of the eight corners contains a twistlock to bolt them to the cargo bay floor or for stacking. Shipping containers for valuable cargo often include burglar alarms.

Standarized cargo containers would become ubiquitous and cheap enough to find secondary markets for just the empty containers.

In the real world there are DIY people who alter shipping containers into inexpensive houses. In a RocketPunk future such containers can be tansformed into crude habitat modules by adding a few incidentals (plugging leaks, a bare bones life-support system, an airlock). Add some engines and you have a scratch-built spacecraft. Ikea in Space will probably offer inexpensive habitat modules based on shipping containers.

A new interstellar space colony on a shirt-sleeve habitable planet might bring along a commercial Farm From A Box to jump-start their agricultural self-sufficiency. Everything you need for a quick farm, neatly packed inside a shipping container. It's a kit!

Other "kits" mounted inside shipping containers include water treatment plants and electrical power generators. The military has shipping container kits containing medical surgery theaters, command and control facilities, and missile launchers.

And science fiction authors looking for an interesting (comments) background situation for their novel can pick up a few hints by doing a web search for news containing the search term "cargo container."

Eric Tolle was of the opinion that hexagonal cargo containers would probably be for bulk dry goods, Liquids would would best in cylinders or spheres, and containerized shipping would be best in rectangular cargo pods.



An intermodal container is a large standardized shipping container, designed and built for intermodal freight transport, meaning these containers can be used across different modes of transport – from ship to rail to truck – without unloading and reloading their cargo. Intermodal containers are primarily used to store and transport materials and products efficiently and securely in the global containerized intermodal freight transport system, but smaller numbers are in regional use as well. These containers are known under a number of names, such as simply container, cargo or freight container, ISO container, shipping, sea or ocean container, sea van or (Conex) box, sea can or c can.

Intermodal containers exist in many types and a number of standardized sizes, but ninety percent of the global container fleet are so-called "dry freight" or "general purpose" containers, durable closed steel boxes, mostly of either twenty or forty feet (6.1 or 12.2 m) standard length. The common heights are 8 feet 6 inches (2.6 m) and 9 feet 6 inches (2.9 m) – the latter are known as High Cube or Hi-Cube containers.

Just like cardboard boxes and pallets, these containers are a means to bundle cargo and goods into larger, unitized loads, that can be easily handled, moved, and stacked, and that will pack tightly in a ship or yard. Intermodal containers share a number of key construction features to withstand the stresses of intermodal shipping, to facilitate their handling and to allow stacking, as well as being identifiable through their individual, unique ISO 6346 reporting mark.

In 2012, there were about 20.5 million intermodal containers in the world of varying types to suit different cargoes. Containers have largely supplanted the traditional break bulk cargo – in 2010 containers accounted for 60% of the world's seaborne trade. The predominant alternative methods of transport carry bulk cargo – whether gaseous, liquid or solid – e.g. by bulk carrier or tank ship, tank car or truck. For air freight, the lighter weight IATA-defined unit load device is used.

Ninety percent of the global container fleet consists of "dry freight" or "general purpose" containers – both of standard and special sizes. And although lengths of containers vary from 8 to 56 feet (2.4 to 17.1 m), according to two 2012 container census reports about 80% of the world's containers are either twenty or forty foot standard length boxes of the dry freight design. These typical containers are rectangular, closed box models, with doors fitted at one end, and made of corrugated weathering steel (commonly known as CorTen) with a plywood floor. Although corrugating the sheet metal used for the sides and roof contributes significantly to the container's rigidity and stacking strength, just like in corrugated iron or in cardboard boxes, the corrugated sides cause aerodynamic drag, and up to 10% fuel economy loss in road or rail transport, compared to smooth-sided vans.

Standard containers are 8-foot (2.44 m) wide by 8 ft 6 in (2.59 m) high, although the taller "High Cube" or "hi-cube" units measuring 9 feet 6 inches (2.90 m) have become very common in recent years. By the end of 2013, high-cube 40 ft containers represented almost 50% of the world's maritime container fleet, according to Drewry's Container Census report.

About 90% of the world's containers are either nominal 20-foot (6.1 m) or 40-foot (12.2 m) long, although the United States and Canada also use longer units of 45 ft (13.7 m), 48 ft (14.6 m) and 53 ft (16.15 m). ISO containers have castings with openings for twistlock fasteners at each of the eight corners, to allow gripping the box from above, below, or the side, and they can be stacked up to ten units high. Regional intermodal containers, such as European and U.S. domestic units however, are mainly transported by road and rail, and can frequently only be stacked up to three laden units high. Although the two ends are quite rigid, containers flex somewhat during transport.

Container capacity is often expressed in twenty-foot equivalent units (TEU, or sometimes teu). A twenty-foot equivalent unit is a measure of containerized cargo capacity equal to one standard 20-foot (6.1 m) long container. This is an approximate measure, wherein the height of the box is not considered. For example, the 9 ft 6 in (2.9 m) tall high-cube, as well as 4-foot-3-inch half-height (1.3 m) 20-foot (6.1 m) containers are equally counted as one TEU. Similarly, extra long 45 ft (13.72 m) containers are commonly designated as two TEU, no different than standard 40 feet (12.19 m) long units. Two TEU are equivalent to one forty-foot equivalent unit (FEU).

In 2014 the global container fleet grew to a volume of 36.6 million TEU, based on Drewry Shipping Consultants' Container Census. Moreover, in 2014 for the first time in history 40-foot High cube containers accounted for the majority of boxes in service, measured in TEU.

Manufacturing prices for regular, dry freight containers are typically in the range of $1750—$2000 U.S. per CEU (container equivalent unit), and about 90% of the world's containers are made in China. The average age of the global container fleet was a little over 5 years from end 1994 to end 2009, meaning containers remain in shipping use for well over 10 years


Other than the standard, general purpose container, many variations exist for use with different cargoes. The most prominent of these are refrigerated containers (a.k.a. reefers) for perishable goods, that make up six percent of the world's shipping boxes. And tanks in a frame, for bulk liquids, account for another 0.75% of the global container fleet.

Although these variations are not of the standard type, they mostly are ISO standard containers – in fact the ISO 6346 standard classifies a broad spectrum of container types in great detail. Aside from different size options, the most important container types are:

  • General-purpose dry vans, for boxes, cartons, cases, sacks, bales, pallets, drums, etc., Special interior layouts are known, such as:
    • rolling-floor containers, for difficult-to-handle cargo
    • garmentainers, for shipping garments on hangers (GOH)
  • Ventilated containers. Essentially dry vans, but either passively or actively ventilated. For instance for organic products requiring ventilation
  • Temperature controlled – either insulated, refrigerated, and/or heated containers, for perishable goods
  • Tank containers, for liquids, gases, or powders. Frequently these are dangerous goods, and in the case of gases one shipping unit may contain multiple gas bottles
  • Bulk containers (sometimes bulktainers), either closed models with roof-lids, or hard or soft open-top units for top loading, for instance for bulk minerals. Containerized coal carriers and "bin-liners" (containers designed for the efficient road and rail transportation of rubbish from cities to recycling and dump sites) are used in Europe.
  • Open-top and open-side containers, for instance for easy loading of heavy machinery or oversize pallets. Crane systems can be used to load and unload crates without having to disassemble the container itself. Open sides are also used for ventilating hardy perishables like apples or potatoes.
  • Platform based containers such as:
    • flat-rack and bolster containers, for barrels, drums, crates, and any heavy or bulky out-of-gauge cargo, like machinery, semi-finished goods or processed timber. Empty flat-racks can either be stacked or shipped sideways in another ISO container
    • collapsible containers, ranging from flushfolding flat-racks to fully closed ISO and CSC certified units with roof and walls when erected.

Containers for Offshore use have a few different features, like pad eyes, and must meet additional strength and design requirements, standards and certification, such as the DNV2.7-1 by Det Norske Veritas and the European standard EN12079: Offshore Containers and Associated Lifting Sets.

A multitude of equipment, such as generators, has been installed in containers of different types to simplify logistics – see containerized equipment for more details.

Swap body units usually have the same bottom corner fixtures as intermodal containers, and often have folding legs under their frame so that they can be moved between trucks without using a crane. However they frequently don't have the upper corner fittings of ISO containers, and are not stackable, nor can they be lifted and handled by the usual equipment like reach-stackers or straddle-carriers. They are generally more expensive to procure.


Basic dimensions and permissible gross weights of intermodal containers are largely determined by two ISO standards:

  • ISO 668:2013 Series 1 freight containers—Classification, dimensions and ratings
  • ISO 1496-1:2013 Series 1 freight containers—Specification and testing—Part 1: General cargo containers for general purposes

Weights and dimensions of the most common standardized types of containers are given below. Values vary slightly from manufacturer to manufacturer, but must stay within the tolerances dictated by the standards. Empty weight (tare weight) is not determined by the standards, but by the container's construction, and is therefore indicative, but necessary to calculate a net load figure, by subtracting it from the maximum permitted gross weight.

20'40'40' high-cube45' high-cube48'53'
Length19 ft 10.5 in
(6.058 m)
40 ft 0 in
(12.192 m)
40 ft 0 in
(12.192 m)
45 ft 0 in
(13.716 m)
48 ft 0 in
(14.630 m)
53 ft 0 in
(16.154 m)
Width8 ft 0 in
(2.438 m)
8 ft 0 in
(2.438 m)
8 ft 0 in
(2.438 m)
8 ft 0 in
(2.438 m)
8 ft 6 in
(2.591 m)
8 ft 6 in
(2.591 m)
Height8 ft 6 in
(2.591 m)
8 ft 6 in
(2.591 m)
9 ft 6 in
(2.896 m)
9 ft 6 in
(2.896 m)
9 ft 6 in
(2.896 m)
9 ft 6 in
(2.896 m)
Length19 ft 3 in
(5.867 m)
39 ft 5 4564 in
(12.032 m)
39 ft 4 in
(11.989 m)
44 ft 4 in
(13.513 m)
47 ft 6 in
(14.478 m)
52 ft 6 in
(16.002 m)
Width7 ft 8 1932 in
(2.352 m)
7 ft 8 1932 in
(2.352 m)
7 ft 7 in
(2.311 m)
7 ft 8 1932 in
(2.352 m)
8 ft 2 in
(2.489 m)
8 ft 2 in
(2.489 m)
Height7 ft 9 5764 in
(2.385 m)
7 ft 9 5764 in
(2.385 m)
8 ft 9 in
(2.667 m)
8 ft 9 1516 in
(2.691 m)
8 ft 11 in
(2.718 m)
8 ft 11 in
(2.718 m)
Width7 ft 8 18 in
(2.340 m)
7 ft 8 18 in
(2.340 m)
7 ft 6 in
(2.286 m)
7 ft 8 18 in
(2.340 m)
8 ft 2 in
(2.489 m)
8 ft 2 in
(2.489 m)
Height7 ft 5 34 in
(2.280 m)
7 ft 5 34 in
(2.280 m)
8 ft 5 in
(2.565 m)
8 ft 5 4964 in
(2.585 m)
8 ft 10 in
(2.692 m)
8 ft 10 in
(2.692 m)
Internal volume1,169 cu ft
(33.1 m3)
2,385 cu ft
(67.5 m3)
2,660 cu ft
(75.3 m3)
3,040 cu ft
(86.1 m3)
3,454 cu ft
(97.8 m3)
3,830 cu ft
(108.5 m3)
gross weight
66,139 lb
(30,000 kg)
66,139 lb
(30,000 kg)
68,008 lb
(30,848 kg)
66,139 lb
(30,000 kg)
67,200 lb
(30,500 kg)
67,200 lb
(30,500 kg)
Empty weight4,850 lb
(2,200 kg)
8,380 lb
(3,800 kg)
8,598 lb
(3,900 kg)
10,580 lb
(4,800 kg)
10,850 lb
(4,920 kg)
11,110 lb
(5,040 kg)
Net load61,289 lb
(27,800 kg)
57,759 lb
(26,199 kg)
58,598 lb
(26,580 kg)
55,559 lb
(25,201 kg)
56,350 lb
(25,560 kg)
56,090 lb
(25,440 kg)

Reporting mark

Each container is allocated a standardized ISO 6346 reporting mark (ownership code), four letters long ending in either U, J or Z, followed by six digits and a check digit. The ownership code for intermodal containers is issued by the Bureau International des Containers (International container bureau, abbr. B.I.C.) in France, hence the name BIC-Code for the intermodal container reporting mark. So far there exist only four-letter BIC-Codes ending in "U".

The placement and registration of BIC Codes is standardized by the commissions TC104 and TC122 in the JTC1 of the ISO which are dominated by shipping companies. Shipping containers are labelled with a series of identification codes that includes the manufacturer code, the ownership code, usage classification code, UN placard for hazardous goods and reference codes for additional transport control and security.

Following the extended usage of pallet-wide containers in Europe the EU started the Intermodal Loading Unit (ILU) initiative. This showed advantages for intermodal transport of containers and swap bodies. This led to the introduction of ILU-Codes defined by the standard EN 13044 which has the same format as the earlier BIC-Codes. The International Container Office BIC agreed to only issue ownership codes ending with U, J or Z. The new allocation office of the UIRR (International Union of Combined Road-Rail Transport Companies) agreed to only issue ownership reporting marks for swap bodies ending with A, B, C, D or K – companies having a BIC-Code ending with U can allocate an ILU-Code ending with K having the same preceding letters. Since July 2011 the new ILU codes can be registered, beginning with July 2014 all intermodal ISO containers and intermodal swap bodies must have an ownership code and by July 2019 all of them must bear a standard-conforming placard.

From the Wikipedia entry for INTERMODAL CONTAINER

The standardized Cargo Containers are the heart of interstellar trade.

Containers come in many different types, each with a designation to distinguish the different types and uses. Designation for each container is (size)(type)/(tech level). There are three sizes of containers, coded as 4A (8 dtons or 112 cubic meters), 4C (4 dtons, 32 m3) or 4D (2 dtons, 16 m3). Containers are 3 meters high by 3 meters wide, and include all doors and fittings for cargo handling equipment. The size 4A containers are 12 meters long, 4C containers are 6 meters long, and 4D containers are 3 meters long.

Cargo Container Types

Container types
Type CodeNameDescription
00 General Purpose A simple box with doors at both ends.
05 Sealed Same as type 00, but capable of being sealed against external atmosphere. Does not include life support or environmental controls.
32 Controlled Environment A type 05 but including environmental controls for heat and cooling. Can maintain any temperature between -35°C and 50°C. Requires external power supply, and has a 24 hour battery power supply.
50 Open Top Same as type 00, but missing the top.
55 Open Frame An open box frame with structural cross members. Used as a frame for heavy equipment. Can be covered with a flexible covering.
67 Modular A box designed to come apart into the six sides. Can be used as a type 00, type 50, or type 55, or folded flat for shipment. Four flat containers can be shipped in the space of one assembled container.
70 Tank A type 55 with a tank for transporting liquids or gasses in bulk.
90 Habitat A modular office, building component, or habitat. Provides full life support and cramped cabin quarters. Requires external power supply for life support, and has a 24 hour battery supply.

(ed note: This is a modification to the rules for the Traveller role playing game. But the reasoning is of general interest to cargo starship designers. Costs are in Travelle "credits" or CR, more or less equivalent to $1 US)

April 2014 issue.

Why are standard cargo containers in Traveller 3m wide, 3m high and 6m long? Because no one consider the implications of containerized cargo on Earth when they wrote that description decades ago. Nor did they consider the standards for starships in Traveller. The standard cargo container, as written, is unusable in the standard starships, as written, in Classic Traveller.

A subsidized merchant (Type R) cannot stack two standard cargo containers in its hold because the deck height is only 6m. There would be no room to maneuver them about. From past experience working in steel yards and manufacturing plants, I would say as a minimum the decks would need to be 6.3m apart in order to safely stack two 3m containers, and it seems the writers of Fire, Fusion, & Steel 2 would agree because they suggest a minimum door size that is 10% larger in dimension than the corresponding dimension of anything that will be moved through it.

So let’s take a fresh look at containerized cargo for Traveller. On Earth, while there are occasionally containers dented by mishandling, it is rare, so a Traveller armor rating of 1 seems to be a reasonable ‘guesstimate’. This is also the standard minimum for grav vehicles, probably for much the same reason.

If the deck heights will be 3m then the maximum height of cargo containers should be 2.7m since starships will be the primary mode of transport. Does anyone know the Imperium’s standard axle size? Never mind, we’ll leave the other two dimensions at 3m and 6m. An Imperial standard shipping container would have a surface area of 84.6m2 and an external volume of 48.6 m3. Other important measurements depend on composition, per the table below.


Standard Cargo Container Measurements
TLMaterialVolume*Mass (kg)Cost (Cr)
0Light Wood42.5572.4171,813
4Soft Steel48.2522.785558
5Hard Steel48.3042.366592
6Titanium Alloy48.4031.5781,973
7Light Composite48.4521.0371,038
8Composite Laminate48.5010.790790
9Light Ceramic Composite48.4820.7111,067
16Collapsed CrystalIron48.5700.385651

* Internal volume available to shipper, in m3

Containers are inexpensive and finding them “repurposed” to other functions would be quite likely. Researching “container architecture” might offer some ideas.

None of these would be vacuum resistant and the TL 0 and 1 containers couldn’t be made so. Adding a cargo door (e.g. one that was proof against vacuum) would add to the cost. Since most starships maintain shirt-sleeve environments in cargo areas this usually won’t be a problem; however, for high end cargos it might be worth a shipper’s while to pop for the added protection.


Cost of Vacuum-resistant Cargo Containers
TLCost (Cr) TLCost (Cr)
33,647 86,825
44,708 96,582
54,604 107,131
65,661 127,540
76,227 167,707

A container could hold a kiloton of high density material so planetary standards bodies would probably call for a maximum gross mass. What that would be IYTU would depend on what standards exist for cargo moving equipment. Present-day ISO standards call for a maximum net load of 28.2 tonnes but present-day standard cargo containers are 21% smaller than those described here, so 38 tonnes would be comparable on a volume for volume basis.

There are probably sub-containers available as well. These would be designed to fit inside the main container with little wiggle room. They might be standardized or not IYTU. Because they are protected by the main container they would have no minimum standards and could be as simple as plastic or cardboard boxes. Standard widths would be 2.8, 1.4, 0.93, 0.7, 0.56, 0.46, 0.4, 0.35, and possibly 0.31, 0.28, 0.25, and 0.23. Standard lengths would be 5.8, 2.9, 1.93, 1.45, 1.16, 0.96, 0.82, 0.72, 0.64, 0.58, 0.52, and 0.48. Standard heights would be less likely, especially on the smaller end, but if you had them they would probably be on the order of 2.4, 1.2, 0.8, 0.6, 0.48, 0.4, 0.34, 0.3, 0.26, 0.24, 0.21, and 0.2.

Note that the widths and lengths refer to their placement within the main container. One could have sub-containers that were longer from side to side of the main container than they were front to back, relatively speaking.

Most PCs won’t know or care what’s inside the shipping containers in the hull, but if you have PCs that do something other than standard merchant type activities this information could be useful. There are actually companies that arrange sub cargos for small concerns that cannot afford to ship full containers and they make good money saving their customers money on shipping by bundling their shipments with others to form full containers.


Space Truckers and Trains

I am arbitrarily defining a conventional cargo ship as one with the engines in the aft section of the spacecraft, while space trucks and space trains have the engines in the fore section (like an 18-wheeler or a choo-choo train). The only difference between space trucks and space trains is the number of cargo cannisters.


As attractive as is the admirable reduction in radiation shield mass offered by the waterskiiing spacecraft concept, there are practical problems in being towed on the end of a kilometer-long cable.

But the bit about using tension instead of compression members is still a worthwhile idea. Take some species of space tug, mount the propusion system on outriggers so the exhaust does not fire directly back along the ship's spine, and attach cargo modules to massive couplings on the bottom of the thrust frame.

If the space tug is hauling one or two cargo modules, this resembles an 18-wheeler hauling a couple of semi-trailers. A "space-trucker" so to speak.

As with all cargo spacecraft, delicate cargo will be housed in pressurized temperature-controlled cannisters but bulk ores and other insensitive cargo will just be dragged along in nets.



“There it is,” Shadow Jack said, with almost a sigh. “Mecca rock.”

Betha watched it come into view at the port: a fifty-kilometer potato-shaped lump of stone, scarred by nature’s hand and man’s. Mecca’s long axis pointed to the sun; the side nearest them lay in darkness, haloed by an eternal corona of sunglare. As they closed she began to see landing lights; and, between them, immense shining protrusions lit from below, throwing their shadows out to be lost in the shadow of the void. She identified them finally as storage tanks—enormous balloons of precious gases. At last… She stirred in the narrow, dimly lit space before the instruments, felt her numbed emotions stir and come alive.

“Out there, Shadow Jack.” She leaned closer to the port, rubbed the fog of moisture from the glass. “A tanker coming in.”

He peered past her. They saw the ship, still lit by the sun: a ponderous metallic tick, its plastic belly bloated with precious gases and clutched inside three legs of steel, booms for the ship’s nuclear-electric rockets. “Look at the size of that! It must be comin’ in from the Rings. They wouldn’t use that on local hauls." He raised his head, following its downward arc. “Down there, that must be the docking field.”

She could see the field clearly now, an unnatural gleaming smoothness in the artificial/light, cluttered with cranes and ringed by more mechanical parasites, gorged and empty. Smaller craft moved above them, fireflies showing red: sluggish tows in a profusion of makeshift incongruity.

From THE OUTCASTS OF HEAVEN BELT by Joan Vinge (1978)

He glanced up, at the purity of blackness unmarred by atmosphere, at the stars. Somewhere below his feet, through kilometers of nearly solid rock, was the tiny, pale spinel of the sun Heaven. He would be seeing it again, soon enough—he focused on the looming grotesqueness tethered at the end of the mooring cable, bifurcated by the abrupt edge of the asteroid’s horizon: the converted volatile freighter that would take them across the Main Belt and on in to Heaven’s second planet, to pick up one man…and a treasure. The three jutting booms that kept its nuclear electric rockets suspended away from the living quarters clutched rigid cylinders instead of the usual flimsy volatiles sack; it carried a liquid fuel rocket for their descent to the planet’s surface.

From LEGACY by Joan Vinge (1980)

(ed note: this is a laser thermal rocket energized by powerful remote lasers on an L5 colony)

     The next item on the agenda was the laser-powered high-acceleration tug, otherwise referred to as the ultra-fast optical system, UFOS having more dash and elan than LPHAT. Corporate Susan made the presentation it had worked up with Skaskash and Lady Dark.

     "The basic idea isn't bad,” said Cantrell. “How would you keep the lens oriented normal to the laser when you start to move the engine to a different orientation?"
     "We have a pair of pipes at the equator of the sphere, pumping water in opposite directions,” said Corporate Susan. “Also, inside the sphere, under the photovoltaic surface, are two pairs of circular loops, set flush with the surface and at right angles to each other. Each pair pumps water in a counterrotary direction. The pumps are all controlled, so the UFOS is gyroscopically stabilized in three planes."

     "I see,” Dornbrock said. “How do you move the engine around on the surface of the geodesic sphere?"
     "The sphere rests on this little egg cup here,” said Corporate Susan. “The egg cup is a plastic perforated surface. When we want to move, we pressurize the surface, and the geodesic sphere floats on an air cushion. Then the mechanical hands around the perimeter of the egg cup orient the engine while the sphere stays put, or the engine stays put and the hands reorient the sphere, depending on how you work the gyroscopic pumps."
     "Wouldn't you lose a lot of air pressurizing the perforated surface?” Corporate Forziati asked.
     "No, actually,” Corporate Susan replied. “We have built a little valve into each perforation which only operates when the surface is depressed by the weight of the element of the sphere in contact with it.” A diagram flashed on her telecon screen for a moment.
     "Thank you,” Forziati said. “And when you are not under thrust, weight is no problem and you don't pressurize. Very good."

     "On the other end of the egg cup,” Bogdanovitch said, “where you have the engines and the tanks for the reaction mass, you have a long cable supporting the warship. Couldn't you have the ship on an egg cup, too?"
     "No,” Corporate Susan replied. “The engines are thrusting against the geodesic sphere, which rests on top of the egg cup. The warship must keep its center of mass in line with the axis of thrust. Put it on the sphere with its own egg cup, and it would have to stay lined up with the engines—on the other side—which means the sphere would have to be built stronger, and heavier."
     "And it would get in the way of the big laser beam,” Cantrell added.

     "Then how does the warship stay out of the jet of ions?” asked Bogdanovitch.
     "It rotates at the end of its cable,” said Corporate Susan, “and makes a little circle around the jet of uranium ions which provide the main thrust. The jet of boron and hydrogen is flared off, simply to provide electrical neutrality, but it also provides a tiny bit of thrust, which can be used to offset the wobble the ship would otherwise cause by swinging around the main jet."

     "I don't understand,” Marian said.
     Corporate Susan dissolved into a diagram. “Consider the vector diagram of the force exerted by the cable supporting the ship,” said the computer. “Most of it runs through the axis of thrust, but there is a small component going at right angles to that thrust. The boron and hydrogen, flared off with the excess electrons from the decaply ionized uranium, can be adjusted to exactly balance that small component. The flare—a very soft jet—would be in the same plane as the ship, and pointing in the same direction, to push where the ship is pulling."
     "The jet—the flare, I mean, turns with the cable?” asked Marian.
     "Of course,” said Corporate Susan.

     "Orange and green,” said Marian. “Very pretty. What color is the uranium jet?"
     "Hard X-ray,” Skaskash said. “It would probably be dangerous for two or three hundred kilometers."
     "That might be an idea whose time has come,” Cantrell said at last. “Any more questions? No? Shall we build it? ... It seems to be unanimous."

     "I have a model at the shop you can use. I'll have the changes you wanted put on, and you can use that, if you want."
     "How big is it?"
     "Not big—” Ilgen stretched his arms. “Maybe a meter and a half. Did you decide what ship you wanted with it?"
     "The Alamo. We need to impress people, and the Alamo is the biggest thing we've got."
     "Right, Charlie. I'll throw in a model of the Alamo to the same scale. The UFOS plus the Alamo figures to go seven to eight times as fast as any cruiser."
     Cantrell whistled softly.
     "I'll tell the Navy,” he said. “That ought to make them very happy."

From THE PIRATES OF ROSINANTE by Alexis Gilliland (1982)

When space westerns decide to get literal with the genre name, these guys tend to show up.

They are usually depicted as, well, southern-fried semi truckers that happen to fly cargo spaceships instead. Usually easygoing, unflappable, and have a backwoods wisdom developed during the time spent alone on long hauls between solar systems. Occasionally they're smugglers, but usually aren't drug mules. From time to time, between hauls they'll stop at a local tavern and challenge various folks to a little arm-wrestling, drinking contests and then drunken brawls. Tend to talk in a Southern or slight Texan drawl.

Overlaps occasionally with the Boisterous Bruiser, Gentle Giant, Warrior Poet or other ersatz cowboy-style archetypes.

Their ships are most likely Used Future pieces of junk, just barely held together — bonus points if they're blocky, and bear a surprising resemblance to modern Mack trucks or other 18-wheelers.

Often a subtrope of Intrepid Merchant.

(ed note: see TV Trope page for list of examples)

We had a lot of luck on Venus
We always had a ball on Mars
Meeting all the groovey people
We've rocked the Milky Way so far
We danced around with Borealis
We're space truckin' round the the stars
Come on let's go Space Truckin'

Remember when we did the moonshot
And Pony Trekker led the way
We'd move to the Canaveral moonstop
And everynaut would dance and sway
We got music in our solar system
We're space truckin' round the stars
Come on let's go Space Truckin'

The fireball that we rode was moving
But now we've got a new machine
Yeah Yeah Yeah Yeah the freaks said
Man those cats can really swing
They got music in their solar system
They've rocked around the Milky Way
They dance around the Borealis
They're Space Truckin' everyday
Come on
From SPACE TRUCKIN' by Deep Purple (1972)

      The observation bubble on the side of the Cay Habitat had a televiewer, Leo discovered to his delight, and furthermore it was unoccupied at the moment. His own quarters lacked a viewport. He slipped within. His schedule allowed this one free day to recover from trip fatigue and jump lag before his course was to begin.

     The curve of Rodeo’s horizon bisected the view from the bubble, and beyond it the vast sweep of stars. Just now one of Rodeo’s little mice moons crept across the panorama. A glint above the horizon caught Leo’s eye.

     He adjusted the televiewer for a close-up. A GalacTech shuttle was bringing up one of the giant cargo pods, refined petrochemicals or bulk plastics bound for petroleum-depleted Earth perhaps. A collection of similar pods floated in orbit. Leo counted. One, two, three … six, and the one arriving made seven. Two or three little manned pushers were already starting to bundle the pods, to be locked together and attached to one of the big orbit-breaking thruster units.

     Once grouped and attached to their thruster, the pods would be aimed toward the distant wormhole exit point that gave access to Rodeo local space. Velocity and direction imparted, the thruster would detach and return to Rodeo orbit for the next load. The unmanned pod bundle would continue on its slow, cheap way to its target, one of a long train stretching from Rodeo to the anomaly in space that was the jump point.

     Once there, the cargo pods would be captured and decelerated by a similar thruster, and positioned for the jump. Then the superjumpers would take over, cargo carriers as specially designed as the thrusters for their task. The monster cargo jumpers were hardly more than a pair of Necklin field generator rods in their protective housings so positioned as to be fitted around a constellation of pod bundles, a bracketing pair of normal space thruster arms, and a small control chamber for the jump pilot and his neurological headset. Without their balancing pod bundles attached the superjumpers reminded Leo of some exceptionally weird and attenuated long-legged insects.

     Each jump pilot, neurologically wired to his ship to navigate the wavering realities of wormhole space, made two hops a day, inbound to Rodeo with empty pod bundles and back out again with cargo, followed by a day off; two months on duty followed by a month’s unpaid but compulsory gravity leave, usually financially augmented with shuttle duties. Jumps were more wearing on pilots than null-gee was. The pilots of the fast passenger ships like the one Leo had ridden in on yesterday called the superjumper pilots puddle-jumpers and merry-go-round riders. The cargo pilots just called the passenger pilots snobs.

     Leo grinned, and considered that train of wealth gliding through space. No doubt about it, the Cay Habitat, fascinating as it was, was just the tail of the dog to the whole of GalacTech’s Rodeo operation. That single thruster-load of pods being bundled now could maintain a whole town full of stockholding widows and orphans in style for a year, and it was just one of an apparently endless string. Base production was like an inverted pyramid, those at the bottom apex supporting a broadening mountain of ten-percenters, a fact which usually gave Leo more secret pride than irritation.

From FALLING FREE by Lois McMaster Bujold (1988)


Space Truckers haul relatively small numbers of cargo modules, often attached to a framework. However if the tug is hauling a long chain of cargo modules, this is more like a freight train with a locomotive at the front and a string of freight cars in tow. A "space train" as it were.

Much like railroad locomotives, this will be less like loading crates into a seagoing container ship and more like latching cargo cans into long strings terminating at the rocket engine at the top.



This was the lead ship for the warp superconvoys, the 100-kilometer cargo carriers that revolutionized interstellar industrial transport. Configured in 8-ship linked octogons at the head of the convoy, with 4-ship squares of booster tugs after each 10-container segment, and all controls subspace-radio synchronized, these superconvoys transported billions of kilograms per superconvoy.

Length225 m
Beam220 m
Draught45.6 m
Mass72.5 million kg
Ship's Complement
Std Ship's Complement66
Range2000 light-years
Cruising SpeedEmpty - Warp 3.5
Loaded - Warp 2
EnginesAdv 3rd Gen Warp Drive
Fuel1:1 matter/antimatter
NotesTractor beam coupling for cargo containers
Most powerful thrust in starship history

SUPERCONVOYS OPEN NEW ERA OF TRADE: Billion ton ships are boon to industry (2161)

Engineering Log:

It's working! Warp effect is being engaged, and this superconvoy is rolling! Next stop—Centauri Spaceworks.

I'll let the boys upstairs take the glory, but the truth is old greasemonkey Sabella down here in the Engine Room is who straightened this whole mess out, I must admit in all humility.

Problem: how to transport raw materials from whistle-stop asteroid belts in the boondock sectors to the space factories of the UFP? And I'm not talking a freighter or two here. I'm talking about the billions and billions of metric tonnage needed each stardate to feed the Federation's ravening industrial plant. Star Fleet is stymied.

Solution: Sabella to the rescue. lt's elementary, I patiently explain, what we need are warp convoys of a hundred freighters and more. It can't be done, sneer the design baboons. No ship could produce a warp effect that great. Who said anything about one ship? I reply.

So I spelled it out for them. At the head of the convoy, assemble a configuration of heavy warp-drive tugs, say eight of them in an octagon. Lock their controls together and use the whole pile as the inertial driver. Next, string out a dozen or so of those new kilometer-long cargo cans, coupling them with tractor beams. Then—and here my brilliance staggers even my own modest self—plug in another configuration of warp tugs, four should do it, and knit the rest of the convoy with the same pattern, synchronize it all with subspace radio so that all warp engines engage simultaneously, and ride into the sky!

It can't be done, cry the designers.

An interesting conjecture, muses star Fleet.

It can be done, admit the designers in wonderment. Maybe only warp 2 or so, but this would save years of travel time, and trillions of credits.

Trillions? asks Star Fleet. Maybe we'll consider it. They considered it, they did it, it's done.

Merely brilliant, Sabella, I say. Merely brilliant.


Admiral's Log:

Our flagship Endurance has run a final sensor scan of Bayard’s Planet, and I can report with certainty that not a single inhabitant has been missed by this, the largest spacelift in history. None too soon either. The shock wave from the supernova explosion that destroyed the Kepler will reach this systems sun in less than three star-dates, and it is 100 percent probable that it will initiate a chain reaction nova.

And the nova will destroy all life in the star system. All oceans will boil away; the gamma ray bombardment will scorch the surface; the planet itself may undergo an internal disruption and blow apart. it was imperative that Bayard’s Planet be evacuated. But how to evacuate ten million inhabitants? With the biggest spacelift ever.

Every starship within a fifty light-year radius was pressed into the effort by special request of the UFP. And I am just amazed by the response. Cruisers, destroyers, scout-ships, corvettes, all rendezvoused. Also trading clippers, low-warp tugs, even pleasure crafts of every type all rallied to the cause.

But all these valiant volunteers twice over could not have removed ten million people in time. Then an engineer in Star Fleet Merchant Marine named Sabella came up with the novel idea of refitting those new super-convoys with life support and jury-rigged decks. And that turned the corner for us. Starbase 5 renovated two superconvoys to accommodate passengers in an amazingly short time, and after weeks of impossible logistics and unmeetable timetables, we have succeeded in evacuating the entire planet. The galaxy has never seen an operation of this scope before. And I for one fervently hope it never has to again.

From STAR TREK SPACEFLIGHT CHRONOLOGY by Stanley and Fred Goldstein (1980)

Type: Warship

This is far more speculative, since as far as we know there have not been any space warships created yet. Refer to Warship Design, Warship Gallery, Space War: Intro, Space War: Detection, Warship Weapons Intro, , Warship Weapons Exotic, Space War: Defenses, Space War: Tactics, and Planetary Attack.

Fundamentally they are weapons platforms, so by definition they will be carrying various weapons systems. They may or may not have armor or other defenses, they may or may not have human crews. They probably will have an over sized delta-V capacity, and a large thrust capacity so they can jink around and complicate the enemy's targeting solution (i.e., dodge around so you are harder to hit). Lasers will require large amounts of power, and huge heat radiators and heat sinks to cope with waste energy. They will probably be carrying little or nothing that cannot be used to attack the enemy.

Type: Space Ark

Space Arks are an outer-space version of that old Noah story: some cosmic apocalypse is going to obliterate the world, so it behoves the human race to evacuate to another world a breeding population of humans, a civilization starter kit, as much of the worlds scientific knowledge and culture they can cram in, and a viable subset of Terra's ecosystem (with redundancy, none of this "two by two" nonsense). Yes, it is a popular scifi trope.

It is basically a colony ship to establish an interstellar colony. Except the stakes are higher and the build time is limited. The time limit is set by the arrival date of the apocalypse. Designing it won't be easy. If the ship can be designed to be indefinitely habitable (a "worldship") then the journey to a safe place can be done leisurely. But since such ships are generally built in a clawing rush, they have a limited life until their warranty runs out. So the journey has to be as fast as possible.

Another challenge is attempting construction of the space ark while all the selfish people in the entire freaking world try to seize it for their own survival.

The space ark can be a generation ship or a sleeper ship. A popular option is putting an engine on the end of a space colony. A more challenging option is putting an engine on Terra large enough to move the entire planet somewhere safer. But that is out of the scope of "types of spaceships." Or is it?

John Brunner's epic novel THE CRUCIBLE OF TIME is about an alien race whose planet is faced with annihilation by an oncoming nebula. However the focus in the novel is more on the thousands of years before the building of the ark. The aliens are starting with medieval levels of scientific ignorance and do not even know they are in danger. It is a race to see if they can develop enough science to make space arks before the nebula clobbers them.


(ed note: When a crazed army of survivors attacks the site where the Space Arks are being built, things look bleak until one of the main characters starts up the almost-complete first Ark, sets the atomic engines to "1 G", and floats over the attacking hordes in blowtorch mode)

     " To the ship! Into the ship!" Tony cried to them. "Everybody into the ship! Spread the word! Jack! . . . Everybody, everybody into the ship!" There was no alternative.
     Three-fourths of the camp was in the hands of the horde; and the laboratories could not possibly beat off another rush. They could not have beaten back this, if it had been more organized.
     Bullets flew through the dark.
     "To the ship! To the ship!"
     Creeping on hands and knees, from wounds or from caution, and dragging the wounded with them, the men started the retreat to the ship. Women were helping them.
     Yells and whistles warned that another rush was gathering; and this would be from all sides; the laboratories and the ship were completely surrounded.
     Tony caught up in his arms a young man who was barely breathing. He had a bullet through him; but he lived. Tony staggered with him into the ship.
     Hendron was there at the portal of the great metal rocket. He was cooler than any one else. "Inside, inside," he was saying confidently...
     ...The second rush was coming. No doubt of it, and it would be utterly overwhelming. There would be no survivors—but the women. None. For the horde would take no prisoners. They were killing the wounded already—their own badly wounded and the camp's wounded that they had captured.
     Eliot James, a bullet through his thigh, but saved by the dark, crawled in with this information. Tony carried him into the ship.
     They were all in the ship—all the survivors. The horde did not suspect it. The horde, as it charged in the dark, yelling and firing, closed in on the laboratories, clambered in the windows, smashing, shooting, screaming. Meeting no resistance, they shot and bayoneted the bodies of their own men and of the camp's which had been left there.

     Then they came on toward the ship. They suddenly seemed to realize that the ship was the last refuge. They surrounded it, firing at it. Their bullets glanced from its metal. Somebody who had grenades bombed it.
     A frightful flame shattered them. Probably they imagined, at first, that the grenade had exploded some sort of a powder magazine within the huge metal tube, and that it was exploding. Few of those near to the ship, and outside it, lived to see what was happening.

     The great metal rocket rose from the earth, the awful blast from its power tubes lifting it. The frightful heat seared and incinerated, killing at its touch. A hundred of the horde were dead before the ship was above the buildings.
     Hendron lifted it five hundred feet farther, and the blast spread in a funnel below it. A thousand died in that instant. Hendron ceased to elevate the ship. Indeed, he lowered it a little, and the power of the atomic blast which was keeping two thousand tons of metal and of human flesh suspended over the earth, played upon the ground—and upon the flesh on the ground—as no force ever released by man before.
     Tony lay on his face on the floor of the ship, gazing down through the protective quartz-glass at the ground lighted by the garish glare of the awful heat.

     In the midst of the blaring, blinding, screaming crisis, a man on horseback appeared. His coming seemed spectral. He rode in full uniform; he had a sword which he brandished to rally his doomed horde. Probably he was drunk; certainly he had no conception of what was occurring; but his courage was splendid. He spurred into the center of the lurid light, into the center of the circle of death and tumult, stiff-legged in stirrups of leather, like one of the horrible horsemen of the Apocalypse.
     He was, for a flaming instant, the apotheosis of valor. He was the crazed commander of the horde.
     But he was more. He was the futility of all the armies on earth. He was man, the soldier.
     Probably he appeared to live after he had died, he and his horse together. For the horse stood there motionless like a statue, and he sat his horse, sword in hand. Then, like all about them, they also crumpled to the ground.

     Half an hour later, Hendron brought the ship down.

From WHEN WORLDS COLLIDE by Philip Wylie and Edwin Balmer (1933)

(ed note: the inhabitants of the planet are treated to a somewhat close star going nova. Study of the explosion advances science, and also gives the secret of a faster-than-light drive. The project starts to build the first starship.

Then they notice that their own primary star is acting a little peculiarly. With horror they realize it is going to go nova in about nine years. The planetary government embarks on a crash program to make as many space arks as possible. Of course those who will left behind are somewhat unhappy.)

      Even for those barely possible few who did not recognize the man himself, the ceremonial blue and gold robes told the tale: he was the World Consort. His presence could only mean that whatever he had to say was the contribution of the Matriarch herself.
     “I am here essentially to answer the young man’s question,” he said. “There is work that we can do—work for a whole people, for a whole world. One Ertak-drive ship is no longer enough; we want hundreds—even thousands if that is possible. We are transforming the Project into a mass crash program for the survival of the race. We are going to build, man and launch a fleet.”

     Being young, Jom was not immediately able to rid himself of his notion—no, it was more than a notion, it was a fact of his brief experience—that five years was a long, long time in the future. He was astonished to see how rapidly Ertak and his staff forced themselves to make huge decisions, which ordinarily should have been weighed for several months at the very least. Now four or five of these might be made on a single typical day.

     For a sufficient example, take ship design. The Project’s ship on the ways, the Javelin, had been planned as a vessel which would return home well within the lifetime of its original crew. Now it had to be thought of, instead, as a colony-in-flight, able to shelter many generations if necessary.
     But spaceships which will also be colonies are not easily designed from nothing ; and an interstellar ship which was specifically designed not to be a colony cannot speedily be torn down and changed over. When presented with the time-budget for such an operation, Ertak decided almost instantly against it. The Javelin was ordered to be modified in as many small ways as possible, but she was not to be rebuilt, nor was she to be nibbled at drastically enough to risk weakening her present structure. This made sense, but Jorn was not prepared for the corollary decision: that all the Javelin's sister ships were to be built to the same design and with only such minor modifications as the Javelin herself could safely withstand. This decision too was eminently reasonable, but not to a man to whom five years seemed like a long time.

     And as with the ships, so with the world. This decision was not Ertak’s to make, but since the principles were the same, so was the outcome. The whole world was not converted overnight, or at any other time, to the production of interstellar ships, as Jorn had fuzzily imagined the World Consort to have implied. Doom or no doom, the fact remained that the original Javelin at completion would have cost half a billion credits, plus four years in construction time. Her sister ships would cost slightly less than that, but not much—mass production is an almost meaningless term for a structure like a bridge or a skyscraper or a ship, the savings involved running narrowly between two and four per cent per structure.
     Jorn had of course supposed that mere financial cost—and in that word “mere” there resounded hollowly a huge hole in his education—would go by the board in so ultimate an emergency. Like all the poor, money to him was an abstraction, a frivolity, a curse ; as a graduate engineer he knew all about oil, but nobody had bothered to tell him that money is even more necessary and valuable. Skyscrapers, battleships, satellite stations or survival fleets all require a high-energy economy, which means that almost all the goods and services in the world—and hence almost all of the money—must continue to be devoted to keeping that economy at the highest possible level. The farmer may not leap from her combine and take up a hammer on the nearest incomplete interstellar ship; the submarine freighter engineer may not abandon the engines which are propelling titanium ore or sponge platinum from one continent to another; the baker may not cease to make bread; the banker may not take her hands away from the guidance of credit, the raw material of political unity and the only enduring testimonial to man’s confidence in man; even the newscaster may not cease from telling all the rest, who in fact do not know how to hold a hammer and cannot feel or see the escapd fleet growing, that grow it does, and any job well done is an investment in the Project.

     All this takes money; nothing else will serve.

     “Of course we’re trading for the moment on the fact that most of the people don’t really believe a word of it,” Ertak remarked. “They’re willing to go along because the government’s buttered on a little inflation that’s how you ease civilians into any war. But that won’t last long enough. By the end of next year the bombs will start falling, and then they’ll want to run the war themselves, for their own personal protection. That’s when the trouble begins...
     “I don’t see the analogy,” Jorn confessed.
     “I mean that by that time they’ll be beginning to feel the heat—all of them, not just the neurotics who think they can feel it now. It’ll occur to them that the Sun really is going to explode. Then they’ll begin to wonder what they’re really working for : in other words, whether or not what they’re doing is going to get them an entrance ticket to one of our ships. And the moment we have to start paying them in hope instead of in credits, we’ll be in trouble—and there won’t be a ship in the fleet that’s much beyond half done at that point, except of course the Javelin.”
     “But we are going to be carrying passengers,” Jom said hesitantly. “Lots of them."
     “My dear Jorn! Never mind, Ailiss O’Kung says you may be a great navigator ... Of course we’ll be carrying passengers—roughly a hundred for every crewman on the Javelin, and even more on the others. But how many people does that come to? We won’t know until we see how many ships we manage to build before we have to leave, but I’ll tell you this: under the best possible circumstances, the total population of the fleet will be less than the differential birthrate of this planet for one single day. Probably a good deal less.”
     “Still, Director, we won’t be taking the old, or the handicapped or . . . certainly not the newborn . . .”
     “Ah,” Ertak said with a frozen smile. “That makes it look much easier. But let’s do a little simple multiplication, by tens. The Javelin will be able to carry about twenty-five hundred people. If the fleet consists of a hundred such ships—which would astonish me—then it will leave carrying a quarter of a million. Correct ?”

     Jorn began to feel sick. The Director saw it, obviously, but he continued his explanation without mercy.
     “Now let’s suppose that you’ve managed to disqualify twenty-five million people, on sure sound principles. This leaves you with 2,476,000,000 eligible candidates from which to pick 250,000. About one from every ten million. Would you like the job?”
     “No,” Jom said. “Great Ghost, no.”

     Jorn had no time to puzzle over the sudden inaccessibility of the Director; everything abruptly was going too fast. The five years had in fact almost gone by; and the fleet was, both by definition and a long accumulation of miracles, well more than half done. By now, Jorn was better equipped to understand the awful logic of the simple theory of numbers involved, which ruled that a fleet half finished today may tomorrow have to be dubbed, arbitrarily, all the fleet that there is going to be.
     “And we are very close to term now,” Dr. Chase-Huebner told a meeting in the red room. These days she spoke for the Director; if anybody knew why, nobody had been able to tell Jorn. “We have thirty ships. A thirty-first, the Haggard, is far enough along to be counted in.”
     “What about the Assegai?” someone asked.
     “Out of the question. It would take more than a year to finish her, and we haven't got a year. And I’m not just talking about the heat and the storms, either —though both are awful enough already. Public panic is rising so rapidly now that we won’t be able to keep workers on the Assegai another year without promising them all a berth on her; and as you all know, our complement is filled. Believe me, I hate to leave that ship behind —I hate to leave any ship behind, but particularly the Assegai with alt her refinements. But we have to stop somewhere. It would be nice to wait for the Boomerang, too; on paper she’s far and away the trimmest ship of her class on the ways—but at the moment she’s nothing but a keel and a heap of loose Ibeams. This has got to be the end.”
     “Why not call a halt on the Haggard, too?” Kamblin proposed. “She’ll take another five months, it seems.”
     “Because,” Dr. Chase-Huebner said gently, “we have a crew and passengers for the Haggard, and the Director doesn’t mean to leave anyone behind whom we have promised can go.”

     In mid-air in Ertak’s office a siren groaned briefly, urgently, and on Ertak’s desk, just to the left and directly in front of Dr. Chase-Huebner, the orange light went on.
     It had never been on before. It would never go on again. It meant, very simply, that Dr. Chase-Huebner—and Director Ertak?—had already waited too long, and that even the Haggard would now never be finished.
     The Sun, baleful though it had become, was still decades away from its last agony; but the cataclysm was upon them, all the same.

     The truck was covered and there was hardly anything to be seen from it. Jorn and fourteen other crew members of the Javelin clung to the hard benches and craned their necks around each other, trying to peer out the back over the tailgate; but at first the administration building blocked off the view, and then the driver was careening across Salt Flats at a pace which made visibility less important than just hanging on. It was maddening.
     All the same, a general distant roar of human and machine sound, massive and ugly, came rolling clearly over the snarling of the truck’s own engine. If the sputtering of gas guns was a part of that clamor, it could not be distinguished, at this distance, from the boundary fences; but there were louder explosions too—explosive bullets, grenades, even an occasional mortar.
     It was hard to believe that any sort of a mob could have gathered outside that fence, in the middle of one of the most forbidding deserts in this entire hemisphere of the world; but that was what the orange light had been triggered to foretell. And the fact that the mob was already here—and that the truck was already racing for the Javelin—could mean only that it was huge, armed, and at least partially organized.
     And it also meant, Jorn was fervently sure regardless of the evidence, that somebody—a great many somebodies—had badly misjudged Jurg Wester, and the likes of him.

     The flickering night framed over the tailgate of the truck was streaked briefly by the track of a rocket shell. The concussion from the tank-killer hung fire long after the wake of the little missile had vanished, and its residual image after it ; and then, blam, there it came, from somewhere in the middle distance. Obviously it hadn’t been aimed at the truck, which in any event was showing no lights ; but it left behind no doubt that the mob was armed. Of course at this speed a tire blowout would kill Jorn and everyone else almost as instantly—
     The tires screamed and the truck, yawing and lurching, slammed down to a dead stop, piling all fifteen of them up against the back wall of the cab. Accompanying the yell of brakes and tires was the awful grinding, pounding note of gears being stripped: the driver had shifted down into first in order to stop shorter than the brakes could manage alone, trusting to the crew’s field gear to protect them and her own skill to pocket her.

     They were still trying to unscramble themselves from their own swearing black homologous knot when the tailgate clanged down. “Out!" a woman’s voice shouted. “Hit that lift! Lock closes in seven minutes! Move!”
     Jorn recognized the voice. It belonged to the armorer. Well, that explained the drastic driving. She was waiting for them as they unscrambled and struck turf, carrying a hooded torch further hooded by her gauntlet, between two fingers of which she allowed only a razor-edge of red light to shear at the ground. Even in the dim monochrome, however, Jorn could see that she was bleeding a black rill from one nostril.
     For an instant thereafter he was totally confused. Then, against the starlight, he picked out the colossal shaft of the Javelin, sweeping motionlessly into the sky as though she would never end. Beside her, seemingly clinging to one long dully-gleaming curve, was the delicate scaffolding of the elevator, waiting to be extinguished like a flame at the moment of takeoff.

     “That way,” the armorer growled, “that way.” She gestured along the sand and salt with the razor-edge of the torch; but Jorn was already running. He could hear others behind him. Far away, something—a bomb?—burst open with a deep, heavy groan, and a minute temblor shook the desert under his pounding feet.
     Then the aluminum deck of the lift car was ringing with the trampling of boots as they charged aboard, shoving each other and grabbing for cables or struts they could only guess were there. “. . . thirteen . . . fourteen ... Now by the Ghost ... All right, get in, dammit, fifteen!" A whistle warbled shrilly, almost in Jorn’s ear. The cab shuddered, and then, without any pause, lurched skyward with a muscle-wrenching jolt.

     After that, it did not seem to be going anywhere at all, despite the piercing, unpredictable screams it sometimes uttered against its guide-rails, and the jittering of the deck beneath their feet. Nevertheless it was rising, and as it rose, Jorn could see more and more of the outskirts of the base. Now they were seething with light and smoke, all along the perimeter. Tracers criss-crossed the hot night air in all directions. The higher the car inched, the more likely it seemed to Jorn that everyone on it would be riddled before they would be able to reach the faraway airlock of the Javelin.
     Then, ages later, they were high enough to begin to see the general shape of the attack. It was huge. Beyond the immediate, writhing lines of fire along the fences, twinkling processions of vehicles were racing in nearly straight lines over the desert toward Salt Flats. Near the horizon there did indeed seem to be some bombs falling, and some of these small “nominal” atomics. Evidently the government still controlled the air—which was good as far as it went, but the planes would be under strict orders to stay well away from the ships, where the main part of the mob obviously was concentrating, and hence the only place where a really comprehensive explosion might be decisive.
     The lift quivered and rose a little faster. It brought them all high enough to test their handholds with a heavy buffeting of wind—though the wind seemed to be just as hot as the air on the desert itself had been. There would be no more cool winds on this planet, not at any altitude at which a man could expect to breathe, not even on the mountains.

     Another rocket shell went searing past in a high hazy arc. Jorn stopped breathing for an instant. That one was close. Didn’t they realize that they might hit the ship itself? For that matter, didn’t they know that they couldn’t pack all of those thousands of people into the Javelin and her sisters ? Didn’t they know that they’d wreck her, just trying? Sure, there were three other ships standing on Salt Flats, but—
     But as he realized the futility of trying to think like a mob, his mind repeated, “thousands of people,” and quailed. That mob was being held off only by the stand-bys and there were very few of those any more, certainly far from a full extra crew for each ship. They had been weeded; and judging by the rocket shells, many of the rejects were now howling on the other side of the fence. Despite the standby training, and the supernal lethality of their gear, the stand they were making was suicidal. They would have to fall back, or—
     But they did not fall back. Not this time.
     They were broken open.

     About two miles northwest of the administration building, the line of flame sagged inward. Then it went dark along at least half a mile; the fence was down. Outside, there was a flaming surge of movement toward the hole like surf foaming around a whirlpool.
     The cab came to a bouncing stop in the middle of the sky.
     “All right, inside!” the armorer shouted. “Lock closes in one minute! Inside—shuffle or dust!”
     Had that whole crawling ascent been only six minutes long? But there was no time for postmortems. The sixteen of them were packed into the lock like fish in a jar, and the outer door swung ponderously, unfeelingly shut on the battle and on the whole outside world . . . for good.
     As it sealed, a hairline semicircle of light, intolerably brilliant after the near-blackness of the field, began to widen on the other side of the lock. Jorn was momentarily startled; it had not occurred to him that the interior of the ship might be fully lit—although, since she had no ports, there was no reason why she shouldn’t have been; and besides, her passengers had been living aboard her ever since she was finished. In the first influx of light he was startled to find Ailiss O’Kung standing next to him, white and sweating with strain.

     “Very good,” the armorer said, a little more quietly, but not much. “Posts, ladies and gentlemen. And thank you.”
     Proper enough, Jorn thought deliriously, since the armorer was the only one in the party who was not an officer. Still the speech had all the irrationality of a dream.
     Everything had been rehearsed over and over long before this. Jorn headed for the control barrel almost by instinct, Ailiss trotting by his side. In the big blinking cavern he ran a fast tally of his navigation section and found them there; he did not stop to count Ailiss’ crew, but he had a vague feeling that she was at least one officer short.
     Ertak was there, hunched in the command chair above them. That was his right, since the Javelin was the flagship. But it was the first time that Jorn had seen him in five years; it increased the dream-like feeling.

     The Director did not turn around. He did not even seem to hear what was going on behind him. After a moment, however, he spoke into a chest microphone, and all the desk screens came to life, including Jom’s own. Once again he had a view of the scene outside.
     It no longer really looked like a battle, but more like a carnival, confusing, gay with light, without real meaning. Nevertheless, from this height Jom was able to see that a miracle had happened around the breach at the fence. Somehow, whoever had been generalling the defense had managed to pinch off the inflow, clean up the stragglers, and order a retreat. The irregular closed curve of fire, curiously amoeboid, was well inside the fences everywhere, and drawing closer and closer to the ships; but it was still unbroken.

     Beside Jorn’s right hand he heard a razzy muttering, and reached guiltily for his operations helmet. Inside it, Ertak’s voice was saying:
     ". . . and maintain routine identification signal census in a continuous cycle. Field officers, continue to hold ground by the Haggard and the Assegai; they both look finished and we want the rabble to assume that they are. On Signal Red, flatten out toward the Assegai; on Signal Blue, let them have her. Lifts are down on Javelin and Quarrel; repeat, lifts down on Javelin and Quarrel . . . Congratulations, Deep Station. To all hands: Deep Station reports it has secured all five ships. . . . Census? Census, report! . . . Field officers, Signal Red, this is Signal Red, execute. . . To all hands: Deep Station is launching . . , Census? . . . Field officers, supersede previous orders. On blue signal, yield both Assegai and Boomerang and fall back toward Javelin. Fall back toward Javelin, we will be last off. . . Attention Quarrel, cycle airlock and begin countdown; we won't need you for personnel.”

     The line of fire bulged inward toward the Javelin, and then toward the incomplete ships. Then there was an even deeper bulge toward the Quarrel.
     “Field officers, blue signal will be on count of zero. At the signal, yield the field and board the Javelin’s lift. One minute allowed for boarding, repeat one minute. Counting toward blue signal: five . . . four . , . three . . . two . . . one . . . zero. Signal Blue! Signal Blue!”
     The line swept inward on all sides—and then suddenly it disappeared utterly. There was noi longer even a part of it to be seen. Instead there were only the torches and vehicle lights of the mob, pouring inward toward the three ships they thought they had gained. In a barely perceptible flickering of smallarms fire, what little there was left of the standby crew funnelled toward the lift shaft of the Javelin, trying to disengage.
     “Census, I have pips for twenty-one survivors and a load estimate of eighteen on the lift. Confirm, please. . . . All right, nineteen now. Time’s up. Lift crew, haul them. . . . Absolutely not. Quarrel will leave in six minutes exactly. If we wait for three stragglers, all twenty-one will die. Haul!”

     A minute went by. The mob continued to concentrate around the bases of the “captured” ships, like phosphorescent ants, until each of them seemed to be standing in a spreading pool of light. The pool around the Boomerang, however, quickly began to seep away toward the others; close up it was self-evident that that ship was radically incomplete.
     “To all hands: Deep Station has launched all five ships. We have garbled reports from other stations indicating at least eighteen more either secured or already launched. There are also still two stations holding radio silence: we are hoping this means that their locations remain unknown and they are undergoing no attack.”

     Three minutes.

     “Passenger census . . . Well, that’s what they get for sightseeing; we warned them. Certainly it could be a lot worse. . . Airlock crew, prepare to admit standbyes.”
     Nobody could call them standbyes after tonight.

     Four minutes. There was turmoil now in the pools of light around the Assegai and the Haggard. Little sparks of light were clambering slowly up the scaffolding of their lift-shafts ; obviously they had discovered that the lifts themselves were inoperable.

     Five minutes. The airlock was open now, gaping for the nineteen seared heroes. The mob was beginning to ooze tentatively toward the Quarrel.
     “. . . seventeen, eighteen, nineteen. Cycle airlock. Field officers, welcome aboard. Get that thing closed, you’ve got four seconds—”


     The Quarrel vanished. On Salt Flats the pools of light were still visible, but they looked dimmer, and completely frozen: truck lights left on, torches fallen from hands. . . . The concussion had probably killed many of them. The rest would be likely to be still unconscious when the Javelin left.
     “A clean takeoff,” Ertak’s voice said calmly. “Ship’s officers, begin countdown. We will follow in eight minutes.” He paused and seemed to check some board hidden by his chest. Then he added, “To. all hands: congratulations. The Javelin is the last ship able to leave, and the last of these still on the ground. Twenty-nine others are all already on their way.”
     Thirty ships, Jom thought numbly. Thirty ships.
     “Correction, we are thirty-one in all. We have a signal from the Kestrel. She is damaged but off safely.”

     There was a ragged cheer in the earphones. Jom did not join in it. What difference could one ship make? What difference would ten have made?
     “Census . . . thank you. To all hands : we now have a final population check. We are carrying seventy-five thousand people, give or take about a hundred. We have escaped—and by that token, we know that we will survive. Take-off in thirty seconds.”
     We have escaped ... we will survive. And yet . . . how many died when the Quarrel vanished, and the lights were stilled on Salt Flats? How many more would die to the departure of the Javelin? How many had been killed to keep them out of the ships, all over the world?
     We will survive. But who are we to survive?

From ...AND ALL THE STARS A STAGE by James Blish (1960)

(ed note: in the novel they are trying to guard an underground shelter instead of a space ark. But the same principles apply to defense)

As Seaton assumed, the near-collision of suns which had affected so disastrously the planet Valeron did not come unheralded to overwhelm a world unwarned, since for many hundreds of years her civilization had been of a high order indeed. Her astronomers were able, her scientists capable, the governments of her nations strong and just. Years before its occurrence the astronomers had known that the catastrophe was inevitable and had calculated dispassionately its every phase — to the gram, the centimeter, and the second.

With all their resources of knowledge and of power, however, it was pitifully little that the people of Valeron could do; for of what avail are the puny energies of man compared to the practically infinite forces of cosmic phenomena? Any attempt of the humanity of the doomed planet to swerve from their courses the incomprehensible masses of those two hurtling suns was as surely doomed to failure as would be the attempt of an ant to thrust from its rails an onrushing locomotive.

But what little could be done was done; done scientifically and logically; done, if not altogether without fear, at least in as much as was humanly possible without favor. With mathematical certainty were plotted the areas of least strain, and in those areas were constructed shelters. Shelters buried deeply enough to be unaffected by the coming upheavals of the world's crust; shelters of unbreakable metal, so designed, so latticed and braced as to withstand the seismic disturbances to which they were inevitably to be subjected.

Having determined the number of such shelters that could be built, equipped, and supplied with the necessities of life in the time allowed, the board of selection began its cold-blooded and heartless task. Scarcely one in a thousand of Valeron's teeming millions was to be given a chance for continued life, and they were to be chosen only from the children who would be in the prime of young adulthood at the time of the catastrophe.

These children were the pick of the planet: flawless in mind, body, and heredity. They were assembled in special schools near their assigned refuges, where they were instructed intensively in everything that they would have to know in order that civilization should not disappear utterly from the universe.

Such a thing could not be kept a secret long, and it is best to touch as lightly as possible upon the scenes which ensued after the certainty of doom became public knowledge.

Humanity both scaled the heights of self-sacrificing courage and plumbed the very depths of cowardice and depravity.

Characters already strong were strengthened, but those already weak went to pieces entirely in orgies to a normal mind unthinkable. Almost overnight a peaceful and lawabiding world went mad — became an insane hotbed of crime, rapine, and pillage unspeakable. Martial law was declared at once, and after a few thousand maniacs had been ruthlessly shot down, the soberer inhabitants were allowed to choose between two alternatives. They could either die then and there before a firing squad, or they could wait and take whatever slight chance there might be of living through what was to come — but devoting their every effort meanwhile to the end that through those selected few the civilization of Valeron should endure.

Many chose death and were executed summarily and without formality, without regard to wealth or station. The rest worked. Some worked devotedly and with high purpose, some worked hopelessly and with resignation. Some worked stolidly and with thoughts only of the present, some worked slyly and with thoughts only of getting themselves, by hook or by crook, into one of those shelters. All, however, from the highest to the lowest, worked.

Since the human mind cannot be kept indefinitely at high tension, the new condition of things came in time to be regarded almost as normal, and as months lengthened into years the routine was scarcely broken. Now and then, of course, one went mad and was shot; another refused to continue his profitless labor and was shot; still another gave up the fight and shot himself. And always there were the sly the self-seekers, the bribers, the corruptionists — willing to go to any lengths whatever to avoid their doom. Not openly did they carry on their machinations, but like loathsome worms eating at the heart of an outwardly fair fruit. But the scientists, almost to a man, were loyal. Trained to think, they thought clearly and logically, and surrounded themselves with soldiers and guards of the same stripe. Old men or weaklings would have no place in the post-cataclysmic world and there were accommodations for only the exactly predetermined number; therefore only those selected children and no others could be saved or would. And as for bribery, threats, blackmail, or any possible form of racketry or corruption — of what use is wealth or power to a man under sentence of death? And what threat or force could sway him?

Wherefore most of the sly were discovered, exposed, and shot.

Time went on. The shelters were finished. Into them were taken stores, libraries, tools and equipment of every sort necessary for the rebuilding of a fully civilized world. Finally the "children," now in the full prime of young manhood and young womanhood, were carefully checked in. Once inside those massive portals they were of a world apart.

They were completely informed and completely educated; they had for long governed themselves with neither aid nor interference; they knew precisely what they must face; they knew exactly what to do and exactly how to do it. Behind them the mighty, multiply seals were welded into place and broken rock by the cubic mile was blasted down upon their refuges.

Day by day the heat grew more and more intense. Cyclonic storms raged ever fiercer, accompanied by an incessant blaze of lightning and a deafeningly continuous roar of thunder. More and ever more violent became the seismic disturbances as Valeron's very core shook and trembled under the appalling might of the opposing cosmic forces.

Work was at an end and the masses were utterly beyond control. The devoted were butchered by their frantic fellows; the hopeless were stung to madness; the stolid were driven to frenzy by the realization that there was to be no future; the remaining sly ones deftly turned the unorganized fury of the mob into a purposeful attack upon the shelters, their only hope of life.

But at each refuge the rabble met an unyielding wall of guards loyal to the last, and of scientists who, their work now done, were merely waiting for the end. Guards and scientists fought with rifles, ray-guns, swords, and finally with clubs, stones, fists, feet and teeth. Outnumbered by thousands they fell and the howling mob surged over their bodies. To no purpose. Those shelters had been designed and constructed to withstand the attacks of Nature gone berserk, and futile indeed were the attempts of the frenzied hordes to tear a way into their sacred recesses.

Thus died the devoted and high-souled band who had saved their civilization; but in that death each man was granted the boon which, deep in his heart, he craved. They had died quickly and violently, fighting for a cause they knew to be good. They did not die as did the members of the insanely terror-stricken, senseless mob... in agony... lingeringly... but it is best to draw a kindly veil before the horrors attendant upon that riving, that tormenting, that cosmic outraging of a world.

The suns passed, each upon his appointed way. The cosmic forces ceased to war and to the tortured and ravaged planet there at last came peace. The surviving children of Valeron emerged from their subterranean retreats and undauntedly took up the task of rebuilding their world. And to such good purpose did they devote themselves to the problems of rehabilitation that in a few hundred years there bloomed upon Valeron a civilization and a culture scarcely to be equaled in the universe.

For the new race had been cradled in adversity. In its ancestry there was no physical or mental taint or weakness, all dross having been burned away by the fires of cosmic catastrophe which had so nearly obliterated all the life of the planet. They were as yet perhaps inferior to the old race in point of numbers, but were immeasurably superior to it in physical, mental, moral, and intellectual worth.

Immediately after the Emergence it had been observed that the two outermost planets of the system had disappeared and that in their stead revolved a new planet. This phenomenon was recognized for what it was, an exchange of planets; something to give concern only to astronomers.

No one except sheerest romancers even gave thought to the possibility of life upon other worlds, it being an almost mathematically demonstrable fact that the Valeronians were the only life in the entire universe. And even if other planets might possibly be inhabited, what of it? The vast reaches of empty ether intervening between Valeron and even her nearest fellow planet formed an insuperable obstacle even to communication, to say nothing of physical passage. Little did anyone dream, as generation followed generation, of what hideously intelligent life that interloping planet bore, nor of how the fair world of Valeron was to suffer from it.

From SKYLARK OF VALERON by E. E. "Doc" Smith (1934)

Type: Covered Wagon

This is a minimal cheap spacecraft used by Maw and Paw to travel to the asteroid belt in order to set up a homestead.

They are lofted into orbit by either a chemical booster or laser launch service. Or manufactured in orbit; with Maw, Paw, and their brood buying tickets on a passenger service then taking possession.

At the cheapest they are basically a habitat module which rents propulsion services from a space tug, momentum bank, or a power-beaming service. Mid-range models will be something like a hydro ship, with some efficient and cheap (but low thrust) integral propulsion system. Top-of-the-line will be something approaching a full blown space tug, with enough delta-V to haul cargo.

These are examined in more detail here.

Type: Hydro Ship

As mentioned in the section on Ice Mining, when it comes to the industrialization and colonization of space, water is the most valuable substance in the Universe. Among other things it can be used for life support, reaction mass, and radiation shielding.

There will be lots of robot asteroid miners, many who will specialize in volatiles such as water. These include the CFW NEO MicroMiner, the Robot Asteroid Prospector (RAP), the Asteroid Provided In-Situ Supplies (APIS), the Kuck Mosquito, the Water Truck, and the Water Ship.

There is a prototype life support system called the Water Wall that is mostly composed of water.

There is even a rocket engine called the Microwave Electrothermal Thruster which uses water for reaction mass, has a respectable exhaust velocity of up to 9,800 m/s, is very reliable, and can easily be powered by solar panels. Oh, and unlike ion drives, you can make massed clusters of the little darlings and they won't electromagnetically interfere with each other. You can make an array of 400 or so to produce a whopping 12,000 Newtons of thrust. They are also very easy to repair. Even by an amateur.

Best of all, if you mix water with a binder and freeze it, you get Pykrete, which is a building material. You could even use it to, well, build a spaceship or space station with. This turned up in Neal Stephenson's science fiction novel Seveneves, but there is no reason it couldn't be done in reality.

Which means you could make a spacecraft that was mostly water.

For an example, see the Spacecoach below.

Now this would not be suitable to make space battleships or space fighters with, but it would be dandy for interplanetary wagon trains for Maw and Paw Kettle to go homesteading in the asteroid belt. Mostly made of water, which cheaply comes from in-situ resource utilization. Not the strongest nor the most durable, but very affordable.

This would also be useful for somebody with limited access to raw materials. Say, refugees from a galactic war entering a remote uninhabited star system, carrying only whatever odd bits of material and tools that will fit into the cargo space not filled with refugees.


      Most of all he liked to watch the rings. At the left, they emerged from behind Saturn, a tight, bright triple band of orange fight. At the right, their beginnings were hidden in the night shadow, but showed up closer and broader. They widened as they came, like the flare of a horn, growing hazier as they approached, until, while the eye followed them, they seemed to fill the sky and lose themselves.
     From the position of the Scavenger fleet just inside the outer rim of the outermost ring, the rings broke up and assumed their true identity as a phenomenal cluster of solid fragments rather than the tight, solid band of light they seemed.
     Below him, or rather in the direction his feet pointed, some twenty miles away, was one of the ring fragments. It looked like a large, irregular splotch, marring the symmetry of space, three quarters in brightness and the night shadow cutting it like a knife. Other fragments were farther off, sparkling like star dust, dimmer and thicker, until, as you followed them down, they became rings once more.
     The fragments were motionless, but that was only because the ships had taken up an orbit about Saturn equivalent to that of the outer edge of the rings.
     The day before, Rioz reflected, he had been on that nearest fragment, working along with more than a score of others to mold it into the desired shape. Tomorrow he would be at it again.

     He strengthened pseudo-grav and lifted the projector a bit. He released pseudo-grav, insuring that the projector would stay in place for minutes even if he withdrew support altogether. He kicked the cable out of the way (it stretched beyond the close “horizon” to a power source that was out of sight) and touched the release.
     The material of which the fragment was composed bubbled and vanished under its touch. A section of the lip of the tremendous cavity he had already carved into its substance melted away and a roughness in its contour had disappeared.
     “Try it now,” called Rioz.
     Swenson was in the ship that was hovering nearly over Rioz's head.
     Swenson called, “All clear?”
     “I told you to go ahead.”
     It was a feeble flicker of steam that issued from one of the ship's forward vents. The ship drifted down toward the ring fragment. Another flicker adjusted a tendency to drift side-wise. It came down straight.
     A third flicker to the rear slowed it to a feather rate.
     Rioz watched tensely. “Keep her coming. You'll make it. You'll make it.”
     The rear of the ship entered the hole, nearly filling it. The bellying walls came closer and closer to its rim. There was a grinding vibration as the ship's motion halted.
     It was Swenson's turn to curse. “It doesn't fit,” he said.
     Rioz threw the projector ground-ward in a passion and went flailing up into space. The projector kicked up a white crystalline dust all about it, and when Rioz came down under pseudo-grav, he did the same.
     He said, “You went in on the bias, you dumb Grounder.”
     “I hit it level, you dirt-eating farmer.”
     Backward-pointing side jets of the ship were blasting more strongly than before, and Rioz hopped to get out of the way.
     The ship scraped up from the pit, then shot into space half a mile before forward jets could bring it to a halt.
     Swenson said tensely, “We'll spring half a dozen plates if we do this once again. Get it right, will you?”
     “I'll get it right. Don't worry about it. Just you come in right.”
     Rioz lumped upward and allowed himself to climb three hundred yards to get an over-all look at the cavity. The gouge marks of the ship were plain enough. They were concentrated at one point halfway down the pit. He would get that.
     It began to melt outward under the blaze of the projector.
     Half an hour later the ship snuggled neatly into its cavity, and Swenson, wearing his space suit, emerged to join Rioz.
     Swenson said, “If you want to step in and climb out of the suit, I'll take care of the icing.”
     “It's all right,” said Rioz. “I'd just as soon sit here and watch Saturn.”
     He sat down at the lip of the pit. There was a six-foot gap between it and the ship. In some places about the circle, it was two feet; in a few places, even merely a matter of inches. You couldn't expect a better fit out of handwork. The final adjustment would be made by steaming ice gently and letting it freeze into the cavity between the lip and the ship.
     Saturn moved visibly across the sky, its vast bulk inching below the horizon.
     Rioz said, “How many ships are left to put in place?”
     Swenson said, “Last I heard, it was eleven. We're in now, so that means only ten. Seven of the ones that are placed are iced in. Two or three are dismantled.” “We're coming alone fine.”
     “There's plenty to do yet. Don't forget the main jets at the other end. And the cables and the power lines."

     It had all seemed perfectly logical back on Mars, but that was Mars. He had worked it out carefully in his mind in perfectly reasonable steps. He could still remember exactly how it went. It didn't take a ton of water to move a ton of ship. It was not mass equals mass, but mass times velocity equals mass times velocity. It didn't matter, in other words, whether you shot out a ton of water at a mile a second or a hundred pounds of water at twenty miles a second. You got the same velocity out of the ship.
     That meant the jet nozzles had to be made narrower and the steam hotter. But then drawbacks appeared. The narrower the nozzle, the more energy was lost in friction and turbulence. The hotter the steam, the more refractory the nozzle had to be and the shorter its life. The limit In that direction was quickly reached.
     Then, since a given weight of water could move considerably more than its own weight under the narrow-nozzle conditions, it paid to be big. The bigger the water-storage space, the larger the size of the actual travel-head, even in proportion. So they started to make liners heavier and bigger. But then the larger the shell, the heavier the bracings, the more difficult the weldings, the more exacting the engineering requirements. At the moment, the limit in that direction had been reached also.
     And then he had put his finger on what had seemed to him to be the basic flaw—the original unswervable conception that the fuel had to be placed inside the ship; the metal had to be built to encircle a million tons of water.
     Why? Water did not have to be water. It could be ice, and ice could be shaped. Holes could be melted into it. Travel-heads and jets could be fitted into it. Cables could hold travel-heads and jets stiffly together under the influence of magnetic field-force grips.
     Long felt the trembling of the ground he walked on. He was at the head of the fragment. A dozen ships were blasting in and out of sheaths carved into its substance, and the fragment shuddered under the continuing impact.
     The ice didn't have to be quarried. It existed in proper chunks in the rings of Saturn. That's all the rings were — pieces of nearly pure ice, circling Saturn. So spectroscopy stated and so it had turned out to be. He was standing on one such piece now, over two miles long, nearly one mile thick. It was almost half a billion tons of water, all in one piece, and he was standing on it.
     But now he was face to face with the realities of life. He had never told the men just how quickly he had expected to set up the fragment as a ship, but in his heart, he had imagined it would be two days. It was a week now and he didn't dare to estimate the remaining time. He no longer even had any confidence that the task was a possible one. Would they be able to control jets with enough delicacy through leads slung across two miles of ice to manipulate out of Saturn's dragging gravity?
     Drinking water was low, though they could always distill more out of the ice. Still, the food stores were not in a good way either.
     Some of the men were having trouble with the cables. They had to be laid precisely; their geometry had to be very nearly perfect for the magnetic field to attain maximum strength. In space, or even in air, it wouldn't have mattered. The cables would have lined up automatically once the juice went on.
     Here it was different. A gouge had to be plowed along the planetoid's surface and into it the cable had to be laid. If it were not lined up within a few minutes of arc of the calculated direction, a torque would be applied to the entire planetoid, with consequent loss of energy, none of which could be spared. The gouges then had to be re-driven, the cables shifted and iced into the new positions.
     The men plodded wearily through the routine.

     Long had no assurance that it would work. Even if the jets would respond to the distant controls, even if the supply of water, which depended upon a storage chamber opening directly into the icy body of the planetoid, with built-in heat projectors steaming the propulsive fluid directly into the driving cells, were adequate, there was still no certainty that the body of the planetoid without a magnetic cable sheathing would hold together under the enormously disruptive stresses.
     “Ready!” came the signal in Long's receiver.
     Long called, “Ready!” and depressed the contact.
     The vibration grew about him. The star field in the visiplate trembled.
     In the rear-view there was a distant gleaming spume of swiftly moving ice crystals.
     “It's blowing!” was the cry.
     It kept on blowing. Long dared not stop. For six hours, it blew, hissing, bubbling, steaming into space; the body of the planetoid converted to vapor and hurled away.

     The flotilla, welded into a single unit, was returning over its mighty course from Saturn to Mars. Each day it flashed over a length of space it had taken nine days outward. Ted Long had put the entire crew on emergency. With twenty-five ships embedded in the planetoid taken out of Saturn's rings and unable to move or maneuver independently, the co-ordination of their power source into unified blasts was a ticklish problem. The jarring that took place on the first day of travel nearly shook them out from under their hair.
     That, at least, smoothed itself out as the velocity raced upward under the steady thrust from behind. They passed the one-hundred-thousand-mile-an-hour mark late on the second day, and climbed steadily toward the million-mile mark and beyond.
     Long's ship, which formed the needle point of the frozen fleet, was the only one which possessed a five-way view of space. It was an uncomfortable position under the circumstances. Long found himself watching tensely, imagining somehow that the stars would slowly begin to slip backward, to whizz past them, under the influence of the multi-ship's tremendous rate of travel.

     “You see that?” Sankov, pointing.
     “Hey!” cried a reporter. “It's a ship!”
     A confused shouting came from the adjoining room.
     It wasn't a ship so much as a bright dot obscured by a drifting white cloud. The cloud grew larger and began to have form. It was a double streak against the sky, the lower ends billowing out and upward again. As it dropped still closer, the bright dot at the upper end took on a crudely cylindrical form.
     It was rough and craggy, but where the sunlight hit, brilliant high lights bounced back.
     The cylinder dropped toward the ground with the ponderous slowness characteristic of space vessels. It hung suspended on those blasting jets and settled down upon the recoil of tons of matter hurling downward like a tired man dropping into his easy chair.
     And as it did so, a silence fell upon all within the dome. The women and children in one room, the politicians and reporters in the other remained frozen, heads craned incredulously upward.
     The cylinder's landing flanges, extending far below the two rear jets, touched ground and sank into the pebbly morass. And then the ship was motionless and the jet action ceased.
     But the silence continued in the dome. It continued for a long time.
     Men came clambering down the sides of the immense vessel, inching down, down the two-mile trek to the ground, with spikes on their shoes and ice axes in their hands. They were gnats against the blinding surface.
     One of the reporters croaked, “What is it?”
     “That,” said Sankov calmly, “happens to be a chunk of matter that spent its time scooting around Saturn as part of its rings. Our boys fitted it out with travel-head and jets and ferried it home. It just turns out the fragments in Saturn's rings are made up out of ice.”
     He spoke into a continuing deathlike silence. ”That thing that looks like a spaceship is just a mountain of hard water. If it were standing like that on Earth, it would be melting into a puddle and maybe it would break under its own weight. Mars is colder and has less gravity, so there's no such danger.
     “Of course, once we get this thing really organized, we can have water stations on the moons of Saturn and Jupiter and on the asteroids. We can scale in chunks of Saturn's rings and pick them up and send them on at the various stations. Our Scavengers are good at that sort of thing.
     “We have all the water we need. That one chunk you see is just under a cubic mile-or about what Earth would send us in two hundred years. The boys used quite a bit of it coming back from Saturn. They made it in five weeks, they tell me, and used up about a hundred million tons. But, Lord, that didn’t make any dent at all in that mountain. Are you getting all this, boys?”

From THE MARTIAN WAY by Isaac Asimov (1952)

      So maybe it was Gallagher and his glacier that changed the times, and not the times that fitted Gallagher.
     A pioneer is a man who goes out into the unknown and solves equations to the best of his ability as he meets them. In that respect, Gallagher was a pioneer, and I knew that in that respect I wasn’t. That hurt the ever-living soul of me, underneath all the degrees and certificates that said I was captain of a ship and he wasn’t. An engineer is a man who gets ajob done, and in that respect Gallagher was an engineer. I didn’t know whether I was an engineer or not, for I had the book learning, but the ship was a push-button affair that took some handling but that mostly took automatics; and the Port Inspector was the one who said how the automatics would be structured. Gallagher had as good a piece of paper to prove he was an engineer as I did, but he held that piece of paper in great contempt, except when he needed a job, which was a good part of the time since, though he was an engineer with a spacelanes-long reputation, he never had developed a talent for staying on a company ship. As a pioneer, he never had been able to latch onto a colony, company, or otherwise, and stay, for he had a sociable nature that needed to be out and visiting around the spaceways.
     Gallagher’s name was black in the company books. He’d jump a ship or stow away out of a colony as soon as sign the papers.
     So now he sat, mostly in Joe ’s Bar, and waited for a ship to orbit that was setting a course the way he wanted to go. How he was planning to sign on with his name so black in the books, he wasn’t saying.

     But when my ship orbited, and us heading for Altura, there was a small series of untraceable incidents that left my engineer in the hospital. At the same time, I got the news of the “incidents,” Gallagher presented himself shipside with his piece of paper.
     “Your next port is Altura, Captain Harald Dundee,” he said proud-like. His name was N. N. Gallagher, and they called him “Dublin” as a pun and for courtesy of his origin. He stood six feet tall in my cabin, his red hair nearly brushing the topsides, making me feel small and a little insignificant for all my fine uniform, for I clear that ceiling by a good four inches.
     “And,” he said, “it’s toward Altura I’m headin’. Now, seeing as it’s not rightly your fault you’re minus an engineer for the course, I’ll take on the job without much cost to you. There’s a glacier that’s orbiting towards Altura. You can compute to intersect her within three hours of your port. I’ll take on your engineer’s post that far and charge you naught, if you’ll put me aboard that glacier, me and my equipment. And your assistant engineer can take her in from there.”

     Well, that was that, but when I found out what Gallagher meant by equipment, I nearly reneged again. The holds would take it, but we’dl be shipping heavy.
     “You’ll be heavy only so long as I’m aboard, and I’ll have your drive talking so pretty she’ll use less mass than if you were running light with anybody else to engineer her,” says Gallagher modestly. “Your assistant will have a light ship to take in, and the motors already purring.”
     The equipment included one of the old Antolaric drives that used to power the ships they sent out when man first entered space, and it was as massive as the old ships used to be. Then there were supplies to last a man for months, but those weren’t much; and machinery enough to stock a small shop.

     I didn’t understand Gallagher, but I knew him for a breed that caught at the heart of me, for we were both from the old country and we were both out in the new spaceways. There was a kinship between us I couldn’t deny, though the frictions said we were alien, and me a corporation man.
     I understood the man even less when we matched courses with his glacier and I had him and his equipment drifted over to it. It couldn’t have been more than a mile the long way, and a quarter mile through; an ungainly hunk of ice idling through space. What the man could want with it was more than I could see. There were plenty of steel meteorites that size, if Gallagher wanted to make himself a meteor ship—and I admit that seeing that old drive was the first inkling I’d got of such a use. But ice? Then I realized. A steel meteor wouldn’t have given him reaction mass for his fusion chamber, but that ice was a good part hydrogen, and that would be his mass.

     Well, I’d be a few days planetbound, and I spent the first of them partly wandering the company town, partly in the port bar. By the end of the fourthday, I was so furious with Gallagher that I was making up conversations with him, telling him off. And, if you come right down to it, curious. I couldn’t figure how he was going to manage the job alone. I had to see.
     By midnight I’d rationalized myself into good reasons. The man was daft. He was alone on an iceberg, drifting helplessly in space. By now he’d have realized how helplessly. The least I could do—now that his senses had had a chance to reorganize—was to offer him an oiler’s job to get him out of the mess he’d talked himself into. I wouldn’t leave a dog alone out there, I told myself. I owed him a chance to stow away honorably.
     I rented a small interplanet scout, and I headed back for Gallagher's glacier.

     What I expected to find I’m not sure. What I found was the glacier—lonely and sparkling cold —and I could make out Gallagher’s vac-suited figure working on its surface as I matched orbit two kilometers off.
     Since he was on the surface and in a vac suit, I hailed him over the ship’s suit comm, but he failed to answer, and I maneuvered the scout in closer, seeking a place to tie up. That’s when I got an answer.
     “Sheer off, you lunkhead,” came his voice. “I’ll not have you upsetting my balances here.” I was readying a tart reply when he went on. “Anyhow, this is already claimed."
     “Okay, Dublin,” I said. “If you’re too proud to let your former captain see the mess you’ve got into, I’ll be heading back to port. I was just being sociable anyhow.”
     The figure stood and waved, and Gallagher’s tones, hardly less gruff than before, came back over the suit comm. “Neighborly of you, captain. Take her around on the far side and hitch up to a mooring line. But gently, mind you. I’ll still not have you upsetting my balance.
     I was blessed if I could see what he might have in mind about balances, but I eased the scout around to the far side, and that’s when I got my first good look at what Gallagher had been doing.

     There was a bubble,dome anchored firmly to one of the smoother parts of the big ice chunk, and a half-dozen standard bourdon mooring tubes—long, snaky pipes of plastic inflated with gas—that extended out from the surface and to which various “dumps” had been attached. The bubble dome was fair enough; normal equipment for airless planetary living. And the bourdon mooring tubes were normal, if they were attached securely enough to the iceberg.
     I hesitated before mooring to a vacant tube. They’d attach to the scout all right; and if they were moored securely at the far end, fine. But if they weren’t? Well, I’d moor, I decided, and keep an eye on the scout. If it pulled the line loose and started to drift, I could catch it in the first few minutes with the rockets on my suit.
     I nudged up to the tube and was rewarded with the hollow clink of a magnalock. The line was a good kilometer long, but I could see a tiny shuttlebug start its whirring way up the mooring line, so I’d have fast travel going in. Fully automatic, that response; keyed to the impulse of the magnalock. Gallagher was doing better than might have been expected.
     While I waited, I looked over the cargo dumps attached to the other tubes. Nothing but the things we had left, of course. And there was the Antolaric drive—not moored to a tube, but carefully stanchioned directly at the far end of the berg itself, lined up with the balance point of the berg as though it were nudging the glacier from behind.
     A pushberger? I asked myself sarcastically. Is he planning to push the damned berg to the nearest planet? It won’t work that way, I assured myself. A drive is internal to the ship. Necessarily, I emphasized warily to myself, but with the haunting feeling that maybe I was missing something, the memory of the Starfire’s tuning fresh upon me.

     The shuttlebug arrived, and I reached out to grasp the awkward thing, flinging my legs over the upside-down crossbar of the T, and grasping the pipe that led to the tiny foot-long motor firmly clamped to a plastic track along the side ofthe mooring tube. I nudged the trigger and got the giddy sensation of being thrown forward at nearly half a gee as the tiny electric motor whined along the semigeared track; but the acceleration was brief, and I seemed more to be floating than actually riding as I descended towards the glacier.
     It’s a funny feeling, watching a glacier come up at you. You’re not actually falling toward it, nor it toward you, but it feels like it. All directions are up from the largest object, when you’re in a vac suit in space—or even when you’re in a small scout. So if you’re “up” from the big object and you’re approaching it, you’re falling—at least in your mind’s eye, and it’s hard to remember that it’s just travel on a straight line.
     The glacier “below” me was a spread-out panorama, nearing rapidly, and as it neared I could make out curious black spots. Huge black spots. Faults? No, they were too regular. Paint? Hardly. Probably radiator surfaces. Very probably, from the looks. But how had the man spread radiators directly on an ice surface? And how the devil had one man handled a standard radiator surface at all?
     I postponed my curiosity. I’d have at least an hour or so to inspect what had been done while Gallagher made his way around the glacier, and I’d not waste the time.

     But as the shuttlebug threw me into deceleration for the landing (and I got the feeling of falling up), I saw a suited figure emerge from the bubble dome near the terminus and wave to me.
     “Welcome aboard, captain.” The voice over the intercom was Gallagher’s. Most voices you can’t recognize over an intercom, but Gallagher’s is different. No intercom can cover that particular tonal quality. How he’d gotten that far that quick I didn’t know; but I did know that he was there. Yet—you couldn’t even have walked that distance on the skin of a metal ship in a suit with electret shoes, much less on the surface of a glacier with whatever crampers or ice-locks he’d dreamed up to keep him from drifting off the berg.
     “Hi,” I said weakly. “About ready to give up this foolishness?” It was too late to change my rationale now, though it did sound a little silly, what with the efficiency with which he’d got his stuff secured and gotten ready to go to work.
     “I rather thought you’d come because you were ready to give up your foolishness,” he replied. “Have they got the Starfire back to its sluggish norm yet? Independent Spaceways, namely me, can use a good navigator. glad you’re volunteering.”
     He’d hit the nail on the head about that retuning, and I could feel myself getting red. I was glad I was in a vac suit and he couldn’t see it. I kept my voice calm and merely said, “You look to be handling the initial stages okay. But maybe you’ve had some second thoughts.”

     I dropped from the shuttlebug. As my feet touched the ice, I was surprised to find that the electret shoes of my own suit gripped it quite satisfactorily. Somehow I hacln’t expected the electrostatic field to work on ice, even though I could see Gallagher standing right there waiting for me with no gripping problem.
     He laughed and led me to the bubble dome, and as we unhelmeted in the airlock, I put my foot in my mouth again. “Who’s working on the far side of your berg?” I asked. “I saw somebody in a vac suit there as I came in. I thought you were alone.”
     He didn’t answer at once, just opened the inner airlock door. And there, leading off from the far side of the dome, was a yawning shaft going straight down into the ice, with a shuttlebug hanging in its mouth as though it were just as logical to use one inside a ship as out.

     “Just me and my bugs, captain,” he said grinning.
     “Bugs?” I glanced sideways at Gallagher and then back at the hold. Then: “Shuttlebugs I understand. But tunnels like that? Why, it would take a man a month to dig a tunnel like that through a berg like this.
     He nodded solemnly. “Aye, and you’re right, captain. But I didn’t mean just shuttlebugs. Most of the cargo ye landed me here with was bugs of one kind and another.” He pointed to a large, odd-looking circular metallic device lying to one side against a wall of the dome. “There’s one of the bigger ones there.”
     I walked over and looked at the thing. It had a rim which I judged would just fit inside the tunnel; and in the center of the rim a rotating nose with a screw thread on it. About one turn every two centimeters, I decided. I looked more closely at the rim and saw that there were ridges so that if it were passing through ice it could slide easily forward, but could not turn readily. The rim itself seemed to be of two different materials, with a leading edge of metal, and a ten-centimeter-long trailing section of plastic that matched the shape, including the grooves.
     “Quite a fancy gadget,” I said. “But—how can a thing like this drill through ice? That nose with the screw thread on it doesn’t look very sharp, and certainly there aren’t any teeth here.” I pointed to the surface between the protruding screw nose and the rim.
     “Careful. It’s hot,” Gallagher said—and the idea of the machine clicked into my mind as an operating device. The surface was sensibly hot. The screw would be heated, too; and if you turned the thing nose-first against a piece of ice and gave it a shove, it could probably melt its way rapidly in and then get hold and keep on going. A sievelike mesh that formed the metallic surface between the rim and the spinner screw would take in water, I realized.
     “Clever,” I said. “Is it self-programming?”
     “Pretty much so. It’s got maybe the brains of a mouse. That’s what I call it. An ice mouse.”

     “What does it do with the water?” I asked.
     “Just kicks it out the back into the tunnel. I have to pump it from there. But I’ve smaller ones as well, and they make nice little water pipes for wherever I want to program them to go, so the pumping’s not all that much of a problem.”
     “And you pump the water out to those radiator surfaces for refreezing?” I asked. “How did you manage to move radiators like that around anyhow? Or, for that matter, where did you get them? I don’t recall having landed anything as heavy as a radiator here.”
     “Well, now. Which question first? The radiators were part of the equipment you landed, believe it or not. But they’re not heavy. They’re very lightweight plastic, and high-temperature stuff at that. It’s amazing how much more heat you can reject at four or five hundred degrees than you can from a low-temperature surface. And since it ’s the difference you’re working with, it makes good sense to have high-temperature radiators where the only energy dumped is by black-box radiation.
     “To answer the first question last, though,” Gallagher went on, “the water is not pumped directly into the radiators. If it were, that’s where it would freeze up. Actually, the refrigeration system is a little more complicated than that. But you’re right; that water is refrozen after it’s pumped where I want it. I scoop it out here and freeze it there. In a few weeks, I’ll have this berg balanced out and hollowed out and set up just the way I want it.”

     I had to admire the system, but I guess I was jealous enough I had to disparage it, too. So, since it was at least chilly if not downright cold in that dome, I shivered as obviously as possible as I said, “It would seem that you’ve picked a pretty well air-conditioned environment, but aren’t you afraid that the constant cold will get to you?”
     Gallagher grinned and motioned me to the tunnel leading down. “Come on in,” he said. “This dome is sort of chilly. It’s acting as my airlock right now, but I’ll probably replace it with a more conventional airlock sooner or later."
     It was a weird sensation, taking a shuttlebug through a tunnel where I could have reached both walls by simply outstretching my arms. The smooth, glistening ridges that had been left behind by Gallagher’s ice mouse as it formed the tunnel were as regularly milled and precise as the machine that had made them. But it seemed to me that we ’d not gone nearly halfway through when the shuttlebug paused and I swung myself off into a short corridor at right angles.
     This one wasn’t milled. It wasn’t ice, for that matter. And there was proper decking for the soles of my boots to get a better hold. Of course there was no gravity, but I automatically assumed that Gallagher would take care of that— and in the not-too-distant future, at the rate he was going.

     “Your hotheaded ice mice,” I asked. “Can they be suitably programmed for making the necessary spin-and-balance tubing for a zero M-I spin-grav system?”
     “Sure. Ought to have that operating now”— Gallagher glanced at his wrist chronometer— “in another four or five hours. The mice are much busier than I am.”
     “But with water rushing around in ice tubes, won’t you have some tendency for the tubes to melt and distort?”
     “Melt? Sure they will. Except that the water will be brine, and a bit colder than the melting point of ice, so they won’t melt very fast. Distort? Well, maybe. Under some conditions of acceleration, the tubes will probably distort a bit, but mostly, since the fluid in the spin tubes goes in one direction and the ship goes in. the other, the net friction and thrust is radial to the spin. There shouldn’t be much distortion. The tubes will simply gradually work themselves right on out towardithe surface. But long before that happens, I’ll make a new tube inside. Anything a mouse can do once, he can do all over again. Like I said, they?re going to be busier than I am”
     “But won’t each spin tube leave a hollow place behind it?” I asked.
     “Nope. You see right above each spin tube there ’s a much smaller and much colder tube. So the tubes will plate back on the top what they lose on the bottom.”
     I paused for a minute and thought that one out. Up, of course, was toward the center of the ship, since we were talking about spin gravity. And down would be toward the outside of the ship.

     ;“Wait a minute, though. Will that tube on top move out along with the other, larger tube? Or, for that matter, why couldn’t "you put the cold tube underneath the spin tube to prevent the spin tube from wearing out?”
     “One at a time.” Gallagher waved me on through the bulkhead and into a comfortable cabin. “No matter how cold I made the ice, when ice is under pressure, it will melt. Obviously, the spin tubes will be under pressure. Therefore they would gradually melt even if they were kept much colder than would be reasonably efficient. So actually it’s much simpler to allow the tube to melt and move itself out, say, three times the distance of its own diameter. Then simply make a new tube in the part it started from. Actually, it’ll probably be more complicated that that. There’ll be one tube being made and another being filled in while a third, somewhere in between them is operating to keep the spin going.”
     I could follow that much, but I had a feeling that if I let Gallagher go on, there would be more and more complications added. I could even visualize part of it. The necessary static balance tanks in which the level of water could be changed as other weights—like people—moved around inside the ship and tended to shift the spin-center according to their own positions. But it was really a very standard sort of thing operationally, and I could have drawn a blueprint for it from the memory of my own ship.

     “Okay, but just one more point,” I finally decided. “This cabin is nice and warm and insulated no doubt. But it does have mass and it will walk, just like that spin tube. What do you plan to do about that?”
     “Now you’re getting the picture, Harald!” Gallagher broke into a huge grin. “There’s no such thing as static stability in a malleable ship. And ice is one of the most malleable media you could ask to work with. Actually, this cabin is built with a hot head, something like that the mice use. You turn everything off and let it sink, it would sink right on out through the ice and get spun off into space, once we got spin gravity going. But its rate of sinking won’t be very fast, when you consider the square area of floor and the actual mass involved—as a matter of fact, it will float and move toward the inside. But we can do something about it whether it floats or sinks. It’s merely a matter of melting a little bit of the ice around the room and then repositioning it by hydrostatic pressure. If I want to move a cabin to the other side of the ship, I can do it in two or three days and scarcely disturb a thing in the process.”
     I shook my head in awe. The idea of floating cabins around in a ship to make new layouts at will was a bit much for a by-the-book captain and engineer such as myself.
     Then Gallagher capped it by summing the whole thing into a nutshell that spelled not only the difference between our ships, but between ourselves and what we represented.
     “You see,” he said, and his damned voice wasn’t even sarcastic, “you’re used to thinking in terms of static stability—forms that keep their shape by being rigid; forms that can’t change because any major change destroys them.
     “My glacier,” he went on, and his voice was warm and loving, “she can change and adapt and grow and evolve. She has dynamic stability, and that’s quite a different thing.”

(ed note: Gallagher hidden meaning is that the megacorporation that has a stranglehold on interstellar trade also has static stability, and cannot change because a major change would destroy the corporation. Gallagher's free trader company has dynamic stability, so it can change and adapt and grow and evolve.)

     That Gallagher. I cursed the day I’d met him, as I orbited back to Altura and my spick-and-span ship with all its properly latest gadgets and technological advances incorporated as they were developed. I’d never own my own ship, but by the gods, I told myself, I captained a good one! And when my time was run, as it runs fast in the spaceways, l’d have the cash to buy a small farm and settle down on any planet that I chose where they were accepting colonists.
     And there was Gallagher, as though he were mocking me, with an old Antolaric drive and probably the finest engineering talent on the starlanes, using it to make an old hunk of ice into a makeshift ship that would be the laughingstock of the spaceways.

     Take those radiator units—made of black plastic which could be turned black side toward the darker portions of space as radiators; or, in event of an emergency, toward the local sun as power collectors. The back surface was a silvery, metalized reflector, air-spaced to insulate the radiators from the icy surface to which they were attached.
     And they were attached, as were the mooring tubes I’d worried about—quite effectively attached with a gadget he called a hothead bug. It was a combination electric motor with a double-acting screw thread and a very hot nose; similar to his ice mice, but designed as an anchor. Place the thing on the ice and start it moving, it would burrow itself in like a tiny animal; and the screw thread with which it drove itself would remain in the tube. behind it, so it could be run in and back out again if you wished. Or it could simply run in pulling a cable behind it and stay there for as long as you liked.
     He had small ones for anchoring and big ones —the ice mice—for corridors; and extensive ones with which he was riddling the surface of the ship, creating small-bore tubing in the ice to be used for such things as circulating the cooling brine to maintain the frozen surfaces, and to carry off the melted water to be refrozen where it was needed.
     And the drive itself, that I’d seen stanchioned back there like a pushberger. Hell, he’d just positioned it so that the hydrostatic force of its driving would melt it right inside the ship to where he wanted it.

     And Gallagher was wasting that engineering genius on a hunk of ice! Why, the man could work up to captain, would he abide the rules!

     But my own ship didn’t look as pretty as she used to look, and though I still saw to it that my men went portside only in threes, I took to going in alone, myself, in full uniform, and be damned to the risk.
     The whole thing worried me, and it worried me more as the months passed and the tales began to be traded from bar to bar.
     At first Gallagher and his glacier were a roar of laughter that swept the spaceways. But it was more than just a roar of laughter. The spaceways had their first independent shipper, and it was a proud thing, there under the stars.

From GALLAGHER'S GLACIER by Walt Richmond and Leigh Richmond (1979)


In 2010 Brian S. McConnell and Alex Tolley developed the Spacecoach concept and published it in a paper Reference Design for a Simple, Durable and Refuelable Interplanetary Spacecraft. This relatively low cost orbit-to-orbit spacecraft would be admirably suited for wagon trains in space. They could actually open up the solar system to pioneers if coupled with a low-cost surface-to-orbit transportation system such as a laser launcher. But McConnell and Tolley think the mass could be brought down enough to bring it within the boost capacity of, say a SpaceX Falcon 9 or Falcon 9 Heavy.

The basic premise of the spacecoach is to create a fully reusable orbit-to-orbit spacecraft that uses water and waste gases from crew consumables as its primary propellant.

So the design makes the consumables mass do double duty: first as life support for the crew, then as propellant. This drastically lowers the mass of the spacecraft, thus lowering the cost.

This also removes the incentive to install an expensive and cantankerous closed ecological life support system. Yes, supplies for a multiple year journey take up a lot of mass, but since it can be lumped under the heading of "propellant" it does not matter as much.

The water component of the consumables can do triple or quadruple duty. Before it is used as propellant, it can also serve as radiation shielding, supplemental debris shielding (as pykrete), and thermal regulation. In his simulation boardgame High Frontier developer Philip Eklund called water "the most valuable substance in the universe", and he was not kidding.

The spacecoach is also mostly constructed of water, in the form of pykrete. Very little metal is to be used. Actually it is very much like the composite ship from The Martian Way

The spacecoach will have sizable solar cell arrays used to power some species of electric rocket. There is some research underway to determine which of the many electric propulsion systems works best with water.

Ion drives, VASIMR, and helicon double layer rockets won't work because they are electricity hogs. They need to be fed by a nuclear reactor or equivalent, solar cells are too weak. Besides the insane price tag on a reactor and the ugly mass penalty, governments will be dubious about entrusting Maw and Paw Kettle with nuclear energy. They do have wonderful exhaust velocities, but the price is just too blasted high. Some won't even work with water as propellant.

Hall Effect Thrusters, Microwave Electrothermal Thruster (MET), and Electrodeless Lorentz Force Thruster (ELF) are much more suitable. They require much more modest amounts of electricity. Their exhaust velocities are weaker than the electricity hogs, but they are still much more potent than puny chemical rockets. These drives are also simpler to fabricate (i.e., cheaper, more reliable, lightweight, durable, and easily serviced). They can be clustered into arrays in order to increase the thrust. Electricity hog drives start interfering with each other if you cluster them.

The MET is especially simple. It isn't much more than a metal tube with a microwave magnetron attached. No moving parts either. It is sort of like a cross between a rocket engine and a microwave oven.

Current research shows a MET using water propellant can crank out a good 8,800 m/s exhaust velocity (Isp 900 sec) while an ELF can do about 16,700 m/s (Isp 1,700 sec). A Hall Effect thruster using water could theoretically do 29,000 m/s (3,000 sec) but researchers are still trying to figure out how to adapt them to water propellant.

For back-of-the-envelope calculations figure a spacecoach engine can do from 7,900 m/s to 20,000 m/s exhaust velocity (Isp 800 sec to 2000 sec). Compare this with chemical rocket's pathetic 4,400 m/s (450 sec).

20,000 m/s might not be quite enough to manage a trip to Ceres (10.593° inclination to ecliptic means a lot of delta V is needed), but the performance may be improved with more research.

The low thrust also minimizes the need for mass-expensive structural members.

McConnell and Tolley do have several design competitions open.


In December 2010, the Journal of the British Interplanetary Society published our peer reviewed paper, "Reference Design For A Simple, Durable and Refuelable Interplanetary Spacecraft".

The paper describes a ship made mostly of water, powered by microwave engines, that will be capable of reaching destinations throughout the solar system, at just 1/10th to 1/100th the cost of conventional chemical rockets.

The system described in the paper is based entirely on existing technologies that have already been flight tested or are well under development, and is feasible with present day technology and Earth launch platforms to low orbit.

These ships, in addition to being cheaper to build, will be fully reusable, and will be mostly organic structures that will be far more comfortable than conventional capsule designs, and more like a scaled down version of Gerard K O'Neil's proposed space colonies than a metal ship.

We're coining the term spacecoach to describe these ships, a reference to the prairie schooners of the Old West.

We hope you enjoy this site and share it with your friends and colleagues.

Brian S McConnell
Alexander M Tolley
From the introduction at the Spacecoach website

The covered wagon or prairie schooner is one of the iconic images of the 19th century westward migration of the American pioneers. The wagon was simple in construction, very rugged, and repairable. They were powered most often by oxen that lived on the food and water found along the trail. The cost of a wagon, oxen and supplies was about 6 months of family wages.

In 2009 my colleague Brian McConnell and I were thinking about how to open up the exploration of space in an analogous way to the opening up of the American West during the 19th century pioneering era. We were looking for an approach that, like the covered wagon, was affordable, relatively low tech, provided safety in the case of emergencies and the space environment, could “live off the land” for propulsion like oxen, and preferably was reusable so that costs could be amortised over a number of flights.

What follows is a description of the “spacecoach” from the perspective of a new crew member making a first visit to the ship that will be on a Phobos return mission.

Our transfer vehicle docked gently with the Martian Queen airlock. On approach, the Martian Queen resolved into 4 fat sausages, linked end to end. On either side, from bow to stern, were solar PV arrays, partially unfurled. She looked like no spaceship seen since the dawn of the space age.. There was no gleaming metal hull, and she was devoid of all the encrustations of antennae and dishes of those earlier ships. Neither were there any signs of fuel tanks holding liquid cryofuels. Instead, the hull looked dull and somewhat like an old blimp, those non-rigid airships of the early 20th century. The only sign of exterior equipment were those solar PV panels. These were lightweight, moderate performance thin film arrays, extended out on booms to face the sun and drink her rays to power the ship. They looked more like square rigged sails as they fluttered every so gently in the tenuous atmosphere remaining at her orbit.

I knew from the briefing that the Martian Queen needed about 160KW of power, requiring about 800 m2 of arrays at Mars orbit. There was also talk of the next generation “spacecoaches” replacing the PV panels with lightweight rectennas, to convert microwave beams from the orbital transmitters. Most crews didn’t trust that idea yet, but adding a lightweight rectenna was considered a good idea to back up the PVs and also compensate for the lower intensity of sunlight as the newer ships were about to explore Jupiter space. So this was the Martian Queen, the “spacecoach” that would be my home, about to make her 2nd voyage to Phobos.

Following my crew mate Vicki, I passed through the airlock and entered a large space, nearly 60 m3 in volume, shaped like a large cylinder. The interior diameter was about 4.5 meters, about the same as the mothballed Orion I’d seen back at the Cape museum.. But with a length of 10 meters, the volume was 3x larger. The Martian Queen was composed of 4 modules, providing over 200 m3 of full sea level atmosphere pressurized volume, about 2/3rds that of the old Mir space station. Touching the inner skin of the hull it felt flexible, and slightly cool to the touch. A few light taps and the resonant sounds confirmed that there was liquid behind the skin.

Vicki answered my unspoken question about the liquid in the hull. Water was sandwiched between several layers of impermeable Kevlar in the hull. The primary, and ultimately end, use of all the water was for propellant. The spacoach had originally been folded for launch in a standard Falcon 9 fairing. Each module, without any propellant, weighed just 4 tonnes including payload. This was very little and reduced the deadweight mass of the ship. Once in orbit, the interior had been inflated and the hull filled with water. Most of that water had been launched by dumb, low cost boosters, but some was being supplied from extra-terrestrial resources. Supplies from the lunar south pole were becoming increasingly available as Chevron-Petrobras’ Shackleton base was building up mining production. Exploratory vessels were also initiating operations on asteroids, with 24 Themis looking promising with confirmed surface water. In a few decades, it was expected that all water would be supplied from extra-terrestrial sources.

“Why do you put all the water in the hull, rather than in separate tanks?” I asked.

Vicki explained that the water had a number of roles, not just as propellant. The primary reason was radiation protection. The water acted as a good radiation shield, with a halving of the radiation flux with every 18 cm (half value thickness of 18 cm). Starting with about 25 cm of water in the hull, the radiation level inside the module was just 40 percent of that striking the hull (0.5 ^ (25/18) = 0.38 = 40%). In the event of a major solar flare, the crew could also redirect the water to an interior tube to provide the best radiation shielding for the crew (storm cellar). It looked like that space could get very cozy for the crew, but better than suffering radiation burns.

But it didn’t end there. Micrometeoroids are a rare, but important hazard. The water acted as a shield, absorbing the energy of these grains and preventing penetration inside the hull. The tiny holes in the outer layers quickly heal too. The outer layers of water could be allowed to freeze, trapping a dense forest of fine fibers between the 2 outer fabric layers. This made a strong material, very much like pykrete [1] that offered a stiff outer hull to protect against larger impacts. At Earth’s 1 AU from the sun, reflective foils deployed over the hull allowed passive freezing of the outer layers providing both protection and a large heat sink for the engines.

A noticeable side effect of the hull architecture was the silence. There are no clicks and bangs from thermal heating stresses. Nor did the sunward side of the interior feel noticeably warmer. Thus the water was going to offer very good thermal control of the interior, with pumps in the hull circulating the water providing dynamic thermal control.

Vicki indicated that I should follow her forward to another module. This included the kitchen and dining space. There was a freezer of dried food packages that was being organized by Pieter. Enough for a long trip with a fair variety of meals.

“You seem to have ordered a lot of Boeuf Bourguignon”, joked Pieter.

I wondered when the taste of Boeuf Bourguignon would become rather tiresome after some months. Perhaps more spicy meals like curries would have been more appropriate. I noted that the water supply for rehydrating the food and drinks was connected to the hull too. Of course, I reminded myself, the hull was a huge reservoir of water, effectively inexhaustible are far as the crew was concerned, at least on the outward bound flight.

The facilities were oriented so that “down” was towards the end of the module. This was because during cruise the Martian Queen was going to be rotated, providing some artificial gravity(tumbling pigeon). This made the flight much more comfortable and familiar. We could even eat off regular plates.

(Spacecraft is 40 meters long, 20 meters spin radius. Nausea limit is 3 rotations per minute. At that rate of spin gravity at nose and tail will be 1/5 g, fading to zero g at spin center.)

Vicki quickly showed me the crew quarters and bathroom in the next module. The inner skin of the hull had been moulded into shapes that could contain water. The baths and showers were also connected to the hull’s water supply. The clean water input was connected to heaters and pumps to the various faucets and shower heads. The grey water from the drains was routed to the main purifier and returned to the hull. I inquired how frequently I could take a shower? Once, twice even three times a week?

“As much as you like”, said Vicki. “There is ample water supply for a single pass through the purifier for all the crew to shower once or twice a day. If the crew is particularly extravagant, even this can be increased with greater recycling. Hygiene is a huge morale booster on these trips.”

The toilet was apparently a composting type, although suitably modified for space. This made sense. The nitrogen and phosphorus was going to be needed for the plants growing in the interior, as well as the Phobos base agricultural areas. Nitrogen and phosphorus were still valuable elements with no rich, off-Earth supplies available. Ducking back into the kitchen space, it was clear that much of the interior was given over to growing plants. They provided the needed psychological connection with Earth, helped recycle the CO2, and freshened the air, removing unpleasant volatiles. The stale, locker room smell of most spaceships was almost absent. Some plants were also growing some fresh foods. I could just imagine the value of a fresh tomato after 6 months of spaceflight!

Pulling ourselves back through the leafy interior of the modules, I looked for the engine compartment in the last module. The engines were not obvious on docking, and I wondered where they were. At the rear of the last module, an airlock was currently open, showing an enclosed space beyond. Inside, Hans, the engineer was taking apart one of the engines. He was removing a metal liner from the engine and replacing it with a fresh one. He handed the old one to me and said “carbon deposits”.

I looked closely and saw what he was talking about. Carbon deposition from contaminants in the water supply could build up in the engines, reducing performance. The engines were not much more complex than microwave ovens, although they were fitted with electric grids to further accelerate the microwave heated water plasma.

The exhaust exited via the rear, when the bay doors were opened. Now they were closed, allowing the shirt sleeve repair of the engines. I asked how frequent engine repairs were. Hans informed me that an engine needed some rework after 3—6 hours of operation. The microwave electrothermal engine performance had an Isp of about 800s, although the secondary electric grids could double that by drawing on reserve energy from the solar arrays. Vicki thanked Hans and we drifted back to the main module.

I was a little surprised at the lack of windows, but pleased that there were many flat screens where windows should have been. I looked “out” and saw that I had missed the vernier and maneuvering jets on the hull.

“How are these powered?” I asked Vicki.

Hydrogen Peroxide, H2O2” she replied.

“Where’s the fuel?”.

“There isn’t any yet. It’s made during the flight. Some of the water in the hull is tapped off, run through that off-the-shelf, standard unit over there. We store the peroxide in hull pockets to wait for the next use. The peroxide engines aren’t very efficient, having an Isp of about 160s, but they provide higher thrust than the main engines and can be used to boost the ship for a faster departure, or land the ship on low gravity worlds with orbital delta-Vs of 0.5 km/s or less. The peroxide has other uses too. It can be decomposed to provide oxygen [3] more quickly than the main ESS electrolyzers, act as an energy store for emergency power [4] and finally as an excellent bactericide to keep the interior clean and remove the bacterial slimes and molds that grow on the inner skin, often in difficult to reach spaces. And before you ask, yes, we have rotating cleaning duties on the Martian Queen.”

So the water in the hull fulfilled a range of uses, before being finally consumed as propellant. Major uses included bathing, direct consumption, rehydrating food, growing plants and, of course, the main oxygen supply. It was converted to peroxide for the high thrust engines, for energy storage and for another emergency O2 supply.

“Vicki, a quick mental calculation seems to come up short on the water requirement for the flight. Is what I see all that is needed?”

Vicki smiled: “The impact of using water as propellant on performance is significant. The total water budget for the trip is about 4 times the total mass of the ship and payload, compared to about 14 times for a conventional liquid hydrogen and LOX chemical rocket, primarily because of the higher Isp of the electrothermal engines. But the low hull mass and reduced consumables payload reduces the main mass of the the Martian Queen allowing a much smaller, more efficient spaceship. She is also a lot roomier, more comfortable and much safer. An Apollo 13 type accident would not be survivable in a conventional ship, but we have very large reserves of consumables and oxygen for the crew to survive until a rescue or the return trajectory was complete. In addition, even without water supplies at Phobos, the baseline mission cost to Phobos and return is on the order of a $100m dollars. That is why your institution can afford to pay for your slot on this mission. Reusability of the Martian Queen for multiple missions, fresh water at Phobos, and better performing solar panels and electric engines will eventually reduce that cost perhaps another order of magnitude.

I pondered that for a moment. While not a cheap solution for interplanetary travel, it put the cost well within the realm of the super-rich and wealthy institutions. A mere decade earlier, a simple lunar flyby and return in an adapted Soyuz craft was priced at around $100m per passenger by Space Adventures. Spaceflight was definitely getting cheaper and safer.

If interplanetary travel is initially based around the design concepts of water propellant craft, then the economics and infrastructure requirements will be dependent on available supplies of water already in space at suitable locations for fuel dumps. Bodies that may harbor economically useful quantities of accessible water include the moon (shadowed polar regions), water rich asteroids and dead comets. A tantalizing possibility is Ceres, that Dawn is expected to rendezvous with this year (2015). Ceres is expected to have prodigious quantities of frozen water, possibly even a subsurface ocean. A mining operation to extract pure water from the brew of ice and chemicals might offer the opportunity to open up the inner solar solar system. Once at Jupiter, the icy moons offer an almost inexhaustible supply of water.


1. Pykrete

2. Bigelow Aerospace B330

3. 47kg O2/1000 kg H2O2 (10%)

4. ~2 MJ, kg.

5. J E Brandenburg, J Kline and D Sullivan, “The microwave electro-thermal (MET) thruster using water vapor propellant,” Plasma Science, IEEE Transactions on (Volume:33, Issue:2) pp 776-782 (2005).

6. E. Wernimont, M. Ventura, G. Garboden and P. Mullens. “Past and Present Uses of Rocket Grade Hydrogen Peroxide

From SPACEWARD HO! by Alex Tolley (2015)

With manned missions to Mars in our thinking, both in government space agencies and the commercial sector, the challenge of providing adequate life support emerges as a key factor. We’re talking about a mission lasting about two years, as opposed to the relatively swift Apollo missions to the Moon (about two weeks). Discussing the matter in a new essay, Brian McConnell extends that to 800 days — after all, we need a margin in reserve.

Figure 5 kilograms per day per person for water, oxygen and food, assuming a crew of six. What you wind up with is 24,000 kilograms just for consumables. In terms of mass, we’re in the range of the International Space Station because of our need to keep these astronauts alive. McConnell, a software/electrical engineer based in San Francisco, has been working with Alex Tolley on the question of how we could turn most of these consumables into propellant. The idea is to deploy electric engines that use reclaimed water and waste gases to do the job.

With a nod to the transportation technologies that opened the American West, McConnell and Tolley have dubbed the idea a ‘Spacecoach.’ Centauri Dreams readers will remember Tolley’s Spaceward Ho! and McConnell’s A Stagecoach to the Stars, and the duo have also produced a book on the matter for Springer called A Design for a Reusable Water-Based Spacecraft Known as the Spacecoach. The new essay is a welcome addition to the literature on what appears to be a practical concept.

What fascinates me about the Spacecoach is that it enables us to begin building a space infrastructure that can extend past Mars to include the main asteroid belt. Using electric propulsion driven by a solar photovoltaic array, it achieves higher exhaust velocity than chemical rockets by a factor or ten, pulling much greater delta v from the same amount of propellant. Use water as propellant and you reduce the mass of the system by what McConnell estimates to be a factor of between 10 and 20. Huge reductions in cost follow.

Water as propellant? McConnell comments:

Electric propulsion is not a new technology, and has been used on many unmanned spacecraft. The idea is to use an external power source, typically a solar photovoltaic array, to drive an engine that uses an electrical or magnetic field to heat and accelerate a gas stream to great speed (tens of kilometers per second). Because these engines can achieve much higher exhaust velocity than chemical rockets, 10x or better, they can achieve greater change of velocity (delta v) using the same amount of propellant. This means they can venture to more ambitious destinations, carry more payload, or a combination of both. It also turns out these engines can also use a wide range of materials for propellant, including water.

We can imagine such ships as interplanetary vessels that never enter an atmosphere. They’re also completely reusable, allowing costs to be amortized, and their habitable areas are large inflatable structures that can be assembled in space. Thus we travel within a modular spacecraft using external landers and whatever other modules are required by the mission at hand. They’re also, compared to today’s chemical rocket payloads, a good deal safer:

The use of water and waste gases as propellant, besides reducing the mass of the system by a factor of ten or more, has enormous safety implications. 90% oxygen by mass, water can be used to generate oxygen via electrolysis, a simple process. By weight, it is comparable to lead as a radiation shielding material, so simply by placing water reservoirs around crew rest areas, the ship can reduce the crew’s radiation exposure several fold over the course of a mission. It is an excellent heat sink and can be used to regulate the temperature of the ship environment. The abundance of water also allows the life support system to be based on a one-pass or open loop design. Open loop systems will be much more reliable and basically maintenance free compared to a closed loop system such as what is used on the ISS. The abundance of water will also make the ships much more comfortable on a long journey.

Having just watched “To the Ends of the Earth,” a superb BBC story about a ship making a passage from Britain to Australia in the age of sail, the word ‘comfortable’ catches my eye. A Spacecoach is a large craft with huge solar arrays and the capability of being spun to generate artificial gravity, thus alleviating another major health hazard. Conditions are more Earth-like, and the abundance of water makes for what would otherwise seem absurd scenarios. Imagine taking a shower on a flight to Mars! The Spacecoach’s water management makes it possible.

McConnell believes that much of the mission architecture can be validated on Earth without the need to build a full-scale spacecraft, with the major emphasis on tuning up the electric propulsion technology that drives the concept. Using water, carbon dioxide and waste gases to test the engines can be the subject of an engineering competition, after which the engines could be tested in small satellites. Ultimately, manned Spacecoaches could be tested in cislunar space before their eventual deployment deeper into the Solar System.

McConnell calls the Spacecoach the basis of a ‘real world Starfleet,’ and adds this:

These ships will not be destination specific. They will be able to travel to destinations throughout the inner solar system, including cislunar space, Venus, Mars and with a large enough solar photovoltaic sail, to the Asteroid Belt and the dwarf planets Ceres and Vesta. They’ll be more like the Clipper ships of the past than the throwaway rocket + capsule design pattern we’ve all grown up with, and their component technologies can be upgraded with each outbound flight.

So if you haven’t acquainted yourself with McConnell and Tolley’s earlier work on the Spacecoach in these pages, have a look at Traveling to Mars? Just Add Water!, which recaps the basics of the design and outlines surface exploration strategies from orbiting Spacecoaches by telepresence. The key, though, is to mitigate the propellant issue by making consumables into propellant. Get that right and much else will follow, including the prospect of reliable, safe interplanetary transport of the kind needed to build a truly space-going civilization.

And after that? I’ve always believed that after sending instrumented interstellar probes, we’ll expand into regions outside our Solar System slowly, building space habitats as we go, mining local objects for needed materials. A functioning, space-going civilization builds out that infrastructure from within. It’s the ‘slow boat to Centauri’ scenario — our machines, enabled by artificial intelligence, get there first — but it’s a deep future that includes a human presence around other stars. When I see something as evidently practical as the Spacecoach, I get a renewed jolt of confidence that we at least know how to begin such a journey.

Water Wall

This is from Water Walls Life Support Architecture: 2012 NIAC Phase I Final Report (2012)

The idea here is to make a environmental control life support system (ECLSS) with a higher redundancy and reliability by making it passive, instead of active. Meaning instead of needing a blasted electrically-powered water-pump moving vital fluids around, use special membranes so that the vital fluids automatically seep in the proper direction. Fewer points of failure, fewer moving parts, no electricity needed, much more reliable.

The system harnesses the power of Forward Osmosis (FO), which mother nature has been using for the last 3.5 billion years since the first single-celled organism. Each unit has two compartments A and B, which share a wall made out of what they call a "semi-permeable membrane".

Compartment A contains contaminated water. Compartment B contains a solution (the "draw solution") which attracts water like a magnet using osmotic pressure. The contaminated water gets sucked through the semi-permeable membrane but leaves the contaminants behind (because the membrane won't let them through). The pure water (or purer water) winds up in compartment B with the draw solution and the contaminants remain in compartment A.

Since osmotic pressure is used there is no need for an electrical-powered water pump. It happens naturally just like a ball rolling downhill.

The research team noted that there already exists a commercial example of this: the X-Pack Water Filter System by Hydration Technology Innovations. You put nasty river water full of toxins and pathogens in compartment A and add a special sports-drink syrup into compartment B as draw solution. In about 12 hours compartment B will be filled with a refreshing sterile non-toxic sports-drink and all the horrible crap will be left behind in A.

So the research team realized that they could make a full ECLSS if they could develop some different types of forward osmosis bags and connect them together. They need bags that can do CO2 removal and O2 production (via algae), waste treatment for urine, waste treatment for wash water (graywater), waste treatment for solid wastes (blackwater), climate control, and contaminant control.

As a bonus cherry on top of the sundae, since all these will basically be bags of water, they can do double duty as habitat module radiation shielding.

The reliability comes from using lots of independent inexpensive disposable bags. The current system depends on driving an electromechanical water pump until it fails, then frantically trying to repair the blasted thing before all the toilets back up. Because the FO bags are cheap and low mass, they can be considered disposable, the spacecraft brings along crates of them with the other life support consumables. Because each bag uses forward osmosis as a built-in pump, there is no single point of failure. When one bag or cluster of bags, or integrated module of bags uses up their capacity, you switch the water line to the next units in sequence. The used bags can be cleaned, filled, and reused. Alternatively they can be stuffed somewhere in the habitat module to augment the radiation shielding.

This might work well as an affordable life support system for a cheap Maw and Paw TransHab habitat module. May or may not be useful in a SpaceCoach.

Kuck Mosquito

RocketCat sez

This thing looks really stupid, but it could be the key to opening up the entire freaking solar system. Orbital propellant depots will make space travel affordable, and these water Mosquitos are just the thing to keep the depots topped off.

Kuck Mosquito
ΔV5,600 m/s
Specific Power4.8 kW/kg
(4,840 W/kg)
Thrust Power484 megawatts
PropulsionH2-O2 Chemical
Specific Impulse450 s
Exhaust Velocity4,400 m/s
Wet Mass350,000 kg
Dry Mass100,000 kg
Mass Ratio3.5
Mass Flow49 kg/s
Thrust220,000 newtons
Initial Acceleration0.06 g
Payload100,000 kg
Length12.4 m
Diameter12.4 m

Kuck Mosquitoes were invented by David Kuck. They are robot mining/tanker vehicles designed to mine valuable water from icy dormant comets or D-type asteroids and deliver it to an orbital propellant depot.

They arrive at the target body and use thermal lances to anchor themselves. They drill through the rocky outer layer, inject steam to melt the ice, and suck out the water. The drill can cope with rocky layers of 20 meters or less of thickness.

When the 1,000 cubic meter collection bag is full, some of the water is electrolyzed into hydrogen and oxygen fuel for the rocket engine (in an ideal world the bag would only have to be 350 cubic meters, but the water is going to have lots of mud, cuttings, and other non-water debris).

The 5,600 m/s delta-V is enough to travel between the surface of Deimos and LEO in 270 days, either way. 250 metric tons of H2-O2 fuel, 100 metric tons of water payload, about 0.3 metric tons of drills and pumping equipment, and an unknown amount of mass for the chemical motor and power source (probably solar cells or an RTG).

100 metric tons of water in LEO is like money in the bank. Water is one of the most useful substance in space. And even though it is coming 227,000,000 kilometers from Deimo instead of 160 kilometers from Terra, it is a heck of a lot cheaper.

Naturally pressuring the interior of an asteroid with live steam runs the risk of catastrophic fracture or explosion, but that's why this is being done by a robot instead of by human beings.

In the first image, ignore the "40 tonne water bag" label. That image is from a wargame where 40 metric tons was the arbitrary modular tank size.

There are more details here.

Water Truck

Water Truck
Specific Power9.6 kW/kg
PropulsionSolid core NTR
Specific Impulse198 s
Exhaust Velocity1,942 m/s
Wet Mass123,000 kg
Dry Mass30,400 kg
Mass Ratio4.1
Total ΔV2,740 m/s
Total Propellant92,600 kg
Boost Propellant75,700 kg
Landing Propellant16,900 kg
Boost ΔV1,859 m/s
Landing ΔV881 m/s
Mass Flow155 kg/s
Thrust301,000 newtons
Initial Acceleration0.25 g
Payload20,000 kg
Tank Length8.5 m
Total Length11.9 m
Diameter3.38 m
Structural Mass
Guidance Package0.45 tons
Tank1.6 tons
Thrust Structure
and Feed Lines
0.91 tons
Primary and
Secondary Structure
1.82 tons
Landing System0.68 tons
25% Growth Factor2.09 tons
Reactor1.82 tons
Turbopumps and
Rocket Nozzles
0.23 tons
Reaction Control
0.68 tons
Total10.3 tons

The Lunar ice water truck is a robot propellant tanker design by Anthony Zuppero. Its mission is to boost 20 metric tons of valuable water from lunar polar ice mines into a 100 km Low Lunar Orbit (LLO) cheaply and repeatably. It is estimated to be capable of delivering 3,840 metric tons of water into LLO per year.

This design uses a nuclear thermal rocket with currently available materials, and using water as propellant (a nuclear-heated steam rocket or NSR) instead of liquid hydrogen). This limits it to a specific impulse below 200 seconds which is pretty weak. However, numerous authors have shown that a NSR could deliver 10 and 100 times more payload per launched hardware than a H2-O2 chemical rocket or a NTR using liquid hydrogen. This is despite the fact that the chemical and NTR have much higher specific impulses. NSR work best when [1] the reactor can only be low energy, [2] there are abundant and cheap supplies of water propellant, and [3] mission delta-Vs are below 6,500 m/s.

The original article describes the water extraction subsystem at the lunar pole. It is a small reactor capable of melting 112.6 metric tons of ice into water (92.6 metric tons propellant + 20 metric tons payload) in about 45 hours. This will allow the water truck to make 192 launches per year, delivering a total of 3,840 metric tons of water per year.

Since the water truck is lifting off under the 0.17 g lunar gravity, its acceleration must be higher than that or it will just vibrate on the launch pad while steam-cleaning it. The design has a starting acceleration of 0.25 g (about 1.5 times lunar gravity).

The landing gear can fold so the water truck will fit in the Space Shuttle landing bay, but under ordinary use it is fixed. The guidance package mass includes radiation shielding. In addition, the guidance package is on the water truck's nose, to get as far as possible away from the reactor. The thrust structure and feed lines support the tank and anchor the reactor. The 25% growth factor is to accommodate future design changes without having to re-design the rest of the spacecraft. The reaction control nozzles perform thrust vector control. They take up more mass than a gimbaled engine, but by the same token they are not a maintenance nightmare and additional point of failure.

The reactor supplies about 120 kilowatts to the tank in order to prevent the water from freezing. The reactor mass is 50% more than minimum. The lift-off burn is about 20 minutes durationa and consumes 0.7 kg of Uranium 235.

Water Ship

Water Ship
Specific Power31 W/kg
PropulsionSolid core NTR
Specific Impulse190 s
Exhaust Velocity1,860 m/s
Wet Mass299,030,000 kg
Water tank mass25,000 kg
Nuclear Engine+
structural mass
123,000 kg
Sans Payload Mass148,000 kg
Payload mass50,000,000 kg
Dry Mass50,148,000 kg
Mass Ratio5.96
ΔV[1] 802 m/s
[2] 1280 m/s
[3] 752 m/s
Mass Flow[1,2] 903 kg/s
[3] 2,684 kg/s
Thrust[1,2] 1,680 kiloNewtons
[1,2] 4,990 kiloNewtons
Nozzle Power[1,2] 4.9 gigawatts
[3] 1.6 gigawatts
Engine Power[1,2] 12.1 gigawatts
[3] 4.1 gigawatts
Initial Acceleration[1] 0.0006 g
[2] 0.0009 g
[3] 0.005 g
Payload50,000,000 kg
Length85 m
Diameter85 m

The Water Ship is a robot propellant tanker design by Anthony Zuppero. Its mission is to deliver 50,000 metric tons of valuable water from the Martian moon Deimos to orbital propellant depots in Low Earth Orbit (LEO) cheaply and repeatably. It is not much more than a huge water bladder perched on a NERVA rocket engine. It might have integral water mining equipment as does the Kuck Mosquito, or it might depend upon a seperate Deimos ice mine.

Mass of water bladder is 25 metric tons (rated for no more than 0.005 g). Mass of nuclear thermal rocket plus strutural mass is 123 metric tons (struture includes computers, navigation equipment, and everything else). Mass without payload is 25 + 123 = 148 metric tons. Payload is 50,000 metric tons of water. Dry mass is 148 + 50,000 = 50,148 metric tons. Propellant mass is 248,882 metric tons. Wet mass is 50,148 + 248,882 = 299,030 metric tons.

At Deimos, only about 4.55 megawatts will be needed to melt 299,000 metric tons of ice into water (50,000 tons for payload + 249,000 tons for propellant). The engine nuclear reactor can supply that with no problem. The water must be distilled, because mud or dissolved salts will do serious damage to the engine nuclear reactor. By "serious damage" I mean things like clogging the heat-exchanger channels to cause a reactor meltdown, or impure steam eroding the reactor element cladding resulting in live radioactive Uranium 235 spraying in the exhaust plume.

Nuclear thermal rocket was designed to be a very conservative 100 megawatts per ton of engine. Engine will have a peak power of 12,142 Megawatts (for stage [1] and [2]). This works out to a modest engine temperature of 800° Celsius, and a pathetic but reliable specific impulse of 190 seconds. A NERVA could probably handle 300 megawatts per ton of engine, but the designer wanted to err on the side of caution. This will require much more water propellant, but there is no lack of water at Deimos.

This design uses a nuclear thermal rocket using water as propellant (a nuclear-heated steam rocket or NSR) instead of liquid hydrogen). This limits it to a specific impulse below 200 seconds which is pretty weak. However, numerous authors have shown that a NSR could deliver 10 and 100 times more payload per launched hardware than a H2-O2 chemical rocket or a NTR using liquid hydrogen. This is despite the fact that the chemical and NTR have much higher specific impulses. NSR work best when [1] the reactor can only be low energy, [2] there are abundant and cheap supplies of water propellant, and [3] mission delta-Vs are below 6,500 m/s.

It is true that electrolyzing the water into hydrogen and oxygen then burning it in a chemical rocket will get you a much better specific impulse of 450 seconds. But then you need the energy to electrolyze the water, and equipment to handle cryogenic liquids. These are just more things to go wrong.

In the table, [1], [2], and [3] refer to different segments of the journey from Deimos to LEO.

  • [1] Start at Deimos. 497 m/s burn into Highly Eccentric Mars Orbit (HEMO). At apoapsis, 305 m/s burn into Low Mars Orbit (LMO)
  • [2] At LMO periapsis, 1,280 m/s burn using the Oberth Effect to inject the water ship into Mars-Earth Hohman transfer orbit
  • [3] 270 days later at LEO periapsis, 752 m/s burn using the Oberth Effect to capture the water ship into Highly HEEO
  • [x] Water ship does several aerobrakes until it reaches an orbital propellant depot in LEO

Total thrust time is about 10 hours.

Water ship's propellant has 15,137 metric tons extra as a safety margin. When it arrives, hopefully some of this will be available. It will take 322 metric tons of propellant for the empty water ship to travel from HEEO to Deimos, or 1,992 metric tons to travel from LEO to Deimos. Plus 0.139 gigawatts of engine power and 10 hours of thrust time.

Traveling from Deimos to LEO will consume about 12.7 kg of Uranium 235. Given the fact that Hohmann launch windows from Mars to Earth only occur every two years, the fuel in the engine nuclear reactor will probably last the better part of a century before it has to be replaced. The engine will be obsolete long before then.

For more details, refer to the original article.

Type Notes

(ed note: this system assumes the presence of propellant depots. Otherwise the the delta-V budgets will have to be more or less doubled)

I imagine 3 types of vehicles for space development.

The yellow vehicles have a nearly 10 km/sec delta-V budget and a thick atmosphere to contend with. It is possible these will always be multi-stage expendable vehicles. (ed note: Space Ferry)

The red vehicles move between locations in different orbits. They need no landing mechanism, no thermal protection or ablation shields, parachutes, etc. They have delta V budgets between 4 and 3 km/sec. It is my belief such vehicles could be single stage, reusable vehicles. (ed note: Orbit-to-Orbit)

The green vehicles (lander/ascent vehicles) move between orbital locations and a surface of a substantial body, but not as substantial as earth. Their delta V budget is around 5 km/sec. I believe these vehicles could also be single stage, reusable vehicles. (ed note: Airless Lander)

It would take some investment to build infrastructure to maintain and supply the propellant depots pictured here. Wouldn't it be cheaper to just send ships directly from Earth to Mars? That depends. If your goal is flags and footprints sortie missions, disposable mega rockets are the way to go. But if you wanted genuine development of Mars, it would take many, many trips. If infrastructure could enable these trips to be done with smaller, reusable vehicles, the infrastructure would return the investment many times over.


Reduced to fundamentals, there are two basic shapes for your atomic rocket: the cylinder (cigar shape) and the sphere. Both have advantages and disadvantages. Of course matters are different in the totally unscientific world of media science fiction.

Any Freudian symbolism is the responsibility of the reader.

Flying saucers are not atomic rockets and are therefore beyond the scope of this website. If you want the absolute best information (including blueprints) of the most famous flying saucers from movies and TV, run, do not walk, and get a copy of The Saucer Fleet by Jack Hagerty and Jon Rogers. For rocket-like spacecraft, the last word is Spaceship Handbook by the same authors. Both books are solid gold.


The cylinder is more aerodynamic (for take-off and landing on planets with atmospheres), and allows the use of a smaller anti-radiation shadow shield (because from the point of view of the reactor the body of the ship subtends a smaller angle). It also lends itself well to the tumbling pigeon concept since it does not have to spin as fast as a sphere of the same volume in order to generate the same centrifugal gravity.

Drawbacks include a larger surface area, and a larger "moment of inertia" for yaw and pitch maneuvers (but a lower moment of inertia for roll maneuvers). This means it takes forever to point the ship's nose in different directions as compared to a sphere, which means poor maneuverability (See short story "Hide and Seek" by Sir Arthur C. Clarke for details). Larger gyros or stronger attitude jets will be needed. A faster roll rate is actually not of much use, unless you are trying to get a weapon turret to bear on an enemy ship (See the wargame Attack Vector: Tactical for details).

Cylinder shapes are also better if your ship has a so-called "spinal mount" weapon, that is, where instead of mounting a weapon on your ship you instead build the ship around the weapon. Such weapons are typically long and skinny, which fits the profile of a cigar more than a sphere.


Spheres have the largest enclosed volume for the smallest surface area of any shape, which is a major advantage where every gram of structural mass is a penalty. They also have a smaller moment of inertia for yaw and pitch maneuvers. Drawbacks are the opposite of the cylinder: they are only slightly more aerodynamic than a brick, they don't shadow shield well, and they are lousy tumbling pigeons.

Spheres also require more internal support structure than cylinder to handle the same acceleration load, particularly if you're going to be putting decks inside of it that rely on the structural framework of the spheroidal hull for rigidity. Cylinders under acceleration support themselves in the same manner as a skyscraper building, spheres need extra bracing to keep the equator from sagging. Of course this only becomes a problem if the acceleration is greater than a tenth of a gee, neither spheres nor cylinders have any problem coping with milligee acceleration.

On the other tentacle, if the shape has to be pressurized, like a fuel tank or a crew compartment, non-spherical shapes require more bracing mass and are more expensive to construct than spherical shapes.

Ken Burnside noted that another drawback of a sphere is that your internal volume is going to have a lot of "wasted dead spaces" near the hull. Odd shaped volumes that are what happens when you have an interior wall sectioning off part of the curved surface of the sphere. Anybody who has tried to lay out a floor plan inside a Buckminster Fuller geodetic dome house knows the problem.

Yet another thing to keep in mind is that using current manufacturing techniques, constructing a cylindrical hull costs about 70% of the cost of constructing a spherical hull with the same volume.

Why? Because it is more difficult to manufactured girders and plates that are bent compared to straight ones. A cylinder is constructed using straight stringers. The frames are circular, but all the frames have the same radius and radius of curvature. A sphere on the other hand uses curved stringers and circular frames all of different sizes (well, there are actually two frames of each given radius, but you understand the point I'm trying to make).

On most modern wet-navy warships, the hull plates are mostly straight, with a few bent in one dimension, and only a couple bent spherically in two dimensions. Bending is expensive. Eliminating the bending cost will require one and perhaps two breakthroughs in manufacturing technology.


Many early designs were cylindrical but also carrying a winged landing craft. This gave the spacecraft the appearance of an arrow or a spear. Granted, the landing craft was usually for the return trip to land the astronauts on Terra, but there were a couple intended for landing on Mars, and even one for landing on a hypothetical planet with an atmosphere around another star.

Now launching an spear-type spacecraft into orbit from Terra surface (or other planet with an atmosphere) has a problem of stability, due to the large landing craft wings. As Tim McGaha noted: "there's a reason the fletching isn't on the front of the arrow." This is why it is so important to ensure that the booster rocket has tail fins at the base that are as large (or larger) than the wings on the landing craft. Otherwise the rocket will tumble. Remember that the end of the ship the flames shoot out of should point toward the ground if you want to go to space. If it starts pointing toward space you are having a bad problem and you will not go to space today.

Stephan Jones points out: "The Titan missiles that would have been used to boost the proposed Dyna Soar rocket glider would have had fins strapped on, to counter the aerodynamic mess created by a winged body up top."

So I guess this means you use "arrow" configuration when boosting from the surface of a planet with an atmosphere, while you can get away with using "spear" configuration in vacuum.

Samples of arrow configuration.

These designs are spears. Either they are to be launched in vacuum, or the artist didn't get the memo.


Other ship geometries are possible. In Sir Arthur C. Clarke's Islands in the Sky there is an Terra-Mars passenger liner shaped like a doughnut (torus). The power plant and propulsion system is in the hole, and the ship spins for centrifugal gravity.

And there is also the open-frame design, where components are attached wherever is convenient and braced by girders. The von Braun Moonship from the Collier's article is an example.

Which Way Is Up?

Remember that in a spacecraft under acceleration, "down" is in the direction the exhaust is shooting (i.e., under acceleration the ship will seem like it is landed, sitting on its tail fins with the nose pointed straight up). The spacecraft living quarters will be arranged stacked like floors in a skyscraper. The floors will be at ninety degrees to the exhaust direction. Spacecraft arranged this way are called Tail-sitters. Most spacecraft are tail-sitters.

Usually spacecraft will NOT have their floors parallel to the exhaust direction, i.e., sideways like an aircraft or boat. This is the idiotic "Confusing-a-spaceship-with-an-passenger-airliner" school of ridiculous spacecraft design, found in science fiction with moronically bad science such as Star Trek, Star Wars, Battlestar Galactica and practically all the rest. Get it through your head: Rocket Are Not Boats people!

The only way this will work is with some sort of hand-waving paragravity. And even then why would anybody use such a stupid layout? If the paragravity fails, the rear wall abruptly becomes the floor, the floor becomes the wall, everybody falls to the new floor and breaks their ankles, and all the control panels are out of reach on the freaking ceiling. Now what, Flash Gordon? If you are going to be routinely dueling with Klingon battle cruisers, you do not want a minor weapons hit on the paragravity generator rendering the entire blasted ship inoperable. Just make the floors parallel to the exhaust direction like Heinlein intended, and you'll eliminate that failure mode.

The producers of the TV series The Expanse understand this. In the first episode, a rescue party approaches the silent derelict ship the Scopuli.

But what's this? The ship's name plate looks upside down! Did the special effects artists make a mistake?

WRONG, you trekkie! Ships do not move through space on their bellies like an airplane. The producers of The Expanse got it exactly right. Ships move vertically like a sky-scraper. If we view it that way:

...suddenly we see that the name plate is perfectly correct.

The Expanse gets a big platinum star from me for that bit of accuracy. With the exception of the 2001 movies I don't recall anybody getting that correct (well, also maybe SyFy's Ascension, but that almost doesn't count). And that is only the start of things they got right. I love this show.

When Rockets Are Boats

As always there are exceptions

There are only two situations where it actually makes sense to use the passenger-airliner arrangement:

  • For spacecraft that actually do act like aircraft at some point, e.g., the Space Shuttle.
  • For cargo spacecraft that do not want to use a crane to move cargo up and down over tens of meters. Instead they become belly-landers.

Yes, an atmospheric lander that is transporting cargo will embody both situations.

The drawback is the crew spaces have to be arranged to accomodate both orientations. Just like the old NASA Space Shuttle. Or the FLIP ship.

Things get confusing if you have a spacecraft equipped with a centrifuge for artificial gravity. Under thrust with centrifuge deactivated, "down" is in the direction of thrust. With no thrust and centrifuge spinning, "down" is in the direction away from the spin axis. Under thrust with centrifuge spinning, "down" will be in a weird corner direction that is the vector sum of the two accelerations. There are ways of dealing with this.

There was an interesting hybrid in Larry Niven's World of Ptavvs. The "honeymoon special" was laid out sideways like an aircraft. The spacecraft resembled a huge arrow. It sat on the takeoff field like any aircraft while the passengers boarded. It would taxi down the runway and take off with JATO units, the "tail feathers" acting as wings. Once aloft, the scramjets kicked in, boosting the ship into Terra orbit. In space, the main fusion propulsion system was in the belly, not the tail. The ship flew through space sideways, which kept the direction of "down" still pointed at the floor. The wings also contained the heat radiators.


The other, far to the right, was a passenger ship as big as the ancient Queen Mary, one of the twin luxury transports which served the Titan Hotel.

Well, at least he had time to burn. As long as he was here, he might as well see what a human called a luxury liner.

He was impressed despite himself.

There were thrintun liners bigger than the Golden Circle, and a few which were far bigger; but not many carried a greater air of luxury. Those that did carried the owners of planets. The ramjets under the triangular wing were almost as big as some of the military ships on the field. The builders of the Golden Circle had cut corners only where they wouldn’t show. The lounge looked huge, much bigger than it actually was. It was paneled in gold and navy blue. Crash couches folded into the wall to give way to a bar, a small dance floor, a compact casino. Dining tables rose neatly and automatically from the carpeted floor, inverting themselves to show dark-grained plastic-oak. The front wall was a giant tridee screen. When the water level in the fuel tanks became low enough, an entrance from the lounge turned the tank into a swimming pool. Kzanol was puzzled by the layout until he realized that the fusion drive was in the belly. Ramjets would lift the ship to a safe altitude, but from then on the fusion drive would send thrust up instead of forward. The ship used water instead of liquid hydrogen, not because the passengers needed a pool, but because water was safer to carry and provided a reserve oxygen supply. The staterooms were miracles of miniaturization.

Like a feathered arrow the Golden Circle fell away from the sun. The comparison was hackneyed but accurate, for the giant triangular wing was right at the rear of the ship, with the slender shaft of the fuselage projecting deep into the forward apex. The small forward wings had folded into the sides shortly after takeoff. The big fin was a maze of piping. Live steam, heated by the drive, circled through a generator and through the cooling pipes before returning to start the journey again. Most of the power was fed into the fusion shield of the drive tube. The rest fed the life support system.

In one respect the “arrow” simile was inexact. The arrow flew sideways, riding the sun-hot torch which burned its belly.

“I’m sure one of them is a honeymoon special. It’s got a strong oxygen line in its spectrum.”

From WORLD OF PTAVVS by Larry Niven (1965)

The scientifically accurate layout of Niven's honeymoon special was commendably used in the otherwise forgettable movie Lifeforce (forgettable unless you are fond of nude lady space vampires). The British spacecraft HMS Churchill has its NERVA engine also located in the ship's belly instead of the tail.

This makes sense since the Churchill is a belly lander, as are all NASA derived space shuttles. Under NERVA thrust the direction of "down" matches the interior arrangement of the shuttle's habitat module. The fact that the ship appears to be moving through space sideways is of no concern.


(ed note: Dr. Floyd is riding up to the space station in the Pan Am Space Clipper)

Now, thought Floyd, we are on our own, more than halfway to orbit. When the acceleration came on again, as the upper stage rockets fired, the thrust was much more gentle: indeed, he felt no more than normal gravity. But it would have been impossible to walk, since “Up” was straight toward the front of the cabin. If he had been foolish enough to leave his seat, he would have crashed at once against the rear wall.

This effect was a little disconcerting, for it seemed that the ship was standing on its tail. To Floyd, who was at the very front of the cabin, all the seats appeared to be fixed on a wall topping vertically beneath him. He was doing his best to ignore this uncomfortable illusion when dawn exploded outside the ship.

From 2001 A SPACE ODYSSEY by Arthur C. Clarke (1969)


For what it is worth , the game GURPS Traveller: Starships defines the following terms:

  • Drive Axis: a line that originates in the center of thrust in the engines. Sometimes called the Thrust Axis. One end points in the direction the exhaust goes, the other end points in the direction the ship moves (Newton's "equal and opposite reaction"). Remember that "down" is in the same direction the exhaust goes. The drive axis should pass through the ship's center of gravity, otherwise under thrust the ship falls off its tail and spins wildly.
  • Tail Lander: a spacecraft whose decks are perpendicular to the drive axis. Almost all the ships described in this website are tail landers. SpaceX's Falcon line of boosters are tail landers.
  • Belly Lander: a spacecraft whose decks are parallel to the drive axis. The Space Shuttle is a belly lander.
  • Fore: in the direction of the drive axis towards the ship's nose. This is the direction of "up".
  • Aft: in the direction of the drive axis towards the ship's tail. This is the direction of "down".
  • Port: a line perpendicular to the drive axis passing through the spacecraft's main airlock. Ship's "left."
  • Starboard: a line perpendicular to the drive axis 180° from Port. Ship's "right."
  • Dorsal: a line perpendicular to the drive axis 90° from Port, counterclockwise when looking aft. Ship's "top" or "back."
  • Ventral: a line perpendicular to the drive axis 90° from Port, clockwise when looking aft. Ship's "bottom" or "belly."
  • Outboard: away from the drive axis.
  • Inboard: towards the drive axis.

The problem with the definition of port is that in a nuclear powered spacecraft, the logical place for the main airlock (and the ship docking point) is the ship's nose. Which makes "port" the same as "fore", thus ruining the nomenclature system. The idea is to have the directions at ninety degrees to each other, not coinciding. Some other distinguishing spacecraft feature will have to be used, but there doesn't seem to be any good candidates.

And what gets my goat is the terms "Dorsal" and "Ventral". They only apply to belly-landers. Applying those terms to a tail-lander is just propagating that accurséd "Confusing-a-spaceship-with-an-airbus" fallacy. Unfortunately there does not seem to be an alternate term for dorsal and ventral. Come to think of it, "Port" and "Starboard" are also airbus like.

Of course there will be a few spacecraft that actually are belly-landers, mostly cargo and aerospace shuttles. That is: spacecraft designed to have the cargo access hatch as near to the ground as possible, or spacecraft that can also operate as aircraft. Most spacecraft will be either tail-landers, or orbit-to-orbit ships that never land (but still have a tail-lander's internal layout).

On NASA spacecraft, they arbitrarily pick a direction for port. The spacecraft's X axis is the Drive axis, with +X in the direction the spacecraft accelerates and -X is the direction the exhaust goes. The astronauts lie on their backs, with eyes facing +X (up) and backs facing -X (down). Y axis passes through astronaut's left and right shoulders. +Y is right (starboard) and -Y is left (port). The Z axis passes through the astronaut's head and feet. +Z is in the feet direction (ventral, pfui!) and -Z is in the head direction (dorsal, ditto). This is important for the pilot to know when they are using rotation and translation controls.

If the ship has some sort of centrifugal gravity where spin gravity does not match thrust gravity, there will be some sort of jargon for "thrust gravity downward direction" and "spin gravity downward direction." The wet navy won't help you with this one, make it up yourself. If the centrifuge's spin axis happens to be the same as the drive axis, up is "inboard" and down is "outboard". Inside a centrifuge the directions "spinward" and "trailing" (anti-spinward) will be used, refering to the direction of centrifuge spin.


     "Mr. Archer — report to compartment nineteen, starboard, G-norm shell," the officer said abruptly, making him feel as though he were being inducted into the navy.
     "That's it," Groton said. "I'll drop you off — or would you rather find your own way?"
     "I would rather find my own way."
     Groton looked at him, surprised, but let him go. "G-norm is level eight," he said.

     He saw the numbers now: 96, 95, 94, each no doubt representing an apartment or office. Those on the right were marked P, those on his left S. Port and Starboard, presumably. Starboard being right, he must be heading for the stern.
     Of a torus? Exactly where were bow and stern in a hollow doughnut spinning in space?

     "But I have one crucially important question — "
     "To wit: which way is Stern?"
     Ivo nodded. "That is the question."
     "I'm surprised at you, den brother. Haven't you learned yet that your stern is behind your stem?"
     "My mind is insufficiently pornographic to make that association."
     "Take your bow. It's inevitable."
     Ivo smiled amiably, realizing that it was his turn to miss a pun of some sort. He would catch on in due course.

     He stopped off at the latrine — and realized suddenly that every toilet faced in the same direction. The arrangement was such that when a person sat, he had to face the "forward" orientation of the torus.
     "When you take your inevitable bow, your stern is sternward." he said aloud, finally appreciating Brad's pun — a pun inflicted upon the nomenclature of the entire station.

From Macroscope by Piers Anthony (1969)

You serve "in" a ship, not "on" one. "Abaft" means "behind", "forward" means "in front of." It is a "deck", not a "floor".

Pressure-tight walls are "bulkheads", pressure-tight doors are "pressure-tight doors." Non-pressure tight doors are just doors and non-pressure tight walls are just walls. Generally non-pressure type items are pretty flimsy. Doors in the decks (floor and ceiling) are "hatches.".

It's not a "restroom" it's a "head", it's not a "kitchen" it's a "galley." It's not the "dining room", it's the "mess deck" (unless it's for officers, then it's the "wardroom"). The "mess" refers to the crewmen currently eating on the mess deck. It's not a "bunk" its a "rack", it's not a "ceiling" it's an "overhead." It's not a "hallway" it's a "companionway" or "passageway", it's not the "stairs", it's a "ladder." And the "brow" is any walkway or catwalk leading to the main airlock.

These are all from the naval tradition, the air force jargon is totally different.

Navigation Lights

Aircraft have about nine different types of lights mounted on them. Most of them will be useful on a belly-landers, a few of them will be useful on a tail-sitter.

Port Light: red light on tip of port wing, visible in arc from 250° clockwise to 0° (110° wide arc centered on 305°)
Starboard Light: green light on tip of starboard wing, visible in arc from 0° clockwise to 110° (110° wide arc centered on 55°)
Aft Light: white light centered on tail, visible in arc from 110° clockwise to 250° (140° wide arc centered on 180°)
Meaning: Allows observer to determine what direction the aircraft is pointing in the black of night.
Notes: If red is on observers right and green is on the left, aircraft is heading straight for the observer. If only white is visible aircraft is heading away. If only red is visible aircraft is heading from right to left. Navigational lights are generally always on.
STROBE (also anti collision)
Light: very bright white pulsating strobe light. Two at each wing-tip (one fore, one aft), one on tail.
Meaning: Signals that the aircraft is entering an active runway. During flight it increases the aircraft's visibility.
Notes: On the ground strobes are off. When plane enter active runway strobes are activated. Strobes remain on during take-off, flight, landing, and are turned off when plane vacates the runway.
BEACON (anti collision)
Lights: Flashing red lights, one centered dorsal, one centered ventral.
Meaning: aircraft engines are running and aircraft is moving or will move soon. Warns ground crews to stay away from the engines or die. Alerts other aircraft that are on the move.
Notes: Lights flash to attract attention, they are red because that is the code for danger. Beacons are generally lit as long as the engines are powered up.
Illuminates wing so pilot can check wing at night for icing or other damage.
Helps pilot see area in front of plane as they taxi along the runway. Generally on nosegear.
Illumniates same area as taxi light but are much brighter. They are too blinding to other traffic to be used during taxi. Generally on nosegear.
Like taxi light except are angled left/right to assist aircraft turning. Generally on nosegear.
Very bright lights on wing to help pilot during landing. They illuminate the area where the plane is going to touch down. Sometimes airlines have procedure to turn them on below 10,000 feet or during climbs/descends.
Light illuminating the airline logo painted on the tail. The Starship Enterprise has lots of these, illuminating the name ENTERPRISE and various StarFleet insignia.

The Cygnus spacecraft uses LED navigational lights from ORBITEC. A standard set of ORBITEC nav light consists of five lights: a flashing red light on the port side, a flashing green on the starboard side, two flashing white lights on the top and one flashing yellow on the bottom side of the fuselage.

The SpaceX Dragon spacecraft has a red port, green starboard, and flashing white strobe light. The white strobe flashes in an irregular/random sequence so as not to confuse the flashing with a rotation.

Bullseye Address

In the US Navy, each compartment had a "bullseye" or Navy Ship Compartment Number. It is sort of a three-dimensional address of each space or compartment. While this is useful to keep new recruits from getting lost, the more important use is for damage control. Reporting a damaged location to, from, or between damage control parties must be rapid and unambiguous.

The compartment number is often stenciled on the walls and/or the doors.

1940-era Numbering

Every door, hatch and manhole  aboard the LST is labeled.  This metal sign provides certain information and learning to read these labels help one navigate through the vessel.  These labels were helpful in reporting emergencies because they utilized a standard method for giving describing any location aboard the ship.  Each label will have a combination of numbers and a name for the compartment.

The first number indicates the deck number.  The second number indicates that the opening is abaft of a particular frame and the last number indicates the number of the opening from the inboard out (port even numbers, starboard odd). A letter after the numbers indicates the use of the compartment.

 A-Supply and Storage L-Living Quarters
C-Control    M-Ammunition
E-Machinery T-Trunks and Passage
F-Fuel V-Voids

So in this example from a hatch aboard the LST:









So in English, 2-28-2 ESC TRUNK, would mean that the opening before you was an escape trunk, starting on the second deck, just aft of the twenty-eighth frame and is the first opening inboard out on the port side.  The second line, 4-28-2-T tells you the trunk continues all the way to the fourth deck, just aft of the twenty-eighth and here it is still the first opening from the inboard out.  This trunk gives access to: ELEC STORES 3-28-2-A or a store room for electrical parts on the third deck, which is aft of the twenty-eighth frame and is the first opening from the inboard out; and AUX ENG ROOM 4-28-O-E or the auxiliary engine room on the fourth deck aft of the twenty-eighth frame and the space is a machinery space.

(ed note: A different system will be needed for spacecraft, since they do not really have a port or starboard and the frames are parallel to the decks instead of perpendicular to them.)

USS Midway Bullseye

(ed note: this is an older form of US Navy compartment numbering)

USS MIDWAY - A "bullseye" is the three dimensional address of each space or compartment

A "bullseye" is the address of each compartment. This is an older form of the bullseye. The C indicates a location in the rear third of the ship. The "2" (in 208) shows we are on the second deck. The "08" indicates how far left or right we are from the keel or center of the ship. "FR 163" shows how far the forward bulkhead (wall) or frame is from the bow. The bottom line indicates which division is responsible for cleaning the space.

One more item: On a carrier the hangar deck is the ONE or first deck. Counting down the decks would be the TWO DECK (Second deck) , THREE DECK (third deck) etc.

Counting decks up from the hangar deck is the "01" (OH ONE) deck, the "02 (OH TWO DECK) etc. On MIDWAY the flight deck is the 03 deck.

from Bob Perry (2010)
Navy Ship Compartment Numbering

Compartments are numbered for identification to facilitate location. The identification number assigned locates each compartment specifically, and generally indicates the function and use of the compartment. Compartment numbers consist of four parts, separated by hyphens, for example 6-150-0-E, in the following sequence:

  1. Deck Number
  2. Frame Number
  3. Position in relation to centerline of ship
  4. Compartment use
Deck Number: The main deck is the basis for this numbering scheme and is numbered 1. The first deck below the main deck is numbered 2, and so on. The first horizontal division above the main deck is numbered 01, and the numbers continue consecutively for subsequent upper division boundaries. Compartments are numbered by the lowest deck within the space.

Frame number: The forward perpendicular is the basis for this numbering scheme and is numbered "0" (zero). "Frames" are consecutively numbered, based on frame spacing, until the aft perpendicular is reached. Forward of the forward perpendicular, frames are "lettered" starting from the perpendicular to the bull nose (A, B, C, etc.) while frames aft of the after perpendicular are "double lettered" to the transom (AA, BB, CC, etc.). Compartments are numbered by the frame number of the foremost bulkhead of the compartment. If this bulkhead is located between "frames," the number of the foremost "frame" within the compartment is used. Fractional numbers are not used except where frame spacing exceeds four feet. 

Frame spacing examples:


Position in relation to centerline: The ship's centerline is the basis for this numbering scheme. Compartments located so that the centerline of the ship passes through them are assigned the number 0. Compartments located completely to starboard of the centerline are given odd numbers, and those to port of centerline are given even numbers. The first compartment outboard of the centerline to starboard is 1, the second is 3 and so forth. Similarly, the first compartment outboard the centerline to port is 2, the second is 4 and so forth. There may be cases in which the centerline of the ship would pass through more than one compartment, all of which may have the same forward bulkhead number. Whenever this occurs, that compartment having the portion of the forward bulkhead through which the centerline of the ship passes is assigned the number 0 and the other carry numbers 01, 02, 03 etc.

Compartment Use: A capital letter is used to identify the assigned primary use of the compartment. Only one capital letter is assigned, except that on dry and liquid cargo ships a double letter identification is used to designate compartments assigned to carry cargo. Examples of compartment use are storage areas, various tanks, and living quarters. 

Some examples from NSTM 079 volume 2:

A Storage area
C Ship and Fire Control operating spaces normally crewed
E Machinery spaces which are normally crewed
F Fuel or Fuel Oil tanks
J JP-5 tank
L Living quarters
M Ammunition (stowage and handling)
Q Areas not otherwise covered
T Vertical access trunk
V Void

Example of Compartment Numbering

Given Compartment "6 - 150 - 0 - E," we can determine that it is located:

a) five decks below the Main Deck,
b) foremost bulkhead is at frame 150,
c) centered upon the centerline of the ship, and
d) is used as an engineering space.

In the science-fictional GURPS Traveller: Starships, they use the following system. Odd numbers are port, even numbers are starboard. Numbering is consecutive in order from inboard to outboard, fore to aft, dorsal to ventral.

Pressure Tight Doors

A pressure tight door is air-tight. Which will prevent you from dying from asphyxiation if the adjacent compartment is hulled by a meteor.

On a naval vessel, "doors" lead from one side of a deck to another side of the same deck; hatches go between decks. In other words, doors are in the walls, hatches are in the floor and ceiling. Doors in non-pressure tight walls are "doors", doors in pressure-tight bulkheads are "pressure-tight door." On a spacecraft with no artificial gravity the distinction between openings in the walls and openings in the decks is sort of academic. Of course all the mechanical details are identical.

A small circular or oval access hatch is called a "scuttle." An escape hatch is usually a quick-acting scuttle (see below), because crew members trying to escape are generally in a hurry.

An opening into an uncrewed space for purposes of inspection and maintenance are called "manholes." This is generally into the interior of tanks and crawl spaces between equipment.

Pressure tight doors have "dogs", which are individual fasteners that clamp the door to maintain the seal with the door coaming. Ordinary doors do not have dogs, and cannot be "dogged down". On wet-navy ships, water-tight doors have eight dogging latches around the edges.

Some pressure tight doors have a clever arrangement where a single handle can close all the dogs simultaneously (a "quick acting" door). Otherwise the dogs have to be turned individually. Naturally the clever doors require more scheduled maintenance than the standard kind.

A pressure-tight door is a damage control barrier, while an ordinary door is an access control barrier.

Fancy pressure-tight doors will have some sort of indicator telling you if there is pressure or vacuum on the other side. The fanciest will have manometers, more bargain-basement models will just have a valve attached to a whistle. Turn the knob, and if it screeches there ain't no air over there.

On wet navy vessels, doors and hatches leading into compartments containing flammables, weapons, high explosives, or petroleum engine fuel are forged out of bronze instead of iron. The latter can strike sparks when closing the hatch or turning the handwheel, with unfortunate results. Bronze is non-sparking. You might see something similar in a spacecraft hab module insanely designed to use pure oxygen as a breathing mix.

On a high-tech spacecraft, there might be an automatic mechanism which will shut pressure-tight doors and hatches if it detects a hull breach or other unexpected drop in air pressure. There is a safety question of just how much the door will insist upon closing if an unfortunate crew member has a body part trapped. If the pressure drop is gradual enough or the well being of the crew is important enough, the door will be programmed to allow the crew member to open the door a bit and free themselves. Otherwise the blasted door will do it darnedest to amputate the unlucky crew member's limb. Also note that such automatic doors will contain complicated components and thus require lots of regular maintenance.

A standard watertight door as used by the US Navy has 8 dogging latches around the edges. These provide leverage to hold the door closed against flooding. The Navy considers these doors to be the most effective way to contain flooding, and doors will have a plaque on them with a letter showing at which level of preparedness the door gets shut and dogged. (A good discussion of those "material conditions" can be found at (navalmaterialconditions.htm)).

The problem with standard watertight doors is that they're a pain in the (posterior). Most often, they're not fully dogged down; sailors will use one dog to hold the door closed as they pass through it on regular duty. I have heard sailors literally curse whoever fully dogged a door.

The easiest kind of quick-acting door actually has a lever, instead of a wheel. The lever moves a bar, the bar moves other bars, and the bars pop the dogs simultaneously open or closed. While not as resistant to flooding as a standard WTD, it has the advantage that all dogs are more likely to be engaged, and so the Navy uses them in high-traffic areas. These are actually what I'd expect to see on out-atmosphere ships. The heavy doors you show on the page are designed for submarines, where they have to hold against very heavy pressures in case of flooding. Remember, water piles up an additional atmosphere of pressure every ten meters of depth, and submarines like the Los Angeles class commonly operate at depths of 200 meters.

I was a surface warfare girl, not a submariner, so I can tell you that the lighter, lever-actuated QAWTD (DSC_9950.jpg) have their machinery on the side that doesn't face a weather deck... or, in the case of a QATD that leads from one interior space to another, the machinery faces the inboard side, as flooding is more likely to come from outboard. I presume that Submarines use the same logic, but I don't know that to be the case.

I've heard my HT/DC buddies complain about servicing doors. More moving parts means more maintenance, of course, and more fiddling to make sure all the parts are working properly at the same time.

From Navy veteran Jennifer Linsky (2015)

Submarine Pressure-Tight Doors

Submarine watertight bulkhead door are entertaining, though they are probably far too wasteful of mass to use on a real spacecraft. But they are instructive. And they are so retro. The technical term is "quick-acting water-tight doors", as opposed to the doors with "dogs."

These are damage control barriers for use when the hab module's hull is breached. As such it is uncertain which side of the door will suddenly contain vacuum. However, in an airlock (or other situation where you are pretty sure you know which side will always have pressure), as a safety measure you want the door to open such that the air pressure will be constantly pushing the door safely shut instead of trying to blow the door open and kill everybody. And to prevent morons from opening a door leading to vacuum, since they cannot possibly tug open something being held shut by 14.7 pound per square inch. If you have a low-IQ individual on your ship who can pull with over 19 metric tons of force, you have a bigger problem than inadequate safety on your pressure-tight doors.

As a general rule you'll want your hab module doors set so that they close in the outboard direction and open inboard. Presumably the drop in air pressure will be from a catastrophic hole in the hull, not the center of the spacecraft. So at a door connecting two compartments, the compartment closer to the hull is more likely to be in vacuum during a disaster. This will not always be true, but that's the way to bet. Thus the air pressure will be helpfully holding the door shut.

On wet-navy surface ships they mount doors such that the gears and mechanism of the quick-acting-door are on the dry side so they are not exposed to corrosive seawater. This means the machinery faces the inboard side, because presumably the water will be coming from a breach in the hull on the outboard side. Whether this is a concern on a spacecraft depends upon how much wear and tear the machinery suffers under vacuum.

Keep in mind that submarine doors have to contain an order of magnitude more pressure than a spacecraft door ever will. That's why they look like bank vault doors. A spacecraft pressure door will only need to cope with one atmosphere of pressure or so, while a submarine at 200 meters depth needs to be able to handle 20 atmospheres. Former Navy Jennifer Linsky is of the opinion that a spacecraft would probably use pressure doors similar to the quick-acting-door pictured above as opposed to these massive submarine doors.

I have yet to locate any description about how submarine bulkhead doors operate, so I had to look at lots of images and use my raw powers of deduction. Besides, the quickest way to find the answer to something on the internet is to post an inaccurate explanation. Experts will come boiling out of the woodwork eager to tell you just how wrong you are.

I got nowhere fast with analyzing the images until I realize there were two types of doors that looked similar. Since I do not know the proper terminology, I'm dubbing them "Innie" and "Outie", much like navels.

  • Innie
    • When the door is opened, the side of the door revealed is concave (full of gears and machinery). When door is shut you see a smooth convex surface.
    • The strike plates are bulges in the door frame
    • Actuators are attached to part of latch farthest from door body
    • The latches rotate towards the door body to engage the strike plate
  • Outie
    • When the door is opened, the side of the door revealed is convex (with no gears exposed). When door is shut you see a concave surface full of gears.
    • The strike plates are curved arching knobs
    • Actuators are attached to part of latch nearest to door body
    • The latches rotate away from the door body to engage the strike plate

How Quick-Acting Water-Tight Doors Work

Color Key:

  • Red: Handwheel and Worm. The handwheel can look like a wheel, a cross bar, or a wheel with a bar extending from the center.
  • Yellow: Worm gears and levers
  • Green: Actuators
  • Blue: Latches

The mechanism of Innie and Outie doors work pretty much the same, with the exception that the latches rotate in opposite directions.

The wheel or crossbar (red) in the center of the door is spun. This rotates the worm of a worm drive (not shown).

The worm engages the four worm gears (yellow) attached to four levers, moving the levers into extended position (far ends of the levers move further away from center).

The ends of the levers push four oddly-shaped actuators (green) away from the center of the door body and closer to the door body edge.

The actuators push on the edge of pivoted latches (blue). The latches rotate on their pivots to engage the strike plates. Innie latches rotate in the opposite direction from Outie latches. To do so, the Innie door has the actuators attached to the latches on the part of the latch furthest from the door body, while Outie actuators are attached to part of latch closest to door body.

"How do you know it doesn't have a leak?" Fred wanted to know.

"Sorry to sound stupid, but this space living's new to me," Tom remarked. "So it has a leak? So what?"

"Do you know there's pressure on the other side of that door?" Fred asked.

"Why, there's bound to be! We sealed it pressurized," Stan said.

"Doesn't mean it still has pressure," Fred explained. He moved to the door and to the control panel next to it. "Look, the secret of living to a ripe old age out here involves a firm belief in Murphy's Law. Never take anything for granted, especially when your life may depend on it. Always assume that something's malfunctioned until you know it hasn't. Suppose the med module sprung a leak during boost to LEO Base, or when they were transferring it to a Cot-Vee, or when they unloaded it here and docked it to GEO Base. What would be the consequences?"

"We'd have lost a lot of our equipment, to say nothing of most of the Pharmaceuticals and lab reagents in there," Dave ventured.

"Plus your life if you managed to get that door opened with vacuum on the other side of it."

"It's not supposed to open with vacuum on the other side of it."

"Hell of a lot of people got killed out here because something was 'supposed' to be fail-safe, Dave. Everybody, look here at the little panel alongside the door. There's one of these at every hatch. If you ignore it, you're likely to kill yourself by what we might call 'traumatic abaryia,' which is a word I just made up, Doc, and that you can steal if you want. Crack that door with vacuum on the other side of it, and the pressure in this module would drop in less than a minute to a level that would kill you. The automatic door on the inboard end of the living module would automatically seal. Hell, Pratt can't afford to let everybody in GEO Base get killed just because some damned fool forgot to look at the tell-tale alongside the door before he tried to open it. Sure, it's supposed to be fail-safe—but don't you ever believe it! You stay alive out here by placing absolutely no trust whatsoever in safety devices that were designed by engineers sitting down on dirt. They aren't going to get killed if it doesn't work. Fired maybe, but they're still alive. You all listen to me. You're part of the same team I'm on, and we can't afford to lose a single one of you. Especially you, Doc. I may not be able to keep you from getting shortened a foot or two, but I may be able to keep you alive."

The pressure indicator showed there was indeed pressure in the med module, but Fred told them not to believe even that. "It could be frozen or have malfunctioned in sixty different ways. Next step is to check the test port in the door."

Fred showed them how to crack the test port on the door and listen for the whistle. Every door and hatch had such a test port, a very simple device that couldn't fail: a small opening that could easily be opened and just as easily shut and sealed again. Any pressure differential across the door would cause the test port to whistle.

"We're in luck. The pressure held," Fred told them.

From Space Doctor by Lee Correy (G. Harry Stine) 1981


An airlock is a way for an astronaut (presumably dressed in a spacesuit) to exit the pressurized habitat module without all the atmosphere blowing out into the limitless vacuum of space.

Basically it is a chamber with two airtight hatches, which do not open simultaneously. One hatch opens into the hab module, one opens into space, and the pressure inside the chamber can be switched from ship pressure down to vacuum. Before opening either hatch, the pressure inside the chamber is equalized with the environment beyond. This is called "cycling" an airlock.

As a mundane analogy, imagine a spaceship is a house, a space suit is winter coat, vacuum is the bitter cold of winter, air is the warmth inside the house, and the airlock is an entryway (the "warmth-lock"). To leave the house, you walk into the entryway, close the door behind you so the heat does not escape, put on your winter coat hanging in the coat closet, open the front door into the cold of winter, leave the house, and close the front door behind you. Just like an airlock.

When cycling down to vacuum all the air in the lock is stored in tanks, of course. Just venting it to space is a criminal waste of limited breathing mix. This would not be done unless it was an emergency or if it was an incredibly primitive airlock. Even with a reasonably designed airlock there is going to be some small unavoidable breathing mix loss with each cycle.

Very small or very cut-rate spaceships might not have an airlock. They take up lots of room and are expensive. They might be optional on a one-man Belter asteroid mining ship. Of course this means the pilot will have to put the toothpaste and any other pressure sensitive supplies into a pressurized locker before they vent the entire hab module and open the hatch. An example is the Lunar Module from NASA's Apollo program.

A stripped-down variant on the airlock is the "suitport". Instead of a chamber, the backpack of a space suit attaches to the ship's hull. An astronaut enters the suit by crawling through the backpack, seals the inner door, then detaches from the hull. It requires much less mass and volume than a full airlock. On the other hand, they are difficult to design if the atmospheric pressure inside the ship/spacestation is not the same as inside the suit. Soft suits commonly have lower pressure than the habitat.

Besides the usual cargo lock we had three Kwikloks. A Kwiklok is an Iron Maiden without spikes; it fits a man in a suit, leaving just a few pints of air to scavenge, and cycles automatically. A big time saver in changing shifts. I passed through the middle-sized one; Tiny, of course, used the big one. Without hesitation the new man pulled himself into the small one.

From Delilah and the Space-Rigger by Robert Heinlein (1949)


1. Personnel must wear vacuum suits before exiting the starship if so indicated by crimson-caution telltales. (Any exceptions must possess “vacuum-capable” endorsement countersigned by Environmental Systems Engineer.) Follow instructions posted in airlock chamber.

2. In an emergency, caution enforcement system may be disabled by opening emergency controls panel. (Alarm will sound in DCC.) Follow procedures posted within. Always attempt egress through interior hatch first, exterior hatch second.


Do not ignore any amber-test or crimson-caution telltales. Spacetight doors may not have properly sealed and/or chamber may not have reached safe pressure differential. Always wait for blue-go “disembark” indicator before trying to exit.

When using emergency controls, always check “hatch sealed” test lights and manual indicators before using manual pressurization override controls. As you proceed, constantly monitor pressurization and differential-pressure gauges, located within emergency controls panel.

In the event of damage or mechanical failure, spare parts and tools for emergency repairs are located beneath the emergency controls panel secondary door.

From And Don’t Hold Your Breath (It Never Helps) by Alistair Young (2014)
Space Shuttle Airlock

(ed note: images are from JSC-20466 EVA Tools and Equipment Reference Book Rev. B, November 1993)

The airlock is normally located inside the middeck of the spacecraft's pressurized crew cabin. It has an inside diameter of 63 inches, is 83 inches long and has two 40-inch- diameter D-shaped openings that are 36 inches across. It also has two pressure-sealing hatches and a complement of airlock support systems. The airlock's volume is 150 cubic feet.

The airlock is sized to accommodate two fully suited flight crew members simultaneously. Support functions include airlock depressurization and repressurization, extravehicular activity equipment recharge, liquid-cooled garment water cooling, EVA equipment checkout, donning and communications. The EVA gear, checkout panel and recharge stations are located on the internal walls of the airlock.

The airlock hatches are mounted on the airlock. The inner hatch is mounted on the exterior of the airlock (orbiter crew cabin middeck side) and opens into the middeck. The inner hatch isolates the airlock from the orbiter crew cabin. The outer hatch is mounted inside the airlock and opens into the airlock. The outer hatch isolates the airlock from the unpressurized payload bay when closed and permits the EVA crew members to exit from the airlock to the payload bay when open.

Airlock repressurization is controllable from the orbiter crew cabin middeck and from inside the airlock. It is performed by equalizing the airlock's and cabin's pressure with equalization valves mounted on the inner hatch. The airlock is depressurized from inside the airlock by venting the airlock's pressure overboard. The two D-shaped airlock hatches open toward the primary pressure source, the orbiter crew cabin, to achieve pressure-assist sealing when closed.

Each hatch has six interconnected latches and a gearbox/actuator, a window, a hinge mechanism and hold-open device, a differential pressure gauge on each side and two equalization valves.

The 4-inch (10 cm) diameter window in each airlock hatch is used for crew observation from the cabin/airlock and the airlock/payload bay. The dual window panes are made of polycarbonate plastic and mounted directly to the hatch by means of bolts fastened through the panes. Each hatch window has dual pressure seals, with seal grooves located in the hatch.

Each airlock hatch has dual pressure seals to maintain pressure integrity. One seal is mounted on the airlock hatch and the other on the airlock structure. A leak check quick disconnect is installed between the hatch and the airlock pressure seals to verify hatch pressure integrity before flight.

The gearbox with latch mechanisms on each hatch allows the flight crew to open and close the hatch during transfers and EVA operations. The gearbox and the latches are mounted on the low-pressure side of each hatch; with a gearbox handle installed on both sides to permit operation from either side of the hatch.

Three of the six latches on each hatch are double-acting and have cam surfaces that force the sealing surfaces apart when the latches are opened, thereby acting as crew assist devices. The latches are interconnected with push-pull rods and an idler bell crank that is installed between the rods for pivoting the rods. Self-aligning dual rotating bearings are used on the rods for attachment to the bellcranks and the latches. The gearbox and hatch open support struts are also connected to the latching system by the same rod/bellcrank and bearing system. To latch or unlatch the hatch, the gearbox handle must be rotated 440 degrees.

The hatch actuator/gearbox is used to provide the mechanical advantage to open and close the latches. The hatch actuator lock lever requires a force of 8 to 10 pounds through an angle of 180 deg rees to unlatch the actuator. A minimum rotation of 440 deg rees with a maximum force of 30 pounds applied to the actuator handle is required to operate the latches to their fully unlatched positions.

The hinge mechanism for each hatch permits a minimum opening sweep into the airlock or the crew cabin middeck. The inner hatch (airlock to crew cabin) is pulled or pushed forward to the crew cabin approximately 6 inches. The hatch pivots up and to the right side. Positive locks are provided to hold the hatch in both an intermediate and a full-open position. A spring-loaded handle on the latch hold-open bracket releases the lock. Friction is also provided in the linkage to prevent the hatch from moving if released during any part of the swing.

The outer hatch (airlock to payload bay) opens and closes to the contour of the airlock wall. The hatch is hinged to be pulled first into the airlock and then forward at the bottom and rotated down until it rests with the low-pressure (outer) side facing the airlock ceiling (middeck floor). The linkage mechanism guides the hatch from the closed/open, open/closed position with friction restraint throughout the stroke. The hatch has a hold-open hook that snaps into place over a flange when the hatch is fully open. The hook is released by depressing the spring-loaded hook handle and pushing the hatch toward the closed position. To support and protect the hatch against the airlock ceiling, the hatch incorporates two deployable struts. The struts are connected to the hatch linkage mechanism and are deployed when the hatch linkage is rotated open. When the hatch latches are rotated closed, the struts are retracted against the hatch.

The airlock hatches can be removed in flight from the hinge mechanism using pip pins, if required.

The airlock air circulation system provides conditioned air to the airlock during non-EVA periods. The airlock revitalization system duct is attached to the outside airlock wall at launch. Upon airlock hatch opening in flight, the duct is rotated by the flight crew through the cabin/airlock hatch, installed in the airlock and held in place by a strap holder. The duct has a removable air diffuser cap, installed on the end of the flexible duct, which can adjust the air flow from 216 pounds per hour. The duct must be rotated out of the airlock before the cabin/airlock hatch is closed for airlock depressurization. During the EVA preparation period, the duct is rotated out of the airlock and can be used for supplemental air circulation in the middeck.

To assist the crew member before and after EVA operations, the airlock incorporates handrails and foot restraints. Handrails are located alongside the avionics and ECLSS panels. Aluminum alloy handholds mounted on each side of the hatches have oval configurations 0.75 by 1.32 inches and are painted yellow. They are bonded to the airlock walls with an epoxyphenolic adhesive. Each handrail has a clearance of 2.25 inches between the airlock wall and the handrail to allow the astronauts to grip it while wearing a pressurized glove. Foot restraints are installed on the airlock floor nearer the payload bay side. The ceiling handhold is installed nearer the cabin side of the airlock. The foot restraints can be rotated 360 degrees by releasing a spring-loaded latch and lock in every 90 degrees. A rotation release knob on the foot restraint is designed for shirt-sleeve operation and, therefore, must be positioned before the suit is donned. The foot restraint is bolted to the floor and cannot be removed in flight. It is sized for the EMU boot. The crew member first inserts his foot under the toe bar and then rotates his heel from inboard to outboard until the heel of the boot is captured.

There are four floodlights in the airlock.

If the airlock is relocated to the payload bay from the middeck, it will function in the same manner as in the middeck. Insulation is installed on the airlock's exterior for protection from the extreme temperatures of space.

From NASA Shuttle Reference Manual: Orbiter Structure: Airlock


"Spacing" or "airlocking" is a nasty form of execution, where the victim is forced into the airlock while not wearing a spacesuit. The airlock is then cycled, hurling the victim into airless space where they suffocate. Sometimes this is made as a threat, e.g., "Follow my orders you scum, or I'll throw you out the airlock stark naked!"

Spacing is more or less the equivalent of a pirate making a victim walk the plank. The more merciful way is to put them in the airlock in ordinary clothing, or nude. They will be unconsious in about ten seconds and dead in 90. The more sadistic way is to have them in a spacesuit with about an half an hour's worth of oxygen, so they can be tortured by the reality of their approaching demise as they watch the oxygen gauge slowely drops to zero.

Some writers have the dramatic idea of opening the airlock while it is still pressurized so as to blow the victim into space. This avoids the necessity for a space suited person to enter the lock and kick the body out. However standard air pressure is not strong enough to blow the victim into space. You need about ten atmospheres for that. Also the victim will probably be frantically hanging onto anything they can grab inside the airlock in any event. Using ten atmospheres of air pressure to remove the executed is probably a waste of good breathing mix.

A more civilized version of this is when somebody happens to die onboard the ship. The airlock can be used to send the dear departed on their way by space burial.


"You know what the folks back home don't understand, the ones who've never left Earth, is just how dangerous space can be. Aside from incidents like this, just the everyday reality of living your days and nights in a big tin can surrounded by a vacuum."

"I remember my first time on a transport, on the Moon-Mars run. I was just a kid, maybe seventeen. A buddy of mine was messing around, and zipping through the halls, and he hid in one of the airlocks. I don't know, I guess he was gonna try to scare us or something, I don't know... But just as I got close, he must have hit the wrong button because the air doors slammed shut, the space doors opened, and he... just flew out into space."

"And the one thing they never tell you is that you don't die instantly in vacuum. He just hung there against the black like a puppet with his strings all tangled up... or one of those old cartoons where you run off the edge of the cliff and your legs keep going."

"You could see that he was trying to breathe, but there was nothing. The one thing I remember when they pulled in his body... his eyes were frozen."

"A lot of people make jokes about spacing somebody, about shoving somebody out an airlock — I don't think it's funny. Never will."


      Channel B, the all-talk channel on the intercom:

     "Hey, when we get back to base, what're we going to say when they ask us why we couldn't catch the bogie?"
     "Our butterfly net had a hole in it?"
     "That's very funny —hey, aren't you the guy who, when they start insulting your ship in the bars, you start nodding your head and agreeing?"
     "Yeah, well —I don't like to argue with my own shipmates."
     "Has anyone ever noticed there something weird about (first officer) Korie? —Like he's always calculating?"
     "There's something weird about everybody on this ship. That's why we're here."
     "Hey, does anybody know what the penalty for mutiny is?"
     "Last I heard, it was death by spacing."
     "Hmm—that's getting more attractive every day."
     "Forget it. The last one to try taking over the ship was Captain Brandt."
     "And what happened to him?"
     "Korie sent him to his room."
     "That bastard—that's pretty harsh treatment for an old man."

From YESTERDAY'S CHILDREN by David Gerrold (1972)

The Autocrat of Ceres sat in his very plain chair in the very plain compartment, and regarded the two very nervous people before him with regret. He was going to have to kill them.

“I’m very much afraid,” he said, “that I don’t have much choice in the matter. You were each expected to show cause why I should not put you to death. I have seen no such cause shown. Instead I have seen two people who have allowed a petty squabble over mining rights to degenerate into another useless rock war. It is your egos, and not the mining rights, that prevent justice in this case. And the Autocrat’s Law requires me to remove all obstacles to justice. Case closed.” The Autocrat nodded toward his marshals, and they stepped forward.

The plaintiff screamed, the defendant fainted. The marshals were good at what they did. Within seconds, both of the claimants were restrained, sedated, and being taken away, toward the Autocrat’s very plain, very famous, very deadly airlock. The one where pressure suits were not allowed. The place to which human obstacles to justice were quite literally removed.

Justice, as with many other things in the Belt, was in short supply, and when available, was not of the best quality—too rough, too harsh and too rushed. To the Inner System dandies who visited now and again, the Autocrat’s Law seemed barbaric, violent and vengeful. But to the Belters, who had no other source of justice, the Autocrat’s Law represented civilization itself. In all the wide, wild, ungovernable vastness of the Asteroid Belt, they knew there was one place, one name, one law that all could trust. Only the Autocrat’s Law could protect them against themselves. Harsh and final it might be, but so too was it impartial.

For the Belters knew the Belt was huge—ungovernably huge. There could be no law when law enforcement was impossible, and no conventional enforcement was possible when the population density was something less than one crotchety misanthropic old coot per million cubic kilometers. It was easy for other things besides law to get lost in the midst of all that vast expanse.

Things like sanity, order, trust, proportion. Megalomania was an easy disease to catch when a man or a woman could have a world—albeit a very small one—for the effort of landing on it. And if your own world, why not your own law, your own empire? Why not declare the divine right of kings and expand outward, conquering your neighbors as you go?

The Belt had seen a thousand rock wars between independent states, many of which consisted of two rock-happy miners taking potshots at each other. If lunatics wanted to exterminate each other, that was their own affair, but there was a more serious and basic problem. Other people could get drawn in, or get caught in the cross fire. In all likelihood, the Autocrat had saved dozens of lives this day by blotting out the leaders in this pointless fight.

But, obvious as the case had been, the Autocrat had taken pause before rendering his decision. The present Autocrat of Ceres was a most careful person. But so was the previous holder of the post, and the one before that. No other sort of person would ever be appointed.

Not only Ceres, but the entire Belt Community as well depended on the Autocrat’s authority to supply order, discipline, regimentation, at least to Ceres and its surrounding satellites and stations. Anarchy surrounded Ceres on all sides, but even the Belt’s wildest anarchists knew they needed Ceres to be stable, orderly, predictable, to be a place where a trader could buy and sell in safety.

The rules might change elsewhere with every passing day, but at Ceres the Law was always the same. Claims filed in the office of the Autocrat were honored everywhere—for they were backed not only by the Autocrat’s Law and Justice, but his Vengeance.

Nothing but fair dealing was ever done in a Ceres warehouse. None but fair prices were ever paid. No one brought suit frivolously. For the Autocrat himself stood in judgment of all cases.

By the Law, the Autocrat was required, in every case from unlicensed gambling straight up to claim jumping and murder, to find cause why the death penalty should not be exacted against one—or both parties—to the case. If the Autocrat could not—or would not—find such cause, plaintiff and claimant, accuser and defendant died.

The Autocrat’s Law had a long reach. Many defendants were tried in absentia, having chosen to flee rather than face a day in court. But as the saying went, If the Autocrat finds you guilty, he will find you in the flesh. His bounty hunters—and his rewards—found the guilty everywhere. Very few places refused to honor his warrant—and none were places a sane man would flee towards.

Indeed, fear of the Autocrat’s Justice prevented all but the most worthy claimants from coming forth to ask it, and prevented all but the most venal from risking its power. Calls for justice were few and far between when the sword was as sharp as it was double-edged.

From THE RING OF CHARON by Roger MacBride Allen (1990)

(ed note: Lazarus Long tells a story of how he ended up staying years — long enough for his babies to be grown men — on a planet because the government confiscated his ship, and it took that long to make enough money to buy his ship back. Also, that planet is a slaver planet, where slavery and slave trading are legal, something Lazarus detests, badly.)

Once I got my hands on my ship, I had it fumigated and checked it over myself and had it loaded with items I thought I could sell and had food and water taken on for the human cargo it had been refitted for, and sent the captain and crew on a week’s leave, and notified the Protector of Servants — the state slave factor, that is — that we would load as soon as the skipper and purser were back. (the Protector of Servants is also the asshat who confiscated Lazarus' ship in the first place, but who doesn't recognize Lazarus)

“Then I took my family on a holiday inspection of the ship. Somehow the Protector of Servants was suspicious; he insisted on touring the ship with us. So we had to take him along when we took off from there, very suddenly, shortly after my family was aboard. Right out of that system and never went back. But before we put down on a civilized planet, me and my boys — two almost grown by then — removed any sign that she had ever been a slaver, even though it mean jettisoning stuff I could have sold.”

“What about the Protector of Servants?” I asked. “Wasn’t he some trouble to you?”

“Wondered if you would notice that. I spaced the bastard! Alive. He went thataway, eyes popped out and peeing blood. What did you expect me to do? Kiss him?”

From TIME ENOUGH FOR LOVE by Robert Heinlein (1973)

Iris Doors

There are two main styles of "iris" doors: Leaf Iris and Petal Iris.

Leaf Iris Doors

In the role playing game Traveller, airlock doors are often in the form of a iris. This is probably due to the authors of Traveller taking the advice of Robert Heinlein. He noted that science fiction writers can evoke a futuristic vibe by throwing out a weird detail as if it was commonplace, e.g., The door dilated. This phrase has evolved to science fiction fan jargon meaning "cool, but inefficient", but I digress.

Anyway, in the artwork for Traveller game supplements, iris doors are generally depicted as something like a titanic camera diaphragm iris. Sort of like the iris shield on the Stargate, but without the sharp pointy bits.

An iris actually will not work on an airlock, since those always have a small hole in the center where the air will leak out. However, NASA is looking into a rugged iris design that is air-tight.

Besides the lack of a hermetic seal, the individual leafs have to be very thin or they cannot interleave. Which makes for a flimsy door, not a good idea for a hatch which is the only thing standing between you and a horrible suffocating death from the airless vacuum of space.

The Traveller drawings and deck plans also ignore the fact that there has to be space around the edge of the door for the leaves to retract into. The entire door diameter is about 1.55 the size of the door opening. If a standard Traveller iris door had an opening 1.5 meters in diameter, the entire door mechanism would be 2.33 meters in diameter.

Petal Iris Doors

Another design that would work is a four, five, or six petal door; like the one on the roof of the Millennium Falcon which Lando Calrissian exited to rescue Luke Skywalker from the underside of Bespin, in the movie The Empire Strikes Back. Like the NASA design they are actually air-tight.

The petals can be of any arbitrary thickness, allowing an overwhelming safety margin protecting you from death by space asphyxiation. The thickness also allows the use of locking cylindrical bolts like in bank vault doors, providing additional protection from door breaches by air pressure or space pirates.

Unfortunately such doors need even more space around the edge for the petals to retract into. For a six-petal rotating design the door diameter is 1.83 times the size of the door opening.

Docking Ports

A docking port is specialized pressure hatch on a spacecraft that can mate to another docking port on another spacecraft or space station. It creates a pressurized connection so that crew can walk or float from one spacecraft into the other without having to put on space suits. It also makes a strong mechanical connection, because if the connection between the two ships fails when the hatches are open the results will be most tragic.

An airlock is not required as part of a docking port, but it is insanely dangerous to leave it out of the design. Having said that, as far as I am aware there are no real-world spacecraft with airlocks due to the mass and volume of an airlock (with the exception of NASA's space shuttle). Airlocks do add lots of extra mass, which cuts into the rest of the module's mass budget.

Space stations components can be connected in a semi-permanent fashion by mating their docking ports.

A docking mechanism is used when one spacecraft actively maneuvers under its own propulsion to connect to another spacecraft. So Flash Fearless—Space Ace manually pilots his space cruiser to dock with Space Station Beta, while the station watches nervously.

A berthing mechanism is used when space station modules or spacecraft are attached to one another via the manipulations of a robotic arm (instead of their own propulsion) for the final few meters of the rendezvous and attachment process. So the uncrewed resupply rocket approaches the space station and turns off its engines. The station crew extends the robot arm, grabs the rocket, and manhandles the rocket to berth it to the station's berthing port.

Currently there exist no mechanisms that can perform both docking and berthing. NASA is developing the NASA Docking System which will do both, but the design has not been finalized yet.

Note that a robotic arm had better be equipped to deal with high-voltage electrostatic discharge. Or the results of the lightning bolt will be unfortunate.

It is also a very bad idea to have no international standards for docking ports. If the Russian ports cannot dock with Chinese ports, this will drastically reduce the number of rescue options if an emergency happens. There is work being done on a Universal Space Interface Standard, but nothing hs been completed yet.

Early docking ports were even more stupid. They were non-androgynous systems, with a male part and a female part. Sort of like the two ends of an electrical extension cord, one with prongs the other with a receptacle. Which means if the rescue spacecraft and the stricken spacecraft both had male ports, they were out of luck. Or at least the stricken ship is.

If spacecraft commonly have nuclear propulsion systems and/or nuclear power systems, ship design will more or less force ships to dock bow-to-bow (nose-to-nose).

Here's why. Radiations shields by their very nature are massive, and thus cut into the payload capacity. So instead of coating the entire reactor, ships will use "shadow shield" as the smallest possible shield. In the left diagram below, the white area is safe, and the blue area is filled with the deadly radioactive shine from the reactor.

Now say that a lunar shuttle vehicle arrives, and wants to dock. It does not want to wander into the blue radiation zone, or its crew will be irradiated. The crew of the nuclear ferry vehicle does not want the lunar shuttle in the radiation zone either, because the shuttle's metal structure could scatter (reflect) radiation from the ferry's reactor into the ferry's crew.

If you examine the situation, the only safe way seems to be bow-to-bow. Even more so if two nuclear spacecraft want to dock. You may remember this is how the Apollo command and service module docked to the lunar module, even though neither was nuclear powered.

This does throw a monkey wrench into Traveller's definition of "Port", but that's just too bad.


The current standard for docking adapters in Imperial space, suitable for both docking and berthing, is defined by IOSS 52114, the Imperial Universal Starship Interface (IUSI).

The standard defines androgynous docking adapters in three standard sizes (IUSI-C/crawlspace, IUSI-P/gangway, and IUSI-F/freight container), in both standard (containing a transfer passage and data interface capability) and extended (containing additionally power and utility transfer connections) formats. These adapters are specifically designed to operate with Imperial-standard airlocks (per IOSS 51008) but can be fitted over any of a wide variety of airlock and/or spacetight door standards.

Standard and extended adapters are mutually compatible, with the redundant connections on the extended adapter fitting into sealing caps on the standard adapter. While adapters of differing sizes cannot directly connect, collapsible connection modules for this purpose are available at many starports or compilable from freely-available recipes.

– The Starship Handbook, 155th ed.

From DOCKING by Alistair Young (2015)

prophylock (n.): Used primarily by free traders, a prophylock is a collapsible docking module used when rendezvousing with untrusted vessels for cargo transfer. Similar to a standard docking module, a prophylock is a cylinder with an IUSI-P or IUSI-F androgynous adapter on each end, one to attach to the host starship and one to dock with the foreign starship.

The prophylock, however, has near its outboard end an armored barrier which prohibits the passage of sophonts, equipped with a secure passage (complete with mechanical interlocks preventing both sides from being opened simultaneously, and sampling systems for testing the contents before opening the inner door) through which the transfers may take place. In the event that both vessels are using prophylocks, the secure passage systems are designed to allow transfers from one to the other without direct integration, but also without requiring anyone to occupy the ‘tween-lock volume.

Rather than the direct data systems connection of a standard IUSI adapter, the prophylock connects the foreign data bus to a limited-functionality terminal, permitting communication and negotiation to take place without information risk.

Finally, the outboard end of the prophylock is equipped, for the case in which a lack of trust should turn out to be justified, with an explosive collar to sever the outboard androgynous adapter, thus reliably breaking the connection between vessels, along with solid-fuel jettison rockets to push the host vessel back immediately upon collar detonation, shortening the time to safe burn clearance as much as possible.

Fly safe. Dock safer.

– A Star Traveller’s Dictionary

(Yes, I was thinking of Out of Gas when I wrote this one…)

From SAFETY by Alistair Young (2016)


Far back in time, long before Captain Kirk ordered the Starship Enterprise to enter Warp Factor Five, longer even before Frank Belknap Long invented the term space warp drive, sailing vessels moved by "warping." Also known as "kedging".

You've seen it a million times. A person is inside a rowboat near a mooring dock, holding a rope tied to said dock. All they have to do is the old "heave-ho" routine, pulling on the rope, and the rowboat moves to the dock. The rowboat is "warped" into place.

On the International Space Station, this was adapted for "berthing", replacing the mooring line with the robot arm. In old Robert Heinlein novels, spacecraft were warped into docking ports on a space station the old fashion way, with space-rated mooring lines. Heinlein figured that a spacecraft attempting to dock by using attitude jets was too dangerous. It wastes reaction control system propellant as well, while a mooring line can be re-used.


      Goddard Hotel stuck out from the side of Circum-Terra like a cartwheel from a pile of junk. The hub on which it turned ran through its center and protruded out into space. It was to this hub that a ship would couple its passenger tube when discharging or loading humans. That done, the ship would then be warped over to a cargo port in the non-spinning major body of the station. When the Glory Road made contact, there were three other ships in at Circum-Terra, the Valkyrie in which Don Harvey had passage for Mars, the Nautilus, just in from Venus and in which Sir Isaac expected to return home, and the Spring Tide, the Luna shuttle which alternated with its sister the Neap Tide.

     The two liners and the moon ship were already tied up to the main body of the station; the Glory Road warped in at the hub of the hotel and immediately began to discharge passengers. Don waited his turn and then pulled himself along by handholds, dragging his bags behind him, and soon found himself inside the hotel, but still in weightless free fall in the cylindrical hub of the Goddard.

From BETWEEN PLANETS by Robert Heinlein (1951)

One of them shot something at us and a line came snaking across. Before the knob on the end of it quite reached us there was a bright purple brush discharge from the end of it and every hair on my head stood straight up and my skin prickled.

The knob on the line clunked against the side of the ship and after a bit the little line was followed by a heavier line and then they warped us together, slowly. The Mayflower came up until she filled the port.

From FARMER IN THE SKY by Robert Heinlein (1950)

      "Damn it—I won't if I don't have to." He was fingering his controls again; the blast chopped off his words. When it stopped, the radio maneuvering circuit was calling him.
     "Flying Dutchman, Pilot speaking," Jake shouted back.
     "Terminal Control—Supro (space station Supra-New York) reports you short on fuel."
     "Don't approach. Match speeds outside us. We'll send a transfer ship to refuel you and pick up passengers."
     "I think I can make it."
     "Don't try it. Wait for refueling."
     "Quit telling me how to pilot my ship!" Pemberton switched off the circuit, then stared at the board, whistling morosely. Kelly filled in the words in his mind: "Casey said to the fireman, 'Boy, you better jump, cause two locomotives are agoing to bump!'"
     "You going in the slip anyhow, Jake?"
     "Mmm—no, blast it. I can't take a chance of caving in the side of Terminal, not with passengers aboard. But I'm not going to match speeds fifty miles outside and wait for a piggyback."
     He aimed for a near miss just outside Terminal's orbit, conning by instinct, for Weinstein's figures meant nothing by now. His aim was good; he did not have to waste his hoarded fuel on last minute side corrections to keep from hitting Terminal. When at last he was sure of sliding safely on past if unchecked, he braked once more. Then, as he started to cut off the power, the jets coughed, sputtered, and quit (he ran out of fuel).
     The Flying Dutchman floated in space, five hundred yards outside Terminal, speeds matched.
     Jake switched on the radio. "Terminal—stand by for my line. I'll warp her in."

From SPACE JOCKEY by Robert Heinlein (1947)

The two ships, perfectly matched to eye and almost so by instrument, nevertheless had drifted a couple. of miles apart while the epidemic in the liner raged and died out. The undetectable gravitational attraction between them gave them mutual escape velocity much less than their tiny residual relative motion. Up to now nothing had been done about it since they were still in the easiest of phone range. But now it was necessary to pump reactive mass from one to the other.

Roger Stone threw a weight fastened to a light messenger line as straight and as far as he could heave. By the time it was slowed to a crawl by the drag of the line a crewman from the War God came out after it on his suit jet, In due course the messenger line brought over a heavier line which was fastened to the smaller ship. Hand power alone took a strain on the line. While the mass of Rolling Stone was enormous by human muscle standards, the vector involved was too small to handle by jet and friction was nil. In warping in a space ship the lack of brakes is a consideration more important than power, as numerous dents to ships and space stations testify.

As a result of that gentle tug, two and a half days later the ships were close enough to permit a fuel hose to be connected between them.

From THE ROLLING STONES by Robert Heinlein (1952)

As for the other passenger decks, they found that when they had seen one, they had seen all. Shipboard refreshers interested them for a while, as the curious and clever modifications necessary to make a refresher function properly in space were new to both of them. But four hours is too long to spend inspecting showers and fixtures; after a while they found another fairly quiet spot to loaf and experienced for the first time the outstanding characteristic of all space travel—its monotony.

Much later the ship’s speaker blared, “Prepare for acceleration. Ten minute warning.”

Strapped down again, each in his place, the boys felt short blasts of power at rather long intervals, then a very considerable wait, after which there was the softest and gentlest of bumps. “That’s the drag line,” remarked the sergeant in Matt’s compartment. “They’ll warp us in. It won’t be long now.”

Ten minutes later the speaker announced, “By decks, in succession—discharge passengers.”

     “Then carry himl”
     “How? Piggy-back?”
     “Any way—but do it! The ship is sinking!”
     Tex opened his mouth, closed it again, and dived toward a small locker. Matt yelled. “Tex—get a line!”
     “What do you think I’m doing? Ice-skating?” Tex reappeared with a coil of thin, strong line used in warping the little craft in to her mother ship. “Easy now—lift him as I slip it under his chest.”

From SPACE CADET by Robert Heinlein (1948)

There was frenetic and noisy activity around the base and halfway up the flanks of the interstellar leviathan. Burdened warehouse trucks scooted out of the gaping holds and empty ones scooted in; winches rose and fell. Ground armor clanked into the maws of big freight copters and the loaded copter lifted swiftly to make room for others. Higher up, pale lemon tractor beams reached out to enfold the long slim paratroop ships as they returned from their drops, and warp them home.

From SLEEPING PLANET by William Burkett (1965)

Electrostatic Discharge

In the space environment, it is possible for parts of a spacecraft to charge up (like shuffling your feet on the carpet on a dry winter's day) which can result in an electrostatic discharge (like when you've shuffled, then touch the door knob).

This can cause a spark to jump between spacecraft components or between two docking spacecraft, resulting in damage. In addition if an astronaut on EVA touches the wrong spacecraft or space station component they could get zapped with a severe electrical shock.

Designers will include some sort of discharge probe to safely equalize the electrical potential between the two objects.


Plasma contactors are devices used on spacecraft in order to prevent accumulation of electrostatic charge through the expulsion of plasma (often Xenon).

An electrical contactor is an electrically controlled switch which closes a power or high voltage electrical circuit. A plasma contactor changes the electrically insulating vacuum into a conductor by providing movable electrons and positive gas ions. This conductive path closes a phantom loop circuit to discharge or neutralize the static electricity that can build up on a spacecraft.

Space contains regions with varying concentrations of charged particles such as the plasma sheet, and a static charge builds up as the spacecraft moves between these regions, or as the electrical potential varies within such a region.

Static electricity may also build up on a spacecraft as a result of space radiation, including sunlight, depending on the materials used on the surfaces of the spacecraft.

A plasma contactor is mounted on the Z1 segment of the International Space Station Integrated Truss Structure.

From the Wikipedia entry for PLASMA CONTACTOR

Astronauts Jeff Williams and Thomas Reiter began a scheduled 6-hour spacewalk outside the International Space Station at 1004 EDT (1404 GMT) on Thursday.

One of their main tasks will be to install a device to measure the potentially dangerous static-electricity build-up outside the ISS. The solar arrays, which generate electricity for the orbiting outpost, operate at a higher voltage and have more adjacent solar cells than most spacecraft.

As a result, they collect electrons from the ionised gas in space more quickly than they can be discharged. Eventually, this charge can be released in the form of a spark. That arcing can vaporise some of the metal on the space station, creating a small, dense cloud of ions that expands across its surface. As it does so, it picks up even more negative charges.

NASA has two major concerns about this build-up of charge. First, sporadic arcing could cause long-term damage to the station’s skin-like thermal heat shield, which keeps the station’s temperatures within an acceptable range.

Second, arcing could shock a spacewalking astronaut. NASA says there is a health risk if the ISS charges to more than 40 volts, and a 2002 NASA report says that voltages as low as 60 volts could cause cardiac arrest in a spacewalking astronaut.

“Space vampires”

“If that breakdown occurs on either the metal glove rings on a spacesuit or the neck ring, then you can potentially discharge a fair amount of current from the space station through the astronaut’s space suit or through the astronaut himself,” says Charles Swenson, the principal investigator for the new device at Utah State University’s Space Dynamics Laboratory in North Logan, US.

NASA had sent a previous device, called the Floating Potential Probe, to measure the charge build-up outside the ISS in 2000, but it failed and was discarded during a spacewalk in 2005.

So in July, the space shuttle Discovery delivered a better device, called the Floating Potential Measurement Unit, to the station. The 130 centimetre by 150 cm device, which is shaped like a cross, will help refine computer models of electrical build-up outside the ISS. “When we’re feeling really punchy, we say it protects the astronauts from space vampires,” Swenson told New Scientist.

Escalating problem

Right now, two plasma contactor units bleed excess charge away from the space station, which helps protect astronauts from dangerous sparks. The units make a dense gas of xenon ions that contact the surrounding ionised gas in space, grounding the ISS to its space environment.

But the problem of charge build-up looks set to get worse because the next shuttle mission, scheduled for launch no earlier than 27 August, will deliver more solar arrays to the ISS. These additions could escalate the charging problem, Swenson warns.

The Floating Potential Measurement Unit will be the first item Williams and Reiter will install during their spacewalk. They will also replace an electronics box called a rotary joint motor controller and a computer for a radiator; attach two experiments that expose different materials to the harsh environment of space; test an infrared camera and add other gear to the outside of the station.

These changes will help prepare the station for its continued construction, which will be accomplished through 15 more shuttle flights by 2010. “We’re now ready to execute one of the most challenging sets of flights in the history of the space station programme,” deputy ISS director Kirk Shireman said last week. This spacewalk “is very important to put us into position for these flights”.


Spacecraft Charging

  • Low altitude plasma -Subject of this talk
    • Cold, dense plasma that most often suppresses satellite surface charging - Roughly similar to an air ionizer
    • Can also cause charging by interaction with spacecraft voltage sources
    • Encountered at orbital speeds (8 km/sec)
  • High altitude plasma
    • A problem at Geostationary, polar orbits, and radiation belts - Many charging anomalies including loss of spacecraft
    • Energetic, rarified plasma, able to charge satellites to high voltages directly
    • Encountered at variety of speeds (trapped plasma, solar wind)
  • Particle radiation
    • Trapped radiation and auroral arcs
    • Encountered over range of speeds up to relativistic

Our natural plasma varies with altitude, past and current solar activity, Earth’s variable geomagnetic index, latitude, longitude, and local time. Cold dense plasma in low earth orbit (LEO) gives rise to different problems than hot, rarified plasma at Geostationary orbit (GEO).

International SpaceStation

  • 440+ tons, mostly aluminum
  • 100 meters wide
  • 160 VDC primary power from 8 wings(120VDC secondary) is grounded to hull. “S” bonding or better between all elements
  • Russian System (28VDC) is not grounded
  • Oxide and other insulators cover outer surface
  • Flies in “F” region of ionosphere at 400km

Is ESD a problem to ISS?

  • A hazard occurs whenever one disturbs an equilibrium: i.e., while passing any sort of energy into anything of value to you.
  • ESD: the act of passing electricity through something of value to you == A hazard
  • We have non-bonded conducting objects (especially including crew) in plasma with B fields and E fields. Lots of ways to make an electrostatic discharge == Lots of hazards


  • The risk of electrostatic discharge through EVA crew was elevated in 2001 to be one of the top ISS program risks
    • Only recently downgraded
    • This presentation shows why

The Players:

  • The EVA crewperson (the potential victim…)
  • The Potential Antagonists:
    • The ISS metallic structure
    • The ISS thin oxide and insulating coatings
    • The ISS high voltage solar power arrays
    • The natural plasma (and sun/earth influences on it)
    • The artificial plasma created by ISS PCUs
    • The Earth’s magnetic field (“B”)
    • The EVA suit(s) and tools/tethers

The Hazards: Simplest spacecraft charging hazard causes in low earth orbit:

  • Un-encapsulated high voltage PV power systems, with negative end grounded to spacecraft conducting structure, that can collect electrons from the cold dense ionospheric plasma
  • Large metallic spacecraft structures that generate motional EMF when flying through earth’s magnetic field at orbital speed (V×B⋅L) and also collect electrons for the plasma.

The “Negative” Plasma Hazard:

  • Electrons preferentially attracted to exposed positive conductors, while ions not as mobile.
    • Cold dense plasma problem: not seen at GEO
    • “High side” circuit potential moves down, toward neutral
  • Voltage regulation causes the return side (equipotential with hull) to move below neutral
  • Oxide layers prevent ion neutralization of negative plane.
  • Un-bonded crew then at one potential while ISS Structure moves to another
    • Surface dielectric breakdown can make a highly-localized, large discharge (ISS is 0.01 Farad capacitance)

Negative Plasma Solutions

  • This is not just a crew problem: Discharge canbreak down dielectrics, create EMI, if too high
  • Solved with plasma contactor unit (PCU) to make slow neutral plasma “bath” around ISS.
    • Essentially forces the collected electrons back into the environment in the form of charged particles.

And if the PCU fails?

  • Redundant PCUs
  • Point the active solar arraysurfaces to wake
    • Potentially significant power loss to ISS
  • Monitor the plasma environment
    • If weak enough, can live with worst-case potential
    • Crew susceptible earlier than dielectrics: we live with some dielectric risk and generally only turn on PCUs during EVAs

How do we know what the environment is?

The Floating Potential Measurement Unit (FPMU), using the The Plasma Interaction Model (PIM)

We worry about Positive, too

  • This is a V×B⋅L problem with a long metal boom perpendicular to B field lines, moving at high speed
  • Amplifies in concentrated field near Earth’s poles
    • Local potential at truss tip changes rapidly from the last time the crew made contact. Renewed ground contact makes a capacitive inrush: an “AC” momentary shock hazard
    • Some conducting surfaces on suit can act like a collector, giving electrons a path through crewperson to local ground: A “DC” hazard


  • Ironically, the positive hazard is exacerbated when the plasma contactor removes the negative hazard.
    • Tries to keep the ground plane from suppressing
    • Pushes the end of truss over the top in positive potential hazard


  • ISS operates in electrically conductive plasma environment
  • PCU’s provide ISS ground to plasma
  • As truss flies through the magnetic field a voltage is created along it
    • Combined with PCU’s creates positive potentials on ISS conducting structure
    • High potentials only seen outboard of rotating truss join
    • Plasma acts as a common ground

Positive Risk Mitigation

The ISS Program has enacted all of the following:

  1. Revisit probabilistic risk assessment
    • Result: Crew severe Injury Risk is 1.94E-4 per 5.5 hrs of EVA outboard of rotary joint in un-modified suit, 1.54E-4 with sensor cable modified as listed below, vs. 5.99E-5 for a 6.5 hour EVA when not in positive plasma region of concern. Risk downgraded from catastrophic consequence to severe injury consequence.
  2. Isolation of US Suit external conductive pathways
    • Result: MMWS can be electrically isolated from the EMU and coated to prevent electrical contact
      • Approved at Program review 10/15/ 2009. Now available on-orbit
      • Isolates the most probable plasma charging/contact area
      • Other isolations not practical without major suit contract mods & recertification
  3. Isolation of US Suit internal conductive pathways
    • Result: Safety panel approved a temporary taping of the connections inside the US suit when needed for EVAs that include activity in the positive charge region.
      • Fixes the most probable conducting path to the crewperson & dramatically reduces the AC portion of the risk cause
      • Now available on-orbit. First implemented 2010
      • Other isolations not practical without major suit contract mods & recertification
  4. Adjustment of plasma potential via ISS attitude
    • Result: “sideways” attitude removes the V×B component . The +/-YVV-Z nadir stage attitudes are approved within NASA & Boeing for overlapping ranges from zero to +/-55 deg Beta. (85% of all days)
    • No critical ops in problem area have been identified requiring immediate high-beta EVA: at worst a nuisance of waiting for right conditions, operating in degraded conditions.
  5. Refine study of neuro-physical pathways, impedances, and responses
    • Result: Detailed model shows neuro-physical startle/strong-reflex/pain response (not death) is still possible
      • Corroborated with new International standards for shock exposure
      • Permanent injury is still criedible

(ed note: Humans have found alien carvings on various planets from an unknown race dubbed the "Plumies". The good ship Niccola is sent to try and find a Plumie ship and make peaceful first contact. Which is appropriate since author Murray Leinster invented the term in 1945. They didn't call Leinster the "Dean of Science Fiction" for nothing.

Unfortunately the Niccola's xenophobic weapons officer starts firing unauthorized missiles at the alien ship because of course he does.)

      There were noises inside the Niccola, now. Taine fairly howled an order. There were yells of defiance and excitement. There were more of those inadequate noises as rockets went out—every tube on the starboard side emptied itself in a series of savage grunts—and the Niccola's magnetronic drive roared at full flux density.
     The two ships were less than a mile apart when the Niccola let go her full double broadside of missiles. And then it seemed that the Plumie ship was doomed. There were simply too many rockets to be seized and handled before at least one struck. But there was a new condition. The Plumie ship weaved and dodged its way through them. The new condition was that the rockets were just beginning their run. They had not achieved the terrific velocity they would accumulate in ten miles of no-gravity. They were new-launched; logy; clumsy: not the streaking, flashing death-and-destruction they would become with thirty more seconds of acceleration.
     So the Plumie ship dodged them with a skill and daring past belief. With an incredible agility it got inside them, nearer to the Niccola than they. And then it hurled itself at the human ship as if bent upon a suicidal crash which would destroy both ships together. But Baird, in the radar room, and the skipper in navigation, knew that it would plunge brilliantly past them at the last instant—

     And then they knew that it would not. Because, very suddenly and very abruptly, there was something the matter with the Plumie ship. The life went out of it. It ceased to steer. It began to turn slowly on an axis somewhere amidships. Its nose swung to one side, with no change in the direction of its motion. It floated onward. It was broadside to its line of travel. It continued to turn. It hurtled stern-first toward the Niccola. It did not swerve. It did not dance. It was a lifeless hulk: a derelict in space.
     And it would hit the Niccola amidships with no possible result but destruction for both vessels.

(ed note: they don't realize it yet, but the Niccola's "magnetronic drive" prevents the Plumie's propulsion system from operating if the two ships are too close together. )

     The Niccola's skipper bellowed orders, as if shouting would somehow give them more effect. The magnetronic drive roared. He'd demanded a miracle of it, and he almost got one. The drive strained its thrust-members. It hopelessly overloaded its coils. The Niccola's cobalt-steel hull became more than saturated with the drive-field, and it leaped madly upon an evasion course—
     And it very nearly got away. It was swinging clear when the Plumie ship drifted within fathoms. It was turning aside when the Plumie ship was within yards. And it was almost safe when the golden hull of the Plumie—shadowed now by the Niccola itself—barely scraped a side-keel.

     There was a touch, seemingly deliberate and gentle. But the Niccola shuddered horribly. Then the vision screens flared from such a light as might herald the crack of doom. There was a brightness greater than the brilliance of the sun. And then there was a wrenching, heaving shock. Then there was blackness.

     He clutched crazily at anything. The Niccola's internal gravity was cut off, and his head spun, and he heard collision-doors closing everywhere, but before they closed completely he heard the rasping sound of giant arcs leaping in the engine room. Then there was silence.
     Guided by the emergency light, he scrambled to the bank of communicator-buttons. What had been the floor was now a side wall. He climbed it and thumbed the navigation-room switch.
     "Radar room reporting," he said curtly. "Power out, gravity off, no reports from outside from power failure. No great physical damage."
     He began to hear other voices. There had never been an actual space-collision in the memory of man, but reports came crisply, and the cut-in speakers in the radar room repeated them. Ship-gravity was out all over the ship. Emergency lights were functioning, and those were all the lights there were. There was a slight, unexplained gravity-drift toward what had been the ship's port side. But damage-control reported no loss of pressure in the Niccola's inner hull, though four areas between inner and outer hulls had lost air pressure to space.

     "Mr. Baird," rasped the skipper. "We're blind! Forget everything else and give us eyes to see with!" 
     "We'll try battery power to the vision plates," Baird told Diane. "No full resolution, but better than nothing—"
     They worked together, feverishly. They were dizzy. Something close to nausea came upon them from pure giddiness. What had been the floor was now a wall, and they had to climb to each of the instruments that had been on a wall and now were on the ceiling. But their weight was ounces only. Baird said abruptly: "I know what's the matter! We're spinning! The whole ship's spinning! That's why we're giddy and why we have even a trace of weight. Centrifugal force! Ready for the current?"
     There was a tiny click, and the battery light dimmed. But a vision screen lighted faintly. The stars it showed were moving specks of light. The sun passed deliberately across the screen. Baird switched to other outside scanners. There was power for only one screen at a time. But he saw the starkly impossible. He pressed the navigation-room button.

     "Radar room reporting," he said urgently. "The Plumie ship is fast to us, in contact with our hull! Both ships are spinning together!" He was trying yet other scanners as he spoke, and now he said: "Got it! There are no lines connecting us to the Plumie, but it looks . . . yes! That flash when the ships came together was a flashover of high potential. We're welded to them along twenty feet of our hull!"
     Diane had returned to the utterly necessary routine of the radar room which was the nerve-center of the ship, gathering all information needed for navigation in space. The fact that there had been a collision, that the Niccola's engines were melted to unlovely scrap, that the Plumie ship was now welded irremovably to a side keel, and that a Plumie was signaling to humans while both ships went spinning through space toward an unknown destination—these things did not affect the obligations of the radar room.

     She looked. The view was of the Plumie as welded fast to the Niccola. The welding was itself an extraordinary result of the Plumie's battle-tactics. Tractor and pressor beams were known to men, of course, but human beings used them only under very special conditions. Their operation involved the building-up of terrific static charges. Unless a tractor-beam generator could be grounded to the object it was to pull, it tended to emit lightning-bolts at unpredictable intervals and in entirely random directions. So men didn't use them. Obviously, the Plumies did.
     They'd handled the Niccola's rockets with beams which charged the golden ship to billions of volts. And when the silicon-bronze Plumie ship touched the cobalt-steel Niccola—why—that charge had to be shared. It must have been the most spectacular of all artificial electric flames. Part of the Niccola's hull was vaporized, and undoubtedly part of the Plumie. But the unvaporized surfaces were molten and in contact—and they stuck.
     For a good twenty feet the two ships were united by the most perfect of vacuum-welds. The wholly dissimilar hulls formed a space-catamaran, with a sort of valley between their bulks. Spinning deliberately, as the united ships did, sometimes the sun shone brightly into that valley, and sometimes it was filled with the blackness of the pit.

From THE ALIENS by Murray Leinster (1959)

      I wanted to see the Mayflower from space, but they made us strap down before I could locate it. I got a pretty good view of Supra-New-York though; the Mayflower was in the 24-hour orbit the space station rides in and we were closing almost directly on it when the word came to strap down.
     Captain DeLongPre was quite some pilot. He didn't fiddle around with jockeying his ship into the new groove; he gave one long blast on the jet, the right time, the right amount, and the right direction. As it says in the physics book, "every one-plane correction-of-orbit problem which can be solved at all, can be solved with a single application of acceleration"—provided the pilot is good enough.
     He was good enough. When we went weightless again, I looked over my shoulder out a port and there was the Mayflower, with the Sun gleaming on her, large as life and not very far away. There was the softest sort of a correction bump and the loudspeaker sang out, "Contact completed. You may unstrap."

     I did and went to the port from which we could see the Mayflower. It was easy to see why she could never land; she had no airfoils of any sort, not even fins, and she was the wrong shape—almost spherical except that one side came out to a conical point.
     She looked much too small—then I realized that a little bulge that was sticking out past her edge at one point was actually the bow of the Icarus, unloading on the far side. Then suddenly she was enormous and the little flies on her were men in space suits.

     One of them shot something at us and a line came snaking across. Before the knob on the end of it quite reached us there was a bright purple brush discharge from the end of it and every hair on my head stood straight up and my skin prickled. A couple of the women in the compartment squealed and I heard Miss Andrews soothing them down and telling them that it was just the electrical potential adjusting between the two ships. If she had told them it was a bolt of lightning she would have been just as correct, but I don't suppose that would have soothed them.
     I wasn't scared; any kid who had fooled around with radio or any sort of electronics would have expected it.
     The knob on the line clunked against the side of the ship and after a bit the little line was followed by a heavier line and then they warped us together, slowly. The Mayflower came up until she filled the port.

     After a bit my ears popped (the two docking ports have mated and the airlocks opened) and the loudspeaker said, "All hands—prepare to disembark."

From FARMER IN THE SKY by Robert Heinlein (1950)

      “Tex — Tex!” Atkill called softly. Texas woke from sleep with a start. Atkill was bending over his telescope, watching something with an expression of unholy joy on his face. “Come here, Tex, and look — we have visitors at last. I knew they’d come eventually. Three ships!”
     Three thin pencil-ships floated in space, tiny things glinting in the harsh light of the great sun. Atkill watched them carefully, calculating their course accurately. They should reach him in a short three hours at their present velocity. He set to work rapidly.
     In an hour he had set the controls in the power-room for starting the Flame, and had set up the little piece of apparatus he had made in the garbage-lock, with a long, thin tube of aluminum held in place by strings of insulators. The rod projected some twenty feet from fee side of the ship. Along with the little apparatus he had made, there were three powerful magnets he had been making, and a little spark-gap of chrome-nickel blocks between the long aluminum tube and a heavy lead that grounded to the ship. Atkill had plans.

     “Tex, sweet lad, we are about to be saved. The mere coming of our friends gives us once more, power, light and life! I can start the Flame!”
     “Uhm — that’s right good news. How come? Yuh couldn’t before. They may decide to wipe us out instead of helping.”
     Atkill laughed cheerfully. “They’ve got to help. The sun’s been doing the necessary work for the last three months! All they have to do is come near — and they will. Remember, Tex, the late unpleasantness we watched from space here that they were having on that planet? War. They want weapons — science. We’ve got it. We’re a strange ship, a ship of neither their world or the enemy world. We are, apparently, a dead ship. They see in us a possibility of help. They will investigate.”
     “Uhm — but how come they’ll have to help?”
     “For three months that sun has been deluging our ship with ejected electrons. We’ve built up a tremendous charge. We haven’t lost a bit of it. Those ships, just come from a planet, have a much smaller charge. We’ll discharge to them, my lad, with a smash of about eighteen mega-volts — an extra two million. Really I need only sixteen or so. I said eighteen for safety — and I’ll have it. My starting apparatus for the Flame is weak on magnetism and gravitational fields, but the extra electric will make it up, I suspect.”

     The ships were slowing now, approaching cautiously. They were less than fifty miles away now. Atkill could see them clearly with the naked eye now as dots of light. He went back to the power-room and started the gyroscope device. It had been improved in the months that had passed, and was now a quite efficient machine for swinging the ship as he wished.
     Anxiously he watched the ships approach. Finally a lone, small ship came out of one of the three greater spaceships, and approached slowly. It circled the earth ship at a distance of a few hundred yards, then finally came toward them. A long metal arm reached out from the ship, and the machine came gently directly toward the out-jutting terminal Atkill had arranged.
     “Tex — get set as I showed you at the controls — one, two and five switches closed, four and six open, three at the midpoint. When the Flame starts, snap the dial seven to 458-23. Got it?”
     Atkill was working at the single, tiny lock. He closed a switch and the magnets ground slightly in their supports, pressing away from each other. Swiftly he made several further adjustments, and watched the ship. Absolute space — an almost perfect insulator. Would the discharge-shock be sudden enough to give the result he so desperately needed? Or would it be a slow leaking that would be perfectly useless?

     The discharge rods were less than a foot apart. Slowly the pilot of the stranger ship maneuvered them skillfully together. There was a terrific strain out there now — enough to have started his Flame if he had been in position to use it.
     They came within an inch — then suddenly they touched. A blinding, roaring smash of electric energy crashed across the gap between Atkill's discharge points. Less than two inches of separation, creating an electric field of terrific intensity. Atkill could feel the charge leak suddenly from his body — and cried out in exultant triumph as the clear white of the Release Flame suddenly sprang into being on his little block of iron. A tiny flame no larger than a flashlight bulb, a dazzling white point of light that pulsed for an instant, steadied, and glowed as it would glow for hundreds of millennia if left undisturbed.

From THE SPACE BEYOND by John W. Campbell jr. (1976)

(ed note: Our heroes on the Venus Equilateral space station are trying to invent an electron particle beam weapon. This hobby project takes on some urgency when a fellow named Murdock becomes a pirate and terrorizes the entire solar system. Engineers Channing and Walt brainstorm how to make the weapon work.)

      "Another thing, whilst I hold it in my mind," said Channing thoughtfully. "You go flinging electrons off the station in basketful after basketful, and the next bird that drops a ship on the landing stage is going to spot-weld himself right to the south end of Venus Equilateral. It wouldn't be long before the station would find itself being pulled into Sol because of the electrostatic stress— if we didn't run out of electrons first!"
     "I hardly think that we'd run out— but we might have a tough time flinging them away after a bit. Could it be that we should blow out a fistful of protons at the same time?"
     "Might make up a concentric beam and wave positive ions at the target," said Channing.
     "Don," said Walt in a worried voice, "how are we going to replace the charge on the station? Like the bird who was tossing baseballs out of the train— he quit when he ran out of them. Our gun will quit cold when we run out of electrons— or when the positive charge gets so high that the betatron can't overcome the electrostatic attraction."
     "Venus Equilateral is a free grid," smiled Channing. "As soon as we shoot off electrons, Old Sol becomes a hot cathode and our station collects 'em until the charge is equalized again."
     "And what is happening to the bird who is holding on to something when we make off with a million volts? Does he scrape himself off the opposite wall in a week or so— after he comes to— or can we use him for freezing ice cubes? ("frozen" is slang for "fried to a crisp and stuck to the wall") Seems to me that it might be a little bit fatal."
     "Didn't think of that," Channing said. "There's one thing: their personal charge doesn't add up to a large quantity of electricity. If we insulate 'em and put 'em in their spacesuits, they'll be all right as long as they don't try to grab anything. They'll be on the up and down for a bit, but the resistance of the spacesuit is high enough to keep 'em from draining out all their electrons at once. I recall the experiments with early Van de Graaff generators at a few million volts— the operator used to sit in the charged sphere because it was one place where he couldn't be hit by man-made lightning. It'll be rough, but it won't kill us. Spacesuits, and have 'em sit in plastic chairs, the feet of which are insulated from the floor by china dinner plates. This plastic wall covering that we have in the apartments is a blessing. If, it were all bare steel, every room would be a miniature Hell. Issue general instructions to that effect. We've been having emergency drills for a long time; now's the time to use the grand collection of elastomer spacesuits. Tell 'em we give 'em an hour to get ready."

(ed note: Murdoch's two other ships are destroyed by the electron gun, and his ship is crippled by a glancing blow)

     Murdoch's radio was completely dead. His ship was yawing from side to side as the static charges raced through the driver tubes. The pilot gained control after a fashion, and decided that he had taken enough. He circled the station warily and began to make a shaky landing at the south end.
     Channing saw him coming, and with a glint in his eye, he pressed the lever for the fourth and last time (firing the electron gun at nothing, but energizing Venus Equilateral's structure with a powerful positive charge).
     Murdoch's ship touched the landing stage just after the charge had been driven out into space. The heavy negative charge on the Hippocrates met the heavy positive charge on Venus Equilateral. The ship touched and from that contact, there arose a cloud of incandescent gas. The entire charge left the ship at once, and through that single contact.
     When the cloud dissipated, the contact was a crude but efficient welded joint that was gleaming white-hot.
     Channing said to Walt: "That's going to be messy."
     Inside the Hippocrates, men were frozen to their handholds (meaning the dead carbonized bodies are stuck to the handholds). It was messy, and cleaning up the Hippocrates was a job not relished by those who did it.

From RECOIL by George O. Smith (1943)

Airlock Tunnels

Sometimes they are docking adaptors, with a different type of connector on each end.

Docking in the Eldraeverse

While IOSS 52114-compliant docking adapters are commonly used in most polities throughout the Worlds, in selected regions and on the fringes non-compliant docking adapters are found in use. For this situation, IOSS 52114 also defines the IUSI-NC universal adapter, consisting of an inflatable tunnel with an IUSI-compatible adapter at one end, and an open end coated with a nanotechnological bonding compound capable of adhering to all commonly used hull materials, releasing upon mesh command without altering the attachment surface. The IUSI-NC can be installed during an extravehicular activity when pressurized transfers are required.

– The Starship Handbook, 155th ed.

From Docking by Alistair Young (2015)

     "One more thing, Captain."
     Rod knew something tricky was coming. Horvath had Dr. Hardy ask for all the things Rod might refuse.
     "The Moties want to build an air-lock bridge between the cutter and the embassy ship," Hardy finished.

     "Doctor, I don't like the idea of joining the two ships."
     "But, Captain, we need something like this. People and Moties are constantly passing back and forth, and they have to use the taxi every time. Besides, the Moties have already started work—"
     "May I point out that if they join those two ships, you and everyone aboard will thenceforth be hostage to the Moties' good will?"
     Horvath was ruffled. "I'm sure the aliens can be trusted, Captain. We're making very good progress with them."
     "Besides," Chaplain Hardy added equably, "we're hostage now. There was never a way to avoid the situation. MacArthur and Lenin are our protection, if we need protection. If two battleships don't scare them—well, we knew the situation when we boarded the cutter."

     The lock was begun as soon as Rod gave permission. A tube of thin metal, flexibly jointed, jutting from the hull of the Motie ship, it snaked toward them like a living creature.

     The landing boat was a blunt arrowhead coated with ablative material. The pilot's cabin was a large wrap-around transparency, and there were no other windows. When Sally and her Motie arrived at the entryway; she was startled to see Horace Bury just ahead of her.
     "You're going down to the Mote, Your Excellency?" Sally asked.
     "Yes, my lady." Bury seemed as surprised as Sally. He entered the connecting tube to find that the Moties had employed an old Navy trick—the tube was pressurized with a lower pressure at the receiving end, so that the passengers were wafted along.

From The Mote In God's Eye by Larry Niven and Jerry Pournelle (1975)

There weren't the questions about cargo or permits. The invaders had come in like they owned the place, and Captain Darren had rolled over like a dog. Everyone else—Mike, Dave, Wan Li—they'd all just thrown up their hands and gone along quietly. The pirates or slavers or whatever they were had dragged them off the little transport ship that had been her home, and down a docking tube without even minimal environment suits. The tube's thin layer of Mylar was the only thing between them and hard nothing: hope it didn't rip; goodbye lungs if it did.

From Leviathan Wakes by James Corey (2011)


Rockets don't got windows. At least nothing like the huge panorama picture windows you see on the Seaview or the bridge of an Imperial Star Destroyer.

When NASA was developing the windows for the Apollo spacecraft, there were some failures. After that, they decreeded the following: A spacecraft window is structurally defined as any piece of glass that is thermally or mechanically stressed and will endanger the crew or mission success if it breaks.

Huge windows on a spacecraft are not a good idea for many of the same reasons as they are not used on a submarine.

  • Window frames create a structural weakness in the hull.
  • If they break they let all the air out of the compartment, killing everybody. At the least you need airtight shutters.
  • They let in deadly space radiation.
  • If the spacecraft performs aerobraking or aerocapture the windows have to be protected from the blowtorch heat. This was a headache when NASA designed the Apollo Command Module. Windows melting or shattering could ruin your whole day.
  • With a few exceptions, there isn't anything to see. Outside of the exceptions the only things to see are
    • Endless black space dusted with stars
    • The eye-melting fury of the Sun
    • The planet you are orbiting, for the small fraction of the total space mission time that you are close enough to see the planet.

"But…but…but…!" you protest, "what about watching the dazzling spectacle of a space battle?" RocketCat does a face-palm at your naïveté. Star Trek, Star Wars, Battlestar Galactica, et al to the contrary, space battles will NOT be fought at spitting distance. Directed energy weapons will force ranges such that the enemy ships will only be visible through a telescope.

Watching a space battle through a port hole, you will either:

  • See nothing because the enemy ships are too far away to see without a telescope
  • See nothing because a reflected laser beam or nuclear explosion has permanently robbed you of your eyesight

Instead of windows, spacecraft will have lots of external sensors and video monitors inside for the crew to watch. Much like watching a football game: you will get a far superior view of the game if you stay home and watch it on TV.

As points of reference, the side windows on the Apollo Command Module (CM) are 33 centimeters square. The CM docking windows were 20×33 cm. The Apollo Lunar Module landing windows were 64×71 cm triangles, with the top edge further from the hull so the pilot can look down at the landing legs. The windows on the Space Shuttle airlock hatches were 10 cm in diameter.

The Cupola on the International Space Station has the largest windows used in space to date, the top window is an 80 cm disc. Yes, it has very thick shutters (made of Kevlar and Nextel). It is used to conduct experiments, dockings and observations of Terra. It also helps with the use of the amazing Canadarm2 remote manipulator.


Places where windows might be worth the drawbacks are"

Window Construction

This is from Apollo experience report: Spacecraft structural windows

Trusting the astronaut's lives to something made out of glass is nerve wracking, since glass is notoriously brittle. The strength of glass is measured by the modulus of rupture (MOR). A safety factor of 3.0 was used.

The Apollo command module has five double-pane windows, as shown in the diagram.

All five windows are double-panes of aluminosilicate glass. The space between the panes is evacuated and fill to 7.0 psia with dry inert nitrogen gas.

Every attempt is made to prevent stress on the windows. The mounting process was designed to preclude installation stress. The frames were design to avoid loads on the window. This was done by injecting a silicone elastomer around the edge of each pane and curing it in place. This potted the windows in their frame and provided an air-tight seal.

The only load was the pressure of the nitrogen, since there wasn't anything that could be done about that.

The aluminosilicate glass thermally tempered to 25,000 psi MOR for hatch and side windows and 23,200 psi MOR for the rendezvous windows. A safety factor of 3.0 was used. Each pane of a double-pane has the same thickness. Hatch 0.23 inch, side 0.25 inch, and rendezvous 0.20 inch. All panes are coated on both sides with a high-efficiency antirefection (HEA) coating.

The double-pane windows are covered with a 0.7 inch thick fused amorphous silica pane as a heat shield. When the command module does its flaming re-entry, the windows have to be protected or the results will be most unfortunate. They will be exposed to thermal loading for about 15 minutes.

The heat shield panes are insulated around the edge by a 0.02-inch-thick fiberglas layerr using a silicone elastomer bonding agent. The 0.080-inch-thick steel frame and retainer were designed so that the flat glazing would fit on the conical hull. It had a 0.05 inch gap on all edges between the insulation and frame so the shell could contract when it hit the cold Pacific ocean without shattering the glass. The pane had an outboard coating of magnesium fluoride, and an inboard blue-red coating.

Docking Window

Docking or rendezvous windows are generally aimed parallel to the axis of the docking port. Since the NASA Apollo CS module and the Russian Soyuz have the docking port on their nose, their docking windows are aimed straight ahead.

There may be a "docking control station" with special windows, either for guiding small craft to docking ports or for bringing the ship itself up to dock to another ship or a station. You could use video screens, but a viewport is simpler, and less likely to go to "snow" at the worst possible moment. The docking control station might be out on a boom or otherwise elevated to give a better field of view.

The Russian Soyuz does not use either a video screen nor a window. It uses a periscope which rear-projects onto a frosted glass screen. This is an admirable low-tech solution. There is no electronic screen which could malfunction, but neither is there a large vulnerable glass window letting in radiation.

Virtual Windows

With the advent of virtual reality there is a semi-plausible solution to the spacecraft window problem: use virtual windows instead. Mount some huge computer monitors on the walls and have them display what would be seen through an actual physical window in that location.

Or even more cyberspacelike: wear some virtual reality goggles, and have the computer paint a fake window wherever you want in your field of vision. With this you can change the location of the windows at your whim. All the immediacy and instinctual utility of a physical window, but with none of the vulnerability.

Except of course if the virtual reality computer is stopped or destroyed, suddenly you are trapped in a metal box you cannot see out of. You might want a couple of emergency physical windows you can unshutter for just such an situation.


Lia was pleased to notice on the ride to the command deck that the ship’s containment field held at a steady one gee. The bridge itself was about twenty-five meters across and held command-nexus stations for the various specialists, as well as a central table—round, of course—where the awakened were gathering, sipping coffee and making the usual soft jokes about cryogenic deep-sleep dreams. All around the great hemisphere of the command deck, broad windows opened onto space: Dem Lia stood a minute looking at the strange arrangement of the stars, the view back along the seemingly infinite length of the Helix itself where heavy filters dimmed the brilliance of the fusion-flame tail that now reached back eight kilometers toward their destination—and the binary system itself, one small white star and one red giant, both clearly visible. The windows were not actual windows, of course; their holo pickups could be changed and zoomed or opaqued in an instant, but for now the illusion was perfect.

From ORPHANS OF THE HELIX by Dan Simmons (1999)

(ed note: in the novel everybody wears virtual reality goggles called zeespecs. They can paint items over your field of vision, like fake windows. They can also paint the controls on your spacecraft control panel, so you can have your station on any convenient flat surface.)

      No windows in Louis Pasteur—have I mentioned that? But there were camera dots embedded in the hull that could assemble a visual image and project it through a zeespec. Somehow, I was coherent enough to manage this task, and so was watching as the exit portal irised open in the ceiling above us. Our ladderdown reactors hissed to life. Propulsion came online.

     The worst of it was that my allocation duties were quickly done with, and everyone else seemed to have a job to do. So it was that I pulled up an external window and a navigation graphic, had time to correlate the two, and made the announcement: “Our orbit takes us right past the starship. I mean, right past it.”
     “Departure conic,” Darren Wallich said distractedly, his eyes on instruments I couldn’t see. “‘Orbit’ usually means you’re not still under thrust.”
     “Not by my dictionary,” I fired back, unaccountably annoyed at the contradiction.
     “Possibly. But learn the language while you’re here, right?”
     “Anyway,” I continued, “our departure conic looks like it’ll bring us very close, like within a couple of kilometers. It should be coming over the horizon right about now.”
     “Coming over the limb,” Wallich corrected. And chuckled. Oh, this was going to be a fun voyage.

     But now everyone started stabbing at the air, pulling up exterior-view windows to see what I was talking about. Here is what these windows showed: a circular opening in space, a hole not only through the ship’s hull but through chairs, instrument panels, and people—a hole looking out at focus infinity, no matter what was in the way. Not so hard on the eye, really, but it takes getting used to, especially the way it tracks head but not eye movements. Turn to look at someone, and suddenly there are stars showing through where a face or a heart should be.

     “You might want to look outside, Baucum said. “Three o’clock high, twenty degrees. We have a visitor.”
     Oh. Reluctantly, I turned and opened a round exterior window, anchoring it to the bulkhead beside me. Where Baucum was pointing, there hung a…smudge? Cloud? No, of course, it was a transient megastructure, a diffuse bloom of loosely interacting mycora, massing maybe twenty or a hundred kilograms smeared across thousands of cubic kilometers of space.

From BLOOM by Wil McCarthy (1998)

Interior Arrangement

In all the crew's "blastoff stations", they will have acceleration couches. As most space fans know, the human body can tolerate more gravities of acceleration when lying horizontal than when sitting upright in a chair. Crew members who will have to operate controls while under multi-gravity acceleration will have fancy chairs which hold their bodies horizontal, vital controls at their fingertips, and critical dials, telltales, repeaters, and read-outs mounted above them in easy view. The rest of the crew will be lucky to get glorified cots or hammocks (They will probably be stuck with using whatever it is that they sleep in. Tough if they are using a "hot bunk" system.). In the movie DESTINATION: MOON, the pilot had the important controls located on a sort of lap-board for easy access. For real high gravity acceleration, the crew will have to use couches that are high-tech waterbeds.

And remember that Rockets Are Not Hotels. They are going to be cramped. Though keep in mind that in free-fall the entire three-dimensional living area can be used so it won't be as cramped as the floor space might lead you to believe.

The corridors will have cables, pipes and ducting either exposed or behind easily removable panels. This is to facilitate repairs. The panel brackets can double as hand-holds. The main function of panels is to protect the cables from clumsy crew members flying in free-fall. Of course all the cables and pipes will be color-coded. If the designers are smart they will double-key them as well.

The corridors will become instantly dark if the power goes off (since port-holes let all the radiation in the ship won't have any). Navy veteran Jennifer Linsky says that US Naval ships have so-called "battle lanterns." They are located in all corridors and most compartments. Each contains a rechargable 12 vold battery hooked to the ship's power grid, constantly charging. If the power grid goes dead, the lamps switch to battery power and turn on. They have red lenses to preserve the night vision of the damage control teams.

This also means that all those color-coded pipes and cables will also have stenciled labels or other double-keying, since red lighting renders color coding worthless.

In James Blish's SPOCK MUST DIE, shuttlecraft have "glow-pups", which are tubes filled with (imaginary) "ethon" gas excited by a built-in radioactive source. They will glow with no power for millions of years.

As with so many other things, high tech items predicted by Star Trek have come to pass. The modern version is called a "Gaseous Tritium Light Source", and is used in submarines. A tube of borosilicate glass is internally coated with a phosphor. It is filled with a trace amount of radioactive Tritium gas and sealed. It will glow for about 10 to 20 years, and is not particularly radioactive. Even if the tube breaks, the gas is too rarefied to be a health hazard. They sell these things in England as glow-in-the-dark keychain fobs.

Glow-pups will be in strategic places for lighting, and will also be placed to indicate hatches and sharp corners of equipment. Anywhere to help getting around in the dark.

"In there. Find your locker and wait by it." Libby hurried to obey. Inside he found a jumble of baggage and men in a wide low-ceilinged compartment. A line of glow-tubes ran around the junction of bulkhead and ceiling and trisected the overhead: the 50ft roar of blowers made a background to the voices of his shipmates.

From "Misfit" by Robert Heinlein (1939)

Rick Robinson notes that the corridors will probably not be cramped like those on a submarine. The main reason subs are so claustrophobic is because the entire sub has to have, on the average, exactly the density of water. Spacecraft don't have to. (spacecraft designers do have to worry about how much air it takes to pressurize the lifesystem, and the mass of the bulkheads enclosing the interior space.)

While not cramped, the interior will probably be similar to the inside of a conventional Naval vessel. That is, it will be full of sharp corners and hard girders to bark your shins or to give you a concussion. The rule in the U.S. Navy is "one hand for the ship, one hand for you." In other words, always keep a hand free, and when moving through the corridors, you put you hand on the thing sticking out into the passageway as you reach it.

The duty stations of the crew members will probably be cramped. In NASA speak the "work envelope" will be small.

Ladderways may be offset between decks. You don't want to have a five story fall awaiting somebody who slips off the ladder. Especially if the spacecraft is pulling three gees. If they are offset, the farthest one can fall is one deck's worth. However, Rick Robinson has an interesting alternate solution. He notes that moving equipment and supplies through a ship is always a problem, and will be exacerbated by offsetting the ladderways. His solution is to have the ladderway openings in a straight line, but while the spacecraft is under thrust, the ladders will be inclined to become stairs. The stairs will prevent fall-through. When the spacecraft enters free-fall, the stairs are rotated to a vertical position, becoming a ladder again and allowing the ladderway to become a fast route for moving equipment. The stair/ladders can be secured in either position by cotter pins. Don't forget to attach the pins to the ladders with wires to prevent them from floating away while the ladders are rotated. And obviously places where the ladderway penetrates a pressure bulkhead will have large hatches.

has some important observations:

Another thing you might want to think about, based on my naval engineering days: how big are the biggest parts in the engineering spaces? That is, what's the size of the biggest thing you might have to move in and out of the craft for repairs or replacement? The radiators are already on the outside. Are there reactor vessels, fusion containment cells, or some other nifty big bits that cannot be broken down into smaller parts? How about tanks (for algae, fuel, water, sewage, recycling, air)? You're going to need a way to get that stuff on and off, and a way to handle the large mass safely.

Barry P. Messina

In the movie Forbidden Planet, there is a small crane mounted over a deck hatch to facilitate moving equipment between decks. It is shown in the scene where the invisible monster enters through the hatch into the bunkroom full of sleeping enlisted men. It is the long metal arm that the invisible monster bumps out of the way.

Submarines In Space

Several times in science fiction, a reactionless drive or antigravity/paragravity drive is invented. And then the scientist gets the bright idea that if they mount the drive inside a submarine they will have Instant Spaceship.

In reality this would not work very well. A submarine is build to resist stronger pressure outside pressing in, not stronger pressure inside pressing out. And if the submarine is nuclear powered, you had better attach some kind of heat radiator. Nuclear submarines get rid of heat by sucking in cold ocean water and spewing out hot heat sink water. This won't work in space, there isn't any ocean. Not to mention the fact that a sub nuclear reactor's coolant system requires gravity to work.

This trope seems to have been invented by John W. Campbell jr., in an article he wrote about the Dean Drive in 1960. Other novels that use this theme include The Daleth Effect by Harry Harrison (1969), Gilpin's Space by Reginald Bretnor (1983), Salvage and Destroy by Edward Llewellyn (1984), and Vorpal Blade by John Ringo (2007). There is a mention of an "inertial drive" (another name for a Dean Drive) in Randall Garrett's Anything You Can Do but there it is used as a way to make recon drones float in the air.

This also seems to have influenced a certain Matt Jeffries, designer of the original Starship Enterprise, Klingon Battle Cruiser, and related works. A couple of his designs feature a "sail" or "conning tower" which are common to submarines. Perhaps he read Campbell's Dean Drive article and was inspired. If the first few starships were actually refitted submarines, maybe purpose-built starships would retain the conning tower for tradition.

The first Matt Jeffries design with a conning tower was the Botany Bay aka DY-100 from the Star Trek episode "Space Seed." It was later re-used as Automated Ore Freighter Woden in "The Ultimate Computer".

Around 1967, the AMT plastic model company wanted to cash in on Star Trek mania. They wanted to make a line of plastic model starship kits, but of their own design. So they hired Matt Jeffries to make a starship, the Galactic Cruiser Leif Ericson. Again it had the signature submarine conning tower. Unfortunately the kit was a financial disappointment, and further starships in the line were cancelled. The kit was re-issued in 2011 due to demand from those who had the original kit when they were young.

In the early 1970's, when Larry Niven and Jerry Pournelle were writing the classic The Mote in God's Eye, they used the Leif model as the inspiration for the INSS MacArthur.

Around 1975 Matt Jefferies was hired by George Pal to work on a TV series based on THE WAR OF THE WORLDS. As you can see the Hyperspace Carrier Pegasus is an outgrowth of the Leif Ericson. Note that instead of two side engines, the Pegasus has four, two on each side. For the TV series, Jefferies actually had the Pegasus upside down in relation to the Leif Ericson, in order to make the connection less obvious. The TV series was never picked up, alas. But this is a facinating glimpse of what might have been.

Occasionally in later science fiction illustrations one again finds the submarine conning tower.

Analog Dean Drive Article

A modern nuclear-powered submarine needs only relatively minor adaptations to make an ideal spaceship; it has everything it needs, save for the space drive.

The Dean drive requires a rotary shaft drive; our nuclear submarines turn nuclear energy into heat, produce steam, drive a turbine, and generate electric power. Electric power is perfect for running the Dean drive.

The modern submarines are — we have learned from past sad experience — equipped with lifting eyes so that, in event of accidental collision, quick salvage is possible. Pontoons can be towed in place, sunk beside the ship, and hitched to the built-in lifting eyes, and the ship refloated. The eyes are, of course, designed into the ship so that the structure can be lifted by those eyes without structural damage to the hull.

Dean drive units could be attached directly to the existent eyes. (ed note: you can see this in the image. The two bands around the submarine's waist hold the Dean Drive units. This also means the ship's direction of motion is in the direction the conning tower is pointed, which would make sense.)

The pressure hull of modern submarines is designed to resist at least 600 feet of water pressure; its actual thickness is a piece of classified data, of course, but we can guesstimate it must be at least 4 inches thick. After the second Bikini bomb test, the old submarine Skate was still in pretty fair condition; the light-metal streamlining hull looked like the remains of an airliner crash, but the pressure hull was perfectly intact. Stout stuff, a sub’s pressure hull.

And very fine stuff indeed as protection against the average meteor; the light streamlining hull would stop the micrometeors, of course.

Not even 4 feet of steel would stop primary cosmic rays, of course… but those inches of armor steel would have considerable damping effect on the Van Allen radiation belt effects.

The nuclear subs have already been tested with full crews for 30 continuous days out of contact with Earth’s atmosphere; their air-recycling equipment is already in place, and functions perfectly. What difference if the ‘out of contact’ situation involves submersion in water, instead of out in space?

The modern nuclear submarine is, in fact, a fully competent space-vehicle, lacking only the Dean drive.

With the Dean drive, the ship, if it can lift off the Earth at all, can generate a one-G vertical acceleration. Since that acceleration is being generated by engines capable of continuous operation for months — if not years — at a time, the acceleration can simply be maintained for the entire run; there would be no period of free-fall for the ship or crew. Therefore the present ship structure, equipment, and auxiliary designs would be entirely satisfactory. Also, a sub has various plumbing devices with built-in locks so the equipment can be used under conditions where the external pressure is widely different from the internal.

In flight, the ship would simply lift out of the sea, rise vertically, maintaining a constant 1000 cm/sec drive. Halfway to Mars, it would loop its course, and decelerate the rest of the way at the same rate. To the passengers, and to the equipment on board, there would be no free-flight problems.

There is one factor that has to be taken in to account, however; the exhaust steam from the turbine has to be recondensed and returned to the boiler. In the sea, seawater is used to cool the condenser; in space, the cold vacuum would do the job.

The tough part would be the first 100 miles up from the Earth; ice could be used.

As a crash program, this could have been done — if work started when Dean first applied for his patent — in 15 months. The application went in in July 1956; 15 months later would have been October 1957.

Under the acceleration conditions described above, a ship can make the trip from Earth to mars, when Mars is closest, in less than three days. And even when Mars is at its farthest possible point, on the far side of the Sun, the trip would only take 5 days.

It would have been nice if, in response to Sputnik I, the US had been able to release full photographic evidence of Mars Base I.

from "The Space Drive Problem" by John W. Campbell, Jr in Analog Magazine June 1960

The Daleth Effect

Analog December 1969. Illustration for Harry Harrison's "In Our Hands, The Stars", which was later expanded into the novel The Daleth Effect.

Harry Harrison wrote an amusing but cautionary tale called The Daleth Effect. In the novel, an Israeli scientist discover the principle for a reactionless drive. Naturally the first real test is the Submarine Spacecraft trick.

He returns to his native Denmark to develop it. He wishes to develop the idea without it falling into the hands of the military, since it also has potential as a weapon. Good luck with that.

Denmark keeps it a secret until they feel obligated to use the technology in public to rescue some cosmonauts stranded on Luna. Any fool could have told the Danes that no good deed goes unpunished.

Naturally the US, Soviet Union, and other powerful nations will stop at nothing to lay their hands on this technology. The race is on! They try all sorts of tactics to pressure the Danes but to no avail. They look on with helpless rage as the Danes establish a Lunar base and make a large ship for a visit to Mars.

Like absolute idiots the Danes invite foreign dignitaries to ride on the Mars trip. Naturally pretty much 100% of the dignitaries turn out to be secret agents. Hilarity ensues. And then the novel has a most ironic and satisfying ending.

Gilpin's Space

Eccentric but brilliant scientist Saul Gilpin invents a magic hyperspace faster-than-light propulsion system / antigravity surface-to-orbit gadget which can be cobbled together from parts available from your local hardware store. He mounts it on a submarine and has instant starship. Then he and the submarine depart for parts unknown.

This makes the totalitarian government very unhappy. They want to use this technology, they do not want citizens getting their hands on it. Makes it far to easy to escape the totalitarian state. Then they find out that Gilpin has mailed blueprints of the gadget to quite a few people. Hilarity ensues.

Salvage and Destroy

An ancient alien interstellar empire is worried about the large US and Soviet submarine fleets. Once Earth discovered anti-grav and FTL drives, the warlike unstable Earthlings would have a ready-made fleet of combat starships. This could turn into a nasty problem.

(ed note: aliens on Earth are covertly observing a US submarine)

“She’s an attack sub.” Joshua altered course as the black hull came sliding toward us out of the dawn mists. He gave one blast on the horn. “Mark, can you read the number on her sail?”

“SSN-767.” Mark put down his binoculars and took Jane’s Fighting Ships from the book rack in the wheelhouse. “USS Muskelunge. Four thousand six hundred tons dived. One hundred and ten meters overall. Six torpedo tubes plus subsurface attack missiles. Pressurized water-cooled reactors feeding two steam turbines. Speed dived-fifty knots plus. Complement—one hundred and ten.” He closed the book. “She’s among the most powerful warships in the Cluster—now the Ult fleets are laid up.”

“Fit that sub with inertial drive and she’d be ready for space!” said Joshua. “And there’s over four hundred like her at sea.”

An instant space fleet!” remarked someone on the foredeck.

“They couldn’t make a vortex passage. They couldn’t get out of this starfield. They wouldn’t have anybody to fight.”

“They’d find somebody. Or settle for fighting each other!”

Add inertial drive and Earth would have a space fleet! However unlikely, the idea was chilling. The men and women with me would gladly crew a human fleet, apparently blind to the outcome of such madness, as the Terrans were blind to the imminent effects of their own folly.

From nuclear submarine to inertial spaceship—an immense leap. Yet that hunter-killer exemplified a leap of the like magnitude. From sail to atomics in a hundred years! If the Terrans survived the next hundred would they leap into the dark? Into the Cluster?

I shook myself. Not even their present exponential advance would take them to vortex transits within a century. But within centuries? Up to the stars or down to hell?

from Salvage and Destroy by by Edward Llewellyn (1984)

Vorpal Blade

Shortly after they'd stopped the invasion, the Adar had given him another strange device. On first tests, it had appeared to be the world's most powerful nuclear hand grenade. Any electrical power sent to it, so much as a spark of static, and, well, there was a boom. A really big boom. "There should have been an earth shattering Ka-Boom!" boom. Putting three-phase on it had, in fact, erased a solar system.

The Adar didn't know what it was supposed to do but Weaver had basically guessed that it was, in fact, some sort of Faster-Than-Light drive. It took nearly a year of tinkering, and two more planets, to figure out that it was, in fact, such a drive. It had taken another year to create the first prototype starship.

By then, Weaver had switched sides in the ongoing sales war, leaving the Beltway and taking a direct commission in the Navy, which was the lead service in developing the world's first spaceship. He'd pointed out even before switching sides that the Navy just made more sense. The President wanted a presence off-world as fast as possible. They'd picked up enough intel in the brief war to know that the Dreen had some sort of FTL as well. Finding out where the Dreen were, whether they were headed to Earth through normal space, was a high priority. The only way to make a spaceship, fast, was to convert something. The obvious choice had been one of the many ballistic missile submarines that were being decommissioned.

So Weaver, while continuing to consult on engineering issues, was now the astrogation officer of the Naval Construction Contract 4144. Despite a couple of shakedown cruises around the solar system, the Top Secret boat had yet to be named. The 4144 had all the beauty and problems of any prototype. Most of the equipment was human, much of it original to the former SSBN Nebraska. Other bits were Adar or Human-Adar manufacture. The fact that it worked at all was amazing.

"How fast are the missiles? I mean, space is big, right, so they have to be fast?" Miller continued peering out the window, on a submarine, in front of him. The window seemed to be harder to get used to than the fact that he was standing inside humanity's first starship. A freakin' window on a submarine, he thought.

"The propulsion system is a mix of Adar tech and human. The thing is basically designed around the old nuclear thermal rocket concept but uses a small quarkium reactor instead of a fission reactor. No radiators needed and we use a dense Adar coolant for propellant instead of LOX or hydrogen or water. The Adar stuff gives us waaaay better m-dot. Using an Adar material for the nozzle we were able to get over eight thousand seconds of specific impulse out of it."

(ed note: 8,000 Isp is an exhaust velocity of about 78,000 m/s. Which would make that propulsion system a torch drive. Freaking missile has performance better than a blasted Zubrin nuclear salt water rocket.)

from Vorpal Blade by John Ringo (2007)

Non-scientific Media SciFi Ships

If you want to ignore this entire website and just make a tired old standard TV or Movie spaceship utterly without scientific accuracy, Mythcreants has you covered. But don't let RocketCat catch you or he will give you an atomic wedgie.

Actually, if you actually want such a thing, what are you doing in this website in the first place?


(ed note: Now remember that this is only for movies and TV shows, not novels. And it is more of a joke than something serious, though it is surprisingly accurate.)

The other day, I was scrolling through Netflix, looking for a distraction from all the pain of my hair and all my terrible car opinions, seeking out some quality space-travel-focused sci-fi, because I love that crap. As I was scrolling, looking at the thumbnails of the various movies and shows and whatever, I realized something: when those thumbnails showed a picture of a spaceship, you could almost instantly know, generally, what that show or movie was about. I mean it! Here, let me show you.

There’s almost always at least one signature spacecraft for any of these space-based sci-fi shows, and I was realizing that they design of the ships, while varying wildly from movie to movie, seemed to be remarkably consistent for a given sub-genre of space sci-fi.

You could look at one ship and immediately know that, say, the show would take place in the relatively near future, and have a pretty good gorunding in science, or look at another and immediately know nobody gave two shits about physics, but it’ll be a fun ride.

I compiled several thousand examples and fed them into the Jalopnik Mainframe (a cluster of over 400 Timex-Sinclair 1000 computers dumped into an abandoned hot tub in a bunker underneath Ed Begley Jr’s combined EV R&D lab/sex-lab) which ran an advanced AI that categorized the ships into eight distinct classes. I took those ship classes, translated the descriptions into English from the AI’s native Dutch, and produced this handy chart, which you can use to make your space-movie choices quicker and better!

Did we miss any categories? I’m pretty sure most space-based sci-fi fits into one of these. Star Wars is 4, Star Trek is 3, I’d put the monolith from 2001 and 2010 in 7 but the Discovery and Leonov in 2, and I think the big cylindrical Heighliners from Dune go in 7.

Categorize your favorites! What could it hurt, right?

(ed note: the following is from a thread on Twitter)


     Class 0 - B Movies
     Class 1 - REALISM
     Class 2 - Kubrick land
     Class 3 - Where every nerd has gone before
     Class 4 - Cosmic thrillers
     Class 5 - The one from Wall-E
     Class 6 - Independence Day and it's imitators
     Class 7 - Overly pretentious crap

     RedPyre: Also, as someone that used to be in the Star Trek ship discussion fandom and left for more hard sci fi pastures, "This type of sci fi generates the most painful geek fights" on class 3 is WAY too accurate.

     Ilan Muskat: This is supposed to be a goof, but boy oh boy is it a handy narrative shorthand. It's real, real hard to separate philosophy from aesthetics.

     Winchell Chung: Agreed!
     "Narrative Shorthand", that's the concept I've been groping for, thanks!
     Anybody who wants a dubious graduate thesis can ask the question if the visual categories in the chart approximate some sort of archetypal images embedded in the human psyche.
     My question is Why is it so easy to make a chart like this?
  • Is the scifi movie visual aesthetic riddled with clichés?
  • Are there too few concept artists?
  • Are the movie visual directors too conservative?
  • Does the target audience demand it?
  • or what?
     My other question: is the chart comprehensive? Or are there other commonly used narrative shorthand tropes that got left out?

     Mike Doscher: These basic categories serve to explain the world and the nature of the story with the need for certain classes of exposition. In a meta sense they also describe the story creators and the expectations of the audience.
     As pipelines become longer and more expensive, visual treatments need sign-off from multiple people, each of which needs convinced as to viability of the project. This ultimately tends to channel visual treatments into certain categories.
     This isn't because people are dumb, but rather that you're playing a high-stakes game of telephone where everyone has their own interests that they're pursuing at the same time the team is trying to get the project made.

     Winchell Chung:

     Makes perfect sense to me. On a related note, I've heard similar arguments about why there are so many re-makes of existing movies. The high-stakes nature of movies makes a "built-in audience" an increase in project viability

     Craig Perko:

     Clarity of first impressions. Just like how we design warriors to be big bulky dudes with huge shoulderpads...

     Winchell Chung:

     From Douglas Adams The Restaurant at the End of the Universe:
     The designer was clearly not instructed to beat about the bush. “Make it evil,” they’ve been told. “Make it totally clear that this gun has a right end and a wrong end. Make it totally clear to anyone standing at the wrong end that things are going badly for them. If that means sticking all sorts of spikes and prongs and blackened bits all over it then so be it. This is not a gun for hanging over the fireplace or sticking in the umbrella stand, this is a gun for going out and making people miserable with.”

     Supership 79:

     What about the Expanse? Class 4 and Class 2 hybrid?
     The expanse has very thought-out ship designs and while they're heavily greebled you can always tell what faction they're from and what the basic function of the ship is, and the science is Good Enough to not be flat out space opera.

     Tom Anderson:

     Is "you can always tell what faction they're from" compatible with "very thought-out"? Why haven't ship designs converged on a global optimum?
     Genuine question, I haven't watched the show!
     I'm trying to think of historical examples of this. Maybe the way the Soviets stuck to jet fighters with an air intake right at the front, when virtually no western jets did that (I can only think of the Lightning)?

     Supership 79:

     Its mostly in what color lighting and paint schemes the ships use. earth ships are bluish, mars ships are reddish, and belter ships are yellowish. Anyways its a great show, highly recommended.

     Cyrs the unsinkable sea serpent:

     Yes, paint is how you tell them apart, not design (too much at least) because regardless of your politics, your physics are pretty fixed

     Pete Appleby:

     All part of having a clear narrative, but still in the real world you can absolutely tell at a glance who are from a Soviet origin as opposed to Western, whatever it may be ship, aircraft, clothing, switch... the cultural aesthetic is everywhere. Good sci fi has that consistency

     Ilan Muskat:

     I don't 100% see where Star Control/Futurama/Cosmic Encounter fit in, the "wacky hijinks" space smorgasbord that's not *quite* the Planetary Romance of Class 0, but not quite the Geek-Continuity Rigmarole of Class 3. (Maybe if the protagonist's ship looks like a banana.)
     Barbarella has enough class 0 for all BD

     Winchell Chung:

     Yes, agreed. Needed is some category for whimsical/absurd ships. Like "Mega Maid" from Spaceballs.

     Don't forget Queen Amora's swan spaceship from Flesh Gordon. Looked all ethereal while flying. Crashed, the swan showed all those girders and burnt airframe members sticking out of the wreckage. Very absurd.

     NickStevens Graphics:

     Or the Flesh Gordon “ship”

     Ilan Muskat:

     Heck, Battle Beyond the Stars. "If your protagonist's space ship looks like a part of human anatomy that would be censored from Instagram..."
     "The ship looks like a giant person" also applies to Necromongers from Chronicles of Riddick (otherwise mostly Class 4) and Gurren Lagann (Class... banana, again)


     Wouldn't Nell be class 7 (bio-inspired shape)? except it fails the deep ideas and being philosophical part.
     Funnily, Battle Beyond the Stars has several examples of the other categories as well.

Mythcreants: Designing Your Spaceship

What Is Your Ship’s FTL Propulsion Method?

It turns out space is big. Really big. Getting around means you’ll have to massage your way past Einstein’s rule that nothing can go faster than the speed of light.

Going Really, Really Fast

Your ship just pours on the speed, never mind what physics says. Despite the talk of warping space, this is essentially the Star Trek method. While the ship accelerates to well past the speed of light, it never leaves normal space. It can still scan the area ahead,* so it won’t be taken by surprise if there’s a hostile fleet lying in wait. Another consequence is that going FTL is only an escape if you’re faster than the other guy. They can still track you after you’ve kicked it up to full throttle.

Visiting a Pocket Dimension

Since this universe won’t let us go FTL, let’s go to another one. This is the hyperspace of Star Wars and Babylon Five (B5). Exiting our universe completely, these ships tunnel through their own personal dimension to get where they need to go. Usually, this means that activating the ship’s FTL drive makes it safe from attack. There can be exceptions, but jumping to hyperspace will usually be a moment of relief. Because it’s such a powerful way to get out of trouble, there should be limits on when it can be used. In Star Wars, ships can’t go into hyperspace within a planet’s gravity well. In B5, it requires specially constructed gates for all but the largest ships.


Even more extreme than the pocket dimension, there’s no travel time at all with this method. The ship simply disappears from one place and reappears in another. It’s most famously seen on Battlestar Galactica (BSG), but it appears in other stories as well, such as the Solar Clipper series by Nathan Lowell.

Ships with this form of propulsion can travel truly massive distances. Even if the jumps they make are relatively short, the only limiting factor is how quickly they can recharge for another one. This means that ships can easily escape any kind of trouble so long as their engines are working. BSG limits this with time consuming FTL equations and a delay as the ship drives spool* up. As a side benefit, a teleportation drive means that ships often end up nose to nose, rather than millions of miles apart.

It Doesn’t Have One

It turns out that the speed of light is a difficult speed limit to break, and authors looking for a more science-friendly story often stay below it. Your ship can still go plenty fast with sublight engines, fast enough to make interplanetary travel a breeze. You’ll be limited to one solar system, sure, but look how much there is to explore right in our own backyard. Limiting your ship to sublight speed will make it more realistic, and allow you to engage in nitty gritty science fiction.

How Does Your Ship Move at Sublight?

No matter what your FTL method is (if you have one), your ship will still need to get around in normal space. How you do this will have a big influence on the level of your setting’s technology, not just how you get from place to place.

On a Carefully Projected Course

This is the current method for navigating our solar system. 21st century spacecraft have very limited fuel, so they have to plan nearly every bit of thrust, leaving nothing to chance. The course that Rosetta took to rendezvous with the comet 67P, for example, is incredibly complicated, and full of complex math. When Apollo 13 suffered a damaging explosion, they couldn’t just turn around and fly back to Earth. They had to keep going on the course they’d committed to.

Using this method will make fuel management an active part of your story. The characters won’t be able to go wherever they please; they’ll have to be constantly watching their tanks. It’s very limiting, but the good news is that because this is how real spaceships work, there’s plenty of reference material. This is hard scifi at its finest.

A variant is to use engines that have extremely long-lasting fuel sources but produce little acceleration. Ion engines fit the bill nicely. Ships can get going at a good clip with a long enough burn, but deviating from their course will be very difficult because of how long it takes to build up thrust.

With Impulse Engines

This is the standard for the vast majority of space-going scifi settings. The ship employs some kind of extremely efficient reaction drives to push it where it needs to go. When Captain Picard orders his ship into orbit of a new M-class planet, he’s not worried about running out of gas before they get there. Even in Firefly, when Mal does occasionally fret about running out of fuel, it’s understood that this isn’t a problem for better funded ships. When in doubt, this is the option to go with. It’s tried and true, letting you explore your setting without much fuss.

By Raising the Solar Sails

This is a quirky third option if you want to give your ship more of an old-timey feel. Solar sails are a real technology that uses solar wind ([sic] They use solar photons, not solar wind) to generate thrust. Your ship will work more like a sailing ship, and who doesn’t want sailing ships in space? With a bit of handwavium, you can even borrow a bunch of nautical terminology to spice up your setting’s jargon. Your ship can tack across the port quarter and run up the mainsail.*

Practically, this method of propulsion has some caveats to consider. Ships will be slower further from the sun,* and going toward the sun will be more difficult than going away. The sail itself is also important. It would be huge and no doubt prone to damage. This is your chance to get an astronaut swinging through the rigging to repair meteorite impacts!

What’s the Interior Like?

The inside of your ship is at least as important as the outside. Do your characters feel at home within its hull, or is each day a strain on their nerves?

NASA Chique

If you ever take a look at the International Space Station, you’ll notice that it’s incredibly crowded. There’s stuff floating everywhere because space is at a premium. This is the look you go with if you want your ship as close to modern technology as possible. There probably wouldn’t be artificial gravity. The food would mostly be slurped from bags. Using the bathroom would be… complicated.

This is the kind of ship one has to be very dedicated to serve on. It lends itself to explorers making the first push to Mars or maybe homegrown space enthusiasts cobbling together their own ship form whatever is lying around.

Military Practical/Cold and Austere

These two are different sides of the same coin and are essentially the difference between Battlestar Galactica and Battlestar Pegasus. Both are function over form. Practicality reigns over comfort. Everything has a purpose, and nothing is wasted. The difference is that on Galactica this is reassuring. Everything is running like a well-oiled machine. On Pegasus it’s unnerving. All human comforts have been swallowed up by the unfeeling ship. On the TV show, they achieve this with lighting, camera work, and music. In prose, you can do this with positive and negative descriptors: “clean” vs “sterile” or “disciplined” vs “controlled.”

Characters on this kind of ship are most likely military or maybe high-level corporate types. They’re here to do a job. That won’t be the only aspect of their characters, but it will be ever-present. They’ll all be part of something bigger than themselves, whether they want to or not.

Warm and Lived In

Welcome aboard either Serenity or the Millenium Falcon. These ships are homes as well as machines. Even if the characters don’t necessarily want to be on board, the ship’s environment will have a calming effect. This works on the audience as well, if you do it right. They will start to feel comfortable with the ship, like slipping on an old sweater. They’ll react viscerally if the ship is threatened by intruders. Use this to set up poignant stories.

This kind of ship is often independently owned but not always. Star Trek’s Deep Space Nine space station fits the bill, as does Babylon Five. It’s a place where people live as well as work, and they can’t help but leave their mark.

Like a Space Hotel

This is an odd choice pioneered by Star Trek: The Next Generation. The Enterprise D is so well appointed that it often feels like some kind of cruise ship. The quarters are palatial, anyone can have anything they want to eat whenever they want it, and the holodecks provide endless forms of entertainment. This kind of ship is meant to awe the audience. To make them think, “Wow, the future is amazing!”

There’s nothing wrong with that, but it can make your characters harder to identify with. Drama loses some of its edge if the characters can return home to their cabins and order a three course meal while getting a deep tissue massage.

How Good Are Its Sensors?

Unless you’re in very old science fiction, your ship’s going to need more than the mark one eyeball to see with. Looking out the window just won’t cut it in the cold vacuum.

Only Blips on a Screen

This level of technology is pretty close to what we have today. Sensors will tell you that something’s out there and maybe its mass, but that’s it. Unless the mystery object is broadcasting a signal, you won’t know anything about it. This is great for building tension and suspense. What’s that blip out there? It’s getting closer. Should we open fire?

The downside is that it’s a very involved method. Your characters can never just know what’s going on with another ship. They’ll always have to question their information, and the audience will want to know how they learned it.

Like Long Range Eyes

The next step up are sensors that give you about the same information as a visual examination of whatever’s being scanned. You can tell that little blip is a TIE fighter, that it has Imperial markings, but not that it’s carrying Lord Vader. This method provides a decent balance, allowing you to easily describe what’s happening around your ship without giving too much information to the audience. It works particularly well for a setting like Star Wars, in which the space battles are clearly analogous to historical naval combat when visual range encounters were common.

They Give a Full Spectrum Scan

Star Trek sensors can tell you what an approaching ship is made of, how many people are on board, and how many of them own cats. There is seemingly no end to the pinpoint information these scanners can produce from remarkably far away. This is another case of wowing your audience with the wonders of the future. It also allows you to put on dazzling displays of description as the characters learn absolutely everything about what they’re looking at. Of course, you have to be good at description in order for that to work.

The drawback to having such powerful sensors is that sometimes drama depends on the characters not having certain information. Many an episode of Trek features the previously all-seeing scanners inexplicably not noticing that a hostile ship was charging weapons. You can sometimes explain this by saying there’s some kind of interference or another, but that excuse will get tired if you aren’t careful.

How Does It Fight?

Space battles are an ever-present element of science fiction, and chances are if there’s a ship in your story, it will eventually be attacked. How does it defend itself? Or, if its crew is a bit more proactive, how does it attack other ships?

It Doesn’t

One of the novel things about Firefly was that, as Jayne so eloquently put it, “A transport ship ain’t got no guns on it.” Serenity was completely unarmed, which made things interesting when it ran into hostile vessels that weren’t. If your ship has no weapons, your characters will have to be more inventive. They can’t just blow the attacking space pirates out of the sky. They have to run and hide or cobble some kind of weapon together. It limits your options, but it can be engaging.

With Directed Energy

Whether it’s a simple laser or something more complicated, this is a beam of energy projected across space at the speed of light. It has very long range. It’s precise and accurate. If you can see something, you can hit it with this weapon. Space battles with such a weapon will be short, as there isn’t a lot of maneuvering to be done when incoming fire is moving at the speed of light. This is good news if you’re in a visual medium with a limited budget, but perhaps bad news if you want to film the Battle of Britain in Space. Early Star Trek used this kind of weapon a lot, before Deep Space Nine (DS9) took things in a more WWII type direction.

Using Space Guns

These are any weapons that operate more or less the way modern firearms do. BSG has actual space guns – that is, shells propelled by explosive chemicals. Star Wars has space guns disguised as directed energy weapons. They call them lasers or blasters, but they clearly operate more like battleship cannons. The biggest advantage to this style of weaponry is that building dramatic space battles is easy. You just take your inspiration from historical naval battles, especially WWII. You can have giant capital ships slugging it out broadside to broadside while fighters dogfight around them.

The downside is that you aren’t taking full advantage of being in space. Space is a completely alien environment, and it’s limiting to focus exclusively on how battles used to be fought.

By Lobbing Missiles

As mentioned, space is really big. Your ships will often be so far apart that light will take several minutes to cross the gulf between them. At that range, even a laser is useless. Instead, your ship could use guided, self propelled projectiles that can travel to the target and adjust their course to ensure a hit. This type of weaponry is seen in the Honor Harrington series, where it introduces a completely different dynamic to space combat.

Battles become tense waiting games as enemy missiles come burning in. The fire-and-forget nature of these weapons means that once they are launched, the characters can only watch and hope for a hit. The main action of combat focuses around using countermeasures against incoming fire. It requires a different mindset than the more fast paced battles with space guns, but it has an appeal all its own.

It Sends Out Fighters

From X-Wings to Vipers to Star Furies, fighters are a mainstay of space combat. If your ship is big enough, it may fight primarily by launching smaller craft to attack the enemy. This allows for some excellent drama. Dogfights between fighters are perfect for moments of individual heroism, and fighter pilots will always be popular as main characters. Plus, removing your characters from the safety of their mothership is a great way to ratchet up the danger.

Of course, this method isn’t always practical. You need a ship big enough to carry fighters, for one thing. For another, space fighters aren’t terribly realistic. Targeting systems would probably be too accurate for dodging and weaving to be an effective defense. Fighters also imply your ship is purpose-built for combat, which won’t work in many stories.

It Uses a Mix

Chances are very good that your ship will use some combination of the above options. Galactica has both fighters and space guns. The Enterprise has directed energy weapons with its phasers, while photon torpedoes are much more like missiles. The key is to remember what each kind of weapon means for your story.

How Do Characters Get Off It?

No matter how cool your spaceship is, eventually the characters will have to leave it. How do they do that?

By Landing and Docking

If your spaceship is on the smaller side, it may let people off directly, whether that means landing on a planet’s surface or docking with a space station. Larger ships can do this as well, but it starts to get impractical, especially with landing. Having this be your ship’s primary means of egress puts a major limit on your characters’ freedom of movement. They can only go where the ship goes. It also means that if the ship is damaged, getting off it will be more difficult, which is great for drama.

On Shuttles

The most practical method, especially for larger vessels, this means your ship carries a number of smaller craft that are fully functional spaceships in their own right. They have a limited range of course, but they’ll get you to the ground and back. This increases your characters’ freedom of movement, allowing some to visit the big city while others explore mysterious alien ruins. It also opens the possibility of a story with one or more characters trapped and isolated on a damaged shuttle.

The important thing to remember is that the ship breaking doesn’t mean the shuttles are broken. If the ship has a power failure, the audience will immediately ask why the characters don’t divert power from the independent shuttle engines.

Via Teleportation

While transporters were originally a way for Gene Roddenberry to save money on landing sequences, they have since carved out a place for themselves in science fiction. These are devices that move a character from one place to another instantaneously. They can work via matter energy conversion, micro-wormholes, or anything else that sounds reasonably scientific. They offer unparalleled freedom of movement, getting your characters into places they’d have no other way of reaching. You no longer have to spend time on travel sequences or explain how the characters arrived so quickly.

The drawback is that sometimes you’ll have stories that only work if your characters can’t get somewhere. Teleportation is such a powerful way of getting around that you may have trouble writing it properly. If you’re going to use this method, establish early what can and can’t be teleported through, and then stick with it.

How Does It Look?

In this last section, we consider your ship’s physical appearance. We’re looking at broad strokes rather than specific details. Decide on the shape and paint job once you’ve considered some broader themes.

Old and Beat Up

As seen with Serenity, the Millenium Falcon, and every other independent trading vessel ever featured in a science fiction story. This is the look of the underdog. It’s a scrappy ship that’s got heart. In other words, something we will always root for. It’s great for communicating how outmatched and poorly equipped the main characters are, which is something the audience will love.

Big and Mean

This ship means business. If it’s not bristling with weapons, it’s some kind of mega cargo carrier that can fit a dozen lesser ships inside it. This look projects power. It is imposing, and communicates a level of seriousness to your story. You don’t want to use this look for a lighthearted romp through the solar system, but it’s perfect for an epic war with evil robots. Note that the ship doesn’t actually have to be large. DS9’s Defiant is a small ship, but it’s definitely Big and Mean.

Sleek and Sexy

The true ship of the future, a triumph of technology and engineering. This ship will dazzle the audience with all its swanky design features. Pair this with a Hotel in Space look for the interior, and you have the Enterprise D. Ships like this work best in optimistic settings, where they portray the awesome heights humanity can achieve. Your protagonist may come off as something of a tool if they’re flying one of these in a gritty, realistic setting where people have to scrounge for survival.

By now you should have a pretty good idea what your spaceship is like, at least in terms of the big picture. The rest can be added as you go. These steps will get you a skeleton, but you’ll still have to fill in the rest. How comfortable is the captain’s chair? What kind of noise do the engines make? These smaller scale questions should be addressed as they come up, but now you have a solid foundation to base them on.


Yes, alien spacecraft are not going to look like ISO Standard Human Spaceships. But it is debatable that they will look as if designed by Cthulhu.


The sci-fi equivalent of a guy wearing a black hat and twirling his mustache. Or rather, one thousand razor-sharp metallic mustaches twirling all at once with the energy of a thousand suns glowing beneath its armored plates.

Or, if you prefer, the Badass Longcoat of spaceships.

Obviously if a spaceship is meant for atmospheric maneuvers too, it would make sense for it to be aerodynamic. This is not about that. Nor is it about dagger-shaped Star Destroyers. No. This is about spaceships with way more than any practical numbers of sharp edges.

This trope describes a spaceship that ranges from a dart-like multi-pronged fighter to a gigantic armored Kraken brimming with blades, spikes, antennae, metallic claws and for good measure, a huge glowing maw at the front like some hellspawned sea creature. Unfortunately, this trope has becoming close to generic, and a new design trick when coming up with such vessels is to make them asymmetrical and thus slightly less conventional.

At first, this kind of starship design was a radical departure from what at the time was standard in film and TV, but with advancing technology, especially computer generated imaging, TV and movie spaceships became increasingly complicated as programmers could animate smaller and smaller individual segments. This has caused an explosion in the number of sharp edges and non-functional moving parts assigned to antagonist spaceship designs to the point where most people in fiction powerful enough to threaten a planet are seen flying around in giant metal squids with a hundred vicious claws and blades on every tentacle.

On the inside, these ships are usually just your standard blue-lit control centers, huge docking bays, and very long metal corridors. But the sheer number of metallic blades and tentacles just screams "Look at me, I am so marvelously evil!"

As a general rule, the spaceships become more squid/octopus-like as they grow in size and in the number of spikes and blades they possess. Often they possess a Wave Motion Gun and for extra points, the ship has to radically and slowly transform its shape just to use it, giving the heroes enough time to disarm the superweapon.

While it makes sense for a small ship designed for atmospheric maneuvers to be aerodynamic and sleek, the larger "Kraken" varieties are almost always Awesome, but Impractical.

If a ship has two long, spear-like engine or weapons pods, it's technically not this trope. This is about when enemy spaceships go way overboard on the sharp edges to impractical levels. How does a pilot climb inside such a ship without tearing their pressure suit?

Compare Spikes of Villainy, the costume version of this trope.

Also compare Eldritch Starship, which can really look like anything, but utilizes mind-bending, conceptually alien principles in its design and may or may not look like a giant metallic sea urchin.

(ed note: see TV Trope page for list of examples)


...something astonishing and strange had happened to Volyova’s ship. The ship had remade itself into a festering gothic caricature of what a starship ought to look like... He had heard of ships being infected with the Melding Plague... but he had never heard of a ship becoming so thoroughly perverted as this one while still, so far as he could tell, being able to continue functioning as a ship.

—Clavain describing the Nostalgia For Infinity, Redemption Ark

The polar opposite of ISO Standard Human Spaceship, these are spacecraft, time machines, and/or interdimensional vehicles whose weirdness goes beyond Living Ship and possibly into Alien Geometries or a mobile version of the Eldritch Location.

The milder form of this usually begins with Bigger on the Inside or dimensionally transcendent in some way other than bog-standard Faster-Than-Light Travel, and it only grows weirder from that point on. May involve Body Horror or invoke elements of Cosmic Horror Story.

They might be constructed from unconventional materials, powered by unconventional power sources, be dimensionally transcendent, or have an Unusual User Interface. Their interiors may even look like they were designed by M. C. Escher. There's no guarantee that the crew or the ship itself won't change its interiors (or even its exterior) from time to time. Frequently they are a Genius Loci or function as a Setting as a Character. They are always surreal in some way that a typical spaceship in fiction just isn't.

The trope has three major variations (with a lot of overlap), but beyond these three archetypes there is much, much variety:

  • "Starfish" Spaceship - as in Starfish Alien, only for technology. These are spacecraft whose very conceptual design, let alone its performance, seems to defy the laws of physics both in-universe and in Real Life.

  • "Changeling" Spaceship - spacecraft that is physically possible, but transforms radically (not just extendable wings and the like). The interior, exterior, or both could transform.

  • "Lobster" Spaceship - spacecraft that is physically possible, and probably has engines, a bridge, etc., but much of the ship seems to be a Lovecraftian mass of antennae, spines, blades, metallic tentacles and other parts of uncertain function.

(ed note: see TV Trope page for list of examples)


Eldritch Starship: Oh, there are a few.

Take esseli starships, for example. Unlike the link!n-Rechesh (who would be another fine example), they know better than to try to grow fully organic starships, so from outside the hulls and drives look relatively normal. Then you go through the airlock, and it’s all flesh, all the time, with heart-valve doors, neuron-cluster control interfaces, food-secreting glands, recycling intestines, and suspicious organic gurgles everywhere. Mining ships have refinery stomachs and tentacles.

Múrast starships are carved out of ice bodies, with the necessary technology fitted within, and then refrozen. Which is all very sensible when you consider their favored environment, but doesn’t explain why they always carve them into baroque cathedral-like structures rather than anything more utilitarian.

And then there are the seb!nt!at, who as creatures of nuclear forces that dwell deep within stars, do not build their starships out of matter in any conventional sense.

Starfish Aliens build Starfish Starships, basically, just as far as physics will allow.

The tortured structures built by rogue mining drones and other wild mechanicals are about as Gigeresque as it gets, though.

Organic Spacecraft

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