• 

     1. CON1: Commanding officer. Stillstorm roves more often than she sits, but no one else sits in this seat in deference to her.
     2. CON2: Executive officer (Mallas Rune-Laurel). When Stillstorm is off the bridge, the officer in charge usually sits here.
     3. OPS: The Operations Chief (Seinen Forest) is directly in charge of flying the ship. Often roving, sometimes sits at NAV1 or NAV3.
     4. AUX1/NAV3: Auxiliary Navigation, sometimes used by OPS.
     5. FIRE1: Primary fire control officer (Nedeil Cobalt).
     6. FIRE2: Secondary fire control officer (Tiris Red-river).
     7. TAC: Tactical Analysis. The Listel at this position (usually Beryl) coordinates the Sensors section and controls the tactical displays.
     8. SEC: Security (Teidar Razorthorn). Coordinates internal security and sometimes small craft. Fireblade sometimes sits at this position.
     9. INTEL: Intelligence (Parat Tempo). The Mizol at this position coordinates the intelligence and communications sections.
     10. SYS: Subsystems Chief. This position coordinates engineering and damage control, assisted by the Subsystems section.
     11. NAV2: Secondary Helmsman. The copilot of the ship.
     12. NAV1: Helmsman. The officer piloting the ship.
     13. AUX2/FIRE3: Auxiliary Fire Control. Tertiary fire control officer, in this case coordinating defensive weaponry.
     14. Port Gallery: Subsystems section. 4 positions for officers who keep track of the ship's systems and their maintenance and repair.
     15. Forward Gallery: Fire Control Support section. 8 positions for officers who assist with target tracking and weapons status.
     16. Starboard Gallery: Sensors section. 4 positions for officers who operate the sensor suite and analyze the data.
     17. & 18. Aft Offices: These offices are used for off-bridge officers including communications and intelligence.
     19. & 20. Balcony Offices: The offices are available for commander's or flag officer's facilities, but are currently empty.
     21. & 22. Observation Couches: These are places for the bridge security officers or observers to sit when necessary.

• 

The Battlestar Galactica’s Combat Information Center, or CIC, is a medical-theater-like room that acts as the military nerve center and brain of the Galactica. It is located near the center of the ship, is heavily armored and protected by armed guards, and has a staff of between 35-50 people.

The two highest ranking officers on the ship, Commander Adama and Colonel Tigh, typically stand at the center of the auditorium around the Command Board. This position lets them hear status reports from around the room, and issue orders to the entire ship.

Various pods of workstations provide seating for the rest of the staff. These stations are grouped by function. We see Navigation crew sitting near other navigation crew, weapons officers near other combat functions, communications near the center, and engineering given a special area up top.

Phone kiosks are placed throughout the CIC, with two high profile kiosks on the Command Board. Large display boards and the central Dradis Console provide information to the entire crew of the CIC.

Organized Chaos

The CIC is dealing with a lot of information from all over the ship and trying to relate it to the lead officers who are making decisions. There is a lot of activity related to this information overload, but the design of the CIC has organized it into a reasonably effective flow.

Teams communicate with each other, then that decision flows forward to lead officers, who relate it to Admiral Adama.

Orders flow in the opposite direction.

Admiral Adama can very quickly shout out an order from the center of the CIC and have his lead officers hear it all around him. It can also act as a failsafe: other officers can also hear the same order and act as a confirmation step. From there, the officers can organize their teams to distribute more detailed orders to the entire ship.

Large screens show information that the entire CIC needs to know, while smaller screens display information for specific crew or groups.

Overall, the stadium-like construction of the CIC works well for the low tech approach that the Galactica takes after. Without introducing automation and intelligent computer networks onto the bridge, there is little that could be done to improve the workflow.

CENTRALIZED EARTH GOVERNMENT AND ADMINISTRATION BOAT BRIDGE

• 

Boat-sized vessels cannot afford the volume needed for a full-sized spherical control center. Instead, they use a reduced four-person design. This smaller size allows a boat to still benefit from the concept of the astronomical display.

The ship's captain is in the center. The chief gunner station, the chief engineering station and a dual role navigation/helmsman station form a triangle around him. Other functions, such as a communication and astronavigation, are supervised from small work stations located just outside the bridge itself.

The chief gunner can access all of the weapon controls from the bridge. Normally, the bridge's gunnery station is used solely to prioritize targets and for overall situational awareness. Actual aiming of weapons is typicaly conducted through the local fire control systems near the weapons themselves.

Engineering interfaces with the ship's computer to run programs, do maintenance reviews and supervise damage control. In combat, the chief engineer may attempt various workaround repairs without leaving the bridge. He may also directs the damage control parties, which are led by the watch officers.

The ship's pilot has full control of the vessel from the navigation and helm station. Constant coordination with gunnery is important, as the ship's maneuvers will move its firing arcs around. New courses may be plotted onto the spherical display for review by the captain prior to them being initiated.

Various data feeds are projected on the datascreen that form the walls and ceiling. In combat, the system functions as a giant headup display, including target identification, range and a symbol showing the object's relative velocity. Each individual station has independent displays for more detailed information.

---

JOVIAN CONFEDERATION BRIDGE

• 

The bridge of the Corsair-class vessels is probably the largest living space aboard the vessel. It is built around the standard Jovian "open space" spherical layout, with crew stations far from one another. In many ways, it would be better to refer to it as the ship's cockpit, since it shares many characteristics with interceptor and exo-armor cockpits.

The Corsair's bridge is covered with a bubble-like canopy, a sophisticated projection system similar to the ones used on most ships' bridges; it can project not only a reconstructed view from any sensor cluster in any wavelength, but it can also overlay tactical information such as trajectories and IFF tags.

Each crew station is equipped with an ergonomic padded seat surrounded by readout panels that can be reprogrammed to fulfill the functions of any of the bridge's posts. The seat features attachment points for a sturdy padded harness for use during combat and alert situations (a thin seat belt is used otherwise to improve comfort). A panel in the base of the seat contains connectors for a space suit air hose and power leads, greatly extending the endurance of said suit.

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COOPERATIVE VENUSIAN NAVAL ADMINISTRATION BRIDGE

• 

The bridge of the Shan-Yu battlecruiser is a spherical chamber which takes up the same volume as the Strategic Operations Center. Just like the latter, the entire room can be rotated so that its overall gravity gradient is aligned with the ship’s axis (when under acceleration) or the outside of the hull (when the ship is under rotation). Entry and exit are accomplished via several large hatches that line up with the ship’s corridors; in the event of a rotation malfunction, emergency cutting tools stored in a locker on one wall allow the bridge crew to cut their way out of the bridge.

The Shan-Yu’s bridge has the same general layout as the bridges of most modern military spacecraft. It has fewer stations than the SOC, and a much more delicate-seeming framework around the seats (the equipment is just as structurally sound as the ones used by other nations, but is more aesthetically pleasing). The captain sits right in the middle of the room in a gimbaled seat that can swivel to face any direction in the room and its wall monitors.

The rest of the crew stations are scattered around, above and below the captain's seat, and are all linked to a walkway and ladders that ring the bridge. Each crew station is surrounded by monitors, facing both inward and outward, that complement the "big picture" presented on the main spherical viewscreen. When fully active, the bridge is a riot of multimedia displays that a good captain must be able to interpret and analyze at a glance.

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COOPERATIVE VENUSIAN NAVAL ADMINISTRATION STRATEGIC OPERATION CENTER

• 

The Strategic Operations Center is a room that will be present on every Shan-Yu. It occupies a large spherical volume in the center of one of the main hulls, exactly in the same location as the bridge but within the opposite hull. The Operations Center‘s primaryfunction is to coordinate fleet activities, but it can also serve as a backup bridge if necessary. At all times, operators move between stations, compiling intelligence and battle reports with the help of the onboard computers to present up-to-date tactical advice to the officers in charge. A number of heavy-duty walkways and liftlines crisscross the room to handle foot traffic, which is much increased in this room compared to the bridge.

The main level is placed at the ”equator” of the room. Computer terminals and monitors line the wall, along with compact and space-saving seating for a large number of operatives. The wall monitors are set to show external views of the ship or other important data. Two extra floor tiers, commonly called the “Tropic of Cancer” and the ”Tropic of Capricorn,” are located midway further up and down along the wall. These partial floors are accessible via ladders or zero-gee floating, and consist primarily of walkways around the rim and several extra workstations and monitoring panels.

A large chair sits on a raised dais at the back of the room. It is meant for use by the Strategic Operations Coordinator, who is usually a flag officer. This seat, unlike the captain‘s chair on the bridge, is designed not for maximum view but rather for easy access to human resources; there is an endless stream of people coming up to the dais to provide updates, explanations and advice. The Coordinator‘s chair is surrounded by the majority of the room’s floor space, which is fitted with clips for fold-down chairs and a small tablekhreat board for impromptu conferences. From this seat, a Venusian admiral can guide the movements and activities of dozens of warships, making use of the Shan-Yu’s extensive communications array to assign new orders and tactics.

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COOPERATIVE VENUSIAN NAVAL ADMINISTRATION ANALYSIS ROOM

• 

This is the room where all the data gathered by the Huang-ti's sensors is collated, inspected, and evaluated by the onboard specialists. lt is located in the same position as the Cloak Room and recreation rooms in the opposite main hull, and is fairly large for a room aboard a spaceship of this size.

The inner room is spherical; since the corresponding space in the other main hull is square-edged, the Analysis Room is actually a sphere positioned within a rectangular volume. The space outside the crew sphere is taken up by computers and data storage equipment which is accessible via access panels in the walls. A tiny bathroom and a snack bin are located right outside the main door for convenience during long shifts.

The room has many chairs along the walls, but the central space is clear of permanent furniture. The walls are covered in monitors; threat boards and other large displays can unfold from the walls, allowing even more data display space. In its fully "open" state, the whole room is packed solid with display devices. Many crew, however, prefer to use virtual reality headsets and use the central space as a virtual environment. Up to a dozen people can work in this room in total comfort (as far as elbow room goes, at least). This room is not set up for ship control functions; it is a think tank, not much else.

Gee, why would US rocket scientists use a German word for something technical? You'd think the answer is "Project Paperclip", where after World War II the US scooped up as many German scientists that they could possibly lay their hands on, so America got them instead the Soviet Union, the UK, and the smoking remains of post-war Germany.

But you'd be wrong.

German rocket scientist Willy Ley saw the hand-writing on the wall in 1934, well before the Nazis had captured all native German rocket scientists and shipped them off to the Peenemünde Army Research Center. Ley forged an authorization allowing him to go for a vacation in London and defected. He wound up in the US and wrote classic books popularizing space flight, which included German terms such as Brennschluß.

• 

      Carefully locking their isolated woodland cabin, Thane turned and strode with Miribel to the shed. There was nothing to be seen in the large space once used to hold cordwood, tools, and animal stalls.
     Thane pressed a knot in a post, concealing a hidden switch. A shimmering violet glow sprang forth, in the outline of a saucer-shaped ship. It solidified in the next moment as the silvery disk Miribel had arrived in.
     The saucer was typical of the many thousands reported all over earth, shaped like two pie plates stuck together. It was twenty feet wide and seven feet high, accommodating only two people. The hatchway was open and, after they stepped in, it swung shut behind them, blending into the wall.
     “I still marvel at your cold welding process," Thane said staring at the blank wall. “Your doors shut so tightly you can never see where they are."
     Miribel shrugged. “If the door edges weren't specially treated to bind with the frame in the wall, we wouldn’t have the completely sealed and leak proof hull around us that we need in space," she said nonchalantly.
     “Super-technology," grunted Thane. He had that annoying feeling again that he was a bushman associating with ultra-civilized beings. But he put it out of his mind and sat at the controls.
     “We have time so let me practice my saucer piloting,” he said. And that too was a marvel. A brass ball hung without support within a globe of pulsing energy. He let the saucer glide out of the shed. Then, as his hand grasped the ball and moved it upward slightly, the saucer leaped soundlessly from the ground and shot straight up. It didn’t accelerate, as all earthly vehicles, even rockets, must, the saucer simply shot from zero speed to supersonic speed in one instant.
     “No grip of gravity, no inertia, no air-drag," said Thane, still impressed after dozens of saucer rides. “No, don't tell me how it’s done. I wouldn't understand.” Miribel reached over from her seat to stroke his hair. “Poor backward Earthman,” she soothed in over-sweet tones. “His ego is bruised.” Her voice changed. “But I’ve told you over and over, my Terrific Terran, that the Earth brain has the full potential of ours. You just don’t have the lifetime of development and training we’ve had in advanced science and technology.”
     Thane moved the brass ball horizontally, and, obediently, the saucer moved over woodlands below at a slow speed. Speed was controlled by how hard he squeezed the brass ball, nothing more.
     When the outskirts of Tanglewood came into view, Thane reached over and snapped on a separate switch for the anti-visio unit. A violet glow shimmered around them and the saucer turned hazy in their eyes, while their own forms looked ghostly. To anyone below, they were now completely invisible.
     Delicately handling the brass ball control, Thane brought the unseen saucer down to street level. The few passing people and cars took no notice. When the saucer hung directly over a mailbox, a mechanical arm reached out of the bottom and dropped a big envelope into the slot deftly.
     “Little does anyone know,” Thane grinned, “that I just mailed my article to Everyday magazine."
     Then, gripping the brass ball tightly, he moved it upward. In response, the saucer catapulted skyward at a speed no airplane could ever match. Thane then switched off the anti-visio unit.

(ed note: again there are two variables being controlled: attitude and thrust. Direction the hovering brass ball is moved establishes attitude, how hard the ball is squeezed controls velocity.)

(Rob Davidoff said: Technically, what's being controlled is only one thing: velocity. Ball deflection establishes direction and the pressure establishes speed. Speed and direction combined are velocity. Attitude is precisely what this control scheme doesn't control—the actual angle of the saucer relative to the flight direction or the ground.)

The computer, his calculations complete, watched the pilot with interest, for, accustomed as he was to traversing the depths of space, there was a never-failing thrill to his scientific mind in the delicacy and precision of the work which Breckenridge was doing -- work which could be done only by a man having had long training in the profession and possessed of almost instantaneous nervous reactions and of the highest degree of manual dexterity and control. Under his right and left hands were the double-series potentiometers actuating the variable-speed drives of the flight-angle directors in the hour and declination ranges (ed note: in the "hours" of Right Ascension and the "degrees" of Declination, which is the longitude and lattitude of celestial navigation.); before his eyes was the finely-marked micrometer screen upon which the goniometer threw its needle-point of light; powerful optical systems of prisms and lenses revealed to his sight the director-angles, down to fractional seconds of arc. It was the task of the chief pilot to hold the screened image of the cross hairs of the two directors in such position relative to the ever-moving point of light as to hold the mighty vessel, precisely upon its course, in spite of the complex system of forces acting upon it.

Astrogator Roger Mannings tells Pilot Tom Corbett that the next burn will require 5,590 m/s of delta V and has a burn start time of Thirteen hundred hours and fifty-four minutes (13:54) in order to put the Polaris on Hohmann trajectory to Mars.

Tom calculates that the Polaris currently has an acceleration of 103 m/s (a triple cluster NSWR can really crank out the thrust). 5,590 / 103 = 54.3 seconds of burn duration.

Half of that is 27.2 seconds. This means the actual burn start time should be 27.2 seconds before the time specified by Roger, or 13:54:00 - 00:00:27.2 = 13:53:32.3

“Kzinti would do that anyway,” Louis said. “Charge right in.”

Acolyte bristled. “We do not worship clocks and calendars, Tunesmith. This ship Diplomat was attacked. They will be wary.”

Louis said, “Spaceborn always worship clocks and calendars. Orbits are like that.”

• 

(ed note: in the name of comic relief, we present this hysterically bad example of 1940's space opera design, the controls of Captain Future's space cruiser the Comet. Particularly amusing is the use of an automobile accelerator pedal to control the rocket cyclotrons. Also the electroscope used to follow enemy spacecraft by their rocket trails. Apparently in the Captain Future universe nobody ever invented radar.)

The power-plant of the Comet consists of nine cyclotrons of unusual design. The cyclotrons are the heart of any space ship. They convert powdered mineral fuel into raving energy, by atomic disintegration.

The process is started by a switch which releases a powerful flash of force from a condenser into the cycs. After that, it is self-continuous, a small fraction of the generated power being constantly "fed back" into the cycs to keep up the process of atomic disintegration.

The main flood of terrific atomic energy flows through the control valves into the various rocket-tubes of the ship, as directed by the pilot. If the energy is blasted out of the tail rocket-tubes, it hurls the ship straight forward. If directed into the bow or braking tubes, it slows down the craft. If turned into the lateral tubes along the aide of the ship, or the top tubes in the upper side or the keel tubes in the lower, it pushes the ship up or down or to one side.

THE SPACE-STICK

The Comet owes its unrivaled speed to the fact that its massive cyclotrons are of such radical design that they can produce an unprecedented output of atomic power. These cycs are one of the greatest inventive achievements of Captain Future.

The control of the Comet is essentially much like that of any space ship. The pilot sits in his chair, the main control panel In front of him. Above, easily in view, is the broad space window.

Between the pilot's knees is the space-stick and under his feet are two pedals.

The space-stick is important. It Is a device to control the flow of the atomic power into the various rocket-tubes at will, without the necessity of opening or closing the individual throttle of each tube. Such individual throttles are on the control panel for delicate maneuvering and special uses, but the space-stick is in use most of the time.

When the space-stick is in upright position, all the power of the cyclotrons is directed out of the tail-tubes, flinging the ship straight ahead. But when you pull the space-stick back toward you, it cuts some of the power into the rear keel tubes, with the result that the ship zooms upward in space. Similarly, when you push the space-stick forward, some of the power is cut into the rear top rocket-tubes, which sends the ship diving downward. The farther forward you push the stick, the more power goes into the top tubes, and the steeper is your dive. Moving the stick sideward cuts power into the right or left lateral tubes and turns your ship to right or left.

Under the pilot's right foot is the "cyc-pedal." This controls the amount of energy produced by the cyclotrons by regulating the flow of powdered mineral fuel into the cycs. When you want their full output, you push the cyc-pedal to the floor. When you want to cut the power off, you let the cyc-pedal come clear back.

Thus, when you get warning of a meteor close ahead and want to zoom up sharply, you do two things simultaneously — you pull the space-stick sharply back, so that the power flows to the tail and rear keel rocket-tubes, and you push in hard on the cyc-pedal.

The pilot has beneath his left foot the brake-blast pedal. When this is pushed inward. It instantly directs the atomic energy of the cyclotrons into the bow or brake-tubes which project from the ship's bow for a few inches. Just beneath the fore window. Pushing in on the brake-blast pedal automatically cuts out all other tubes. To make a quick stop, you simply jam both brake-blast and cyc-pedals to the floor, which pours all the power of the cycs into a blast ahead.

These standard principles of space ship control are used by Captain Future and his companions in the Comet. They are all such consummate pilots, however, that they often ignore the convenience of the space-stick and use the individual rocket-throttles, to cut a course as close as possible.

• 

INSTRUMENTS OF SPACE NAVIGATION

The control panel of any space ship is a bewildering sight. But that of the Comet would baffle any ordinary pilot, even if he were of Rocketeer rating. All the ordinary instruments of space navigation are on the Comet's panel — the meteorometers that warn of distance and direction of nearby meteors, the gravitometers that indicate the pull of all bodies in space, the ether-drift indicators and main cyc-switch and auxiliary televisor screen and microphone. But also, the Comet has on its panel a variety of unusual instruments.

There's the atmosphere-tester, an ingenious device of Captain Future which automatically takes in and analyzes a sample of any air. and shows the percentage of all elements in it. There's the comet-camouflage switch. When turned on, it actuates a mechanism which ejects a cloud of shining ions from all rocket-tubes, concealing the Comet and making it look like a small real comet with long, glowing tail.

There's the electroscope, one of the Brain's pet instruments, and which has done sterling service in tracking criminals in space. It's a device that can detect a recent rocket-trail of a ship in space, by the faint trail of ions always left in a rocket-discharge.

• 

The moment of inertia, otherwise known as the angular mass or rotational inertia, of a rigid body is a quantity that determines the torque needed for a desired angular acceleration about a rotational axis; similar to how mass determines the force needed for a desired acceleration. It depends on the body's mass distribution and the axis chosen, with larger moments requiring more torque to change the body's rotation rate. It is an extensive (additive) property: for a point mass the moment of inertia is just the mass times the square of the perpendicular distance to the rotation axis. The moment of inertia of a rigid composite system is the sum of the moments of inertia of its component subsystems (all taken about the same axis). Its simplest definition is the second moment of mass with respect to distance from an axis. For bodies constrained to rotate in a plane, only their moment of inertia about an axis perpendicular to the plane, a scalar value, matters. For bodies free to rotate in three dimensions, their moments can be described by a symmetric 3 × 3 matrix, with a set of mutually perpendicular principal axes for which this matrix is diagonal and torques around the axes act independently of each other.

Introduction

When a body is free to rotate around an axis, torque must be applied to change its angular momentum. The amount of torque needed to cause any given angular acceleration (the rate of change in angular velocity) is proportional to the moment of inertia of the body. Moment of inertia may be expressed in units of kilogram meter squared (kg·m²) in SI units and pound-foot-second squared (lbf·ft·s²) in imperial or US units.

Moment of inertia plays the role in rotational kinetics that mass (inertia) plays in linear kinetics - both characterize the resistance of a body to changes in its motion. The moment of inertia depends on how mass is distributed around an axis of rotation, and will vary depending on the chosen axis. For a point-like mass, the moment of inertia about some axis is given by mr² where r is the distance of the point from the axis, and m is the mass. For an extended rigid body, the moment of inertia is just the sum of all the small pieces of mass multiplied by the square of their distances from the axis in question. For an extended body of a regular shape and uniform density, this summation sometimes produces a simple expression that depends on the dimensions, shape and total mass of the object.

Moment of inertia also appears in momentum, kinetic energy, and in Newton's laws of motion for a rigid body as a physical parameter that combines its shape and mass. There is an interesting difference in the way moment of inertia appears in planar and spatial movement. Planar movement has a single scalar that defines the moment of inertia, while for spatial movement the same calculations yield a 3 × 3 matrix of moments of inertia, called the inertia matrix or inertia tensor.

I was perusing your page wherein you calculate the probability for missing an accelerating target with a light-speed weapon at a distance of 1 light-second.

You carefully prefaced your equations with "Just wait'll you get a load of my assumptions" — but there's one additional assumption you were making that I think you might not be aware of. You assumed that the target's acceleration (a) could be applied in ANY randomly-chosen direction with equal ease.

This implies that the target is able to point its engine in any direction instantly, or nearly instantly. I did some calculations and discovered that it's much harder for a sizable spacecraft to rotate along its pitch or yaw axis than I thought.

Consider a modestly-sized 100 meter long spacecraft with a mass of 1000 tonnes, with a great big torch engine at the back capable of producing 20 million Newtons of thrust (enough for 2g of acceleration) and small attitude thrusters pointing sideways at its nose and tail. These attitude thrusters are what the spacecraft uses to rotate. We'll assume that the spacecraft is roughly rod shaped with its mass uniformly distributed along its length, so that its center of mass is at the 50 meter mark.

Let's say this spacecraft wants to start rotating. We want to apply a VERY MODEST angular acceleration of 1 radian per second squared — that is, after firing its attitude thrusters for 1 second continuously, its angular velocity will be 1 radian per second (it'll take 3.14 seconds to face the opposite direction at this angular speed). We fire the attitude thruster on one side of the nose, and simultaneously fire the attitude thruster on the opposite side of the tail.

How hard will each those attitude thrusters have to push?

For a rod-shaped object, the Moment of Inertia. (I) is 1/12*M*L². Here, L = 100 meters, so I is 833 * 1,000,000 kg = 833 million. Our angular acceleration is 1 rad/s². Thus, the total amount of TORQUE we need to apply to the spacecraft is 833 million meter-Newtons. Each of the 2 attitude thrusters will have to provide half this torque, or 416 mega-meter-Newtons each. Since each thruster is situated 50 meters from the center of mass, each will have to push with a FORCE of 416/50 = 8.33 million Newtons.

In other words, each of the ATTITUDE THRUSTERS has to produce enough thrust to accelerate the ENTIRE SPACECRAFT at 0.83 g !! The thrusters themselves would have to be torch drives!

And this is JUST to produce a very modest 1 radian/sec² angular acceleration.

If you want to be able to point your nose in any direction in only, say, half a second, you'd need at least 12 radians/sec² of acceleration — 24 rad/s² if you wanted to angularly accelerate through half this angle and then angularly decelerate through the other half.

Oh, and the amount of attitude thrust force required works out to being proportional to your spacecraft's length as well as its mass. A 200 meter long 1000-tonne spacecraft would require 16.6 million Newtons from each thruster for 1 rad/s² of angular acceleration. Note that I haven't increased the spacecraft's MASS there, JUST its length. A 200 meter long 2000-tonne spacecraft would require 33 million Newtons from each thruster.

As a side note, if a 100-meter long spacecraft WERE rotating at 1 radian/sec, everything in its nose and tail section would be pinned to the outer wall by a centripetal acceleration of 5g.

And if you keep making your spacecraft longer from nose-to-engines, there'll come a point where you can actually jink more rapidly by thrusting SIDEWAYS with your attitude thrusters than you will by rotating and using your main engine. (In my example, a 100 meter long spacecraft requires 0.83 g from its nose thruster and another 0.83g from its tail thruster to get 1 rad/s² of angular acceleration. If you point both of those thrusters in the same direction, though, you'd get 1.66 g of acceleration sideways, which is almost as much as the 2g that its main engine can provide! You'd still have to ROLL the spacecraft to position those side thrusters onto the correct side, but rolling a rod-shaped spacecraft requires much less torque than pitching or yawing.)

• 

8-5 Influence of Vehicle Dynamics

     The dynamics of a spacecraft are governed by its distribution of mass about its center of gravity. Heavy masses distributed at large distances impose unwanted motions on a rocket vehicle in flight. These unwanted motions are spinning, tumbling, wobbling, bending, twisting, and other gyrations. These are called the dynamic characteristics of a vehicle. The dynamic characteristics are greater in the case of nuclear rockets than for equivalent thrust chemical rockets.

     To a first approximation, the I_sp of a nuclear system is about twice that of a chemical system. Therefore, for equivalent thrust systems, the nuclear propellant weight is about one-half that of chemical propellant weight.

(This follows simply from W_p = wdot × t = F/I_sp × t for equal thrusting times.)

     However, because of the low density of LH₂ for nuclear systems (4.48 lb/ft³) compared to LO₂ for chemical systems (71.15 lb/ft³), nuclear tank volume is roughly eight times that of chemical tankage. From this, it follows that a nuclear tank is more than twice the length and twice the diameter of equivalent chemical tanks.

(Based on volume (π/4) D²ℓ where D is tank diameter and ℓ is tank length.)

     As a consequence, the nuclear tank structure weight (devoid of propellant) is about 1.5 times that of a chemical system.

     Generally speaking, nuclear engine weight is roughly 3 to 4 times that of equivalent-thrust chemical engine weight. For the same conditions, nuclear payload weight is approximately 2 to 3 times that of chemical payload weight. These approximations, together with those on the tank above, are summarized in Figure 8-7. The arrangements are in the form of “dumbbell” schematics. This gives a better physical insight into the dynamic differences between chemical and nuclear systems. Although the nuclear system is larger and has greater masses at its ends, its overall weight is less than that of its chemical counterpart. This is due to the lower propellant weight and the greater propulsion efliciency of nuclear systems. Nuclear vehicles, therefore, are characteristically large with heavily-weighted ends. We should expect that their dynamic characteristics will differ substantially from chemical systems.

     To get some feel for the dynamic dilierences, let us reexamine Equation 8-3. It is reasonable to assume that the θ, θ̇, and θ̈ terms would be essentially the same for nuclear and chemical systems. The maximum value of these terms is set by structural, component, and pilot considerations. These considerations would not difier significantly between nuclear and chemical spacecraft. The differences, therefore,are more closely keyed to the moment of inertia I terms. Each I term in Equation 8-3 has three subcomponents, namely

     where the subscripts are L for payload, T for tank, and E for engine. Each I term is of the general form I = mr², where m is the distributed mass. Using the approximate weight and dimension data in Figure 8-7, the following comparisons are presented:

     In a rough sort of way, we can say that moment of inertia of a nuclear vehicle ranges from about 10 to 30 times that of an equivalent thrust chemical vehicle. Hence, the restoring or corrective torques must be greater in the nuclear case. Taking into account the relative moment arms, the corrective thrust components in Equation 8-3 would be 4 to 12 times greater for nuclear systems.

(The general form is F_i = (Iθ)_i/r_i)

      This implies that conventional thrust vectoring approaches may not be fully adequate for nuclear thrust maneuvering needs.

Lastly, there may be a question of rotation. A more massive and longer ship would have a greater moment of angular inertia than a smaller ship, thus requiring more torque to change its rate of rotation. Again, I don't feel this will be a major concern. At the ranges involved, you again have some time to change direction. However, this does pose the problem in quick, random accelerations to throw off enemy targeting.

Going with the 10,000 metric ton ship, let's assume it has an average density equal to that of water: one tonne per cubic meter. For the shape, I am going to assume a cylinder, about 10 meters in diameter (about the same as the Saturn V), with all the mass gathered at points at the end. The reason of this is to demonstrate a possible upper number for difficulty of rotation (moment of inertia), not to actually propose this is what it would look like. Actually determining an optimal realistic shape for such a ship would take much more thought.

With this, we can determine the length of the cylinder to be 10000 / (π r²) = about 130 metres long. Now, we can estimate the moment of inertia, for which, we will assume there are two point masses of 5000 tons, each 65 meters away from the center. So moment of inertia for the turning axis (as opposed to rotating), is 2*5000 * 65^2 = about 4e10 kilogram meters squared.

Now, let's assume there are maneuvering jets on each end that would fire on opposite sides to rotate the ship. Let's further assume these have thrust about equal to that found on the space shuttle, simply because it is a realistic number that I can find: about 30 kilo-newtons. Let's determine torque, which is radius times force, so 3e4 * 65 * 2 (two thrusters) = about 4e6 newton meters. Outstanding, now we can determine angular acceleration possible.

Angular acceleration = It, where I is moment of inertia and t is torque. So, we have 4e6 / 4e10 = 1e-4 radians per second squared. This is about a meager 10th of a degree per square second. Remember this is acceleration — change in rotation rate. Once spinning, it would tend to continue spinning. This is also a lower limit: most likely, the thrusters would be more numerous than I assumed, and probably more powerful as well, and the mass probably would be more evenly distributed. But anyway, let's see if it might be good enough.

As I said when discussing linear acceleration, you would want some quick randomness to help prevent a concentrated laser beam from focusing on you, and you would want the ability to change your path within a scale of minutes to prevent long range coilgun shells from impacting. There isn't much you can do about missiles except point defense: a ship cannot hope to outmaneuver them due to limitations of the crew, if nothing else.

Some unpredictable linear acceleration should be enough to do these tasks, unless the enemy can get lined up with you, in which case, you will want to change direction to prevent him from using your own acceleration against you, and blasting you head on. So the concern is can you rotate fast enough to prevent the enemy from lining up with you. So, let's assume the enemy can change direction infinitely fast, and can thrust at 3 g's. The range will still be one light-second.

We can calculate how much of an angle he can cut into the circle per second if he attempted to circle around you. His thrust must provide the centripetal acceleration, so we can use that as our starting point. Centripetal acceleration is equal to radius times angular velocity squared, thus, sqrt(30 / 3e8) = 3e-4 radians per second.

So, its angular velocity is three times that of the acceleration of the battleship. Thus, it would take the battleship three seconds to match that rotation rate. It would also want to spin faster to make up for lost time, thus lining up on your terms again. I feel this is negligible because of two factors: if the enemy actually was orbiting like this, its position at any time would be predicable, thus vulnerable, and the battleship can probably see this coming: the enemy's tangential velocity must also be correct to do such a burn - he can not randomly change the orientation of his orbit due to his limitations on linear acceleration. This means you can see what he is doing and prepare for it with a small amount of time of him setting the terms. In this small time, he would not even move a degree on you: still easily within your armor and firing arc. (Also, weapons turrets on the battleship would surely be able to rotate at a much, much faster rate, so outrunning them is impossible anyway).

• 

(ed note: Secret agent K-15 is being chased by enemy ship Doradus. If K-15 can survive a few hours, friendly spacecraft will come to his rescue. So to buy time, K-15 bails out of his ship in a spacesuit, and goes to ground on the tiny Martian moon of Phobos. The commander of the Doradus is most displeased.)

To the layman, knowing nothing of the finer details of astronautics, the plan would have seemed quite suicidal. The Doradus was armed with the latest in ultra-scientific weapons: moreover, the twenty kilometers which separated her from her prey represented less than a second’s flight at maximum speed. But Commander Smith knew better, and was already feeling rather unhappy. He realized, only too well, that of all the machines of transport man has ever invented, a cruiser of space is far and away the least maneuverable. It was a simple fact that K-15 could make half a dozen circuits of his little world while her commander was persuading the Doradus to make even one.

There is no need to go into technical details, but those who are still unconvinced might like to consider these elementary facts. A rocket-driven spaceship can, obviously, only accelerate along its major axis-that is, "forward." Any deviation from a straight course demands a physical turning of the ship, so that the motors can blast in another direction. Everyone knows that this is done by internal gyros or tangential steering jets, but very few people know just how long this simple maneuver takes. The average cruiser, fully fueled, has a mass of two or three thousand tons, which does not make for rapid footwork. But things are even worse than this, for it isn’t the mass, but the moment of inertia that matters here — and since a cruiser is a long, thin object, its moment of inertia is slightly colossal. The sad fact remains (though it is seldom mentioned by astronautical engineers) that it takes a good ten minutes to rotate a spaceship through 180 degrees, with gyros of any reasonable size. Control jets aren’t much quicker, and in any case their use is restricted because the rotation they produce is permanent and they are liable to leave the ship spinning like a slow-motion pinwheel, to the annoyance of all inside.

In the ordinary way, these disadvantages are not very grave. One has millions of kilometers and hundreds of hours in which to deal with such minor matters as a change in the ship’s orientation. It is definitely against the rules to move in ten-kilometer radius circles, and the commander of the Doradus felt distinctly aggrieved, K-15 wasn’t playing fair.

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      Re. "Hide and Seek": Actually the commander of the Doradus used a very inefficient method of circling Phobos. As I recall he would fire his "jets", travel in a straight line for some minutes while making a 180-degree turn, fire his jets again to brake to a halt, reorient, then repeat.

     A much more efficient method of circumnavigating Phobos would be to align the rotation and thrust so that the Doradus was thrusting in towards Phobos while spinning at the same rate as it took to complete the circumnavigation. In other words, substitute the ship's drive for the nearly non-existent gravity needed to make an orbit. The maximum rate would be dictated by the circumference of the circle, the drive's thrust and the maximum allowable spin rate.

     I was trying to calculate hard figures for the Doradus, how fast it would have to go to circumnavigate Phobos and how much acceleration would be required. If my math is correct here's what I've got:

     The story mentions a spin rate of 10 minutes to flip 180 degrees, so 20 minutes for 360 degrees. Let's take that as the working spin rate and circumnavigation time. The story then mentions a 10 km radius. That would mean a circumference of 2Pi x 10, which rounds up to 62,832 meters.

     If Doradus travels that distance in 1200 seconds the tangential velocity is (rounded up again) 52.36 m/s. If the formula for centripetal acceleration is A=V²/R then Doradus has to maintain a centripetal acceleration of 0.27415 m/s² to artificially orbit Phobos at maximum speed, or about 1/36 of a G.

     If Doradus attempts to maintain this for (iirc) six hours, the delta-V budget needed would be a little over 5.9 km per sec. Of course a slower speed can probably be used since that's faster than a man in a suit can move around Phobos.

• 

The Mercury space capsule and Gemini re-entry module both used groupings of nozzles to provide attitude control. The thrusters were located off their center of gravity, thus providing a torque to rotate the capsule. The Gemini capsule was also capable of adjusting its re-entry course by rolling, which directed its off-center lifting force. The Mercury thrusters used a hydrogen peroxide monopropellant which turned to steam when forced through a tungsten screen, and the Gemini thrusters used hypergolic mono-methyl hydrazine fuel oxidized with nitrogen tetroxide.

The Gemini spacecraft was also equipped with a hypergolic Orbit Attitude and Maneuvering System, which made it the first manned spacecraft with translation as well as rotation capability. In-orbit attitude control was achieved by firing pairs of eight 25-pound-force (110 N) thrusters located around the circumference of its adapter module at the extreme aft end. Lateral translation control was provided by four 100-pound-force (440 N) thrusters around the circumference at the forward end of the adaptor module (close to the spacecraft's center of mass). Two forward-pointing 85-pound-force (380 N) thrusters at the same location, provided aft translation, and two 100-pound-force (440 N) thrusters located in the aft end of the adapter module provided forward thrust, which could be used to change the craft's orbit.

"Pursuit fighters," I told the Ship. "Easily fast enough to catch one of our boats, if they can do it within their limited range. It's limited because they're the only kind of craft designed for dogfight tactics.

They're just enormous multidirectional motors in a spheroid hull with one pilot in the centre and a few missile tubes scattered between the motor vents. Fast maneuvering in space means killing momentum one way as well as building it up in another, so there's murderous acceleration and deceleration every few seconds, with the motor blasting in all directions, eating up hydrogen and putting incredible stress on the pilots. Even with all the aids — liquid suspension cocoons, special suits, body reinforcement, field-shields, the lot — it takes years of training to stand it for more than a few minutes at a time.

The American call fighter pilots Globetrotters, for some old game where you had to bounce a ball all the time. I've been in a fighter simulator once — I came out black and blue, and they say the real thing's worse.

And that's our hope — that Liang can hold them off, make them maneuver so much they'll have to give up, or just outrun them. That's what he's trying to do now, but he's got to be careful. They mustn't box him in and stop him maneuvering, that'd let them swarm over him like hornets, killing the boat or crippling it till the gunships catch up —"

(ed note: Troy Campbell noted In ENTERING SPACE, astronaut Allen gives this description of the Shuttle RCS sounds:)

The forward primary thrusters sound like exploding cannons at thrust onset; and during their firing, jets of flame shoot out from the orbiter's nose…

…The orbiter reacts to the primaries' shove by shaking slightly and moving very noticeably. For the crew on board, a series of attitude changes using primaries resembles a World War I sea battle, with cannons and mortars firing, flashes of flame shooting in all directions, and the ship's shuddering and shaking in reaction to the salvos…

…The nose jets, merely a few yards forward of the windows, hammered the cockpit as if howitzers were firing next to us. Checklists strained at their Velcro anchors.

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The first technique is simple. Firing a thruster off center of your spacecraft will cause it to torque. Since rotation is the goal, and rotational acceleration is not, a second thruster must be fired to decelerate it at the end. And because such a thrust would send the center of mass off center, often two thrusters on opposite sides are used to start rotating, and two different opposing thrusters are fired to stop rotating.

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These are called Vernier Thrusters, and see heavy use in space travel.

There are significant disadvantages to this method, however, chiefly that additional reaction mass is needed. Not only that, such thrusters usually can’t be Nuclear Thermal Rockets (NTRs), due to radiation concerns (recall that most crew modules are placed as far away from the main engine NTRs as possible). Cold gas thrusters don’t provide near enough thrust to be useful in combat, which means combustion rockets and resistojets are in.

Combustion rockets suffer from the issue that they require propellant(s) that are almost guaranteed to be different than NTR propellants, so additional propellant tanks must be added in, which takes up space and mass. This leaves resistojets as the prime method of providing torque to your spacecraft, since they can use the same propellant as your NTR...

...This leaves thrusters as the only viable method of spinning about in combat. How fast can they spin?

Because thrusters affect acceleration rather than velocity, the answer is that it varies. For instance, the time to spin 90 degrees is not going to be twice the time it takes to spin 45 degrees. And it varies based on which axis of rotation is used.

A simple metric is the Full Turnabout Time, which is the time it takes to spin 180 degrees about the slowest axis. This is essentially the “slowest” possible turning time for the ship, and most turns will be much faster, a fraction of this time.

For medium sized capital ships with gimbaled thrusters in game, 20-30 seconds is a common value. Capital ships with vernier thrusters tend in the 10-20 second range, as do small sized capital ships. Very large capital ships can take up to a minute to do a full turnabout. Gimbaled drones and missiles tend to take 5 seconds or less for a full turnabout, with some being able to do a 180 in under a second.

Much faster turnabouts are possible by simply adding more and more vernier thrusters or gimbaled thrusters. However, this is often fast enough to deal with the rapidly changing nature of space combat. It is rare for a capital ships to ever need to flip a 180. Most of their turns are much smaller angle shifts, small dodges and broadsides.

A critical structural problem arises at the junction between the engine and rocket body, however. Across this junction must be transmitted the entire engine thrust that is conveyed upwards from the nozzle through the engine exoskeleton. Ordinarily, such a joint would present no engineering difficulties. But in this case, the joint must be flexible. All big rockets have their engines mounted on gimbals that permit the "driver" to steer them.

Gimballing chemical engines is relatively easy because they are lightweight. But, in a nuclear rocket, the heavy reactor replace the empty combustion chamber of the chemical rocket. Despite the added weight, suitable flexible joints now have been designed.

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...Alternatively, instead of a system of multiple Vernier Thrusters spread out across your hull, simply putting a gimbal on your main thruster will do the trick instead. This allows your main engine to turn, producing off center thrust on your ship, rotating it. In this way, your main engines can serve the dual purpose of getting you places as well as orienting you in combat. This is one of the cheapest forms of thrust vectoring.

• 

The primary disadvantage of it is that propellant is still expended when turning, however, no additional propellant tanks are needed as your main thrusters are doing the turning. For capital ships, the amount of delta-v spent turning is negligible, though for smaller crafts like missiles, the delta-v spent can raise a few eyebrows.

A more subtle disadvantage of gimbaled thrusters is that the size of the opening that the engines need to have can balloon significantly. This can yield much larger aft sections of the ship, and increase the targetable cross section of the spacecraft heavily.

Gimbaled thrust tends to be the cheapest and simplest solution to turning in space, and many capital ships and all drones and missiles in Children of a Dead Earth use them. Some capital ships opt for resistojet Vernier Thrusters, primarily for getting a smaller targetable cross section...

• 

...This leaves thrusters as the only viable method of spinning about in combat. How fast can they spin?

Because thrusters affect acceleration rather than velocity, the answer is that it varies. For instance, the time to spin 90 degrees is not going to be twice the time it takes to spin 45 degrees. And it varies based on which axis of rotation is used.

A simple metric is the Full Turnabout Time, which is the time it takes to spin 180 degrees about the slowest axis. This is essentially the “slowest” possible turning time for the ship, and most turns will be much faster, a fraction of this time.

• 

For medium sized capital ships with gimbaled thrusters in game, 20-30 seconds is a common value. Capital ships with vernier thrusters tend in the 10-20 second range, as do small sized capital ships. Very large capital ships can take up to a minute to do a full turnabout. Gimbaled drones and missiles tend to take 5 seconds or less for a full turnabout, with some being able to do a 180 in under a second.

Much faster turnabouts are possible by simply adding more and more vernier thrusters or gimbaled thrusters. However, this is often fast enough to deal with the rapidly changing nature of space combat. It is rare for a capital ships to ever need to flip a 180. Most of their turns are much smaller angle shifts, small dodges and broadsides.

There was nothing to see on the screens except for the hazy globe of Earth slowly growing smaller as they rose. A hum sounded in the cabin as the gyroscopes began to turn the ship under the maneuvering of the automatic pilot. It had no effect on the movement of the ship through space, but only served to swing the ship on its axis, to bring the rockets around, pointed where they would have to be. According to Newton's law of motion, every action was balanced by an equal and opposite reaction; the eighty tons of the ship would turn once for thousands of turns of the gyroscope's few pounds. It was cheaper than trying to steer with side rockets.

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...But suppose you don’t want to spend precious propellant turning? Then you need to invest in the second technique towards turning in space: exploiting Conservation of Angular Momentum.

Given a system without little or no external medium (such as space) and assuming you don’t want to expend propellant, the only way to rotate is by using conservation of angular momentum.

A quick example. Consider a pair of identical masses loosely attached to one another, floating in space. If one of the masses begins to spin in one direction, the other mass must spin in the opposite direction at an equal speed, otherwise it would violate Newton’s Laws of Motion.

This is the basic principle of operation for a Reaction Wheel, which is a flywheel with a motor attached. A flywheel is a mass with a high Moment of Inertia, or ability to resist rotational changes, along a single axis. When you spin a reaction wheel inside your ship using the motor, your spacecraft must spin in the opposite direction. Three reaction wheels must be used to get a full range of motion (one for each axis: pitch, yaw and roll). The Kepler Spacecraft uses reaction wheels.

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A Momentum Wheel is a reaction wheel which is constantly spinning at a very high speed. If a momentum wheel is spinning inside a spacecraft, simply braking it can cause a huge change in rotational momentum, causing a significant torque on your ship. Six momentum wheels are needed instead of three, two for each axis in opposite directions.

Momentum Wheels are often used for spin stabilization, as the huge amount of stored rotational energy will resist external torques. The Hubble Space Telescope uses Momentum Wheels.

A Control Moment Gyroscope (CMG) is a single momentum wheel on a dual-axis gyroscope. By rotating the momentum wheel about the two gimbal axis, the angular momentum balance of the spacecraft can be altered at a whim. A single CMG can rotate a spacecraft along any axis by simply rotating the gyroscope to be in line with that axis. They are the most expensive and complex of the above systems, and are used on the ISS.

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These systems promise the ability to rotate your spacecraft without expending propellant. Not only that, they require no exposed external systems, so they can’t be damaged unless the main bulkhead armor is penetrated. Sounds like a win-win, right?

Unfortunately, their effectiveness is very poor for combat operations. Modern CMGs are often used to very slowly change orientations over the course of minutes and hours. I originally had never intended to implement Vernier Thrusters or Gimbaled Thrusters in game, and was only going to use Momentum Wheels and CMGs. That rapidly fell apart when I did the math on them.

Consider the above example with the two masses on a string. Because they are identical, the spins will be equal and opposite. But if one mass has twice the moment of inertia, it will spin at half the (reverse) speed as the other. The greater the moment of inertia, the slower the spin.

If one of these masses is the spacecraft and the other is the reaction wheel, you want the spacecraft to have a lower moment of inertia. Thus, if your spacecraft has a moment of inertia 100 times that of your reaction wheel, it will spin 100 times slower than that reaction wheel.

Moment of Inertia is proportional to mass and the square of distance from the rotation axis. Roughly speaking then, very voluminous and very massive objects will have the greatest moment of inertia.

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Spacecrafts by nature will have a greater volume than your reaction wheels, since they envelope these wheels. And they are guaranteed to have a greater mass than your reaction wheels, unless you are okay with an abysmal mass ratio (less than 2). Thus, you are guaranteed a moment of inertia far tinier than your spacecraft’s moment of inertia. And as I discovered, even spinning your wheels at enormous speeds yields rotations that take minutes or even hours.

In short, these techniques were not viable for combat rotations, barring some sort of future technology...

Over the past few decades, numerous space probes sent to the far-flung reaches of the Solar System have fallen silent. These failures weren’t due to communications problems, probes flying into scientifically implausible anomalies, or little green men snatching up the robotic scouts we’ve sent out into the Solar System. No, these space probes have failed simply because engineers on Earth can’t point them. If you lose attitude control, you lose the ability to point a transmitter at Earth. If you’re managing a space telescope, losing the ability to point a spacecraft turns a valuable piece of scientific equipment into a worthless, spinning pile of junk.

The reasons for these failures is difficult to pin down, but now a few people have an idea. Failures of the Kepler, Dawn, Hayabusa, and FUSE space probes were due to failures of the reaction wheels in the spacecraft. These failures, in turn, were caused by space weather. Specifically, coronal mass ejections from the Sun. How did this research come about, and what does it mean for future missions to deep space?

What Is A Reaction Wheel?

A reaction wheel is important to any space mission: it’s the main method nearly every space probe uses to orient itself. It’s how a space telescope points at a star, and it’s how a Martian lander makes sure the heat shield is pointed towards the atmosphere before reentry. But how does it do this?

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A reaction wheel is really just a flywheel — a heavy, spinning disk — that normally rotates at a few hundred to a few thousand RPM. This flywheel stores angular momentum, and changing this rotation speed imparts a tiny bit of torque around the axis of the flywheel. Think of it as a very advanced version of the infamous introduction to physics experiment where a volunteer sits on a spinny chair, holding a spinning bicycle wheel. The bicycle wheel stores angular momentum, and by tilting the wheel the volunteer can spin in their chair. No, it’s not a perfect representation of a reaction wheel, because the flywheels in a satellite don’t tilt, but the idea is the same: controlling a flywheel means you can spin. Do it on a satellite in microgravity, and you can spin the entire spacecraft.

Of course, reaction wheels aren’t the only way a spacecraft can orient itself. Satellites flying in Low Earth Orbit (or any magnetosphere, really), can use magnetorquers, or long electromagnets, to orient themselves within a magnetic field. The cubesats from several universities, in fact, use magnetotorquers for all their attitude control requirements. But magnetotorquers don’t work outside of a magnetosphere, and in deep space, space probes will also use thrusters in conjunction with reaction wheels. Using two methods of attitude control is a necessity for any deep space mission. Not only can one method fail, but reaction wheels can become ‘oversaturated’, or have the flywheel spin at the limits of its bearings. If this happens, the flywheel would need to be de-spun, which means thrusters must provide an opposing torque to keep the spacecraft from spinning out of control.

Despite these limitations, reaction wheels really are the best way to orient a small spacecraft. They only require electricity to keep them spinning, which is abundant thanks to solar panels. Using thrusters as the sole means of orientation uses valuable fuel, and the mass of that fuel would be better spent on sensors and experiments anyway.

Failures of Reaction Wheels

Reaction wheels are found in nearly every spacecraft, and over the last few decades there have been a few notable failures. The Hubble space telescope was suffering from failures of multiple reaction wheels before a servicing mission saved the space telescope in 1997. This was vitally important, because without a full suite of reaction wheels, the Hubble could not point at anything; an impressive failure for a telescope. Before the servicing mission, the problem was solved to an extent by using two of the remaining reaction wheels and magnetotorquers. With the replacement of the reaction wheels, Hubble happily continued exploring the cosmos.

Beyond Earth orbit, there have been numerous failures of reaction wheels in space. The Dawn mission to Vesta and Ceres is still continuing, but while this space probe was in orbit of Vesta, it suffered a loss of its reaction wheels. The cause of the failure was excessive friction in the bearings, and while engineers managed to get Dawn to Ceres, it wasn’t easy. A combination of the remaining reaction wheels and ion engines did allow Dawn to travel to Ceres, but it couldn’t even do that with its main antenna pointing at Earth.

In the summer of 2005, the Hayabusa spacecraft was cruising towards an asteroid named Itokawa, when a reaction wheel controlling its X axis failed. As Hayabusa had redundant reaction wheels, the mission continued towards the asteroid until September of 2005 when it assumed a 7 km orbit around its target asteroid. Just days after achieving this orbit, a second reaction wheel failed, this time controlling the Y axis. Despite this, Hayabusa landed on Itokawa momentarily, collected a small sample, and returned to Earth, sending a recovery capsule to land in the Australian desert.

While not launched into deep space, the FUSE spacecraft — the Far Ultraviolet Spectroscopic Explorer — was launched into orbit in 1999, and designed as a telescope for the far ultraviolet portion of the spectrum. This satellite was launched into a 760 km orbit around Earth (still close enough that magnetotorquers were also used in the design). After several years, two of the four reaction wheels showed a sudden increase in friction and stopped spinning. Engineers managed to update the software to use the two remaining wheels and magnetotorquers, allowing the mission to continue for several years but in 2007, the last two wheels failed, bringing an end to the mission.

But perhaps the greatest failure of reaction wheels in space is that of the Kepler spacecraft. This spacecraft was designed to sit in deep space and look at a small speck of the cosmos for planets passing in front of stars. If there was ever a mission that required accurate pointing and redundant reaction wheels, Kepler is it. Launched in 2009, the planet-finding mission was at first expected to last until 2016. This changed in the summer of 2012, when one of the four reaction wheels failed. Less than a year later, a second reaction wheel failed, causing the cancellation of the primary mission.

While the Dawn, Hayabusa, FUSE, and Kepler missions were saved by Apollo 13-level engineering heroics, all of these missions have another thing in common. The reaction wheels were all manufactured by Ithaco Space Systems. Sounds like a great opportunity for a root cause analysis, doesn’t it?

Finding The Failures In Reaction Wheels

Simply due to their nature as space probes, we’ll probably never recover the reaction wheels from Dawn or Kepler. The reaction wheels from Hayabusa were a fine mist over the Australian desert before they weren’t anymore. So, how do we figure out how these reaction wheels failed? That’s exactly what one researcher did, and the evidence is intriguing.

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The failures of these reaction wheels can be traced to one problem: friction in the bearings which allow these flywheels to spin at thousands of rotations per minute. When the motor inside the reaction wheel can’t overcome the friction of the bearings, the reaction wheel has failed. But what would cause this in deep space, millions of miles away from Earth?

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As it turns out, the failures of reaction wheels, specifically on the FUSE and Kepler missions, was correlated with space weather, specifically coronal mass ejections (CMEs) from the Sun. These CMEs induce a voltage across the bearings and the bearing races in the reaction wheels, and after testing, these researchers discovered it doesn’t take much to generate a small arc from the bearing to the bearing race. This arc causes a small bit of pitting, which over time increases the friction on the reaction wheels, eventually causing it to fail.

Solving Bearing Friction Failure

While the researchers provide the experimental data showing that bearings can fail due to a voltage across a bearing and a race, it’s unlikely we’ll ever be able to prove Kepler, FUSE, or Dawn suffered a reaction wheel failure because of space weather. To recover these space probes for an inspection of the bearing races we need to wait for the development of impulse drives or space pirates on a salvage mission.

The good news is the failures of these reaction wheels may be in the past. Ithaco Space Systems has since changed from metal ball bearings to ceramic bearings in their reaction wheels, greatly reducing the chance of arcing across the bearing races. While we might never know for sure if these reaction wheels failed due to space weather, the problem, at least in these Ithaco reaction wheels, is solved.

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(ed note: SPB is spacecraft Secular Plum Blossom, MR is Mundito Rosinante asteroid colony)

—From the log of the Secular Plum Blossom.

8/15/39
2459: Achieved zero velocity relative to MR. as ordered. Docking maneuvers begin. Distance 1542 meters, angle between MR and SPB axes of rotation 28°40'.

8/16/39
0312: Spin jets frozen at right angles to antispin direction, where they had been used as auxiliary braking jets after main jets focusing magnet lost supercooling.
0315: Begin internal ballistic flywheels to damp rotation.
1209: Rotation stopped. Distance 1504 meters.
1330: Y-axis and Z-axis flywheels have aligned axes of rotation. X-axis flywheel will not start to match SPB's rotation to MR's.
1342: X-axis flywheel delaminated. Begin replacement of X-axis flywheel with Z-axis flywheel, since spare is wrong size.
1548: Flywheel replaced. Begin matching MR's rotation. Distance 1468 meters to MR.
1807: Rotation matches. Explosive delamination of X-axis flywheel on braking. No casualties.
1810: MR's docking crew extends braking beams. Distance 1420 meters.
1814: Braking cables secured to outfacing eyebolts. Tug line extended.
1825: MR reports tug line secure.
2350: Contact with loading dock, #2 cargo hold.
2425: Annular seal tumesced at contact point. MR docking crew reports seal is tight.
2455: Pressure equalized, #2 cargo hold airlock opens.

8/17/39
0015: Begin discharging supercargo. Chief Engineer MacInterff submits formal resignation.
0018: Capt. Furukawa to sickbay with broken nose.

• 

     "Nice landing, Skipper!" called out Oscar.
     "Yea bo!" agreed Tex.
     "Thanks, fellows. Well, let's get the stilts down." He punched a stud on the control board. Like most rockets built for jet landings, the jeep was fitted with three stabilizing jacks which came telescoping out of the craft's sides and slanting downward. Hydraulic pressure forced them down until they touched something solid enough to hold them, whereupon the thrusting force was automatically cut off and they locked in place, propping the rocket on three sides, tripod fashion, and holding it erect.
     Thurlow waited until three little green lights appeared under the stud controlling the stilts, then unclutched the jeep's stabilizing gyros. The jeep held steady, he unstrapped. "All right, men. Let's take a look. Matt and Tex, stay inside. Oscar, if you don't mind my mentioning it, since it's your home town, you should do the honors."
     "Right!" Oscar unstrapped and hurried to the lock. There was no need to check the air, since Venus is man-inhabited, and all of them, as members of the Patrol, had been immunized to the virulent Venerian fungi.
     Thurlow crowded close behind him. Matt unstrapped and came down to sit by Tex in the passenger rest Oscar had left. The space around the lock was too limited in the little craft to make it worthwhile to do anything but wait.
     Oscar stared out into the mist. "Well, how does it feel to be home?" asked Thurlow.
     "Swell! What a beautiful, beautiful day!"
     Thurlow smiled at Oscar's back and said, "Let's get the ladder down and see where we are." The access door was more than fifty feet above the jeep's fins, with no convenient loading elevator.
     "Okay." Oscar turned and squeezed past Thurlow. The jeep settled suddenly on the side away from the door, seemed to catch itself, then started to fall over with increasing speed.
     "The gyros!" yelled Thurlow. "Matt, clutch the gyros!" He tried to scramble past Oscar; they fouled each other, then the two fell sprawling backwards as the jeep toppled over.
     At the pilot's yell Matt tried to comply — but he had been sprawled out, relaxing. He grabbed the sides of the rest, trying to force himself up and back to the control station, but the rest tilted backwards; he found himself "skinning the cat" out of it, and then was resting on the side of the craft, which was now horizontal.

(ed note: re 'skinning the cat', "In America, as any country boy knows, this means to hang by the hands from a branch or bar, draw the legs up through the arms and over the branch, and pull oneself up into a sitting position." -- "A Hog on Ice" by Charles Earle Funk)

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     A quick look around was enough to confirm Oscar's prediction; the jeep lay on her side with her fins barely touching solid ground. The nose was lower than the tail and sinking in thin, yellow mud. The mud stretched away into the mist, like a flat field, its surface carpeted with a greenish-yellow fungus except for a small space adjacent to the ship where the ship, in failing, had splashed a gap in the surface.
     Matt had no time to take the scene in; the mud was almost up to the door.

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     "Quit talking and get busy." Oscar trotted the length of the craft, taking the end of the line with him. He made it to the bank by stepping from a tail fin.
     Matt and Tex had no trouble carrying Thurlow as far as the fins, but the last few feet, from fins to bank, were awkward. They had to work close to the jet tube, still sizzling hot, and balance themselves in a trough formed by a fin and the converging side of the ship. They finally made it by letting Oscar take most of the lieutenant's weight by hauling from the bank with his one good arm,
     When they had gotten Thurlow laid out on the turf Matt jumped back aboard the jeep. Oscar shouted at him. "Hey, Matt — where do you think you're going?"
     "Back inside."
     "Don't do it. Come back here." Matt hesitated, Oscar added, "That's an order, Matt."
     Matt answered, "I'll only be a minute. We've got no weapons and no survival kits. I'll duck in and toss them out."
     "Don't try it." Matt stood still a moment, balanced between Oscar's unquestioned seniority and the novelty of taking direct orders from his roommate. "Look at the door, Matt," Oscar added. "You'd be trapped."
     Matt looked. The far end of the door was already in the mud and a steady stream was slopping into the ship, like molasses. As he looked the jeep rolled about a quarter turn, seeking a new stability. Matt made it to the bank in one flying leap.

(ed note: Beowulf Shaeffer is in a flying car, while Bellamy is in a spacecraft called "Drunkard's Walk" with an unreasonably powerful engine. Bellamy is trying to kill Beowulf. Beowulf bashes his flying car into the side of Drunkard's Walk then crashes into the ground. Drunkard's Walk lands using a "gravity drag" {don't ask})

     The car was on its nose in high fern grass. All the plastic windows had become flying shards, including the windshield; they littered the car. The windshield frame was crushed and bent. I hung from the crash web, unable to unfasten it with my crippled hands, unable to move even if I were free. And I watched the Drunkard's Walk, its fusion drive off, floating down ahead of me on its gravity drag. I didn't notice the anomaly then. I was dazed, and I saw what I expected to see: a spaceship landing. Bellamy? He didn't see it, either, but he would have if he'd looked to the side when he came down the landing ladder. He came down the ladder with his eyes fixed on mine and Emil's sonic in his hand. He stepped out into the fern grass, walked over to the car, and peered in through the bent windshield frame.

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I could walk, barely. I could keep walking because he kept prodding the small of my back with the gun.

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     We were halfway to the ship when I saw it. The anomaly. I said, "Bellamy, what's holding your ship up?"
     He prodded me. "Walk."
     "Your gyros. That's what's holding the ship up."
     He prodded me without answering. I walked. Any moment now he'd see ...
     "What the —" He'd seen it. He stared in pure amazement, and then he ran. I stuck out a foot to trip him, lost my balance, and fell on my face. Bellamy passed me without a glance.
     One of the landing legs wasn't down. I'd smashed it into the hull. He hadn't seen it on the indicators, so I must have smashed the sensors, too. The odd thing was that we'd both missed it, though it was the leg facing us.
     The Drunkard's Walk stood on two legs, wildly unbalanced, like a ballet dancer halfway through a leap. Only her gyros held her monstrous mass against gravity. Somewhere in her belly they must be spinning faster and faster ... I could hear the whine now, high-pitched, rising ...
     Bellamy reached the ladder and started up. He'd have to use the steering jets now, and quickly. With steering jets that size, the gyros — which served more or less the same purpose — must be small, little more than an afterthought.

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     Bellamy had almost reached the air lock when the ship screamed like a wounded god.
     The gyros had taken too much punishment. That metal scream must have been the death agony of the mountings. Bellamy stopped. He looked down, and the ground was too far. He looked up, and there was no time. Then he turned and looked at me.
     I read his mind then, though I'm no telepath.
     Bey! What'll I DO?
     I had no answer for him. The ship screamed, and I hit the dirt. Well, I didn't hit it; I allowed myself to collapse. I was on the way down when Bellamy looked at me, and in the next instant the Drunkard's Walk spun end for end, shrieking.
     The nose gouged a narrow furrow in the soil, but the landing legs came down hard, dug deep, and held. Bellamy sailed high over my head, and I lost him in the sky. The ship poised, braced against her landing legs, taking spin from her dying flywheels. Then she jumped.
     The landing legs acted like springs, hurling her somersaulting into the air. She landed and jumped again, screaming, tumbling, like a wounded jackrabbit trying to flee the hunter. I wanted to cry. I'd done it; I was guilty; no ship should be killed like this.
     Somewhere in her belly the gyroscope flywheels were coming to rest in a tangle of torn metal.
     The ship landed and rolled. Bouncing. Rolling. I watched as she receded, and finally the Drunkard's Walk came to rest, dead, far across the blue-green veldt.
     I stood up and started walking.
     I passed Bellamy on the way. If you'd like to imagine what he looked like, go right ahead.
     It was nearly dark when I reached the ship.
     What I saw was a ship on its side, with one landing leg up. It's hard to damage hullmetal, especially at the low subsonic speeds the Drunkard's Walk was making when she did all that jumping. I found the air lock and climbed in.
     The lifesystem was a scrambled mess. Parts of it, the most rugged parts, were almost intact, but thin partitions between sections showed ragged, gaping holes. The flywheel must have passed here.

---

     The bouncing flywheel hadn't reached the control cone.
     Things lighted up when I turned on the communications board. I had to manipulate switches with the heel of my hand. I turned on everything that looked like it had something to do with communications, rolled all the volume knobs to maximum between my palms, and let it go at that, making no attempt to aim a com laser, talk into anything, or tap out code. If anything was working on that board — and something was delivering power, even if the machinery to use it was damaged — then the base would get just the impression I wanted them to have. Someone was trying to communicate with broken equipment.

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A magnetorquer or magnetic torquer (also known as a torque rod) is a satellite system for attitude control, detumbling, and stabilization built from electromagnetic coils. The magnetorquer creates a magnetic dipole that interfaces with an ambient magnetic field, usually Earth's, so that the counter-forces produced provide useful torque.

Construction

The construction of a magnetorquer is based on the realization of a coil with a defined area and number of turns according to the required performances. However, there are different ways to obtain the coil; thus, depending on the construction strategy, it is possible to find three types of magnetorquer, apparently very different from each other but based on the same concept:

Air-core magnetorquer

This comprises the basic concept of magnetorquer, a conductive wire wrapped around a non-conductive support anchored to the satellite. This kind of magnetorquer can provide a consistent magnetic dipole with an acceptable mass and encumbrance.

Embedded coil

This is constructed creating a spiral trace inside the PCBs of solar panels which generates the effect of the coil. This solution is the one with the least impact on the satellite as it is entirely contained within the solar panels. However, due to the physical limit in the board thickness and the presence of other circuits and electronic components, it is not possible to reach a high value of the magnetic dipole.

Torquerod

This is the most efficient solution. A conductive wire is wrapped around a ferromagnetic core which is magnetized when excited by the coil, thus generating a dipole considerably higher than the other solutions. However, the disadvantage is the presence of a residual magnetic dipole that remains even when the coil is turned off because of the hysteresis in the magnetization curve of the core. It is therefore necessary to demagnetize the core with a proper demagnetizing procedure. Normally, the presence of the core (generally consisting of heavy metal) increases the mass of the system.

Typically three coils are used, although reduced configurations of two or even one magnet can suffice where full attitude control is not needed or external forces like asymmetric drag allow underactuated control. The three coil assembly usually takes the form of three perpendicular coils, because this setup equalizes the rotational symmetry of the fields which can be generated; no matter how the external field and the craft are placed with respect to each other, approximately the same torque can always be generated simply by using different amounts of current on the three different coils.

As long as current is passing through the coils and the spacecraft has not yet been stabilized in a fixed orientation with respect to the external field, the craft's spinning will continue.

Very small satellites may use permanent magnets instead of coils.

Advantages

Magnetorquers are lightweight, reliable, and energy-efficient. Unlike thrusters, they do not require expendable propellant either, so they could in theory work indefinitely as long as sufficient power is available to match the resistive load of the coils. In Earth orbit, sunlight is one such practically inexhaustible energy source, using solar panels.

A further advantage over momentum wheels and control moment gyroscopes is the absence of moving parts and therefore significantly higher reliability.

Disadvantages

The main disadvantage of magnetorquers is that very high magnetic flux densities are needed if large craft have to be turned very fast. This either necessitates a very high current in the coils, or much higher ambient flux densities than are available in Earth orbit. Consequently, the torques provided are very limited and only serve to accelerate or decelerate the change in a spacecraft's attitude by minute amounts. Over time active control can produce very fast spinning even here, but for accurate attitude control and stabilization the torques provided often aren't enough. To overcome this, magnetorquer are often combined with reaction wheels.

A broader disadvantage is the dependence on Earth's magnetic field strength, making this approach unsuitable for deep space missions, and also more suitable for low Earth orbits as opposed to higher ones like the geosynchronous. The dependence on the highly variable intensity of Earth's magnetic field is also problematic because then the attitude control problem becomes highly nonlinear. It is also impossible to control attitude in all three axes even if the full three coils are used, because the torque can be generated only perpendicular to the Earth's magnetic field vector.

Any spinning satellite made of a conductive material will lose rotational momentum in Earth's magnetic field due to generation of eddy currents in its body and the corresponding braking force proportional to its spin rate. Aerodynamic friction losses can also play a part. This means that the magnetorquer will have to be continuously operated, and at a power level which is enough to counter the resistive forces present. This is not always possible within the energy constraints of the vessel.

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The Sphere: The Ideal Shape For Space-Craft

Then we should no longer have to economise on every pound of payload, as we do today, when for every pound that a space-craft takes on a journey to the moon, an extra 2,590 lb of fuel is needed. Once that was the case, space-craft would soon be built in a very different shape.

Old texts and archaeological finds around the world have convinced me that the first space-craft that reached the earth many thousands of years ago were spherical, and I am sure that the space-craft of the future will (once again) be spherical.

I am no rocket designer, but there are a couple of reflections that we can all make and which seem completely convincing. A sphere has no 'forward' or 'aft', no 'above' or 'below', no 'right' or 'left'. It offers the same surface in every position and direction. So the sphere is the ideal shape for the cosmos, which also has no 'above' or 'below', no 'forward' or 'aft'.

Let us take a walk round a space sphere that still seems like a science-fiction dream today. But let's not skimp matters. Imagine a sphere with a diameter of 17,000 ft (5 kilometers). This monster stands on sprung, retractable spider legs. Like an ocean liner, the interior is divided into decks of various sizes. Around the belly of the gigantic ball—at its equator—runs a massive ring housing the twenty or more propulsion units that can all be swivelled through 180°—a simple technical feat (if you ignore minor incidentals like the challenge of designing a 180° thrust frame). When the countdown has reached zero, they will radiate concentrated light waves amplified a million-fold. If the cosmic sphere is to rise from the surface of the planet or one of the launching areas stationed in orbit, the propulsion units shoot their columns of light directly down on to the launching pad, giving the sphere a tremendous thrust. Once the sphere has reached the extra-gravitational field and is on its course to a fixed star, the propulsion units around its equator will only be fired now and then for course corrections. There is no risk of the sphere moving out of its flight path in a way that might endanger the crew because it can immediately adapt itself to any situation.

It is important to realise that in this kind of space sphere course corrections in any direction are possible without danger. The propulsion units mounted on the steel girdle round the sphere permit lightning avoiding action or quick turns in any direction. Billiards players will easily catch on to the idea. If a right turn is needed, the sphere gets a light touch from a steering jet mounted on the left and vice-versa (though I hesitate to describe any thrust capable of altering the course of a 5 kilometer diameter mass of titanium as "light touch").

(ed note: then the narrative shifts to crack-pot pseudoscience land, claiming the nebulous possibility of spherical spaceships shows that every single ancient inscription and drawing depicting something vaguely circular is actually proof positive of alien starships from outer space. Yeah, right.)

"Pursuit fighters," I told the Ship. "Easily fast enough to catch one of our boats, if they can do it within their limited range. It's limited because they're the only kind of craft designed for dogfight tactics.

They're just enormous multidirectional motors in a spheroid hull with one pilot in the centre and a few missile tubes scattered between the motor vents. Fast maneuvering in space means killing momentum one way as well as building it up in another, so there's murderous acceleration and deceleration every few seconds, with the motor blasting in all directions, eating up hydrogen and putting incredible stress on the pilots. Even with all the aids — liquid suspension cocoons, special suits, body reinforcement, field-shields, the lot — it takes years of training to stand it for more than a few minutes at a time.

The American call fighter pilots Globetrotters, for some old game where you had to bounce a ball all the time. I've been in a fighter simulator once — I came out black and blue, and they say the real thing's worse.

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Conventional Displays

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     For illustration purposes, a cockpit layout is considered, in which conventional instruments are utilized as a means of meeting the mission, information, display, and control requirements.

     Referring to Fig. 27.4, the following is a description of what the instrument panel might contain.

     Orientation information would be given through an attitude indicator, showing pitch, roll, and yaw. Stabilization of the indicator would be provided by a gyro-stable platform, a horizon scanner, or some other sensor for seeking a vertical. In addition, there would be indicators showing displacement in pitch, roll, and yaw, with rate of displacement shown by a separate instrument centrally located with the displacement gauges.

     Direction would be displayed by an indicator similar to a compass, but indicating direction relative to the reference system being used for azimuth. This may utilize star-tracking inputs, infrared inputs, or magnetic inputs, depending on the area of operation. In addition, there would be a radio compass and distance indicator.

     Altitude would be displayed with a barometric indicator for operation within the atmosphere, a radio altimeter for greater distance, and a radar altimeter for low altitudes. The distance indicators would be used when altitude became miles instead of feet.

     Velocity would be displayed on a Mach airspeed indicator for operation within the atmosphere, and a velocity indicator for space operation, probably using a Doppler input.

     Clocks would be used showing Greenwich time, elapsed time, and time to retrofire.

     Power indicators would display information concerning the power being used, and probably would be calibrated in thrust units.

     Power-plant-condition indicators would be used in accordance with the type of power unit being employed.

     Fuel quantity would also be displayed as a function of the type of fuel being used, and would show fuel remaining and rate of usage.

     Accelerometers would display acceleration about all three axes: laterally, longitudinally, and vertically.

     In addition to these, more or less standard types of display provisions must be made for alignment of the thrust axis, in order to ensure that the resultant trajectory will conform to the equations of space mechanics (i.e., if the engine is pointing the wrong way, the thrust will put the ship off-course). The thrust alignment display would probably be similar to the zero reader or other type of rate-director indicator.

     Radar would consist of both forward- and downward-looking types, for obstacle warning, and as an assist to navigation when operating close to a body such as the earth or other planet. Periscopes would also be used for position information, when operating in close proximity with a body.

     The consoles would probably contain the information relative to environment conditions and control as well as communication equipment. The environment console would contain indicators for cabin pressure, atmospheric content, temperature, noise level, and radiation level. Some type of meteor-hit indicator would also be included. Appropriate controls for maintaining and controlling the environment would be present.

     It is difficult to state what actual communication equipment would be utilized, except that adequate coverage of the available frequency ranges would be necessary, with both transmitter and receiver controls available to the pilot.

     The controls for operation would include a power control on the left and an attitude control on the right. These wold not be manual in the sense of direct linkages as they are in conventional vehicles, but rather would operate as reprogramming devices, in which corrections would be made through the computer (Fly-by-wire was science fiction back in 1961, but is now standard equipment). There will probably be instances where direct manual control is desired, such as rendezvous, reentry, and in some instances, landing, and for emergencies. In this event, the computer would be bypassed by establishing a manual control mode. It is important to emphasize that the command pilot will not be controlling the ship through continuous contact with the controls, as is done in present aircraft, automobiles, and other vehicles (..."present" meaning "1961"). The ship will be under the control of the automatic system, into which changes will be programmed through the computer by these controls, only when a change is required. The pilot will be operating these controls in a conventional manner, only when the ship is in the complete manual mode.

     Referring back to the types of displays shown in Fig. 27.4, it is not essential that the indicators be configured as a round dial. Development in the instrumentation field has resulted in vertical-reading scales, which appear to be more readable and less subject to reading error (Fig. 27.5). Although vertical or tape-like instruments are easier to read, they still only indicate factors, rather than an integrated display. Combination has been attempted in these instruments, which has tended toward clutter.

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Integrated Displays

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     As stated earlier, research and development programs in man-machine relationships have resulted in concepts which appear, from experimental evidence, to provide a more adequate solution to displays and controls for space vehicles. Referring to Fig. 27.6, it can be seen that the cockpits consists primarily of two basic displays.

     A vertical display presents orientation and director information, which may be classified as short-term information. Since the display is integrated, information with regard to pitch, roll, and yaw is inherent in the contact analogue, or background display. Heading, altitude, and velocity, as well as position within the Vn envelope, are indicated by the "flight path." (nowadays we call this an aircraft Head-Up Display or a video game status bar)

     The horizontal display presents situational information or long-term data. Such information as present position, flight path, destination, radius of action, azimuth, "how goes it," and points of interest or obstacles is included in this indicator. Periscope information can also be displayed.

(ed note: in latter years, the Integrated Display concept was used in several computer games:)

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     Both indicators are cathode-ray tubes, which may be conventional type; thin-tube types such as the Kaiser Aiken tube; or, when developed, a solid-state or nonvacuum-type tube (yes, kiddies, they are talking about prehistoric CRT type TV and computer monitors, which were replace by new-fangled solid-state nonvacuum flat-panel displays back in 2005. Some of my younger readers have never even seen a CRT.). The use of cathode-ray tubes permits superimposing of information to create integrated displays. Transparent phosphors can be used, which permit better illumination, because the ambient light being absorbed within the tube instead of being reflected from the phosphor. Tubes using transparent phosphors are readable at levels of 5000 ft-L ambient.

     Side panels are provided for quantitative information such as environmental conditions, power-plant and fuel information (i.e., how close is the gasoline gauge to "empty"?), time, and general vehicle condition. Mode selectors and condition selectors are also provided on these panels, along with controls for actuating the application systems. Communication controls and indicators are also included on the side panels.

     It is important to state that the same sensors required for supplying data to the conventional displays would be utilized in this display. The exception is that the information is relayed to the displays through a central control computer (which means if an evil computer hacker has infected you ship's computer with a virus, the displays could be lying to you).

     The controls for operating the vehicle consist of a power control on the left and an attitude control on the right. The use of these controls is the same as stated in the description of the conventional system. They are essentially reprogramming controls, except when in complete manual mode.

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      At mid-morning, they took seats in the tiny galley and compared notes.
     “Other than a poor taste in coffee and a really bad couch, I didn’t find anything that would keep us from taking the ship out for a spin,” Zoya said. “Did you?”
     Natalya shook her head. She took a sip of coffee and sighed. “The coffee is pretty bad, but that’s an easy fix. The couch is still horrible.”

     Zoya nodded. “What’d you think of the instrumentation?”
     Natalya frowned. “I didn’t notice anything terribly off. The couch was distraction enough.”
     Zoya stood and beckoned Natalya to follow. She stepped into the cockpit and waved Natalya into the couch. “What’s the fuel status?”
     Natalya pulled up the engineering display on the console. “Full,” she said.
     “How do you know?” Zoya asked.
     “Green light on the monitor.”
     “Atmosphere? How’s our gas mix?”
     Natalya flipped to environmental and saw a similar interface. “Another green light.” She frowned. “No data on the actual mix.”
     Zoya nodded. “Just the one green light.”
     “Presumably that means we can breathe but that’s less than helpful.”
     “None of the instrumentation is actually calibrated,” Zoya said. “They’re all idiot lights.”

     Natalya frowned and pulled up potable water. Same problem. She flipped back to engineering and scanned through the various status indicators. “Capacitor charge level. Maneuvering fuel. They’re all like this?”
     Zoya lifted one shoulder in a half shrug. “Every single one that I checked. I think the only display I found with actual numbers on it was the clock.”
     “We’ll need to get that reprogrammed,” Natalya said. “I wouldn’t have noticed until we got underway.”

     “I probably wouldn’t have if I hadn’t run into this same problem at home.”
     Natalya looked up at her. “Barge?”
     “Manchester was working on a ‘less taxing’ pilot interface. It was so ‘less taxing’ that it was useless. Pop-pop (grandfather, i.e., "pop's pop") wasn’t happy with it but accepted it.”
     “I’ll bet this story doesn’t end well.”
     “No bet. The problem was the crossover point between green-for-go and red-for-stop.”
     “What about yellow-for-needs-attention?”
     “They overlooked that part. We discovered it on potable water relatively early and close to station,” Zoya said. “The indicator stayed green as long as there was water in the tank.”
     Natalya winced. “That’s all well and good if you can run next door for a few thousand liters of potable water.”

     Zoya nodded. “Pop-pop made Manchester reprogram the system but they had to replace all the binary sensors before the programming would take.”
     Natalya sighed. “Lemme guess. The correct sensors were cheaper?”
     Zoya tapped an index finger to the tip of her nose. “They tried to bill us for the repair.”
     “Pop-pop wasn’t amused, I take it?”
     “Gram (grandmother) runs the books. She accepted the invoice, paid it, and sent it back with a twenty-five percent service charge on all future metals deliveries to the yard.”
     Natalya pondered that for a few heartbeats. “Merciful Maude, that would have bankrupted them.”
     Zoya nodded. “They refunded the repair payment, tossed in a few crew amenities while they had it in the dock, and Gram dropped the service charge from their bills.”
     “I bet they weren’t happy with that.”
     “They weren’t but they thought they had us over a barrel because they’re the only source for the barges we needed.” Zoya sipped her coffee and grimaced. “They didn’t like it when we just did it back to them. Without our metals, they couldn’t make their ships.”

Predictor Displays

A powerful technique for stabilizing man-machine loops by putting lead information into the display, without removing the human operator from his role as an adaptive controller, is the use of a predictor instrument. A trace extends from the current output or error into the future. The trace representing future output is generated rapidly and repeatedly by use of a fast time model of the controlled element, which has the same initial conditions and control signals as those being applied to the actual controlled element. When used with systems having several integrations or with very slowly responding systems, the predictor display is of great value. It allows the operator to experiment with several different control possibilities off-line before actually applying one to the controlled element.

Preview Displays

Preview displays are related to predictor displays. In most control apphcations involving human operators, some explicit information concerning the input which will reach him in the future is available, and his control actions are based to a great extent on this preview. A view of the road and obstacles ahead or of the runway on which he will be landing is used by the operator in his role as a preview controller. Displays which can incorporate information on future inputs may be presented in a manner analogous to those of predicted future outputs for the predictor display. Models of the human controller, developed for compensatory tracking situations and extendable to pursuit tracking, are clearly inappropriate for the preview situations so common in controlling vehicles with a view of the external surround.

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Last week in reviewing the spinners in Blade Runner, I included mention and a passing critique of the tunnel-in-the-sky display that sits in front of the pilot. While publishing, I realized that I’d seen this a handful of other times in sci-fi, and so I decided to do more focused (read: Internet) research about it. Turns out it’s a real thing, and it’s been studied and refined a lot over the past 60 years, and there are some important details to getting one right.

Though I looked at a lot of sources for this article, I must give a shout-out to Max Mulder of TU Delft. (Hallo, TU Delft!) Mulder’s PhD thesis paper from 1999 on the subject is truly a marvel of research and analysis, and it pulls in one of my favorite nerd topics: Cybernetics. Throughout this post I rely heavily on his paper, and you could go down many worse rabbit holes than cybernetics. n.b., it is not about cyborgs. Per se. Thank you, Max.

I’m going to breeze through the history, issues, and elements from the perspective of sci-fi interfaces, and then return to the three examples in the survey. If you want to go really in depth on the topic (and encounter awesome words like “psychophysics” and “egomotion” in their natural habitat), Mulder’s paper is available online for free from researchgate.net: “Cybernetics of Tunnel-in-the-Sky Displays.”

What the heck is it?

A tunnel-in-the-sky display assists pilots, helping them know where their aircraft is in relation to an ideal flight path. It consists of a set of similar shapes projected out into 3D space, circumscribing the ideal path. The pilot monitors their aircraft’s trajectory through this tunnel, and makes course corrections as they fly to keep themselves near its center.

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Please note that throughout this post, I will spell out the lengthy phrase “tunnel-in-the-sky” because the acronym is pointlessly distracting.

Quick History

In 1973, Volkmar Wilckens was a research engineer and experimental test pilot for the German Research and Testing Institute for Aerospace (now called the German Aerospace Center). He was doing a lot of thinking about flight safety in all-weather conditions, and came up with an idea. In his paper “Improvements In Pilot/Aircraft-Integration by Advanced Contact Analog Displays,” he sort of says, “Hey, it’s hard to put all the information from all the instruments together in your head and use that to fly, especially when you’re stressed out and flying conditions are crap. What if we took that data and rolled it up into a single easy-to-use display?” Figure 6 is his comp of just such a system. It was tested thoroughly in simulators and shown to improve pilot performance by making the key information (attitude, flight-path and position) perceivable rather than readable. It also enabled the pilot greater agency, by not having them just follow rules after instrument readings, but empowering them to navigate multiple variables within parameters to stay on target.

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In Wilckens’ Fig. 6, above, you can see the basics of what would wind up on sci-fi screens decades later: shapes repeated into 3D space ahead of the aircraft to give the pilot a sense of an ideal path through the air. Stay in the tunnel and keep the plane safe.

Mulder notes that the next landmark developments come from the work of Arthur Grunwald & S. J. Merhav between 1976–1978. Their research illustrates the importance of augmenting the display and of including a preview of the aircraft in the display. They called this preview the Flight Path Predictor, or FPS. I’ve also seen it called the birdie in more modern papers, which is a lot more charming. It’s that plus symbol in the Grunwald illustration, below. Later in 1984, Grunwald also showed that a heads-up-display increased precision adhering to a curved path. So, HUDs good.

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I have also seen lots of examples of—but cannot find the research provenance for—tools for helping the pilot stay centered, such as a “ghost” reticle at the center of each frame, or alternately brackets around the FPP, called the Flight Director Box, that the pilot can align to the corners of the frames. (I’ll just reference the brackets. Gestalt be damned!) The value of the birdie combined with the brackets seems very great, so though I can’t cite their inventor, and it wasn’t in Mulder’s thesis, I’ll include them as canon.

The takeaway from the history is really that these displays have a rich and studied history. The pattern has a high confidence.

Elements of an archetypical tunnel-in-the-sky display

There are lots of nuances that have been studied for these displays. Take for example the effect that angling the frames have on pilot banking, and the perfect time offset to nudge pilot behavior closer to ideal banking. For the purposes of sci-fi interfaces, however, we can reduce the critical components of the real world pattern down to four.

1. Square shapes (called frames) extending into the distance that describe an ideal path through space
   1. The frame should be about five times the width of the craft. (The birdie you see below is not proportional and I don’t think it’s standard that they are.)
   2. The distances between frames will change with speed, but be set such that the pilot encounters a new one every three seconds.
   3. The frames should adopt perspective as if they were in the world, being perpendicular to the flight path. They should not face the display.
   4. The frames should tilt, or bank, on curves.
   5. The tunnel only needs to extend so far, about 20 seconds ahead in the flight path. This makes for about 6 frames visible at a time.
2. An aircraft reference symbol or Flight Path Predictor Symbol (FPS, or “birdie”) that predicts where the plane will be when it meets the position of the nearest frame. It can appear off-facing in relation to the cockpit.
   1. These are often rendered as two L shapes turned base-to-base with some space between them. (See one such symbol in the Snow example above.)
   2. Sometimes (and more intuitively, imho) as a circle with short lines extending out the sides and the top. Like a cartoon butt of a plane. (See below.)
3. Contour lines connect matching corners across frames
4. A horizon line

• 

There are of course lots of other bits of information that a pilot needs. Altitude and speed, for example. If you’re feeling ambitious, and want more than those four, there are other details directly related to steering that may help a pilot.

• Degree-of-vertical-deviation indicator at a side edge
• Degree-of-horizontal-deviation indicator at the top edge
• Center-of-frame indicator, such as a reticle, appearing in the upcoming frame
• A path predictor 
• Some sense of objects in the environment: If the display is a heads-up display, this can be a live view. If it is a separate screen, some stylized representation what the pilot would see if the display was superimposed onto their view.
• What the risk is when off path: Just fuel? Passenger comfort? This is most important if that risk is imminent (collision with another craft, mountain) but then we’re starting to get agentive and I said we wouldn’t go there, so *crumbles up paper, tosses it*.

I haven’t seen a study showing efficacy of color and shading and line scale to provide additional cues, but look closely at that comp and you’ll see…

• The background has been level-adjusted to increase contrast with the heads-up display
• A dark outline around the white birdie and brackets to help visually distinguish them from the green lines and the clouds
• A shadow under the birdie and brackets onto the frames and contours as an additional signal of 3D position
• Contour lines diminishing in size as they extend into the distance, adding an additional perspective cue and limiting the amount of contour to the 20 second extents.

• 

What can you play with when designing one in sci-fi?

Everything, of course. Signaling future-ness means extending known patterns, and sci-fi doesn’t answer to usability. Extend for story, extend for spectacle, extend for overwhelmedness. You know your job better than me. But if you want to keep a foot in believability, you should understand the point of each thing as you modify it and try not to lose that.

1. Each frame serves as a mini-game, challenging the pilot to meet its center. Once that frame passes, that game is done and the next one is the new goal. Frames describe the near term. Having corners to the frame shape helps convey banking better. Circles would hide banking.
2. Contour lines, if well designed, help describe the overall path and disambiguate the stack of frames. (As does lighting and shading and careful visual design, see above.) Contour lines convey the shape of the overall path and help guide steering between frames. Kind of like how you’d need to see the whole curve before drifitng your car through one, the contour lines help the pilot plan for the near future. 
3. The birdie and brackets are what a pilot uses to know how close to the center they are. The birdie needs a center point. The brackets need to match the corners of the frame. Without these, it’s easier to drift off center.
4. A horizon line provides feedback for when the plane is banked.

• 

Since I mentioned that each frame acts as a mini-game, a word of caution: Just as you should be skeptical when looking to sci-fi, you should be skeptical when looking to games for their interfaces. The simulator which is most known for accuracy (Microsoft Flight Simulator) doesn’t appear to have a tunnel-in-the-sky display, and other categories of games may not be optimizing for usability as much as just plain fun, with the risk of crashing your virtual craft just being part of the risk. That’s not an acceptable outcome in real-world piloting. So, be cautious considering game interfaces as models for this, either.

So now let’s look at the three examples of sci-fi tunnel-in-the-sky displays in chronological order of release, and see how they fare.

Three examples from sci-fi

So with those ideal components in mind, let’s look back at those three examples in the survey.

• 

• 

Quick aside on the Blade Runner interface: The spike at the top and the bottom of the frame help in straight tunnels to serve as a horizontal degree-of-deviation indicator. It would not help as much in curved tunnels, and is missing a matching vertical degree-of-deviation indicator. Unless that’s handled automatically, like a car on a road, its absence is notable.

• 

Some obvious things we see missing from all of them are the birdie, the box, and the contour lines. Why is this? My guess is that the computational power in the 1976 was not enough to manage those extra lines, and Ridley Scott just went with the frames. Then, once the trope had been established in a blockbuster, designers just kept repeating the trope rather than looking to see how it worked in the real world, or having the time to work through the interaction logic. So let me say:

• Without the birdie and box, the pilot has far too much leeway to make mistakes. And in sci-fi contexts, where the tunnel-in-the-sky display is shown mostly during critical ship maneuvers, their absence is glaring.
• Also the lack of contour lines might not seem as important, since the screens typically aren’t shown for very long, but when they twist in crazy ways they should help signal the difficulty of the task ahead of the pilot very quickly.

Note that sci-fi will almost certainly encounter problems that real-world researchers will not have needed to consider, and so there’s plenty of room for imagination and additional design. Imagine helping a pilot…

• Navigating the weird spacetime around a singularity
• Bouncing close to a supernova while in hyperspace
• Dodging chunks of spaceship, the bodies of your fallen comrades, and rising plasma bombs as you pilot shuttlecraft to safety on the planet below
• AI on the ships that can predict complex flight paths and even modify them in real time, and even assist with it all
• Needing to have the tunnel be occluded by objects visible in a heads up display, such as when a pilot is maneuvering amongst an impossibly-dense asteroid field. 

…to name a few off my head. These things don’t happen in the real world, so would be novel design challenges for the sci-fi interface designer.

The navigation station of the Canterbury didn't dress to impress. The great wall-sized displays Holden had imagined when he'd first volunteered for the navy did exist on capital ships but, even there, more as an artifact of design than need. Ade sat at a pair of screens only slightly larger than a hand terminal, graphs of the efficiency and output of the Canterbury's reactor and engine updating in the corners, raw logs spooling on the right as the systems reported in.

      A few years ago, back when the Constellation Program was still alive, NASA engineers discovered that the Ares I rocket had a crucial flaw, one that could have jeopardized the entire project. They panicked. They plotted. They steeled themselves for the hundreds of millions of dollars it was going to take to make things right.

     And then they found out how to fix it for the cost of an extra value meal.

     The problem facing Ares 1 wasn't a booster malfunction or a computer glitch. It was simple cause-and-effect physics. During the final stages of a launch, as the solid booster rocket burns down it makes the entire vehicle oscillate rapidly. Add that oscillation to the resonant frequency of the large tube that separates the booster and the crew cabin, and you get a crew capsule that vibrates like crazy. When humans are vibrating to that extent, it's impossible for them to read a digital display. If the astronauts can't read, they can't do their jobs. If they can't do their jobs, no more mission.

     To evaluate the extent of the problem, NASA called in its Human Factors Division. They're the ones who study human perception and performance, from very basic research to very applied research. In fact, they were the ones who had done the most recent round of vibration tests: 50 years ago, for the Gemini project, back when displays were analog, steam-actuated dials and gauges instead of the computer screens of today. Cockpits, like everything else, have changed a lot since those days. It was time for some new tests.

     Step one was to set up a chair so it would vibrate purely in an up-down motion (or in-out, if you're lying on your back like an astronaut would be), which is how the launch vehicle was predicted to shake. The vibrational frequency of the rocket would be 12 hertz (on average, but it would fluctuate between 10Hz and 13Hz) so they needed something that could hit that range exactly. Luckily, that technology already existed; the same mechanism that causes your chair to shake in simulation rides at amusement park made for a perfect prototype.

     The engineers also knew that as Ares I gained speed the shake would increase. They calculated that toward the final stage, when astronauts would be already subjected to 4 G's of acceleration, they would be getting an additional 0.7 G's of vibration. As NASA slowly ramped up testing in the chair, they discovered that at 0.7 G's even the largest numbers on the digitized display were almost entirely illegible.

     Houston, we have a major effing problem.

     Plans were drawn up to reduce the vibrations. Spring and counter-firing motors. Hundreds of millions of dollars to implement. Added years of development and implementation. A nearly insurmountable setback.

     And then the people in the Vibration Lab had a really, really good idea: By simply strobing the display in time with the vibration, they could kill this problem altogether. They bought a handful of circuits that only cost a few bucks, hooked them up to the screen, and set it to strobe at 12Hz. And it worked!

     Well, almost.

     The readability was vastly improved, but it wasn't perfect. The chair was vibrating at 12Hz and the screen was strobing at 12Hz, but they weren't perfectly in sync. The text was more visible, sure, but it looked like it was swimming around. NASA could do better. So they grabbed a few accelerometers and attached them to the chair. With the vibration and the strobing now perfectly in sync, the display became crystal clear. And the final cost was a fraction of a fraction of a fraction of what they'd anticipated. Victory.

     If it sounds too simple to actually work, believe me, I felt the same way until I saw it with my own eyes during a recent visit to NASA Ames. My guides were only willing to take me up to 0.5 G's, but even at that rate the smallest column of numbers was completely illegible. As soon as they flipped on strobing? I could see it perfectly. The effect was stunning. We did our best to show the before/after by putting our camera on the sled, but the image-stabilization was just too damn good (well played, Sony. Well played). You'll have to take my word for it.

     Because it was also important to know if the system worked while vibrating and feeling the real, face-melting G-forces that astronauts experience, NASA's big brains have incorporated a similar strobing/vibrating rig into the iconic G-force simulation centrifuge. They wouldn't let me anywhere near that thing without all kinds of medical evaluations. Begging, bribery, and tearful theatrics proved ineffective. Maybe someday.

     NASA has a patent pending on the technology, although the problems it solves are decidedly not NASA-specific; helicopters, planes, and fast-moving boats have similar vibrational issues, so it's very possible we'll see this implemented elsewhere. I just want to sync my TV up to a shiatsu massage chair. Nobody blurs my Beyonce.

     So while the the Ares I rocket has been grounded, there's no question this research will live on and be implemented in NASA's next launch vehicle. It's nice to know that the next generation of astronauts will be able to see what they're doing, and that it didn't cost the tax-payers hundreds of millions of dollars. Good deal.

"Vesta acquisition."

In response to the verbal from the autopilot, Dieter Ulans flipped his datavisor in front of his eyes and prepared to take direct command of the massive ring of lasers and reaction engines that was Hercules. He hit the juicer button and felt the rush as the drugs began to wash into his veins. "Com'mon jockey juice!" he whispered and then began to croon: "All my thoughts of you, you, you — all that I've sought is you, you, you." The tiny green symbols on the datavisor began to zip past his eyes at an increasing speed.

His subconscious easily absorbed and processed the information even as his conscious mind took in the blue numbers and symbols on the main screen that showed the gross situation as Hercules and five other ships of the Martian battlefleet began their final approach to Vesta Main Station. "Joey Kolnichok, I know you're here and I'm going to personally fry your tender little parts." The ship thrummed as the main three o'clock engine cut in and changed vector in response to a movement of Dieter Ulan's right ring finger. It was his former classmate he sought — Josip V. Kolnichok — the one who had beaten him out his bid for a cushy transport command and who had also cast aspersions on his loyalty to the company. This had cost Ulans two points on his profit sharing plan and that was a deficit he intended to make up by turning J.V. Kolnichok and the DesJardin into a bright, glowing gas.

"80-80. Ready track. Ready main. On my mark FC to you and...mark!"

A second green line began streaming across the datavisor as Ulans took control of the main laser fire control systems. Every time he blinked, the little green symbols paused. Every time he squinted his eyelids, a bright blue bullseye magically appeared where he looked on the main screen. Just tap your foot when your buddy shows, he thought, and you'll make him a star. He began to click his teeth together. His finger tips sweated in the close-fitting control caps. Only eighteen k-k's from Vesta and still no Company. What had they done — written the station off? The entire ship reached into his heightened awareness. The awesome engines designed to hurl inert cargo on multi-million-kilometer tracks through space. The heavy mining laser converted into a terrifying main weapon now slung in the cargo grapples. The thousands of bits of information from the ship's computers and sensing radars. Where the hell were they? "Come on, you Company fish, swim out into the pan."

Arms enclosed in the couch, Sandra slipped her fingers into the concealed gloves and touched the key pads, one for each hand. Each pad had five keys, you talked into it by pressing with fingers and thumb in varying patterns. All five at once meant "activate" and "space." You could talk with the left hand, with the right hand, or allegedly with both at once, holding two distinct conversations with the computers. She had yet to meet someone who had been proved to be able to do that.

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She keyed her screen to life. An arm's length in front of her part of the crystal surface darkened and featured reference codes she already knew by heart. She dug deeper into the retrieval routine. The key pad had a symbol pattern for everything, you entered a signal by pressing the appropriate pattern and separated the symbols by releasing pressure from all five keys at once. There were only thirty-one static key patterns, but every pattern above one-key pressure was internally variable. With a two finger pattern you could add two more values by releasing one finger or the other after the initial pressure, signaling the end of the symbol by releasing all keys. With a three finger pattern you could release any single or any pair of keys during the signalling of the symbol. With a four finger pattern you could release one, two, or three keys. With the single five finger pattern plus key releases, one symbol value was expanded into thirty-one. And the permutations went on. Instead of just fingering a full pattern and then releasing, you could release and then restore, release in sequence, or you could build up sequences by adding keys, or by adding and subtracting them. The possibilities went on and on. But the complexity was unnecessary. With static patterns and simple partial releases you arrived at two hundred and six separate signals—more than enough for alphabet, numerals, and a whole repertoire of shortened instruction codes.

Sandra and Shapir talked into their key pads almost as fast as talking with tongues, and never noticed the automatic skill. It was one of those things you learned over the professional years, from teenage initial career area selection to practising and practised ship pilot. It was just something that you could do, like all those other thoughtlessly miraculous accomplishments.

All over the ship — and down on Thalassa — men and women were tapping out messages on the seven buttons of their little one-hand keypads. Perhaps the earliest skill acquired by any child was the ability to touch-type all the necessary combinations without even thinking about them.

A glass cockpit is an aircraft cockpit that features electronic (digital) flight instrument displays, typically large LCD screens, rather than the traditional style of analog dials and gauges. While a traditional cockpit (nicknamed as a "steam cockpit" within aviation circles) relies on numerous mechanical gauges to display information, a glass cockpit uses several displays driven by flight management systems, that can be adjusted (multi-function display) to display flight information as needed. This simplifies aircraft operation and navigation and allows pilots to focus only on the most pertinent information. They are also popular with airline companies as they usually eliminate the need for a flight engineer, saving costs. In recent years the technology has become widely available in small aircraft.

As aircraft displays have modernized, the sensors that feed them have modernized as well. Traditional gyroscopic flight instruments have been replaced by electronic Attitude and Heading Reference Systems (AHRS) and Air Data Computers (ADCs), improving reliability and reducing cost and maintenance. GPS receivers are usually integrated into glass cockpits.

A multi-function display (MFD) (part of multi-function structures) is a small screen (CRT or LCD) in by multiple soft keys (configurable buttons) that can be used to display information to the user in numerous configurable ways. MFDs originated in aviation, first in military aircraft, and later were adopted by commercial aircraft, general aviation (GA), and automotive use.

Often an MFD will be used in concert with a primary flight display, and forms a component of a glass cockpit. MFDs are part of the digital era of modern planes or helicopter. The first MFD were introduced by air forces in the late 1960s and early 1970s; an early example is the F-111D (first ordered in 1967, delivered from 1970–73). The advantage of an MFD over analog display is that an MFD does not consume much space in the cockpit, as data can be presented in multiple pages, rather than always being present at once. For example the cockpit of RAH-66 "Comanche" does not have analog dials or gauges at all. All information is displayed on the MFD pages. The possible MFD pages could differ for every plane, complementing their abilities (in combat).

Many MFDs allow the pilot to display their navigation route, moving map, weather radar, NEXRAD, GPWS, TCAS and airport information all on the same screen.

MFDs were added to the Space Shuttle (as the glass cockpit) starting in 1998 replacing the analog instruments and CRTs. The information being displayed is similar, and the glass cockpit was first flown on the STS-101 mission. Although many corporate business jets had them in years prior, the piston-powered Cirrus SR20 became the first part-23 certified aircraft to be delivered with an MFD in 1999 (and one of the first GA aircraft with a 10" flat-panel screen), followed closely by the Columbia 300 in 2000 and many others in the ensuing years.

In modern automotive technology, MFDs are used in cars to display navigation, entertainment and vehicle status information.

• 

Screen-labeled function keys are a special case of soft key (function keys) where keys are placed near a screen, which provides labels for them. These are today most commonly found in kiosk applications, such as automated teller machines and gas pumps. Screen-label function keys generally date to the late 1960s, and kiosk applications were particularly common in the 1990s and 2000s. Most recently, these keys have found use in point of sale systems; NCR Corporation claims that their DynaKey system "has been proven to reduce training time and cashier errors". An alternative to screen-labeled function keys is buttons (virtual keys) on a touchscreen, where the label is directly pushable. The increased prevalence of touchscreens in the 2000s has led to a decrease in screen-labeled function keys. However, screen-labeled function keys are inexpensive and robust, and provide tactile feedback.

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History

Early examples are found in aviation glass cockpits, such as the Mark II avionics of the F-111D in the late 1960s/early 1970s (first ordered 1967, delivered 1970–73). Hewlett-Packard developed them for use in computers/calculators in the 1970s.

I saw your exchange with David Hinerman about the test switch and started thinking about how modern cockpits differ from Apollo-era ones.

The most obvious thing is that the "burnt-out bulb" problem is likely much less common, since using solid-state indicators (read: LEDs) is cheaper, easier, more reliable and draws a lot less power. So maybe there would still be a test mode to check them, but it would happen a lot less frequently.

Similar to bulbs vs. LEDs, what used to be mechanical may be replaced with displays ("glass cockpit"). I (think) the qualification here is strong: there is something to be said for diversity, and having both mechanical and electronic indicators may be worth the instrument panel real estate used. This of course depends on how fragile the specific mechanical instruments are and how reliable the sensor inputs for the on-display indicators can be made.

Right after the passive indicators, the next question is the reliability of inputs (beyond the major controls of yaw/pitch/roll and throttle). Mechanical buttons and switches break, throw sparks and can be bumped by accident unless protected from such (making the system more fragile). Touch-screens have precision problems and are close to impossible to use when the user can't see for some reason. They need power beyond the signal/sensor lines they use. Failure of one display can make a whole slew of actions (and data) inaccessible if there is no redundancy.

Plus, their advantage of not being easily bumped by accident may work against them: if the user wears "unexpected" gloves, they may not work at all, necessitating a stylus (which obviously will be nowhere to be found in an emergency). And then there's the question if such a display can half-fail in a way that makes it represent information wrongly; beyond dead/hot pixels but short of completely garbled. Maybe there would be a test mode that shows an easily-checked test pattern?

Looking at modern airliners (or the slightly less modern Space Shuttle cockpit), there usually are prominent displays, usually at least two (but as far as I can tell, never more than three in the main field of vision) that can be configured and interacted with by buttons on their edges ("screen-labeled function keys"). I have yet to see a touch-screen interface in a potentially mission-critical capacity. Beside these screens (sometimes literally) are "classic" instruments, like altimeters, speed indicators and artificial horizons, making for both information flow redundancy and failure resilience.

Long story short: I think some of the "must-haves" of Apollo-era control panels are on the way out, but a lot of the same concerns and requirements are still there and thus things like the test-button for dead-bulb-diagnosis may go away, but will have spiritual successors.

• 

• 

What is happening in your brain as you are scrolling through this page? In other words, which areas of your brain are active, which neurons are talking to which others, and what signals are they sending to your muscles?

Mapping neural activity to corresponding behaviors is a major goal for neuroscientists developing brain–machine interfaces (BMIs): devices that read and interpret brain activity and transmit instructions to a computer or machine. Though this may seem like science fiction, existing BMIs can, for example, connect a paralyzed person with a robotic arm; the device interprets the person's neural activity and intentions and moves the robotic arm correspondingly.

A major limitation for the development of BMIs is that the devices require invasive brain surgery to read out neural activity. But now, a collaboration at Caltech has developed a new type of minimally invasive BMI to read out brain activity corresponding to the planning of movement. Using functional ultrasound (fUS) technology, it can accurately map brain activity from precise regions deep within the brain at a resolution of 100 micrometers (the size of a single neuron is approximately 10 micrometers).

The new fUS technology is a major step in creating less invasive, yet still highly capable, BMIs.

"Invasive forms of brain–machine interfaces can already give movement back to those who have lost it due to neurological injury or disease," says Sumner Norman, postdoctoral fellow in the Andersen lab and co-first author on the new study. "Unfortunately, only a select few with the most severe paralysis are eligible and willing to have electrodes implanted into their brain. Functional ultrasound is an incredibly exciting new method to record detailed brain activity without damaging brain tissue. We pushed the limits of ultrasound neuroimaging and were thrilled that it could predict movement. What's most exciting is that fUS is a young technique with huge potential—this is just our first step in bringing high performance, less invasive BMI to more people."

The new study is a collaboration between the laboratories of Richard Andersen, James G. Boswell Professor of Neuroscience and Leadership Chair and director of the Tianqiao and Chrissy Chen Brain–Machine Interface Center in the Tianqiao and Chrissy Chen Institute for Neuroscience at Caltech; and of Mikhail Shapiro, professor of chemical engineering and Heritage Medical Research Institute Investigator. Shapiro is an affiliated faculty member with the Chen Institute.

A paper describing the work appears in the journal Neuron on March 22.

In general, all tools for measuring brain activity have drawbacks. Implanted electrodes (electrophysiology) can very precisely measure activity on the level of single neurons, but, of course, require the implantation of those electrodes into the brain. Non-invasive techniques like functional magnetic resonance imaging (fMRI) can image the entire brain but require bulky and expensive machinery. Electroencephalography (EEGs) does not require surgery but can only measure activity at low spatial resolution.

Ultrasound works by emitting pulses of high frequency sound and measuring how those sound vibrations echo throughout a substance, such as various tissues of the human body. Sound travels at different speeds through these tissue types and reflects at the boundaries between them. This technique is commonly used to take images of a fetus in utero, and for other diagnostic imaging.

Ultrasound can also "hear" the internal motion of organs. For example, red blood cells, like a passing ambulance, will increase in pitch as they approach the source of the ultrasound waves, and decrease as they flow away. Measuring this phenomenon allowed the researchers to record tiny changes in the brain's blood flow down to 100 micrometers (on the scale of the width of a human hair).

"When a part of the brain becomes more active, there's an increase in blood flow to the area. A key question in this work was: If we have a technique like functional ultrasound that gives us high-resolution images of the brain's blood flow dynamics in space and over time, is there enough information from that imaging to decode something useful about behavior?" Shapiro says. "The answer is yes. This technique produced detailed images of the dynamics of neural signals in our target region that could not be seen with other non-invasive techniques like fMRI. We produced a level of detail approaching electrophysiology, but with a far less invasive procedure."

The collaboration began when Shapiro invited Mickael Tanter, a pioneer in functional ultrasound and director of Physics for Medicine Paris (ESPCI Paris Sciences et Lettres University, Inserm, CNRS), to give a seminar at Caltech in 2015. Vasileios Christopoulos, a former Andersen lab postdoctoral scholar (now an assistant professor at UC Riverside), attended the talk and proposed a collaboration. Shapiro, Andersen, and Tanter then received an NIH BRAIN Initiative grant to pursue the research. The work at Caltech was led by Norman, former Shapiro lab postdoctoral fellow David Maresca (now assistant professor at Delft University of Technology), and Christopoulos. Along with Norman, Maresca and Christopoulos are co-first authors on the new study.

The technology was developed with the aid of non-human primates, who were taught to do simple tasks that involved moving their eyes or arms in certain directions when presented with certain cues. As the primates completed the tasks, the fUS measured brain activity in the posterior parietal cortex (PPC), a region of the brain involved in planning movement. The Andersen lab has studied the PPC for decades and has previously created maps of brain activity in the region using electrophysiology. To validate the accuracy of fUS, the researchers compared brain imaging activity from fUS to previously obtained detailed electrophysiology data.

Next, through the support of the T&C Chen Brain–Machine Interface Center at Caltech, the team aimed to see if the activity-dependent changes in the fUS images could be used to decode the intentions of the non-human primate, even before it initiated a movement. The ultrasound imaging data and the corresponding tasks were then processed by a machine-learning algorithm, which learned what patterns of brain activity correlated with which tasks. Once the algorithm was trained, it was presented with ultrasound data collected in real time from the non-human primates.

The algorithm predicted, within a few seconds, what behavior the non-human primate was going to carry out (eye movement or reach), direction of the movement (left or right), and when they planned to make the movement.

"The first milestone was to show that ultrasound could capture brain signals related to the thought of planning a physical movement," says Maresca, who has expertise in ultrasound imaging. "Functional ultrasound imaging manages to record these signals with 10 times more sensitivity and better resolution than functional MRI. This finding is at the core of the success of brain–machine interfacing based on functional ultrasound."

"Current high-resolution brain–machine interfaces use electrode arrays that require brain surgery, which includes opening the dura, the strong fibrous membrane between the skull and the brain, and implanting the electrodes directly into the brain. But ultrasound signals can pass through the dura and brain non-invasively. Only a small, ultrasound-transparent window needs to be implanted in the skull; this surgery is significantly less invasive than that required for implanting electrodes," says Andersen. (Obviously this is less invasive than cutting the dura and implanting electrodes, but cutting a hole in the skull is a long way away from being non-invasive)

Though this research was carried out in non-human primates, a collaboration is in the works with Dr. Charles Liu, a neurosurgeon at USC, to study the technology with human volunteers who, because of traumatic brain injuries, have had a piece of skull removed. Because ultrasound waves can pass unaffected through these "acoustic windows," it will be possible to study how well functional ultrasound can measure and decode brain activity in these individuals.

The paper is titled "Single-trial decoding of movement intentions using functional ultrasound neuroimaging." Additional co-authors are Caltech graduate student Whitney Griggs and Charlie Demene of Paris Sciences et Lettres University and INSERM Technology Research Accelerator in Biomedical Ultrasound in Paris, France. Funding was provided by a Della Martin Postdoctoral Fellowship, a Human Frontiers Science Program Cross-Disciplinary Postdoctoral Fellowship, the UCLA–Caltech Medical Science Training Program, the National Institutes of Health BRAIN Initiative, the Tianqiao and Chrissy Chen Brain–Machine Interface Center, the Boswell Foundation, and the Heritage Medical Research Institute.

• 

Fearon praised android industriousness at length. Watchman fretted. No work was getting done while they were up here—he didn’t dare let blocks be hoisted with visitors in the construction zone. And he had schedules to keep. To his relief, Krug soon signaled for a descent; the rising wind, it seemed, was bothering Quenelle.

When they came down Watchman led the way over to the master control center, inviting them to watch him take command of operations. He slipped into the linkup seat. As he pushed the computer’s snub-tipped terminal node into the input jack on his left forearm the android saw Leon Spaulding’s lips tighten in a scowl of—what? Contempt, envy, patronizing scorn? For all his skill with humans, Watchman could not read such dark looks with true precision. But then, at the click of contact, the computer impulses came flooding across the interface into his brain and he forgot about Spaulding.

It was like having a thousand eyes. He saw everything going on at the site and for many kilometers around the site. He was in total communion with the computer, making use of all of its sensors, scanners and terminals. Why go through the tedious routine of talking to a computer when it was possible to design an android capable of becoming part of one?

The data torrent brought a surge of ecstasy.

Maintenance charts. Work-flow syntheses. Labor coordination systems. Refrigeration levels. Power-shunt decisions. The tower was a tapestry of infinite detail and he was the master weaver. Everything rushed through him; he approved, rejected, altered, canceled. Was sex something like this? (Watchman is an android, they have no sexual organs) That tingle of aliveness in every nerve, that sense of being extended to one’s limits, of absorbing an avalanche of stimuli? Watchman wished he knew. He raised and lowered scooprods, requisitioned next week’s blocks, ordered filaments for the tachyon-beam men, looked after tomorrow’s meals, ran a constant stability check on the structure as completed, fed cost data to Krug’s financial people, monitored soil temperature in fifty-centimeter gradations to a depth of two kilometers, relayed scores of telephone messages per second and congratulated himself on the dexterity with which he accomplished everything. No human could handle this, he knew, even if there were some way for humans to jack themselves directly into a computer. He had a machine’s skills and a human's versatility and therefore, except for the fairly serious matter of being unable to reproduce himself, he was in many ways superior to both other classes and therefore—

The red arrow of an alarm cut across his consciousness.

Construction accident. Android blood spilling on the frozen ground.

A twitch of his mind gave him close focus. A scooprod had failed on the northern face, A glass block had fallen from the ninety-meter level. It lay slightly skewed, one end buried about a meter deep in the earth, the other slightly above ground level. A fissure ran like a line of frost through its clear depths. Legs stuck out from the side closest to the tower. A few meters away lay an injured android, writhing desperately. Three lift-beetles were scurrying toward the scene of the accident; a fourth had already arrived and had its steel prongs under the massive block.

Watchman unjacked himself. He shivered in the first moment of the pain of separation from the data flow.

      Jane made a dismissive noise with her mouth. She and Wilmarth had met each other on the old HMSS Audacious, he as a midshipman and she as a Reserve ensign on her first cruise. Though in different departments (his was engineering), they had gravitated together, partly because they were both North Americans, albeit from different dominions—Carolina in her case, Oregon in his. “Well,” she said, “I certainly hadn’t expected to see you here.”

     “I did expect to see you—I’d heard who’d been assigned to be our new helmsman. No surprise, considering …” Wilmarth gave a gesture vaguely indicating Jane’s head.
     What he meant went unspoken. It was one of the reasons she still outranked him, even though he was regular Royal Space Navy and she was RSNR (Royal Space Navy Reserve).

     Direct neural interfacing had never lived up to the more extravagant predictions, largely because very few humans had the ability to use it without suffering a terrifying descent into psychosis. But a small percentage possessed, for reasons that still baffled cyberneticists and neurologists alike, the ability to mind-link with a computer with only a brief and relatively mild initial disorientation. Even for this minority, DNI hardly possessed the near-magical properties claimed for it by its early enthusiasts. It did, however, greatly enhance the speed and precision with which computerized controls could be used—such as a starship’s controls.

     It was only by coincidence that interface talent and the attributes required of a military officer occurred in the same person. When they did, such personnel were extremely valuable … and Jane Grenville was one. The helmsman’s station was fitted for manual control, of course, but it also had an interface jack. It helped account for the fact that the piloting of the mighty Resolute was being entrusted to a reservist. Sometimes pragmatism trumped snobbery.

     Jane sat in the helmsman’s chair, her head capped with a neural-induction helmet connected by cable to the interface jack of the ship’s barely subsentient brain. (A cranial implant by which the jack could be plugged directly to the brain was perfectly possible. But that Just Wasn’t Done.) She had, by now, gotten past the initial unpleasantness of direct neural interfacing, and was reflecting that it was worth it to feel the titanic ship and its sensor array as an extension of her own body and senses.
     “Bernheim Drive engaged, Captain,” Jane reported, unnecessarily but as per custom. She raised the helmet into its housing in the overhead, and her immediate physical surroundings came back into sharp focus as her senses contracted to those of her body. “On course as plotted.”

• 

The multitude of sensory information received by the Star King Ship Yale from without was fed into the computer which digested it and relayed the result via the headgear designed by Caesar Smith directly into the brain of British descended, professorial George Bronson, who was at that moment brushing his stubby moustache and puffing on a pipe that burned tobacco that had never seen the soil of Earth, while walking among the stainless steel artificial wombs that housed his experiments.

Bronson was a short, graying individual with a tendency to lecture. Inside the ship he knew the condition of each and every element, transistor and fuel cell; the air pressure in every compartment; how efficiently machinery—including even the watch on his wrist—was working, and approximately when replacements and/or repairs would have to be made. In a score of labs, experiments were being carried out by automatic equipment.

He knew the results of each experiment as soon as it occurred, without consulting one meter, dial, or other data receiving device; he also knew the age, overall temperature, abnormalities, measurements, gene history and present general health of each of the thirty embryos at that exact moment as they floated within their vats.

In addition, if anything of a hostile nature were detected, he could locate, track and fire a whole arsenal of weapons that ranged from recoilless guns shooting explosive steel slugs the size of an ear of corn to the deadly hellfire of the pure energy blasters, again without consulting any controls, instrument banks or pushing any button, switches or toggles except those that were in his mind in the form of the Caesar Smith—shortened by the normal evolution of human language to C-S—headgear.

---

There were no controls, no gauges, dials, lights, switches, buttons or levers; the C-S headgear had done away with that. The Star Kings now lived in a symbiotic relationship with their computers and their ships.

They sat in the deep chairs, watching the splendor of the Universe unfold on the master forward view screen. Bronson had hooked his visitor into the Yale's computer with his C-S headgear and so their talk progressed much faster than it would have if they had used their vocal cords. The headgear connected both to the computer, which in turn linked both brains together and permitted a limited form of telepathy. In addition, any desired information the computer possessed on any subject they were discussing appeared immediately in the mind of each.

---

The C-S headgear rested lightly on Deal, almost an extension of his own body. He seemed to hear the distant chittering of myriad tiny insects as the cells of the headgear compared stimuli from the drifting life craft. He smiled to himself as the origin of the little craft was traced through its cellular history, down to the very origin of the mineral ores.

At the same time, the infinitely complex structure contained within the headgear was examining the woman's every thought and action, comparing them against the master file of human impressions from the living, and when no analogue was found there, against the vastly more complex file of the past.

• 

New effort aims for fully implantable devices able to connect with up to one million neurons

A new DARPA program aims to develop an implantable neural interface able to provide unprecedented signal resolution and data-transfer bandwidth between the human brain and the digital world. The interface would serve as a translator, converting between the electrochemical language used by neurons in the brain and the ones and zeros that constitute the language of information technology. The goal is to achieve this communications link in a biocompatible device no larger than one cubic centimeter in size, roughly the volume of two nickels stacked back to back.

The program, Neural Engineering System Design (NESD), stands to dramatically enhance research capabilities in neurotechnology and provide a foundation for new therapies.

“Today’s best brain-computer interface systems are like two supercomputers trying to talk to each other using an old 300-baud modem,” said Phillip Alvelda, the NESD program manager. “Imagine what will become possible when we upgrade our tools to really open the channel between the human brain and modern electronics.”

Among the program’s potential applications are devices that could compensate for deficits in sight or hearing by feeding digital auditory or visual information into the brain at a resolution and experiential quality far higher than is possible with current technology.

Neural interfaces currently approved for human use squeeze a tremendous amount of information through just 100 channels, with each channel aggregating signals from tens of thousands of neurons at a time. The result is noisy and imprecise. In contrast, the NESD program aims to develop systems that can communicate clearly and individually with any of up to one million neurons in a given region of the brain.

Achieving the program’s ambitious goals and ensuring that the envisioned devices will have the potential to be practical outside of a research setting will require integrated breakthroughs across numerous disciplines including neuroscience, synthetic biology, low-power electronics, photonics, medical device packaging and manufacturing, systems engineering, and clinical testing. In addition to the program’s hardware challenges, NESD researchers will be required to develop advanced mathematical and neuro-computation techniques to first transcode high-definition sensory information between electronic and cortical neuron representations and then compress and represent those data with minimal loss of fidelity and functionality.

To accelerate that integrative process, the NESD program aims to recruit a diverse roster of leading industry stakeholders willing to offer state-of-the-art prototyping and manufacturing services and intellectual property to NESD researchers on a pre-competitive basis. In later phases of the program, these partners could help transition the resulting technologies into research and commercial application spaces.

DARPA anticipates investing up to $60 million in the NESD program over four years.

• 

(ed note: this is the eponymous "Monsters from the ID" problem. The alien Krell had created a titanic thought-controlled machine capable of creating and projecting matter to any place on the surface of Altair IV)

      Dr. Morbius: In times long past, this planet was the home of a mighty, noble race of beings who called themselves the Krell. Ethically and technologically they were a million years ahead of humankind, for in unlocking the mysteries of nature they had conquered even their baser selves, and when in the course of eons they had abolished sickness and insanity, crime and all injustice, they turned, still in high benevolence, upwards towards space. Then, having reached the heights, this all-but-divine race perished in a single night, and nothing was preserved above ground.

---

     Doc Ostrow: Morbius was too close to the problem. The Krell had completed their project. Big machine. No instrumentalities. True creation.
     Commander Adams: Come on, Doc, let's have it.
     Doc Ostrow: But the Krell forgot one thing.
     Commander Adams: Yes, what?
     Doc Ostrow: Monsters, John. Monsters from the Id.
     Commander Adams: The Id? What's that? Talk, Doc!

     [Doc slumps and dies]

     Commander Adams: What is the Id?
     Dr. Morbius: [frustrated] Id, Id, Id, Id, Id! [calming down] It's a... It's an obsolete term. I'm afraid once used to describe the elementary basis of the subconscious mind.
     Commander Adams: [to himself] Monsters from the Id...
     Dr. Morbius: Huh?
     Commander Adams: Monsters from the subconscious. Of course. That's what Doc meant. Morbius. The big machine, 8,000 miles of klystron relays, enough power for a whole population of creative geniuses, operated by remote control. Morbius, operated by the electromagnetic impulses of individual Krell brains.
     Dr. Morbius: To what purpose?
     Commander Adams: In return, that ultimate machine would instantaneously project solid matter to any point on the planet, In any shape or color they might imagine. For any purpose, Morbius! Creation by mere thought.
     Dr. Morbius: Why haven't I seen this all along?

     Commander Adams: But like you, the Krell forgot one deadly danger — their own subconscious hate and lust for destruction.
     Dr. Morbius: The beast. The mindless primitive! Even the Krell must have evolved from that beginning.
     Commander Adams: And so those mindless beasts of the subconscious had access to a machine that could never be shut down. The secret devil of every soul on the planet all set free at once to loot and maim. And take revenge, Morbius, and kill!

     Dr. Morbius: My poor Krell. After a million years of shining sanity, they could hardly have understood what power was destroying them. [pause] Yes, young man, all very convincing, but for one obvious fallacy. The last Krell died 2,000 centuries ago. But today, as we all know, there is still at large on this planet a living monster.
     Commander Adams: Your mind refuses to face the conclusion.
     Dr. Morbius: What do you mean?

(ed note: Dr. Morbius is unaware that it is his own Id that has created the living monster still at large, unconsiously sending it to slay any man who looks lustfully at Morbius' beautiful nubile daughter.)

• 

(ed note: The protagonist is using the psionic power of psychometry to uncover the history of a non-human race called the Old Ones, who lived for millions of years on Terra and who created the human race to be slaves. But the Old Ones all perished in a single month, in an event called the Night of the Monsters. You guessed it, the old Monsters from the ID problem strikes again.

A few of the human slaves survived, the greatest of which was K'Tholo. "C'thulhu", get it? )

      In spite of their crudity, their underground cities were the greatest achievement that has ever appeared on the earth. It is impossible for a human being to grasp the discipline that went into creating them; the task of engraving the Lord’s Prayer on a pinhead is nothing compared to it. The Old Ones had no reason to be jealous of the civilisation of human beings, for their own efforts were god-like. They deserved to become lords of the solar system.
     And then what happened? I already knew the answer to this question, even before I turned my attention to the ‘night of the monsters’. They advanced too quickly – even though the building of their city took them ten thousand years. They actually learned to record their knowledge in books – great stone tablets held together by indestructible metal bands: iron compressed so tight that a cubic inch weighed a ton. They explored the mechanical secrets of this world of dead matter, and learned to use its laws for their own benefit. They made the amazing discovery that matter does not need to be coerced by brute force, that once its laws are understood, it becomes compliant and obedient.
     And so the next step was obvious: to learn all the laws of the universe, to become super-scientists.
     And there came their downfall. They had overlooked one absurd point. As the conscious mind learned to project its visions of reason and order, the vast energies of the subconscious writhed in their prison, and projected visions of chaos.
     At first, no one understood what was happening. One day, a tremendous explosion rocked the city. The building housing the central library was completely destroyed. At first they were inclined to believe that some strange hostile agency – perhaps beings from another planet – was at work. Gradually, it dawned on them that one of their own number had done this. And everyone was gripped with a tremendous sense of shock. For they suddenly realised the consequences of their evolution into separateness. In their early days of ‘unity’, this would have been impossible.
     What was worse, twenty of the Old Ones had been destroyed in the explosion of the library, hurled back into non-existence. In their earlier days they had been indestructible. Now they could be killed. A deep and terrible doubt possessed them. Had it all been a mistake? The road of evolution had seemed long and straight. Suddenly, it looked like a trap.
     And who had destroyed the library? Every one of them opened his mind to the examination of the others. And every one was innocent. And then they began to understand. Whoever had done it was totally unaware that he had done it. Some monster from the subconscious mind had taken advantage of his sleep – for the Old Ones now slept after long periods of concentration – to strike this blow for chaos.
     As I watched all this, I saw the solution. They were simply trying to evolve too fast. It was like trying to train a wolf to become a sheep dog. It was not an impossible task, but it needed to be done with great deliberation. They were rushing it. All they needed to do was to slow down, perhaps even to retreat a step or two. Even K’tholo could have told them this, if they had explained the situation to him. But they were terrified; it seemed that an abyss had opened underneath them, and they shrank back. And the Night of the Monsters began.
     It was not an ordinary night of twelve hours or so. It went on for several weeks, and it spread to all of their cities. When K’tholo spoke later of the Night of the Monsters, he meant the blackness of their underground cities.
     The outrages became more frequent – the great walls defaced, whole areas destroyed. As the fear increased, so did the sense of claustrophobia; and the unconscious desire to destroy everything and start afresh increased. A few of them even understood this, and killed themselves rather than endanger all they had created. But it made no difference.
     And then, like a dam bursting, it happened. Monstrous forces ripped the cities apart. Sometimes they had forms – the form of nightmares – monstrous red things, hundreds of feet high, with faces like human beings, great white worms, a vortex in the shape of an octopus into which things vanished without leaving a trace. Total madness reigned. The surface of the earth was convulsed. All Mu would have been destroyed if it had not been for K’tholo, who used all his powers to set up immense counter-forces to protect the continent. During the Night of the Monsters, K’tholo remained the only sane man on the surface of the earth, observing the fall of his Masters, determined that human beings should not share in that fall. He watched the Old Ones disintegrate under the terror and slip into non-existence. He saw some of them become insane from the effort of trying to break down the barriers between the conscious mind and the forces that were destroying them. He saw the destruction of Haidan Kolas, struck by a shock wave that crumpled the ground like a sheet of paper, and then spilled its fragments into a great void. (This was the immense chasm that opened up down the western side of Mu.) He expected his own destruction from minute to minute – for he was surely a symbol of the subconscious fears of the Old Ones?
     And then, quite abruptly, there was silence. At first, he thought they had all been destroyed. Then he understood. They had taken the only possible course to preserve some fragment of their achievement. Just as a great fire may be prevented from spreading by destroying everything that lies in its path, so this madness had been prevented from spreading by a form of self-destruction. What the Old Ones had done was the equivalent of knocking themselves out. They did this simply by allowing an uncontrolled explosion of the psychic energy they had learned to control – an explosion within the mind. They were hurled back into unconsciousness – but not into death.
     The convulsions of the earth gradually ceased. The winds dropped; the sea became a great mirror reflecting the sunlight. And K’tholo looked at the broken ruins of the civilisation of Mu, and the few thousand survivors, still half insane with fear, and knew that he had won.
     The Old Ones would awaken one day. Meanwhile, he would keep the faith. He kept it for half a million years . . .

• 

"Here's the dining room," Seaton said briskly. "And here's the headset you put on to order dinner or whatever is appropriate to the culinary department. You will observe that the kitchen of this house is purely ornamental—never to be used unless you want to."

"Just a minute, Dick," Dorothy's voice was tensely serious. "I have been really scared ever since you told me about the power of that Brain, and the more you tell me of it the worse scared I get. Think of the awful damage a wild, chance thought would do—and the more an ordinary mortal tries to avoid any thought the surer he is to think it, you know that. Really, I'm not ready for that yet, dear—I'd much rather not go near that headset."

"I know, sweetheart," his arm tightened around her. "But you didn't let me finish. These sets around the house control forces which are capable of nothing except duties pertaining to the part of the house in which they are. This dining-room outfit, for instance, is exactly the same as the Norlaminian one you used so much, except that it is much simpler.

"Instead of using a lot of keyboards and force-tubes, you simply think into that helmet what you want for dinner and it appears. Think that you want the table cleared and it is cleared—dishes and all simply vanish. Think of anything else you want done around this room and it's done—that's all there is to it.

"To relieve your mind I'll explain some more. Mart and I both realized that that Brain could very easily become the most terrible, the most frightfully destructive thing that the universe has ever seen. Therefore, with two exceptions, every controller on this planetoid is of a strictly limited type. Of the two master controls, which are unlimited and very highly reactive, one responds only to Crane's thoughts, the other only to mine. As soon as we get some loose time we are going to build a couple of auxiliaries, with automatic stops against stray thoughts, to break you girls in on—we know as well as you do, Red-Top, that you haven't had enough practice yet to take an unlimited control."

• 

      Eventually Clifford found himself sitting before the operator’s console in one of the cubicles adjacent to the machine room while an instructor adjusted the lightweight skull-harness around his head for the first time. For about a half-hour they went through the routine of calibrating the machine to Clifford’s brain patterns, and then the instructor keyed in a command string and sat back in his chair.

     “Okay,” the instructor pronounced. “It’s live now. All yours, Brad.”

     An eerie sensation instantly seemed to take possession of his mind, as if a bottomless chasm had suddenly opened up beside it to leave it perched precariously on the brink. He had once stood in the center of the parabolic dish of a large radio telescope and had never forgotten the experience of being able to shout at the top of his voice and hear only a whisper as the sound was reflected away. Now he was experiencing the same kind of feeling, but this time it was his thoughts that were being snatched away.

     And then chaos came tumbling back in the opposite direction — numbers, shapes, patterns, colors — twisting, bending, whirling, merging…growing, shrinking…lines, curves…His mind plunged into the whirlpool of thought kaleidoscoping inside his head. And suddenly it was gone.

     He looked around and blinked. Bob, the Navy instructor, was watching him and grinning.
     “It’s okay; I just switched it off,” he said. “That blow your mind?”
     “You knew that would happen,” Clifford said after he had collected himself again. “What was it all about?”

     “Everybody gets that the first time,” Bob told him. “It was only a couple of seconds…gives you an idea of the way it works, though. See, the BIAC acts like a gigantic feedback system for mental processes, only it amplifies them round the loop. It will pick up vague ideas that are flickering around in your head, extrapolate them into precisely defined and quantitive interpretations, and throw them straight back at you. “If you’re not ready for it and you give it some junk, you get back superjunk; before you know it, the BIAC’s picked that up out of your head too, processed it the same way, and come back with super-superjunk. You get a huge positive feedback effect that builds up in no time at all. BIAC people call it a ‘garbage loop.’”

     “That’s all very well,” Clifford said. “But what the hell do I do about it?”

     “Learn to concentrate and to continue concentrating,” Bob told him. “It’s the stray, undisciplined thoughts that trigger it…the kinds of thing that run around in your head when you’ve got nothing in particular to focus on. Those are the things you have to learn to suppress.”

• 

      "But," Zezdon Afthen asked, "while you men of Earth work on this problem, what is there for us? We have no problems, save the problem of the fate of our world, still fifty thousand years of your time in the future. It is terrible to wait, wait, wait and think of what may be happening in that other time. Is there nothing we can do to help? I know our hopeless ignorance of your science. Stel Felso Theu can scarcely understand the thoughts you use, and I can scarcely understand his explanations! I cannot help you there, with your calculations, but is there nothing I can do?"

     "There is, Ortolian, decidedly. We badly need your help, and as Stel Felso Theu cannot aid us here as much as he can by working with you, I will ask him to do so. I want your knowledge of psycho-mechanical devices to help us. Will you make a machine controlled by mental impulses? I want to see such a system and know how it is done that I may control machines by such a system."

     "Gladly. It will take time, for I am not the expert worker that you are, and I must make many pieces of apparatus, but I will do what I can," exclaimed Zezdon Afthen eagerly.

     So, while Arcot and his group continued their work of determining the constants of the space-energy field, the others were working on the mental control apparatus.

---

     "These are all coordinated under the new mental relay control. Some of you will doubt this last, but think of it under this light. Will, thought, concentration—they are efforts, they require energy. Then they can exert energy! That is the key to the whole thing.
     "But now for the demonstration."

     Arcot looked toward Morey, who stood off to one side. There was a heavy thud as Morey pushed a small button. The relay had closed. Arcot's mind was now connected with the controls.

     A globe of cloudiness appeared. It increased in density, and was a solid, opalescent sphere.
     "There is a sphere, a foot in diameter, ten feet from me," droned Arcot. The sphere was there. "It is moving to the left." The sphere moved to the left at Arcot's thought. "It is rising." The sphere rose. "It is changing to a disc two feet across." The sphere seemed to flow, and was a disc two feet across as Arcot's toneless voice of concentration continued.

---

     "And now I am going to give a demonstration of the theatrical possibilities of this new agent. Hardly scientific—but amusing."
     But it wasn't exactly amusing.

     Arcot again donned the headpiece. "I think," he continued, "that a manifestation of the supernatural will be most interesting. Remember that all you see is real, and all effects are produced by artificial matter generated by the cosmic energy, as I have explained, and are controlled by my mind."

     Arcot had chosen to give this demonstration with definite reason. Apparently a bit of scientific playfulness, yet he knew that nothing is so impressive, nor so lastingly remembered as a theatrical demonstration of science. The greatest scientist likes to play with his science.

     But Arcot's experiment now—it was on a level of its own!

     From behind the table, apparently crawling up the leg came a thing! It was a hand. A horrible, disjointed hand. It was withered and incarmined with blood, for it was severed from its wrist, and as it hunched itself along, moving by a ghastly twitching of fingers and thumb, it left a trail of red behind it. The papers to be distributed rustled as it passed, scurrying suddenly across the table, down the leg, and racing toward the light switch! By some process of writhing jerks it reached it, and suddenly the room was plunged into half-light as the lights winked out. Light filtering over the transom of the door from the hall alone illuminated the hall, but the hand glowed! It glowed, and scurried away with an awful rustling, scuttling into some unseen hole in the wall. The quiet of the hall was the quiet of tenseness.

     From the wall, coming through it, came a mistiness that solidified as it flowed across. It was far to the right, a bent stooped figure, a figure half glimpsed, but fully known, for it carried in its bony, glowing hand a great, nicked scythe. Its rattling tread echoed hollowly on the floor. Stooping walk, shuffling gait, the great metal scythe scraping on the floor, half seen as the gray, luminous cloak blew open in some unfelt breeze of its ephemeral world, revealing bone; dry, gray bone. Only the scythe seemed to know Life, and it was red with that Life. Slow running, sticky lifestuff.

     Death paused, and raised his awful head. The hood fell back from the cavernous eyesockets, and they flamed with a greenish radiance that made every strained face in the room assume the same deathly pallor.

     "The Scythe, the Scythe of Death," grated the rusty Voice. "The Scythe is slow, too slow. I bring new things," it cackled in its cracked voice, "new things of my tools. See!" The clutching bones dropped the rattling Scythe, and the handle broke as it fell, and rotted before their eyes. "Heh, heh," the Thing cackled as it watched. "Heh—what Death touches, rots as he leaves it." The grinning, blackened skull grinned wider, in an awful, leering cavity, rotting, twisted teeth showed. But from under his flapping robe, the skeletal hands drew something—ray pistols!

     "These—these are swifter!" The Thing turned, and with a single leering glance behind, flowed once more through the wall.

     A gasp, a stifle, groaning gasp ran through the hall, a half sob.

     But far, far away they could hear something clanking, dragging its slow way along. Spellbound they turned to the farthest corner—and looked down the long, long road that twined off in distance. A lone, luminous figure plodded slowly along it, his half human shamble bringing him rapidly nearer.

     Larger and larger he loomed, clearer and clearer became the figure, and his burden. Broken, twisted steel, or metal of some sort, twisted and blackened.

     "It's over—it's over—and my toys are here. I win, I always win. For I am the spawn of Mars, of War, and of Hate, the sister of War, and my toys are the things they leave behind." It gesticulated, waving the twisted stuff and now through the haze, they could see them—buildings. The framework of buildings and twisted liners, broken weapons.

     It loomed nearer, the cavernous, glowing eyes under low, shaggy brows, became clear, the awful brutal hate, the lust of Death, the rotting flesh of Disease—all seemed stamped on the Horror that approached.

     "Ah!" It had seen them! "Ahh!" It dropped the buildings, the broken things, and shuffled into a run, toward them! Its face changed, the lips drew back from broken, stained teeth, the curling, cruel lips, and the rotting flesh of the face wrinkled into a grin of lust and hatred. The shaggy mop of its hair seemed to writhe and twist, the long, thin fingers grasped spasmodically as it neared. The torn, broken fingernails were visible—nearer—nearer—nearer—

     "Oh, God—stop it!" A voice shrieked out of the dark as someone leaped suddenly to his feet.

     Simultaneously with the cry the Thing puffed into nothingness of energy from which it had sprung, and a great ball of clear, white glowing light came into being in the center of the room, flooding it with a light that dazzled the eyes, but calmed broken nerves.

     "I am sorry, Arcot. I did not know, for I see I might have helped, but to me, with my ideas of horror, it was as you said, amusement," said Torlos. They were sitting now in Arcot's study at the cottage; Arcot, his father, Morey, Wade, Torlos, the three Ortolians and the Talsonian.

     "I know, Torlos. You see, where I made my mistake, as I have said, was in forgetting that in doing as I did, picturing horror, like a snowball rolling, it would grow greater. The idea of horror, started, my mind pictured one, and it inspired greater horror, which in turn reacted on my all too reactive apparatus. As you said, the things changed as you watched, molding themselves constantly as my mind changed them, under its own initiative and the concentrated thoughts of all those others. It was a very foolish thing to do, for that last Thing—well, remember it was, it existed, and the idea of hate and lust it portrayed was caused by my mind, but my mind could picture what it would do, if such were its emotions, and it would do them because my mind pictured them! And nothing could resist it!" Arcot's face was white once more as he thought of the danger he had run, of the terrible consequences possible of that 'amusement.'

• 

The first sight of the controls startled me. The old Javelin hadn't been too difficult to feel, because in terms of control there weren't too many fancy gadgets. Just a pair of manipulative levers and a panel of on/off switches. Plus instrumentation. But this ship was different. Lots of input and output. Setting registers all over the place. A profusion of dials, a sensor hood that looked like a beehive, a set of spinal electrodes. Some people like to fly a ship as if they were undergoing a major operation, but not me. Some people like every imaginable datum available to them on the panel, like how fast is their heart beating, and how much ash is there in the ashtray. But I want to know what's vital and what's necessary, in that order, and nothing else. At that point I was sure that I couldn't fly the ship and never would be able to. Nor anyone else, for that matter.

'It takes some getting used to,' said delArco. 'But most of the monitor devices are on automatic circuitry. You don't have to worry about the spinal hook-up, because that all works without any conscious control. The hood's so big because of the vastly increased sensory range and sensitivity made possible by the organo-metallic synapses in the ship's nerve-net. You can achieve a much higher degree of integration with the ship than you ever could with a conventional model, and this will make the sheer complexity of the controls less frightening. It will take some getting used to, but once you're acclimatised, the directness of sensation will more than compensate for the profusion of incoming and outgoing signals. You can be the ship's mind, literally — its reason and its judgement. You'll be more a part of this ship than you ever could be on board your old Javelin. The Hooded Swan and her pilot are inseparable. They are the same super-organism. You can be a giant, Grainger — a spacefaring giant.'

---

The captain couldn't seem to understand that while I sat in the control cradle, hooked up and doing absolutely nothing, I was working hard. I was doing necessary work, too — just acclimatising to the sensory range and potential of the ship, just feeling the size and the shape of my new body. DelArco knew every relay in those controls, all right. He knew what every inch of wire was for. But he didn't understand how to use it.

I had to have the contacts in my neck resculptured in order to fit the spinal electrodes comfortably. It's hell to fly with an itch where you can't scratch, or with a clip that pinches even slightly. I insisted on having the hood modified as well so that it was perfectly tailored to the shape of my skull, the distance between my foveae, the depth of my face. All this took time that delArco thought was dead.

---

Despite all the hours I'd spent sitting at the console with everything switched on, the first time I put the hood on for real it felt completely different. The sensors were beautiful — tuned and focused exactly. Through the ship's thousand eyes I watched the tower split, and the halves roll back out of our way. I put my hands around the levers, and felt the power growing inside them, swelling up from the bowels of the ship.

For the first time, I began to get some positive sensation in my ship-body. I could feel the wind that blew across the yards. I could feel threads of force reaching out from the gathering drive to the limits of the nerve-net. I felt the Hooded Swan come alive inside me. My heartbeat fused with the rhythmic discharge inside the piledriver. The flux-field of the mass-relaxation web was cold and inert, but I could sense its enfolding presence, like a carefully clutching hand. And the background sensation — the knowledge that I was the ship, the admission of common identity — grew stronger. The dials whose information was reflected in the hood around the image of the empty sky showed the gain creeping up to the meagre potential that was all I could use in taking off from the yards.

---

I let my tactile senses spread via the electrode contacts until I was sure that I could feel every synapse in the vessel. I couldn't feel them as entities, but I could feel the wholeness of the system. My hands grew into great wings, my spine was the ship's long axis, my legs were the tail stabilisers, my groin the atomic cannons, my heart the relaxation web wrapped around the drive, my lungs the ship's lacunae.

---

I breathed deeply, still feeling the pain that had possessed my throat when the flux jammed. There were great red bruises on my neck — so Johnny told me afterwards. I felt for and with my ship. Her pain was mine, and her injuries were mine. If the Hooded Swan were ever to go down, I need not worry about spending another two lonely years on some bleak rock.

• 

      "Eric, you there?"
     "Where would I go?" he mocked me.
     "Well," said I, "if I watched every word I spoke I'd never get anything said." All the same, I had been tactless. Eric had had a bad accident once, very bad. He wouldn't be going anywhere unless the ship went along.
     "Touché," said Eric.

---

     "I'd better check your maintenance."
     "Okay, good. Go oil my prosthetic aids."
     "Prosthetic aids"—that was a hot one. I'd thought it up myself. I pushed the coffee button so it would be ready when I was through, then opened the big door in the forward wall of the cabin. Eric looked much like an electrical network, except for the gray mass at the top which was his brain. In all directions from his spinal cord and brain, connected at the walls of the intricately shaped glass-and-soft-plastic vessel which housed him, Eric's nerves reached out to master the ship. The instruments which mastered Eric—but he was sensitive about having it put that way—were banked along both sides of the closet. The blood pump pumped rhythmically, seventy beats a minute.

---

     "Jackass! Am I still alive?"
      "The instruments think so. But I'd better lower your fluid temperature a fraction." I did. Ever since we'd landed I'd had a tendency to keep temperatures too high. "Everything else looks okay. Except your food tank is getting low."
     "Well, it'll last the trip."
     "Yeah.
     "'Scuse me. Eric, coffees ready." I went and got it. The only thing I really worry about is his "liver." It's too complicated. It could break down too easily. If it stopped making blood sugar Eric would be dead.
     If Eric dies I die, because Eric is the ship. If I die Eric dies, insane, because he can't sleep unless I set his prosthetic aids.

Beyond the four-foot-square access door was Eric. Eric's central nervous system, with the brain perched at the top and the spinal cord coiled in a loose spiral to fit more compactly into the transparent glass-and-sponge-plastic housing. Hundreds of wires from all over the ship led to the glass walls, where they were joined to selected nerves which spread like an electrical network from the central coil of nervous tissue and fatty protective membrane.

Space leaves no cripples; and don't call Eric a cripple, because he doesn't like it. In a way he's the ideal spaceman. His life support system weighs only half of what mine does, and takes up a twelfth as much room. But his other prosthetic aids take up most of the ship. The ramjets were hooked into the last pair of nerve trunks, the nerves which once moved his legs, and dozens of finer nerves in those trunks sensed and regulated fuel feed, ram temperature, differential acceleration, intake aperture dilation, and spark pulse. These connections were intact. I checked them four different ways without finding the slightest reason why they shouldn't be working.

"Test the others," said Eric.

It took a good two hours to check every trunk nerve connection. They were all solid. The blood pump was chugging along, and the fluid was rich enough, which killed the idea that the ram nerves might have "gone to sleep" from lack of nutrients or oxygen. Since the lab is one of his prosthetic aids, I let Eric analyze his own blood sugar, hoping that the "liver" had goofed and was producing some other form of sugar. The conclusions were appalling. There was nothing wrong with Eric—inside the cabin.

• 

      She was born a thing and as such would be condemned if she failed the encephalograph test required of all newborn babies. There was always the possibility that though the limbs were twisted, the mind was not, that though the ears would only hear dimly, the eyes see vaguely, the mind behind them was receptive and alert.

     The electro-encephalogram was entirely favorable, unexpectedly so, and the news was brought to the waiting grieving parents. There was the final harsh decision, to give their child euthanasia or permit it to become an encapsulated “brain,” a guiding mechanism in any one of a number of curious professions. As such, their offspring would suffer no pain, live a comfortable existence in a metal shell for several centuries, performing unusual service to Central Worlds.

     She lived and was given a name, Helva. For her first three vegetable months she waved her crabbed claws, kicked weakly with her clubbed feet and enjoyed the usual routine of the infant. She was not alone, for there were three other children in the big city’s special nursery. Soon they all were removed to the Central Laboratory School, where their delicate transformation began.

     One of the babies died in the initial transferal, but of Helva’s “class,” seventeen thrived in the metal shells. Instead of kicking feet, Helva’s neural responses started her wheels; instead of grabbing with hands, she manipulated mechanical extensions. As she matured, more and more neural synapses would be adjusted to operate other mechanisms that went into the maintenance and running of a space ship. For Helva was destined to be the “brain” half of a scout ship, partnered with a man or woman, whichever she chose, as the mobile half. She would be among the elite of her kind. Her initial intelligence tests registered above normal and her adaptation index was unusually high. As long as her development within her shell lived up to expectations, and there were no side-effects from the pituitary tinkering, Helva would live a rewarding, rich, and unusual life, a far cry from what she would have faced as an ordinary, “normal” being.

     However, no diagram of her brain patterns, no early I.Q. tests recorded certain essential facts about Helva that Central must eventually learn. They would have to bide their official time and see, trusting that the massive doses of shell-psychology would suffice her, too, as the necessary bulwark against her unusual confinement and the pressures of her profession. A ship run by a human brain could not run rogue or insane with the power and resources Central had to build into their scout ships. Brain ships were, of course, long past the experimental stages. Most babies survived the perfected techniques of pituitary manipulation that kept their bodies small, eliminating the necessity of transfers from smaller to larger shells. And very, very few were lost when the final connection was made to the panels of ship or industrial combine. Shell-people resembled mature dwarfs in size whatever their natal deformities were, but the well-oriented brain would not have changed places with the most perfect body in the Universe.

     So, for happy years, Helva scooted around in her shell with her classmates, playing such games as Stall, Power-Seek, studying her lessons in trajectory, propulsion techniques, computation, logistics, mental hygiene, basic alien psychology, philology, space history, law, traffic codes. All the et ceteras that eventually became compounded into a reasoning, logical, informed citizen. Not so obvious to her, but one of more importance to her teachers, Helva ingested the precepts of her conditioning as easily as she absorbed her nutrient fluid. She would one day be grateful to the patient drone of the subconscious-level instruction.

     Helva’s civilization was not without busy, do-good associations, exploring possible inhumanities to terrestrial as well as extraterrestrial citizens. One such group, Society for the Preservation of the Rights of Intelligent Minorities, got all incensed over shelled “children” when Helva was just turning fourteen. When they were forced to, Central Worlds shrugged its shoulders, arranged a tour of the Laboratory Schools and set the tour off to a big start by showing the members case histories complete with photographs. Very few committees ever looked past the first few photos. Most of the original objections about “shells” were overridden by the relief that these hideous (to them) bodies were mercifully concealed.

     On the anniversary of her sixteenth year, Helva was unconditionally graduated and installed in her ship, the XH-834. Her permanent titanium shell was recessed behind an even more indestructible barrier in the central shaft of the scout ship. The neural, audio, visual, and sensory connections were made and sealed. Her extendibles were diverted, connected or augmented and the final, delicate-beyond-description brain taps were completed while Helva remained anesthetically unaware of the proceedings. When she woke, she was the ship. Her brain and intelligence controlled every function from navigation to loading as a scout ship of her class needed. She could take care of herself, and her ambulatory half, in any situation already recorded in the annals of Central Worlds and any situation its most fertile minds could imagine.

     Her first actual flight, for she and her kind had made mock flights on dummy panels since she was eight, showed her to be a complete master of the techniques of her profession. She was ready for her great adventures and the arrival of her mobile partner. The ship always chose its own partner.

     Scouts were colloquially known as “brawns” as opposed to the ship “brains.” They had to pass as rigorous a training program as the brains and only the top one percent of each contributory world’s highest scholars were admitted to Central Worlds Scout Training Program.

     Hers was a curious courtship, this would be only the first of several marriages for her, for brawns retired after 75 years of service, or earlier if they were unlucky. Brains, their bodies safe from any deterioration, were indestructible. In theory, once a shell-person had paid off the massive debt of early care, surgical adaptation and maintenance charges, he or she was free to seek employment elsewhere. In practice, shell-people remained in the service until they chose to self-destruct or died in the line of duty. Helva had actually spoken to one shell-person 322 years old. She had been so awed by the contact she hadn’t presumed to ask the personal questions she had wanted to.

• 

      Valthyrra Methryn slipped smoothly out of starflight to cruise at a speed that was just sublight, paralleling the freighter lane, just far enough out to avoid being seen. She was as vast and black as space itself, three kilometers long and more than one across the short wings of her arrowhead shape. Flaring main drives were tucked protectively beneath her wings; her upper hull was a smooth, armored shell that she could turn toward enemy fire. She moved like a warship, with the smooth, graceftil control of a big ship with more than enough power for its size. She was beautiful and frightening to behold.
     By design, the Methryn was a destroyer of immense size, all engines and weapons and very little crew. She could turn and accelerate like a ship a fraction her size, while the cannons in her shock bumper were more than a match for a fleet of heavy cruisers. On the underside of her tapered nose was a cannon that could turn an entire planet into dust.
     Velmeran entered the wide bridge from the left wing. Bridge crewmembers in white armored suits sat at their stations or hurried about their duties. Consherra glanced up at him from the helm console on that side of the raised middle bridge, and an instant later Valthyrra quickly rotated her camera pod around and focused both lenses on him before turning her attention back to the Commander's console on the upper bridge. Velmeran frowned. The three of them together, Commander, helm and ship herself, was entirely too much motherly attention, and it only seemed to him like an accusation of his inability to make a pack of students fly like veterans.
     Velmeran, with a final gesture of hopelessness, turned away a last time.
     Mayelna turned back to her monitors, but Valthyrra made no secret of watching him go. Several of the others, Consherra in particular, watched him just as closely. Valthyrra swung her boom back around to the Commander's console.
     "Is he still your choice?" Mayelna asked without looking up.
     The pod itself nodded in agreement. "More than ever."
     Mayelna looked up sharply. "He is a good pilot, I will grant you that. But that does not make him a good leader."
     "No, the two are not related," she agreed. "But I still believe that when he learns to lose his fear of being a leader, then he will make a very good one."
     Mayelna leaned back in her chair, crossing her arms defiantly. "How can you know that better than me? I am his mother..."
     "And I have been a carrier for nearly twenty thousand years," Valthyrra replied firmly. "I should know who I want to command on my bridge. He will prove himself soon enough."

---

     "Do you know what this is?"
     "It looks like part of a large computer," he speculated cautiously.
     "This is a memory cell from a Starwolf carrier," she said. "The traits and personal memories of a ship are held in there. There are eight scattered throughout a ship, with enough duplication in the information they store and the computers they drive that even extensive damage does not affect the operation of a ship. That, for all practical purposes, holds the life of a ship. The Theralda Vardon, to be exact.

• 

      As it happened, she had almost guessed wrong. The Starwolves were there before her. The carrier appeared suddenly on scan almost directly behind them, passing swiftly over the Carthaginian before matching speed barely twice her own great length ahead of the battleship, clearly visible now on the main bridge viewscreen. Then she rotated slowly, until she was facing them, a vast black hull vaguely in the shape of an arrowhead, her short, slightly downs wept wings protecting her main drives. Her color was an unreflective black, difficult enough to see against space, even at close range. There were no windows to betray her presence with their glow, although she did have her recognition lights burning as a courtesy. That was actually encouraging.
     If there was trouble, Tarrel decided that the Starwolves could not have been more obliging in stationing their immense carrier directly in front of her missile racks. She doubted that those missiles could do the great ship any harm, but they might provide enough distraction to get her own ship to the vague safety of starflight.
     “Message coming in,” communications reported. “No visual.”
     “I’ll take it at my station,” Tarrel said.
     “I should take it,” Pesca offered in his excitement. “I am the linguist.”
     “You’re also an a**hole, and neither attribute qualifies you for this,” she snapped, then addressed the communication unit at her station. “This is Captain Tarrel of the battleship Carthaginian. We wish to parlay on an urgent matter.”
     “This is Trendaessa Kerridayen,” the response came, a strong female voice. “Just what seems to be the problem?”
     Tarrel was surprised at that lack of concern. It made her wonder if the Starwolves found her battleship at all threatening. “Some large ship is moving through our systems, destroying every ship and station it finds. The situation is very alarming to us.”
     “So?”
     No sympathy there. “So, we were wondering if the Starwolves were behind this, or if we have an alien threat to deal with.”
     “No. It is not Starwolves.”
     Tarrel was grateful that this was not a visual link, since she could not stop herself from making faces. “I have encountered this machine on three separate occasions. My opinion is that this is an automated weapon designed to seek out and destroy all power sources it encounters in space. It is also my opinion that a single Starwolf carrier could not fight it.”
     “Is that a fact? You seem to expect us to do something about it.”
     “This monster is efficient and absolutely merciless,” she said. “We cannot fight it. Damn it, we can’t even see it. Our military ships might be one thing, but this beast eats commercial ships and stations, both our own and the independents, without discrimination, and we can’t protect them. System Commander Lake has empowered me to negotiate for your help, even to the point of declaring a truce between us.”
     “On our terms?”
     “On just about any terms.”
     “My word, this thing does have you people rattled. I suspect that I would do best to call Commander Daerran to the bridge. That way, you only have to explain all of this once.”
     “I can wait,” Tarrel agreed.
     She muted the communication unit and leaned back in her seat, thinking that she had not started out at all well. She decided now that the Starwolf ship’s odd manner had been deliberate, intended to keep her from presenting a prepared speech in the way she might have meant, possibly flustering her enough to say things she did not intend. She would have to be more oh her guard.
     “I thought that Starwolves didn’t have last names,” Pesca commented.
     “They don’t,” she said. “That was the ship.”
     “The ship?” He was obviously greatly surprised. “Do you mean that their ships can talk?”
     “They use sentient computer systems completely integrated into their carriers,” Tarrel explained; “That way, their captains can circumvent the need to ever talk to knock-headed crew-members.”

• 

• 

Cargraves yelled, "Hang on to your hats, boys! Here we go! He turned full control over to Joe the Robot pilot. That mindless, mechanical-and-electronic worthy figuratively shook his non-existent head and decided he did not like the course. The image of the moon swung "down" and toward the bow, in terms of the ordinary directions in the ship, until the rocket was headed in a direction nearly forty degrees further east than was the image of the moon.

Having turned the ship to head for the point where the moon would be when the Galileo met it, rather than headed for where it now was, Joe turned his attention to the jet. The cadmium plates were withdrawn a little farther; the rocket really bit in and began to dig.

Ross found that there was indeed a whole family on his chest. Breathing was hard work and his eyes seemed foggy.

If Joe had had feelings he need have felt no pride in what he had just done, for his decisions had all been made for him before the ship left the ground. Morrie had selected, with Cargraves' approval, one of several three-dimensional cams and had installed it in Joe's innards. The cam "told" Joe what sort of a course to follow to the moon, what course to head first, how fast to gun the rocket and how long to keep it up. Joe could not see the moon — Joe had never heard of the moon — but his electronic senses could perceive how the ship was headed in relation to the steady, unswerving spin of the gyros and then head the ship in the direction called for by the cam in his tummy.

The cam itself had been designed by a remote cousin of Joe's, the great "ENIAC" computer at the University of Pennsylvania. By means of the small astrogation computer in the ship either Morrie or Cargraves could work out any necessary problem and control the Galileo by hand, but Joe, with the aid of his cousin, could do the same thing better, faster, more accurately and with unsleeping care — provided the human pilot knew what to ask of him and how to ask it.

Joe had not been invented by Cargraves; thousands of scientists, engineers, and mathematicians had contributed to his existence. His grandfathers had guided the Nazi V-2 rockets in the horror-haunted last days of World War II. His fathers had been developed for the deadly, ocean-spanning guided missiles of the UN world police force. His brothers and sisters were found in every rocket ship, private and commercial, passenger-carrying or unmanned, that cleft the skies of earth.

Trans-Atlantic hop or trip to the moon, it was all one to Joe. He did what his cam told him to do. He did not care, he did not even know.