Atomic Rockets

Introduction

This is where the spacecraft's pilot flies the ship. In fiction it is often the dramatic focus, even though without help from the astrogator, engineer, and ship's captain one will find that the pilot is helpless.

Each spacecraft mission is composed of several "maneuvers". In between maneuvers, the spacecraft is falling along a trajectory to its next maneuver. In between maneuvers, the pilot has nothing to do.

A maneuver consists of using attitude controls to aim the thrust axis in the prescribed direction, and using the thrust controls to do an engine burn for the prescribed amount of delta V. And this maneuver must be performed at the prescribed time. Maneuvers are calculated by the astrogator and given to the pilot.

The two main controls are the ship's attitude controls and the thrust controls (i.e., similar to the steering wheel and the accelerator pedal on an automobile). They will probably look like a joystick and a throttle.

In some cases, the thrust controls are so complicated that they are delegated to the ship's engineer. "Sufficiently complicated" usually means there is a fission or fusion reactor involved in the thrust. Holms Cronch has a pilot's console and an engineer's console. This is similar to the situation on many US wet Naval vessels. There the Helmsman steers the ship by controlling the rudder, while the Lee Helmsman sets ship's speed by controlling the engine and the propeller. On a US Naval vessel, the current Conning Officer is the only person the Helmsman and Lee Helmsman listen to when it comes to direction of the ship. The officer assuming the role of Conning Officer does so by announcing "I Have The Conn".

But in most science fiction, it is assumed for dramatic purposes that the spacecraft is sufficiently automated so the pilot can fly the entire spacecraft like it is a huge jet fighter, all by themselves.

Flight Controls

The most important controls to the pilot are of course the piloting or flight path controls. These are the 3D equivalents of the steering wheel and accelerator in an automobile. To get an idea of what the bare minimum is, we will unashamedly be taking a good look at the solution in the computer game Kerbal Space Program. Since that is a game, the designers were forced to distill the controls to the very essentials (because the players will quickly get fed up and leave if they think the game is too complicated). As a matter of fact, that game is so wonderfully educational yet fun, you might be better off if you skipped this section of the website and instead started playing the Kerbal game.

The bottom line is that piloting boils down to aiming the ship's nose in the proper direction, then at the proper time performing a burn of the proper amount of delta V. This will put the ship on a trajectory to its destination. Calculating the values of all these proper parameters is the job of the astrogator. It is the captain's job to tell the astrogator the destination to be calculated for. But I digress.

The combination of burn direction, delta V, and timing is called a "maneuver."

The pilot will have to look over the parameters the astrogator passes to them and squawk if there is a problem, such as the spacecraft not having enough remaining propellant to create enough delta V. The astrogator is supposed to avoid problems like that but mistakes will happen.

The technical term for the direction the astrogator wants the ship's nose to pointing at is "Axis of Acceleration." Why the ship's nose? Because it points in the same direction as the engine's thrust axis. For most spacecraft, when they do an engine burn, the exhaust goes directly aft (out the rear of the ship) and the thrust goes forward in the direction the ship's nose is pointing. To do the maneuver properly, the thrust axis and the acceleration axis must be the same and stay the same. This is half of the pilot's job. Remember: the acceleration axis is the course specifed by the astrogator, the thrust axis is where the ship is currently aimed.

During the flight, the astrogator will keep track of the spacecraft's course and timing. If the spacecraft starts to move off track, the astrogator will calculate a mid-course correction maneuver to fix things.

Since under acceleration "down" feels like it is in the direction the exhaust is going, the ship's nose will feel like it is directly overhead.


As far as controls are concerned, there are only three: Rotation, Translation, and Thrust.

The rotation control spins the ship on one or more of its three axes, it is used to aim the ship's nose in the proper direction (i.e., controls the thrust axis).

The translation control move the ship laterally on the three axes, it is only used for docking but it is generally located next to the rotation control. Sometimes the translation control and the thrust control were combined into one, with a selector switch. You generally never need to translate while doing a burn, neither do you need to thrust while docking. Combining the controls saves mass, and every gram counts.

The thrust control turns on the rocket motor and sets the thrust level, it is used to control the delta V.


The pilot needs feedback in order to full fill all the proper parameters. Where is the ship's nose currently pointing? Is it time for the burn yet? How much delta V has been created? The pilot uses the display instruments for the necessary feedback.

The attitude display tells where the ship's nose is currently pointing (the thrust axis). Feedback for the rotation control.

The time display tells the current time with split-second accuracy. Feedback for the thrust control.

The delta V display tells how much delta V has been generated so far by the current burn. Feedback for the thrust control.

Rotation and Translation Controls

When a spacecraft is falling along a trajectory to its destination, there is no need for a pilot. The ship's course is determined by Newton's Laws of Motion and the effect of gravity, the pilot can go play poker with the atomjacks. It is when the ship has to have its nose pointed in the proper direction so that a scheduled engine burn gives the desired vector that the pilot earns their pay. Or when the ship needs to be docked to a space station or something.

The pilot moves the spacecraft via rotations and translations. A rotation spins the ship around its center of gravity, the ship's orientation in space changes but its position does not. A translation, on the other hand, moves the ship's position but does not affect its orientation. So if you were standing up and pivoted in place clockwise, you would be doing a rotation. But if you took a step to the right, you would be doing a translation. Aircraft can do rotations, but they generally do not do non-thrust-axis translations (with exceptions like helicopters, Harrier jump jets, and unfortunate aircraft in the process of augering in).

And please try and remember that Rockets are not Arrows, there is no law that says the spacecraft has to be traveling in the direction its nose is pointing (i.e., the thrust axis and the ship's trajectory are independent). While the Polaris' vector is a Hohmann transfer to Mars, no law of physics will prevent Tom Corbett from using the controls to make the ship's nose point anywhere he pleases. So the Polaris is now traveling sideways through space, so what?

For a given maneuver, the pilot will use the rotation control to aim the nose in the required direction. The translation control is not needed for a burn, it generally is required only for a docking maneuver. Both controllers will have a "trim" control. The trim will set whether each tap of the grip will move the ship's nose by a large amount (for big coarse movements) or by a small amount (for tiny high-precision movements). The trim control might be on the hand controller proper or might be on the main control panel.

The pilot might need to make rotational corrections during the burn, if the ship's nose wanders off-target due to engine irregularities, crewman Joe Idiot walking around during the burn, or something like that (which will earn Joe Idiot a free trip out the nearest airlock when the angry pilot catches up with him). Generally the spacecraft will have stabilization gyros or automatic attitude jets to keep the nose from wandering, but those can only go so far.

Rotation spins the ship around one of its (imaginary) axes. A "yaw" pivots the ship's nose to the left or right, spinning around the Z axis. A "pitch" pivots the ship's nose up or down, spinning around the Y axis. And a "roll" makes the ship spin like a old-style propeller prop, spinning around the X axis.

In most NASA vehicles, pushing the control grip left or right does roll, forwards and back does pitch, holding it upright and twisting left or right for yaw. In other words, imagine that there is a little model spacecraft glued on the top of the hand grip with the nose pointing forwards. Move the hand grip in such a way that the model's nose moves the way you want the spacecraft's nose to move.

According to NASA human factor design, the hand controller should be set to operate according to the viewpoint of the operator. So if you had a control for the pilot facing in the direction of the ship's nose, and a second control for an operator facing in the direction of the ship's tail, the "pitch" control for each operator will be the reverse of the other. For instance a pull back for the nose controller will pitch the nose upwards, while a pull back for the tail controller will pitch the nose down. This is because according to human factor design, the operator at the tail controller expects to pitch the tail upwards when they pull back the hand grip.


In NASA designs, pushing the control up or down translates in the Z direction, left or right translates in the Y direction, push or pull translates in the X direction.


In the game Kerbal Space Program, rotation and translation is handled by the computer keyboard. A and D are for yaw, W and S are for pitch, Q and E are for roll, H and N translate x, J and L translate y, I and K translate z, and the coarse/fine trim control is the caps-lock key.


Attitude Jets And Flywheels

Rotations are created by attitude jets or momentum wheels. Attitude jets are also called a Reaction Control System (RCS). Momentum wheels are also called flywheels or reaction wheels. It is also possible to do mild yaw and pitch by gimbaling the engine. If you have two or more engines that are off-axis, gimbaling can also do a mild roll as well.

Translations are only done by attitude jets, never by momentum wheels. This is because converting rotary motion into linear motion is impossible (the Dean Drive notwithstanding).

The Apollo spacecraft used attitude jets. A more elegant way is with a large precessing flywheel on a gimbal. Aim the axis of the flywheel so it is parallel to the desired axis of rotation, start spinning it, and the spacecraft will start to yaw, pitch, or roll in the opposite direction. Stop the flywheel and so will the ship. Be sure to unclutch the gyros first. Trying to use the precessing flywheel while the gyros are clutched is like trying to drive a car with the emergency brake on.

Rapidly changing the ship's attitude is a problem, it will require unreasonably powerful attitude jets. A possible solution is using Cascade Vanes instead. Of course exploration and merchant spacecraft generally do not need to rapidly change attitude, this is only needed with warships.

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.

From Step to the Stars by Lester Del Rey (1954)

You may or may not need thermal protection on the hull to shield it from the thruster exhaust. Depends upon how the thrusters are angled, and how hot the exhaust is.

Hop David has an exceedingly clever arrangement of attitude jets on his Tetrahedral spaceship concept. This takes the "jet on a long lever arm" arrangement of Babylon-5 Starfuries to the logical ultimate.

Since the spacecraft has far more mass that the flywheel, the ship will rotate far more slowly than the flywheel does. So if you want the ship to rotate faster than the hour hand on an analog watch the flywheel will have to spin like a x100 CD-ROM drive. It might be prudent to put an armored cage around the flywheel, in case of "explosive delamination". This will ensure that the deadly shrapnel from the delaminating flywheel will shred the armored cage instead of shredding the unlucky crewmembers who happened to be in the plane of the flywheel. Unfortunatly the mass of the armor cuts into payload mass.

Also note that for certain types of inertial reference platforms, one cannot rotate the ship through certain directions or you will send the platform into gimbal lock and tumble it.

A flywheel is too slow to be used during a burn. For that one will use gyros, either massive ones to prevent tumbling by brute force or a tiny ones connected to gimbaled nozzles on the propulsion system.

Stabilizing Gyroscope

How do you keep the ship from spinning, tumbling, or otherwise stationary? Equip the ship with a massive stabilizing gyroscope. If you cannot construct or otherwise use a single massive gyroscope, you can use a series of smaller ones. The International Space Station can limp along with only two, but three is preferred, and the fourth is a back up.

The technical term is "control moment gyroscope." You mount each inside a spherical framework which rotates inside a slightly larger spherical framework. This larger framework is anchored to the ship's structure. The ISS gyros spin at about 6,600 revolutions per minute and take eight hours to rev up to full speed.

Once you spin up a given gyro, the inner framework will stay in one orientation. If the gyro frame is "unclutched", the inner frame can freely rotate (actually it stays stable while the ship rotates around it). When you "clutch" the gyros, the inner frame is clamped onto the outer frame, and the gyro cage will do its best to keep the ship from changing orientation.

Aerospace Engineer Bill Kuelbs Jr corrected an error on an earlier version of this page. I mistakenly stated that the control moment gyroscopes had to be mounted at the center of gravity of the ship. Mr. Kuelbs pointed out that due to a force known as a 'moment couple' the the translative forces are balanced out (i.e., you can mount the gyros anywhere inside the ship and they will work).

Some spacecraft designers will try to economize by specifying gyros that are too light for the spacecraft's moment of inertia (i.e., the rotational analogue to mass ). Such ships will tend to wobble under acceleration. This will also happen if a gyro's bearings start to go bad.

Since gyros heavy enough to stabilize the entire spacecraft are rather massive, a more elegant solution is to use tiny gyros to detect changes in the spacecraft's orientation and connect this to an attitude control system to automatically counteract it (generally a RCS). In the old Heinlein novels ships had gyros massive enough to keep a landed ship from tipping over, but this might not be realistic.

(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.


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


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.


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.

From Grendel by Larry Niven (1968)

Thrust Controls

Some propulsion systems only have "on" or "off", there is no fine control over the amount of thrust. The amount of delta V is set by controlling the duration of the engine burn. This can prove uncomfortable to the hapless astronauts, since the gees of acceleration will go up as the mass of the ship goes down (as propellant is expended). Acceleration is thrust divided by ship mass, as the mass goes down the rising acceleration tries to mash the crew into a pulp.

More advanced systems have variable thrust levels, they can be throttled. This gives more fine control. Or at least a way to keep the acceleration from rising and turning the astronauts into chunky salsa. The amount of thrust will have to be reduced in proportion in order to keep the acceleration constant. There may be some sort of control that will do this automatically.

The throttle may be a direct control link to the engine, or it may be a glorified engine order telegraph. In the latter case, the pilot pushes the 50% thrust button, and down in the reactor room the atomjack's control panel lights up the indicator for "GET OFF YOUR BLASTED BACKSIDE AND MAKE THE REACTOR SPIT OUT 50% THRUST!". The nuclear engineer on watch throws down the poker hand, scoops up their winnings, and then proceeds to perform all the delicate complicated procedures required to make the reactor thrust as required without exploding into a nuclear fireball. You find this set-up when the task of piloting the ship and the task of controlling a touchy reactor simultaneously is too much multi-tasking for one person to do.

In the Apollo command module, the thrust was computer controlled. The flight crew would type the start time and duration of the thrust into the computer, the computer would do the rest. The computer would initiate the burn at the start time, then act as a brennschluss timer, automatically cutting off the engine.

In the Apollo lunar module things were a little more like flying by the seat of your pants. They did not have any moon maps with fine detail. The flight commander had to run the throttle manually, to take control in case the lunar module was trying to land on top of a bolder or something equally stupid. So the lunar module translation controller had a switch that would change it into a thrust controller. You never needed to do both functions at the same time, and combining the two controls saved payload mass.

Burn start and stop might be under autopilot control. But the pilot will still keep their hand hovering over the manual start key (or cut-off switch), as they never quite trust the auto-pilot. The co-pilot and the power officer will also have their hands hovering over their manual keys, since they never quite trust the auto-pilot nor the pilot.

There might be a brennschluss timer. When a burn is initiated, this is pre-set to count-down to burn stop time. The term is from German Brennschluß, or "End of burn". Brennen is 'to burn', schluß is 'end' or 'finish'. This was popularized in the 1950's by former German rocket engineer Willy Ley.


In the game Kerbal Space Program, thrust control is handled by the computer keyboard. In the game, most propulsion systems have variable thrust settings instead of just a rocket on/off setting. Shift key increases the throttle, ctrl key decreases the throttle, and X sets the throttle to zero. If the thrust is zero the engine is off, otherwise it is on. The current thrust setting is displayed on a dial on the left side of the nav ball.

Attitude Display

The direction the ship's nose is pointing is displayed by the attitude indicator, also known as gyro horizon, artificial horizon or attitude director indicator. In Kerbal Space Program it is called the Nav Ball. This was originally developed for aircraft, and was adapted for spacecraft. An artificial horizon for a spacecraft is actually a pretty poor display for the data, but the NASA astronauts were mostly former test pilots who demanded a familiar instrument.

At the center of the display is the miniature airplane icon, indicating the postion of the ship's nose. It is painted on the glass cover since it does not move. Underneath is the sky ball, with a grid painted on. The sky sphere does rotate in place. The position of the miniature airplane on the sky ball shows what position on the celestial sphere the ship's nose is aimed at.

Primitive displays are vulnerable to the dread horror of gimbal lock, but modern ones are immune. If the ship is really primitive it might have to make do with a coelostat instead of an attitude indicator.

The attitude indicator has two modes, only one of which we are interested in.

The first mode is where the ball mirrors the celestial sphere around the ship, and is only of interest to astrogators (the ball is slaved to the inertial guidance platform). The miniature airplane will be over the part of the sky ball corresponding to the point on the celestial sphere the ship's nose is aimed at. The three scales around the ball show the rate at which the spacecraft is yawing, pitching, and rolling.

The second mode is where the pilot dials in the required ship's nose position for the next burn (on the main control panel), and the ball shows how far off the actual ship's nose is from where it should be (the ball is slaved to the gyro display coupler). When the ship's nose is on target, the miniature airplane will be over the sky ball's north pole. The three scales around the ball show how far off the nose is from being on target (the technical term is "attitude errors"). The pilot then uses the rotation controls while watching the attitude indicator, and moves the ship's nose into position. During the burn, the pilot keeps an eye on the attitude indicator, ready to correct things if the nose drifts off target.

In more sophisticated control boards, the attitude errors can be slaved to the attitude jets, so the spacecraft will automatically put and keep the ship's nose on target. Which of course gives space pilots anxiety about job security.


In the game Kerbal Space Program the display is slightly different, and a lot of the work is done automatically for you. The miniature aircraft is called the "level indicator". The astrogator will use Map View with maneuver nodes to set up the maneuver. A "maneuver icon" will magically appear on the nav ball. This is the point where the ship's nose should be pointed. So the pilot's job is to keep the level indicator on the maneuver icon. A variety of other informative icons will also be automatically added to the nav ball as needed.

The sky ball does not correspond to the celestial sphere, nor is is zeroed in on the burn target. Instead it is always set so the center of the brown "ground" hemisphere is aimed at the nearest planet or moon. This makes it easier for players to enter into orbits around planets.

The prograde icon is where the ship's current vector is pointing. The retrograde icon is the exact opposite direction. Since the ship's trajectory is generally a curve, these icons will move with time. If the level indicator is over the prograde and a burn is made, the ship will maximally accelerate. If the level indicator is over the retrograd and a burn is made, the ship will maximally decelerate. If the level indicator is anywhere else and a burn is made, it will do something in between.

If the astrogator enters Map View and selects another ship as a "target", the two target icons will appear on the nav ball. The target prograde icon the point in the sky where the target appears, from the ship's point of view. The target retrograde icon is the opposite point in the sky. Placing the level indicator over the target prograde and burning will start altering the ship's trajectory towards the target. And the opposite for the target retrograde icon. And both icons will be moving, since both the ship and the target are too.


Heinlein short stories have rockets with a coelostat for use as an attitude display. The coelostat is the old-school clunky percursor to the artificial horizon. It is a series of prisms. For a given burn, once the astrogator has calculated the direction of the axis of acceleration, they will calculate how to set the prisms on the coelostat. The settings for each prism will be passed to the pilot, along with the burn start time and amount of delta V. When the pilot sets the coelostat, each prism will reflect a "guide star" onto a screen with cross hairs. (say, three prisms using Vega, Antares, and Regulus) When the ship is pointed in the correct direction, all the guide stars will be dead center in the cross hairs. If the nose is not pointed properly, the guide stars will be all over the screen. G. Harry Stine calls this instrument an "astrostat".

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.

From Spacehounds of IPC by E.E. "Doc" Smith (1931)

Time Display

The time is displayed by the ship's chronometer. Both the astrogator and the pilot are obsessed with keeping the chronometer accurate, because mistiming a burn is a good way to doom the ship to a slow journey to oblivion.


In the game Kerbal Space Program there are two substitutes for a chronometer.

[1] The pilot can enter Map view and see the planets, moons, and ships like an animated diagrame of the solar system (an orrey in other words). The pilot can fly by the seat of their pants by starting the burn when the ship reaches certain marked points, such as apoapsis and periapsis.

[2] The astrogator can use Map view and maneuver nodes to create a maneuver. The maneuver parameters are automatically sent to the nav ball display in front of the pilot. Next to the nav ball, a count-down timer will tell the pilot when to start the next burn (and they had better have the ship's nose pointed properly by then).

The burn start time as given by the astrogator should actually occur at the mid-point of the burn. First the pilot will figure the total burn duration needed to generate the specifed delta V. Divide burn duration by 2, and subtract this from the astrogator-supplied burn start time. In Kerbal, the burn duration is helpfully displayed next to the nav ball, 12 seconds in the case of the illustration.

Example

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

Delta-V Display

The delta V is displayed by a pendulous integrating gyroscopic accelerometer, or by a laser gyroscope attached to a microprocessor. On the Apollo command module, the delta V was displayed on the entry monitoring system (see illustration). The use of the EMS is an example of redundancy in the Apollo design. Delta V could be measured via the main command module guidance and nav inertial system, but this is more complex and liable to errors due to drift. The fixed EMS accelerometer provides a simple, reliable means of making this critical measurement.

In more primitive rockets they have no fancy delta V displays. Instead they do it by dead reckoning. The duration of thrust required to create the needed delta V is calculated, and a brennschluss timer is used to keep the engine thrusting for exactly the corrent amount of time.


In the game Kerbal Space Program the amount of delta V required for a maneuver is displayed as a green arc to the right of the nav ball.

Atomic Rocket Pilot Control Console

This amusing example of 1960's style user interface design is from NUCLEAR SPACE PROPULSION by Holmes F. Crouch (1965). This complements the Engineer's console from the same book. This design assumes that it is for a solid-core nuclear thermal rocket. Mr. Crouch decided that controlling the rocket's trajectory while simultaneously juggling the power levels of the nuclear reactor was a little too much to ask of a single human being, so he split it into two jobs. Each subsystem has too many displays, control functions, and automatic interlocks.

According to Mr. Crouch, there are four independent subsystems involved with flying a nuclear thermal rocket:

  1. Thrust vectoring (Engine exhaust nozzle)
  2. Spacecraft orientation and stability (Attitude jets)
  3. Heat generation for specific impulse (Reactor)
  4. Propellant flow (Turbopump)

The pilot will be controlling the thrust vectoring and spacecraft orientation, the engineer will be controlling heat generation and propellant flow. So the pilot is flying the rocket, while the engineer is flying the reactor and turbopump.

The "space scanner" is an array of displays showing TV field of vision views fore, port, starboard, dorsal, and ventral; plus radar views.

Above is the collision detector. If anything is on a collision course, the light will flash, the buzzer will buzz, the linear range will display how far away it is, and the range rate will display how fast it is approaching. The way to avoid collision is to do a short thrust in any direction. For reasons explained in more detail here, the simple way to detect a collision is to have the radar watch for any object that maintains a constant bearing while having a range that decreases.

Around the space scanner are panels displaying astronomical data, navigational data (including an accelerometer, chronometer, coelostat, integrating accelerograph, brennschluss timer, and gyroscopic artificial horizon. Not to mention radar plotted trajectories of all other spacecraft and objects in the vicinity), astrophysical data (including solar storm warnings), and radio communications.

The pilot has two 3-axis joysticks, sorry, Translational Hand Controllers and Rotational Hand Controllers. The left is a rotational controller. It activates the attitude jets in order to control the spacecraft orientation (basically which way the nose is pointing and thus the direction of thrust). The right is a translational controller. It controls the thrust vectoring of the engine. This allows "translation control", which is a fancy term for moving the ship left or right without turning the nose in that direction. This also allows thrust neutralization. This means letting the engine blast but with no thrust. You need this because a nuclear thermal rocket relies upon the propellant to cool off the reactor, sometimes the reactor needs coolant when the ship does NOT need to be thrusted. Please not that for translations, an engine is limited to vectoring the thrust to no more than ten degrees or so off-axis.

Each hand controller would be fitted with step and trim buttons to throttle and vernier the maneuver commands as desired. Note that the hand controllers are analogous to the Ship's Wheel on a sea going vessel. The compass and the windows are like the other displays.

Finally there is the Thrust Mode Selector. This is basically a glorified Engine Order Telegraph from the age of steam. The pilot uses it to tell the engineer what sort of thrust is required. It is then the engineer's job to juggle the reactor control rod and the propellant turbines to produce what is requested. When the engineer has the engine configured to the requested thrust mode, they turn on the appropriate yes/no light on the pilot's console (next to the thrust mode line) to indicate the state of nuclear readiness.

On an old-time engine order telegraph, the pilot uses the lever to set the desired engine setting. The engine crew acknowledge the order on their own telegraph. At the pilot's telegraph, the acknowledgement moves the tiny inner arrow. This should move so it matches the pilot's setting, otherwise Something Is Wrong. This includes both no acknowledgement and incorrect acknowledgement. In that case, the pilot repeats the setting on the telegraph. If things are still wrong, the situation is immediately reported to the officer of the deck (unless the officer of the deck is also the current pilot, of course).

Sometimes a situation will develop in the engine, and the engineer will have to alter the thrust mode due to the measures taken to prevent the reactor from melting down or doing something else unfortunate. The engineer will probably not bother manually changing the thrust mode yes/no lights (as you would with an order telegraph on a steam ship), instead they will hit the "discoverer" button and the big red nuclear disaster alarm on the pilot's console will start screaming.

Other Controls

What else is in the control room? A radarscope, accelerometer, gyroscope platform, periscope, and chronometer. And maybe an integrating accelerograph. This will display elapsed time, velocity, and distance in dead-reckoning for empty space. If the spacecraft is under programmed controls, the programmed values for the three items will be displayed below the actual values, so the pilot can see how results matched prediction.

Another important item is the control panel lock. When the lock engaged, all the other controls are locked in place. So the pilot can sleep in their chair and not have to worry about accidentally brushing a toggle switch. This also comes in handy if the pilot is forced to allow into the control room a bratty kid who just happens to be the son of the boss.

A control of dubious utility is the three-position control switch. It is available if one has duplicate sets of controls for pilot and co-pilot. The control switch is labeled "Pilot & Co-Pilot", "Pilot only" and "Co-Pilot only". It determines which sets of controls are live. One would expect to find this only on a training spacecraft, or if you would commonly expect a non-pilot to be occasionally riding in one of the control seats.

There may also be repeater displays. Such as a red indicator light from the power room which will change to green when the power officer unlocks the safety on the reactor damper. Or maybe the colors will be the other way around, depending upon how much you trust the reactor.

User Interface

Displays

The three types of instrument displays are Analog, Digital, and Binary. Analog are typically circular like a clock with hands, semicircular like a multimeter or some automobile speedometers, or tape-like similar to a ruler. Digital displays numbers, such as an automobile odometer or a pocket calculator. Binary are "idiot lights" that are either on or off.

The advantage of analog is in displaying the relationship between the current reading and any "red-line" minimum or maximum. The gas (petrol) gauge on an automobile typically has a red area adjacent to "Empty" as a warning that you'd better fill your tank soon. Analog displays are also good at showing the rate of change. You can tell at a glance if the temperature is rising too quickly. The disadvantage of analog displays is that they can seldom be read with more than three figures of accuracy.

The advantage of digital displays is that it can be read with as many figures of accuracy as there are digits in the display. Disadvantages include having memorize what the red-line values are, and not being able to read the display if the figures change so rapidly as to be a blur.

The advantage of binary displays is the simplicity of an immediate warning. Disadvantages include the necessity of a test mode (so you can tell if an indicator light has burnt out) and the lack of extra information. Airplane pilots have many worries when they hit the "lower the landing gear" button and the "landing gear down" binary display fails to light up. Is the gear still up, or is gear actually down but the light is burnt out or the sensor wiring connection loose? All you can do is make a low pass by the control tower so they can look at the status of your landing gear. An analog or digital display with the angle of gear would avoid that worry.

Physical Interface

"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'monn 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."

From the introduction to the wargame BATTLEFLEET MARS by Redmond Simonsen

Programmable Interface

Audiopad

The Audiopad is an innovative music controller.

Whoever invented dynamic configs deserves a medal - I'd give him all of mine. Imagine the chaos we'd have without them. A kid joins the Navy on Viand, learns the ropes, and then musters out and joins a merchant company operating out of the Marches.

So what happens? The merchant vessel he's on was built by a company light-years away from the yard that fabbed the dreadnought. All the controls are different: the power switch that was under the thumb of his left hand is now under the third finger of his right. The heads-up attitude display is now flat on the board, and the blue light that signaled a problem is an amber one on the merchant. If he doesn't scuttle her first time out of the dock, you're lucky.

With a dynamic config, he keys in the layout he likes, and if he wants to further customize the panel, he moves the controls around and logs it in the computer so he can call it up any time he wants.

There are moments on the bridge, too many moments, that call for split-second thinking. You set that panel up to your liking - you live with that panel - you marry that panel - and it will always be right there when you need it. Your fingers (and feet, if you use them, but I never do) learn every inch of the board, and you can fly a ship in your sleep. A skilled crewman never looks at the controls - his eyes are on the tell tales and other displays.

If a man's skilled with the configs, too, he can handle any board in a crisis. Commo needs help set ting up a line-of-sight during a battle? Fine, if he's not tied up it takes him a second to pull up commo's board at his station. That's why it's so critical that your bridge crew be skilled at several tasks.

Personally, when I configure a panel I always ignore the leg controls. I don't stop my crew from using them, because a man knows what he likes or he doesn't know anything. But I was never much of a dancer, either, and I feel like my legs just flail around under the console.

I keep the most common controls under my index fingers, but I won't overlap. If there's two things I need to do at once, they've got to lie under different fingers. I'm left handed, so I put anything I need quick under those fingers. I use my thumbs as anchors, mostly. If controls need locked, sure, I'll put in a toggle where I want it, but if the control needs a sensitive touch but still must be held down, l put it under a thumb so the rest of my hand can still swivel around to all the positions.

Another good place for anchors is the little fingers. Little fingers are good, too, to set up alternative controls. For example, on my commo board I like my left index to handle fine tuning of radio frequency, but once I've zeroed in on what I want, that spot's wasted. So when I'm ready to transmit the burst, my right pinkie holds what I call my "second set". Then the burst pad is under my left index where fine tuning normally is. Once the burst is through, I let up my pinkie and I can reset the frequency if I want to. (ed note: In other words, the "second set" button is like the shift key on a computer keyboard.)

I keep any displays I want in front of me, using heads-up holo. If the station can't handle a holo, I'll use a data-display/recorder headpiece, but I don't like to because I get tired faster.

The main displays are right in front all the time. I map telltales to the center in a contrasting color - for the important ones, I use a mixture of red and green, chosen so they clash with each other. I don't like `em to blink, because I want to look at them and catch the info at any time. The split second between blinks might be the split second I need to make the decision. Choose your own colors; your eyes are different from mine.

I use my right third finger to move the telltale once I've spotted it, and I never use this finger for any other purpose on any board. The warning light appears, in the center as I said, then once I've noted it I punch the board and the light moves off to one side. They're all set so that if the condition lasts over a certain time, the telltale will reappear, and I'll just punch it over to the side again if I'm handling it. I want to know, but once it's in my brain I don't need to keep staring at the light all the time.

From MegaTraveller Starship Operator's Manual by Digest Group Publications

Brain-Computer Interface

Neuroprosthetics is connecting electronic equipment to the human nervous system. The most common example is the cochlear implant, but a lot of work has been done recently on connecting artificial arms to be controlled by nerves in the stump of the arm. In Samuel R. Delany's novel Nova, starship crew have neuroprothetic sockets in their wrists and at the base of their spine to issue commands to the starship equipment they operate. In David Drake's Counting the Cost military officers activate their implanted radio transceivers by willing their left little finger to crook. The finger does not move, the nerve impulse is re-routed to the transceiver.

A Brain–computer interface (BCI) uses electronics to directly communicate with the human brain itself, instead of just some nerve endings. This allows the pilot to issue commands to the spacecraft, mecha, or whatever. Sometimes the BCI can communicate back, with sensory information. In extreme cases the BCI can give the pilot the illusion that the entire spacecraft is their body. Also known as mind-machine interface (MMI), brain–machine interface (BMI), or direct neural interface.

The advantages are that the pilot can control the ship with the speed of thought instead of with slow clumsy hands, and the ship can be controlled while under such high acceleration that the g-force prevents lifting the hands to the control panel. Sometimes they are used to pilot man-amplifiers instead of spacecraft.

It can also be used to give the operator a "math coprocessor for their brain", that is, a way that the operator can simply think of the desired equation and the computer will instantly solve it and report it back.

There are draw-backs of course. The best control comes when the operator actually has the BCI surgically implanted in their brain instead of wearing an external headset (which is kind of invasive). If the interface is sensitive, a stray thought on the part of the operator can inadvertently send a catastrophic control command to the ship (Pilot: "Gee, the ground looks pretty down there..." BCI controlled ship instantly puts the ship into a crash dive and augers into the ground). And if the BCI sends back information to the brain, certain circumstances can trigger a disorienting feedback loop. Finally there is the "Monsters from the ID" problem.


BCI feedback is analogous to audio feedback.

Audio feedback can happen when you connect a microphone to an amplifier connected to a speaker. If you aim the mike at the speaker, you'll created an agonizing high-pitched feedback whine. What happens is that [a] random external noise enters mike [b] amplifier makes random noise louder and sends it out the speaker [c] amplified random noise leaves speaker and enters mike where it feeds back into another loop through the system. The noise rapidly becomes louder until you snatch the mike away from the speaker.

BCI feedback is when one is using the BCI for a math coprocessor input (or similar) and the math coprocessor sends the answer back. Otherwise the mechanism is much like with audio feedback. Operator thinks of some random garbage, coprocessor turns it into super-garbage and feeds it back, operator thinks about super-garbage, coprocessor turns it into super-duper-garbage and feeds it back, feedback look repeats until screaming operator yanks out the plug or goes insane from the flood of mental garbage. The solution is the mental discipline to keep a tight rein on the thoughts sent to the coprocessor.


Another danger is the "Monsters from the ID" problem. If your conscious mind can use the BCI to control the spacecraft, there is a danger that your subconscious mind can use the BCI as well. This is a problem since the subconscious is a lot more barbaric and impulsive than the conscious mind. This appears in the movie Forbidden Planet (see quote below) which is where the phrase "Monsters from the ID" originated.

It also appears in the 1963 episode of The Outer Limits titled "The Man With the Power", where the poor hen-pecked and demeaned professor has implanted in his brain a device that can manipulate objects through mind power. The US space agency wants this for astronaut to use to move asteroids and other objects. Unfortunately the man is constantly humiliated and bullied, as he swallows his frustration his angry subconscious uses the device to slay his persecutors. The man does not realize that he is the cause of the freak "accidents" that are killing everybody. Of course, neither did Dr. Morbius.

In Ben Bova's As on a Darkling Plain (1972), a mission is sent into the atmosphere of Jupiter, using a spacecraft that is also a high-pressure submarine. The pilot uses a BCI to control the vessel. Unfortunately, the pilot has mental issues and subconsciously wants to commit suicide. When it is time to leave Jupiter, the submarine diving planes are somehow locked into the "down" position, making it impossible to leave Jupiter. There are some tense times with the crew, until the pilot realizes that his subconscious is secretly locking the diving planes. The pilot disconnects from the BCI, puts in a substitute pilot, and the ship escapes Jupiter.

In Daniel Galouye's Lords of the Psychon (1963), the alien invaders use "psychon plasma" as their machines, a weird substance that can be controlled by conscious thought. Unfortunately it can be controlled by unconscious thought as well. Psychon plasma will instantly manifest all of a person's deep seated psychoses and other horrors lurking in the depths of their subconscious, sometimes with lethal results. Actually, the psychon plasma merely creating a visual image of the observer's subconscious fears is enough to drive a person into insanity. It can only be safely handled by a person who has somehow psychologically purged their subconscious to become perfectly mentally balanced. The novel does not mention it, but I'm sure the psychon plasma is perfectly capable of lashing out at other people besides the controller, and the dangerous aspects can be amplyfied by BCI feedback (see quote below from Invaders from the Infinite).


BCI have made an appearance in many works of science fiction, such as the movies Forbidden Planet, Pacific Rim, The Matrix, Ghost in the Shell, "The Man With the Power"; and in novels such as Neuromancer, Nova, Forever Peace, The Genesis Machine, As on a Darkling Plain, Skylark of Valeron, Invaders from the Infinite, Crown of Infinity, and The Halcyon Drift.

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.

From The Halcyon Drift by Brian Stableford (1972)

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.

From Crown of Infinity by John Faucette (1968)

(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, sending it to slay any man who looks lustfully at Morbius' beautiful nubile daughter.)

From Forbidden Planet (1956)

(ed note: this is an example of a BCI that is too sensitive. )

"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."

From Skylark of Valeron by E. E. "Doc" Smith (1934)

(ed note: this is an example of BCI feedback. )

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.”

From The Genesis Machine by James P. Hogan (1978)

(ed note: this is an example of BCI feedback. )

"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.'

From Invaders From the Infinite by John W. Campbell Jr. (1961)

Cams

For complicated maneuvers, one programs the controls with an autopilot. Nowadays one uses computers. In pre-computer days, they "cut a cam". A cam operates in a similar fashion to the paper roll on a player piano. When I was little they were all the rage in motorized toys, to program various movement patterns. But those have gone the way of eight track tapes and slide rules.

Currently the only place one is likely to encounter a cam in on the camshaft in the engine of your automobile. Each cam is a "program" that controls the state of the intake and exhaust valves, synchronizing them to the position of the pistons.

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.

From Rocket Ship Galileo by Robert Heinlein, 1947

Logs

Last but not least is the pilot's logbook in the corner. Or log tape. Or DVD. Or holographic crystal. Or whatever.

Space Jockey

When the Skysprite locked in with Supra-New York, Pemberton went to the station’s stellar navigation room. He was pleased to find Shorty Weinstein, the computer, on duty. Jake trusted Shorty’s computations—a good thing when your ship, your passengers, and your own skin depend thereon. Pemberton had to be a better than average mathematician himself in order to be a pilot; his own limited talent made him appreciate the genius of those who computed the orbits.

"Hot Pilot Pemberton, the Scourge of the Spaceways — Hi!" Weinstein handed him a sheet of paper.

Jake looked at it, then looked amazed. "Hey, Shorty—you’ve made a mistake."

"Huh? Impossible. Mabel can’t make mistakes." Weinstein gestured at the giant astrogation computer filling the far wall.

"You made a mistake. You gave me an easy fix — ‘Vega, Antares, Regulus.’ You make things easy for the pilot and your guild’ll chuck you out." Weinstein looked sheepish but pleased.


Pemberton fed Weinstein’s tape into the robot-pilot, then turned to Kelly. "Control ready, sir."

"Blast when ready, Pilot." Kelly felt relieved when he heard himself make the irrevocable decision.

Pemberton signaled the Station to cast loose. The great ship was nudged out by an expanding pneumatic ram until she swam in space a thousand feet away, secured by a single line. He then turned the ship to its blast-off direction by causing a flywheel, mounted on gimbals at the ship’s center of gravity, to spin rapidly. The ship spun slowly in the opposite direction, by grace of Newton’s Third Law of Motion.

Guided by the tape, the robot-pilot tilted prisms of the pilot’s periscope (coelostat) so that Vega, Antares, and Regulus would shine as one image when the ship was headed right; Pemberton nursed the ship to that heading … fussily; a mistake of one minute of arc here meant two hundred miles at destination.

When the three images made a pinpoint, he stopped the flywheels and locked in the gyros. He then checked the heading of his ship by direct observation of each of the stars, just as a salt-water skipper uses a sextant, but with incomparably more accurate instruments. This told him nothing about the correctness of the course Weinstein had ordered—he had to take that as Gospel—but it assured him that the robot and its tape were behaving as planned. Satisfied, he cast off the last line.

Seven minutes to go—Pemberton flipped the switch permitting the robot-pilot to blast away when its clock told it to. He waited, hands poised over the manual controls, ready to take over if the robot failed, and felt the old, inescapable sick excitement building up inside him.


He caught a last look through the periscope. Antares seemed to have drifted. He unclutched the gyro, tilted and spun the flywheel, braking it savagely to a stop a moment later. The image was again a pinpoint. He could not have explained what he did: it was virtuosity, exact juggling, beyond textbook and classroom.

Twenty seconds … across the chronometer’s face beads of light trickled the seconds away while he tensed, ready to fire by hand, or even to disconnect and refuse the trip if his judgment told him to. A too-cautious decision might cause Lloyds’ to cancel his bond; a reckless decision could cost his license or even his life—and others.

But he was not thinking of underwriters and licenses, nor even of lives. In truth he was not thinking at all; he was feeling, feeling his ship, as if his nerve ends extended into every part of her. Five seconds … the safety disconnects clicked out. Four seconds … three seconds… two seconds… one—He was stabbing at the hand-fire button when the roar hit him.

Kelly relaxed to the pseudo-gravity of the blast and watched. Pemberton was soberly busy, scanning dials, noting time, checking his progress by radar bounced off Supra-New York.

Weinstein’s figures, robot-pilot, the ship itself, all were clicking together.

Minutes later, the critical instant neared when the robot should cut the jets. Pemberton poised a finger over the hand cut-off, while splitting his attention among radarscope, accelerometer, periscope, and chronometer. One instant they were roaring along on the jets; the next split second the ship was in free orbit, plunging silently toward the Moon. So perfectly matched were human and robot that Pemberton himself did not know which had cut the power.


No co-pilot is needed in space and most pilots would rather share a toothbrush than a control room. The pilot works about an hour at blast off, about the same before contact, and loafs during free flight, save for routine checks and corrections. Pemberton prepared to spend one hundred and four hours eating, reading, writing letters, and sleeping—especially sleeping.


(Spoiled brat of a kid, son of company exec, gets to the control panel and starts a random burn, due to poor impulse control issues. Clueless father insists that his precious little snowflake could not have possibly done such a naughty thing, and in any event no harm was done. Pilot disagrees.)

"No harm, eh? How about broken arms—or necks? And wasted fuel, with more to waste before we’re back in the groove. Do you know, Mister ‘Old Spacehound,’ just how precious a little fuel will be when we try to match orbits with Space Terminal—if we haven’t got it? We may have to dump cargo to save the ship, cargo at $60,000 a ton on freight charges alone. Fingerprints will show the Commerce Commission whom to nick for it."

When they were alone again Kelly asked anxiously, "You won’t really have to jettison? You’ve got a maneuvering reserve."

"Maybe we can’t even get to Terminal. How long did she blast?"

Kelly scratched his head. "I was woozy myself."

"We’ll open the accelerograph and take a look."

Kelly brightened. "Oh, sure! If the brat didn’t waste too much, then we just swing ship and blast back the same length of time."

Jake shook his head. "You forgot the changed mass-ratio."

"Oh … oh, yes!" Kelly looked embarrassed. Mass-ratio under power, the ship lost the weight of fuel burned. The thrust remained constant; the mass it pushed shrank. Getting back to proper position, course, and speed became a complicated problem in the calculus of ballistics. "But you can do it, can’t you?"

"I’ll have to. But I sure wish I had Weinstein here."

Kelly left to see about his passengers; Jake got to work. He checked his situation by astronomical observation and by radar. Radar gave him all three factors quickly but with limited accuracy. Sights taken of Sun, Moon, and Earth gave him position, but told nothing of course and speed, at that time—nor could he afford to wait to take a second group of sights for the purpose.

Dead reckoning gave him an estimated situation, by adding Weinstein’s predictions to the calculated effect of young Schacht’s meddling. This checked fairly well with the radar and visual observations, but still he had no notion of whether or not he could get back in the groove and reach his destination; it was now necessary to calculate what it would stake and whether or not the remaining fuel would be enough to brake his speed and match orbits.

In space, it does no good to reach your journey’s end if you flash on past at miles per second, or even crawling along at a few hundred miles per hour. To catch an egg on a plate — don’t bump!

He started doggedly to work to compute how to do it using the least fuel, but his little Marchant electronic calculator was no match for the tons of IBM computer at Supra-New York, nor was he Weinstein. Three hours later he had an answer of sorts.


He called the radio room. "Get me Weinstein at Supra-New York."

"Out of normal range."

"I know that. This is the Pilot. Safety priority—urgent. Get a tight beam on them and nurse it."

"Uh … aye aye, sir. I’ll try."

Weinstein was doubtful. "Cripes, Jake, I can’t pilot you."

"Dammit, you can work problems for me!"

"What good is seven-place accuracy with bum data?"

"Sure, sure. But you know what instruments I’ve got; you know about how well I can handle them. Get me a better answer."

"I’ll try." Weinstein called back four hours later. "Jake? Here’s the dope: You planned to blast back to match your predicted speed, then made side corrections for position. Orthodox but uneconomical. Instead I had Mabel solve for it as one maneuver."

"Good!"

"Not so fast. It saves fuel but not enough. You can’t possibly get back in your old groove — and then match T without dumping."

Pemberton let it sink in, then said, "I’ll tell Kelly."

"Wait a minute, Jake. Try this. Start from scratch."

"Huh?"

"Treat it as a brand-new problem. Forget about the orbit on your tape. With your present course, speed, and position compute the cheapest orbit to match with Terminal’s. Pick it!, new groove."

Pemberton felt foolish. "I never thought of that."

"Of course not. With the ship’s little one-lung calculator it’d take you three weeks to solve it. You set to record?"

(of course nowadays the computing power of tons of IBM computer at Supra-New York will fit in a cell phone)

"Sure."

"Here’s your data." Weinstein started calling it off. When they had checked it, Jake said, "That’ll get me there?"

"Maybe. If the data you gave me is up to your limit of accuracy; if you can follow instructions as exactly as a robot, if you can blast off and make contact so precisely that you don’t need side corrections, then you might squeeze home. Maybe. Good luck, anyhow." The wavering reception muffled their goodbyes.

Jake signaled Kelly. "Don’t jettison, Captain. Have your passengers strap down. Stand by to blast. Minus fourteen minutes."

"Very well, Pilot."


Around the bulge of the Moon, Terminal came into sight — by radar only, for the ship was tail foremost. After each short braking blast Pemberton caught a new radar fix, then compared his approach with a curve he had plotted from Weinstein’s figures—with one eye on the time, another on the ‘scope, a third on the plot, and a fourth on his fuel gages.

From Space Jockey by Robert Heinlein (1947)