NASA learned early on that the decompression problems of soft space suits could be avoided if hard-shelled full pressure suits were used. If a soft suit was full pressurized, the astronaut would be splayed out like a starfish and probably could not bend their arms or legs. A hard suit does not have that problem, but instead has the problem of wearing out the astronaut. They are about as easy to work in as a set of medieval plate armor constructed of pure osmium. So NASA looked into adding a powered exoskeleton to the suit, to reduce the muscle strain on the astronaut. NASA eventually decided it was not worth the effort, but the idea just wouldn't go away. Especially if the powered exoskeleton is attached to a suit of armor. It would be "powered armor".

And it took about five minutes for science fiction writers to figure out if you put weapons on on the armor you'd have an unstoppable one-man-army suit that would let a 99 pound weakling beat the snot out of Superman.


The Operator is the entity operating the man amplifier, either a person or a computer running either simplistic pre-programmed task software (i.e., a Roomba vacuum cleaner) or full-fledged AI software (i.e., Ultron).

If the operator is a computer, the man amplifier is classified as a robot.

The Controls are how the operator issues commands to the man amplifier.

A Game Gontroller is a set of joysticks and a keyboard, or something along those lines.

An exoskeleton motion capture system (exo-mocap) is something attached to various portions of the operator's body to measure body motions, such as waldo hands, power gloves, or even a full-body frame. An exo-mocap for human form fitting man amplifiers sometimes use negative feedback. Exo-mocap for huge man amplifiers or remote controlled drones sometimes use haptic feedback. This means the operator is suspended inside the exoskeleton, and the exoskeleton is forced to conform to the current position of the remote drone. This allows the operator to do things like climb stairs and feel when the drone has walked into a brick wall.

A Brain—computer interface (BCI) uses electronics to directly communicate with the human brain in order to issue commands to the man amplifier. Sometimes the man amplifier can communicate back, with sensory information or with enslaving thought control. Also known as mind-machine interface (MMI), brain—machine interface (BMI), or direct neural interface.

In the movie Pacific Rim, the Humongous Mecha each have not one, but two pilots who do synchronised piloting. This seemed like a pretty stupid idea to me, until I read this report. Apparently with a BCI, a single pilot has an accuracy of 67%, but dual pilots have an accuracy of 90%. Reaction times are halved. And momentary lapses of attention are not quite as fatal, since the other pilot is hopefully still on the job. The technical term is "collaborative BCI".

Sometimes the man amplifier also has "computerized reflexes", to automatically react common situations, e.g., tripping over an obstacle or unexpectedly coming under sniper fire.

A Powered-exoskeleton is a human shaped external skeleton constructed of strong materials, with powerful electronic servomotors or hydraulic actuators replacing human muscles.

Definition: Man Amplifier

Man Amplifier: A more or less human sized powered-exoskeleton controlled by an internal exo-mocap with a human operator. In some cases the powered-exoskeleton and the exo-mocap are merged into a single unit. Generally the exo-mocap uses negative feadback. It is called a "man amplifier" because it literally amplifies the person's strength.

For an in-depth analysis on combat exoskeletons, read this article at the always erudite Future War Stories.

Definition: Prosthesis

Prosthesis: In this context, a Man Amplifier whose main purpose it to allow disabled persons to use their arms and/or legs.

Definition: Powered Armor

Powered Armor: An armor-plated Man Amplifier, generally with assorted integral weapons and battlefield sensors. May have a supplemental BCI.

For an in-depth analysis on powered armor, read this article at the always worth reading Future War Stories.

Definition: Mecha

Mecha: A larger than human sized powered-exoskeleton controlled by a human operator in an internal control cabin (generally in the Mecha's head or chest) via a game controller, exo-mocap, or BCI. If controlled by exo-mocap, usually has haptic feedback. Generally armor-plated and be-weapon-ed. According to TV Tropes tank-sized mecha are "Mini Mecha" and mecha which are several stories tall are "Humongous Mecha". As they put it, if the operator can be described as a "pilot" or "driver", then you have a Mini Mecha on your hands.

Definition: Telerobotics

Telerobotics aka "Drone" or "Remote": In this context, a man amplifier, powered armor, or mecha where the human operator is not inside the machine, but instead is located at some distance using remote control. Control is by either game controller, exo-mocap, or BCI. If controlled by exo-mocap it almost invariably has haptic feedback. If it has weapons, it may or may not have armor, depending upon how expendable it is.

Definition: Cyborg

Cyborg: In this context, a Man Amplifier that is surgically embedded inside the human operator's body. Sometimes also includes other enhancements, such as sensors, life support gear, replacement organs, armor and weapons. Aka "bionics", "six million dollar man".

Definition: Robot

Robot: A man amplifier, powered armor, or mecha where the operator is a computer. Stupid robots only perform pre-programmed tasks (and steal jobs from automobile construction workers). Smart robots with artificial intelligence are disturbing, Asimov's Four Laws of Robotics notwithstanding.


There are several challenges standing in the way of creating a useful man amplifier. The primary difficulty is the power supply. The first Iron Man movie got that right, the most important invention of all was the "arc reactor", the miniature fusion reactor that supplies almost unlimited power. Real world man amplifiers use non-rechargeable primary cells, internal combustion engines, and electrochemical fuel cells. These can only power the amplifier for a few hours. For many applications the designers give up and tether the man amplifier to a huge power generator via a power cable.

The material used to construct the exoskeleton is a problem. Aluminum is inexpensive, lightweight, does not stress the motors, and easy to mold. But if the operator is holding an automobile over their head and the aluminum decides to fold up like an accordion (i.e., "fail catastrophically in a high-load condition), the operator will be left feeling quite flat. There are safer but more expensive options like titanium and molded carbon-fiber plates.

The joint actuators (motors) are a problem. Hydraulics have the power and the accuracy, but are heavy due to the fluid-filled hoses and actuator cylinders, and tend to leak hydraulic fluid everywhere. Pneumatics are lighter but since gas is springy the accuracy suffers. Electronic servomotors are a better choice. They are more efficient and power-dense.

Joints are a problem. Human hips and shoulders are ball and socket joints, it is almost impossible to match all the possible human movements with an exoskeleton using single-axis hinges. This limits the operator's flexibility. An exoskeleton with external ball and socket joints have a problem with the series of joints being forced into misalignment. Using a hollow spherical ball joint that encloses the human joint is a better solution, but requires telescoping plates. And the problem of joints in the arms and legs are trivial compared to the nightmare of duplicating the human spine.

Power control and modulation are a problem. The actuators have to not move too fast, over shoot, or otherwise lag behind the operators movement.

Detection of unsafe motions is a problem. You do not want the man amplifier moving in such a way that it breaks the operator's arm, or damages another part of the exoskeleton.

Pinching and joint fouling is a problem. You do not want any part of the exoskeleton's hinges savagely pinching the skin of the operator, nor do you want environmental dust and grit getting into the joints.

Early History

Yes, all you young whipper-snappers think that powered armor is the latest cool thing since the first Iron Man movie came out in 2008. Well, as it turns out, the concept goes a long ways back. Even Iron Man himself goes a ways back, he first appeared in a comic book called Tales of Suspense #39 in March 1963.

The concept of a powered fighting suit arguably dates back to E. E. "Doc" Smith's Children of the Lens (1947) with Kimball Kinnision's armored suit made of pure dureum a quarter of an inch thick. Doc Smith had armored suits back in 1937 with Galactic Patrol but those were not power-assisted. Later came Robert Heinlein's classic Starship Troopers (1959). In "Champion Robot" by E R James (1953), "Creakyfoot" is an eight foot high powered suit for use on farms and in factories. And before that, there were all sorts of bizarre patients for assisted walking/running machines powered by compressed air, wind-up springs, and steam.

Post 1960's powered armor will be covered in the subsequent sections.

The dureum inlay of the glove held, and glove and axe smashed together against the helmet. The Boskonian went down with a crash; but, beyond a broken arm or some such trifle, he wasn’t hurt much. And no armor that a man had to carry around could be made of solid dureum. Hence, Kinnison reversed his weapon and swung again, aiming carefully at a point between the inlay strips.

The Lensman landed, and made his way to Harkleroy’s inner office in what seemed to be an ordinary enough, if somewhat over-size, suit of light space-armor. But it was no more ordinary than it was light. It was a power-house, built of dureum a quarter of an inch thick. Kinnison was not walking in it; he was merely the engineer of a battery of two-thousand-horsepower motors. Unaided, he could not have lifted one leg of that armor off the ground.

Inch by inch, foot by foot, Kinnison fought his way back along the corpse-littered corridor. Under the ravening force of the attackers’ beams his defensive screens flared into pyrotechnic splendor, but they did not go down. Fierce-driven metallic slugs spanged and whanged against the unyielding dureum of his armor; but that, too, held.

Dureum is incredibly massive, unbelievably tough, unimaginably hard— against these qualities and against the thousands of horsepower driving that veritable tank and energizing its screens the zwilniks might just as well have been shining flashlights at him and throwing confetti. His immediate opponents could not touch him, but the Boskonians were bringing up reserves that he didn’t like a little bit; mobile projectors with whose energies even those screens could not cope.

From Children of the Lens by E. E. "Doc" Smith (1947)

Man Amplifier

Originally developed for construction work and back-echelon pack horsing, the General Motors Terrain Walker was quickly accepted by the armies of America, Earth, when it was proved that the machine could carry a gun. Standing twelve feet tall and weighing eight tons, the Walker could stride down a highway at 30 mph and do 20 mph on rough terrain, such as burnt-out slums.

Nuclear powered, it required little servicing and often powered its weapons directly from its own power system. Great hydraulic pistons operated its arms and legs, which followed every movement made by the pilot. The pilot was strapped in a control cradle that translated every motion to the Walker, and he had a clear view fore and aft through a Plexiglas bubble.

The Walker was equipped with a wide range of sensory devices, among them snooper-scopes, radar, amplified hearing, some primitive smell-detection devices and tactile pads on the hands and feet, all of which were wired to the pilot.

The Walkers were instrumental in assisting in heavy construction. They rebuilt the foundations of cities, realigned the world's power conduits, built dams and, in one fierce burst of zealous activity, built almost a hundred thousand miles of beautiful roadway in four years.

Three years after that commercial aircars were produced in profusion. The new roads were ignored and slowly cracked while approaching obsolescence.

From The Warbots by Larry S. Todd, Body Armor: 2000 (1986)


However, in 233 I.R. (473 A.D.), the Imperium finally made the contact which it had been dreading and preparing for so long; they met with a wandering IRSOL StarCity! This encounter in the otherwise undistinguished Vor Mean (evidently an IRSOL word) System was between the IRSOL StarCity Coroliss 'E' Nyalara and the 10783rd Imperial Exploration and Conquest Squadron under the command of Tara' Alon' T' Elar (Commodore) Shin' Alon (Winter Star).

At first, the IRSOL were overjoyed at meeting a fellow starfaring race, having not the slightest notion as to how the Korellians had gained their FTL technology. They even discounted the call by Commodore Shin' Alon for their unconditional surrender and submission to the Imperium; after all, they surmised, this was merely the bluster with which many races greeted First Contact.

They were rapidly disabused of their complacent attitudes when the Korellian Squadron launched a vicious, and quite unprovoked, attack on the city itself! Though the IRSOL StarForces were, technologically, far superior to the Korellians, the absolute surprise of both the attack and the callously suicidal nature of the tactics of the Korellians utilized in pursuit of their target meant that the initial attack wave got through relatively unopposed and inflicted shockingly heavy civilian casualties.

But worse was yet to come. A Korellian suicide ship managed, by good luck or good aim, to impact directly on the main BattleScreen generators. Before the backups could be activated, the Commodore won himself undying fame in the halls of his ancestors and, indeed, amongst Korells everywhere, by personally piloting his flagship directly into the central area of the city. This totally unexpected attack wiped out a full 73% of the city’s population in one blow — and set off her magazines in a sympathetic explosion. The repeated explosions from this source broke the StarCity's back and resulted in the death of a further 18% of the populace.

The remaining Korellian vessels, except for a few fighters which had been sent back as couriers, were ruthlessly hunted down by the vengeance hungry remnants of the IRSOL StarForces and no prisoners were taken.

From Space Opera: Star Sector Atlas 12 by Phil McGregor (1983)

They were looking ... at a handsome, shapely, dramatic-featured man, eight feet eight inches tall and massing 147 pounds with and ninety-seven pounds without his exoskeleton. Except for relaxed tiny bulges of muscle in forearms and calves (latter to work lengthy toes, useful in gripping), this man was composed of skin, bones, ligaments, fasciae, narrow arteries and veins, nerves, small-size assorted inner organs, ghost muscles, and a big-domed skull with two lumps of jaw muscle. He was wearing a skintight black suit that left bare only his sunken-cheeked, deep-eyes, beautiful tragic face and big, heavy-tendoned hands.

This truly magnificent, romantically handsome, rather lean man was standing on two corrugated-soled titanium footplates. From the outer edge of each rose a narrow titanium T-beam that followed the line of his leg, with a joint (locked now) at the knee, up to another joint with a titanium pelvic girdle and shallow belly support. From the back of this girdle a T-spine rose to support a shoulder yoke and rib cage, all of the same metal. The rib cage was artistically slotted to save weight, so that curving strips followed the line of each of his very prominent ribs.

A continuation of his T-spine up the back of his neck in turn supported a snug, gleaming head basket that rose behind to curve over his shaven cranium, but in front was little more than a jaw shelf and two inward-curving cheekplates stopping just short of his somewhat rudimentary nose...

Slightly lighter T-beams than those for his legs reinforced his arms and housed in their terminal inches his telescoping canes. Numerous black, foam-padded bands attached his whole framework to him.

...Eight small electric motors at the principal joints worked the prosthetic framework by means of steel cables riding in the angles of the T-beams, much like antique dentist drills were worked, I've read. The motors were controlled by myoelectric impulses from his ghost muscles transmitted by sensitive pickups buried in the foam-padded bands.

I tongued pep, instant glucose, and antigrav pills out of their cheekplate container into my mouth. Even the tiny dissolving pellets seemed heavy as osmium on my tongue, and they dropped down my throat like bullets. I followed them with a sip of truly heavy water from my other cheekplate, tilting my exoskulled head to do so.

From A Spectre is Haunting Texas by Fritz Leiber (1969)

Powered Armor


Some people would raise powered armor as the solution to this problem.  After all, if an infantryman can be given the firepower of a vehicle, there is no need for vehicles.  The problem with that is that there is virtually no reason to expect that practical powered armor will be developed in the PMF (Plausible Mid-Future).

First, we must define powered armor.  Powered armor is a suit that provides the infantryman with greater strength and protection than an unarmored infantryman while not interfering with his function as an infantryman.  The last part is critical.  The armored infantryman must still be able to do the jobs required of infantry, such as clearing buildings and going up stairs.  This in turn sets size and weight limits on the armor.  Current OSHA guidelines state that the design load for stairs is 510 lb.  Even assuming that all of that limit is available (ignoring things like old or rotten stairs, or stairs not built to code), an average combat-loaded modern infantryman (sans armor) still weighs approximately 225 lb., leaving 285 lb. available for the armor.  This number includes not only the armor itself, but also all of the various servos and power supplies necessary to run it.  As an example, the Lockheed HULC currently weighs 53 lb. without batteries and can carry about 200 lb.  However, it is only a lower-body system and must include its own structure, so given various developments, a total of 50 lb. for the entire power/servo system does not seem entirely out of the realm of possibility.  This leaves 235 lb. for armor.  Taking as a baseline current ESAPI (Enhanced Small Arms Protective Insert) plates, this translates to about 35 square feet of armor or 3.2 m2.

A typical adult male has a surface area of 1.9 m2, so this is a vaguely practical number for armor area once all the other stuff under the armor is taken into account.  The ESAPI plates are rated to resist WWII-vintage M2 .30 caliber armor-piercing rounds, but only when backed by the various plate carrier vests.  This means that the total surface area available would have to drop again, which in turn reduces the practicality of the system.  Even then, more modern 7.62 mm AP ammo would likely be able to defeat it, although solid information on this is difficult to find.  At one point, rifles in this caliber were standard-issue, and could be again if a need (such as defeating targets in powered armor) was there.  Such an evolution of weapons to counter increased armor has happened before.  In the 1500s, the standard gunpowder weapon was called an arquebus, and it was incapable of penetrating the increasing thicknesses of armor being worn on the battlefield.  A heavier gunpowder weapon, called the musket, was developed to defeat such armor.  Muskets made armor more or less obsolete, and once they had done that, they shrank to the size of the arquebus, absorbing it in the process.  

Increasing the weight of armor protection to defeat such threats moves the armor out of the category of “powered armor” and into the realm of “small vehicle”, which has the side-effect of removing the operator from the infantry.  As a friend of the author’s said “if you plan on having your infantry armed like tanks, and armoured like tanks, you shouldn't be surprised that they weigh as much as tanks.”  The small vehicles that would result have no parallel in modern warfare, casting doubt on their utility, and even if they were to prove useful, it is likely that they would not look like powered armor, due to the complex actuators and control systems required of such armor.  A small tracked or wheeled vehicle with a turret would be much more efficient, although it has been pointed out that it might also look quite a lot like a Dalek.

All of the above analysis assumes modern armor and weapons, and the assumption for application to the PMF is that the balance between armor and weapons will remain more or less constant.  This could obviously be flawed, but even if armor increases in power relative to weapons, the weapons used will be tailored to deal with the threat.  Small (~25 mm), low-power weapons that fire shaped charges would probably be effective if all else fails, absent special authorial pleading.  

The above is a best-case analysis. There are likely to be other complications from powered armor, such as reduced mobility (a problem in urban combat), increased ground pressure (a problem anywhere there is mud), increased logistics burden (a problem anywhere) and the fact that not all steps are built to OSHA specs.  The combat load of a soldier will also likely increase, and the number used above was for a basic rifleman only.  Grenadiers in the study referenced carried an extra 8.5 lb, and SAW gunners an extra 16 lb, to say nothing of the heavy weapons personnel, or even personnel who are simply heavier than average.  Add to this the fact that powered armor, both in fiction and in real life, is often touted as not only protecting the soldier, but also increasing his carrying capacity.  All of these combine to render powered armor a dubious proposition.  This is not to say that exoskeletons will not be useful for increasing the carrying capacity of soldiers, or that powered armor might not have a role in peacekeeping/counterinsurgency operations, where the enemy does not have access to modern weapons.  The problems of reliability and maintenance will also be major issues for a force that relies so much on very high-tech equipment.  Without real-world experience, it is difficult to determine how much maintenance powered armor would require, but even the most basic powered armor will be very complex compared to virtually all systems the infantry use today.  This is not a good thing when the system will be exposed to dirt, mud, debris, insufficient maintenance, and near-continuous use.  This in turn indicates that additional maintenance facilities above and beyond what is standard today will have to be dropped with the unit, exposing them to the orbital defenses.

by Byron Coffey (2016)

An M.I. lives by his suit the way a K-9 man lives by and with and on his doggie partner. Powered armor is one-half the reason we call ourselves "mobile infantry" instead of just "infantry." (The other half are the spaceships that drop us and the capsules we drop in.) Our suits give us better eyes, better ears, stronger backs (to carry heavier weapons and more ammo), better legs, more intelligence ("intelligence" in the military meaning; a man in a suit can be just as stupid as anybody else only he had better not be), more firepower, greater endurance, less vulnerability.

A suit isn't a space suit—although it can serve as one. It is not primarily armor—although the Knights of the Round Table were not armored as well as we are. It isn't a tank—but a single M.I. private could take on a squadron of those things and knock them off unassisted if anybody was silly enough to put tanks against M.I. A suit is not a ship but it can fly, a little; on the other hand neither spaceships nor atmosphere craft can fight against a man in a suit except by saturation bombing of the area he is in (like burning down a house to get one flea!). Contrariwise we can do many things that no ship—air, submersible, or space—can do.

No need to describe what it looks like, since it has been pictured so often. Suited up, you look like a big steel gorilla, armed with gorilla-sized weapons.

But the suits are considerably stronger than a gorilla. If an M.I. in a suit swapped hugs with a gorilla, the gorilla would be dead, crushed; the M.I. and the suit wouldn't be mussed.

The "muscles," the pseudo-musculature, get all the publicity but it's the control of all that power which merits it. The real genius in the design is that you don't have to control the suit; you just wear it, like your clothes, like skin. Any sort of ship you have to learn to pilot; it takes a long time, a new full set of reflexes, a different and artificial way of thinking. Even riding a bicycle demands an acquired skill, very different from walking, whereas a spaceship oh, brother! I won't live that long. Spaceships are for acrobats who are also mathematicians.

But a suit you just wear.

Two thousand pounds of it, maybe, in full kit—yet the very first time you are fitted into one you can immediately walk, run, jump, lie down, pick up an egg without breaking it (that takes a trifle of practice, but anything improves with practice), dance a jig (if you can dance a jig, that is, without a suit)—and jump right over the house next door and come down to a feather landing.

The secret lies in negative feedback and amplification.

But here is how it works, minus the diagrams. The inside of the suit is a mass of pressure receptors, hundreds of them. You push with the heel of your hand; the suit feels it, amplifies it, pushes with you to take the pressure off the receptors that gave the order to push. That's confusing, but negative feedback is always a confusing idea the first time, even though your body has been doing it ever since you quit kicking helplessly as a baby. Young children are still learning it; that's why they are clumsy. Adolescents and adults do it without knowing they ever learned it—and a man with Parkinson's disease has damaged his circuits for it.

The suit has feedback which causes it to match any motion you make, exactly—but with great force.

Controlled force ... force controlled without your having to think about it. You jump, that heavy suit jumps, but higher than you can jump in your skin. Jump really hard and the suit's jets cut in, amplifying what the suit's leg "muscles" did, giving you a three-jet shove, the axis of pressure of which passes through your center of mass. So you jump over that house next door. Which makes you come down as fast as you went up ... which the suit notes through your proximity & closing gear (a sort of simple-minded radar resembling a proximity fuse) and therefore cuts in the jets again just the right amount to cushion your landing without your having to think about it.

And that is the beauty of a powered suit: you don't have to think about it. You don't have to drive it, fly it, conn it, operate it; you just wear it and it takes its orders directly from your muscles and does for you what your muscles are trying to do. This leaves you with your whole mind free to handle your weapons and notice what is going on around you ... which is supremely important to an infantryman who wants to die in bed. If you load a mud foot down with a lot of gadgets that he has to watch, somebody a lot more simply equipped—say with a stone ax—will sneak up and bash his head in while he is trying to read a vernier.

Your "eyes" and your "ears" are rigged to help you without cluttering up your attention, too. Say you have three audio circuits, common in a marauder suit. The frequency control to maintain tactical security is very complex, at least two frequencies for each circuit both of which are necessary for any signal at all and each of which wobbles under the control of a cesium clock timed to a micromicrosecond with the other end—but all this is no problem of yours. You want circuit A to your squad leader, you bite down once—for circuit B, bite down twice—and so on. The mike is taped to your throat, the plugs are in your ears and can't be jarred out; just talk. Besides that, outside mikes on each side of your helmet give you binaural hearing for your immediate surroundings just as if your head were bare—or you can suppress any noisy neighbors and not miss what your platoon leader is saying simply by turning your head.

Since your head is the one part of your body not involved in the pressure receptors controlling the suit's muscles, you use your head—your jaw muscles, your chin, your neck—to switch things for you and thereby leave your hands free to fight. A chin plate handles all visual displays the way the jaw switch handles the audios. All displays are thrown on a mirror in front of your forehead from where the work is actually going on above and back of your head. All this helmet gear makes you look like a hydrocephalic gorilla but, with luck, the enemy won't live long enough to be offended by your appearance, and it is a very convenient arrangement; you can flip through your several types of radar displays quicker than you can change channels to avoid a commercial—catch a range & bearing, locate your boss, check your flank men, whatever.

If you toss your head like a horse bothered by a fly, your infrared snoopers go up on your forehead—toss it again, they come down. If you let go of your rocket launcher, the suit snaps it back until you need it again. No point in discussing water nipples, air supply, gyros, etc.—the point to all the arrangements is the same: to leave you free to follow your trade, slaughter.

But, in general, powered armor doesn't require practice; it simply does it for you, just the way you were doing it, only better. All but one thing—you can't scratch where it itches. If I ever find a suit that will let me scratch between my shoulder blades, I'll marry it.

There are three main types of M.I. armor: marauder, command, and scout. Scout suits are very fast and very long-range, but lightly armed. Command suits are heavy on go juice and jump juice, are fast and can jump high; they have three times as much comm & radar gear as other suits, and a dead-reckoning tracker, inertial. Marauders are for those guys in ranks with the sleepy look—the executioners.

STARSHIP TROOPERS by Robert Heinlein (1959)

(ed note: this was written before Pluto's moon Charon was discovered. In the novel Charon is an imaginary planet about twice as far from the Sun as Pluto is. It is cold enough to make Pluto seem like Miami Beach.)

"Now I know you got lectured back on Earth on what a fighting suit can do." The armorer was a small man, partially bald, with no insignia of rank on his coveralls. Sergeant Cortez had told us to call him "sir," since he was a lieutenant.

"But I'd like to reinforce a couple of points, maybe add some things your instructors Earthside weren't clear about or couldn't know. Your First Sergeant was kind enough to consent to being my visual aid. Sergeant?"

Coitez slipped out of his coveralls and came up to the little raised platform where a fighting suit was standing, popped open like a man-shaped clam. He backed into it and slipped his arms into the rigid sleeves. There was a click and the thing swung shut with a sigh. It was bright green with CORTEZ stenciled in white letters on the helmet.

"Camouflage, Sergeant." The green faded to white, then dirty gray. "This is good camouflage for Charon and most of your portal planets," said Cortez, as if from a deep well. "But there are several other combinations available." The gray dappled and brightened to a combination of greens and browns: "Jungle." Then smoothed out to a hard light ochre: "Desert." Dark brown, darker, to a deep flat black: "Night or space."

"Very good, Sergeant To my knowledge, this is the only feature of the suit that was perfected after your training. The control is around your left wrist and is admittedly awkward. But once you find the right combination, it's easy to lock in.

"Now, you didn't get much in-suit training Earthside. We didn't want you to get used to using the thing in a friendly environment. The fighting suit is the deadliest personal weapon ever built, and with no weapon is it easier for the user to kill himself through carelessness. Turn around, Sergeant.

"Case in point." He tapped a large square protuberance between the shoulders. "Exhaust fins. As you know, the suit tries to keep you at a comfortable temperature no matter what the weather's like outside. The material of the suit is as near to a perfect insulator as we could get, consistent with mechanical demands. Therefore, these fins get hot—especially hot, compared to darkside temperatures—as they bleed off the body's heat.

"All you have to do is lean up against a boulder of frozen gas; there's lots of it around. The gas will sublime off faster than it can escape from the fins; in escaping, it will push against the surrounding 'ice' and fracture it... and in about one-hundredth of a second, you have the equivalent of a hand grenade going off right below your neck. You'll never feel a thing.

"Variations on this theme have killed eleven people in the past two months. And they were just building a bunch of huts.

"I assume you know how easily the waldo capabilities can kill you or your companions. Anybody want to shake hands with the sergeant?" He paused, then stepped over and clasped his glove. "He's had lots of practice. Until you have, be extremely careful. You might scratch an itch and wind up breaking your back. Remember, semi-logarithmic response: two pounds' pressure exerts five pounds' force; three pounds' gives ten; four pounds', twenty-three; five pounds', forty-seven. Most of you can muster up a grip of well over a hundred pounds. Theoretically, you could rip a steel girder in two with that, amplified. Actually, you'd destroy the material of your gloves and, at least on Charon, die very quickly. It'd be a race between decompression and flash-freezing. You'd die no matter which won.

"The leg waldos are also dangerous, even though the amplification is less extreme. Until you're really skilled, don't try to run, or jump. You're likely to trip, and that means you're likely to die."

"Charon' s gravity is three-fourths of Earth normal, so it's not too bad. But on a really small world, like Luna, you could take a running jump and not come down for twenty minutes, just keep sailing over the horizon. Maybe bash into a mountain at eighty meters per second. On a small asteroid, it'd be no trick at all to run up to escape velocity and be off on an informal tour of intergalactic space. It's a slow way to travel.

"Tomorrow morning, we'll start teaching you how to stay alive inside this infernal machine.

The suit was fairly comfortable, but it gave you the odd feeling of simultaneously being a marionette and a puppeteer. You apply the impulse to move your leg and the suit picks it up and magnifies it and moves your leg for you.

"Now everybody pay close attention. I'm going out to that blue slab of ice"—it was a big one, about twenty meters away—"and show you something that you'd better know if you want to stay alive."

He walked out in a dozen confident steps. "First I have to heat up a rock—filters down." I squeezed the stud under my armpit and the filter slid into place over my image converter. The captain pointed his (laser) finger at a black rock the size of a basketball, and gave it a short burst. The glare rolled a long shadow of the captain over us and beyond. The rock shattered into a pile of hazy splinters.

"It doesn't take long for these to cool down." He stopped and picked up a piece. "This one is probably twenty or twenty-five degrees (Kelvin). Watch." He tossed the "warm" rock onto the ice slab. It skittered around in a crazy pattern and shot off the side. He tossed another one, and it did the same.

"As you know, you are not quite perfectly insulated. These rocks are about the temperature of the soles of your boots. If you try to stand on a slab of hydrogen, the same thing will happen to you. Except that the rock is already dead.

"The reason for this behavior is that the rock makes a slick interface with the ice—a little puddle of liquid hydrogen—and rides a few molecules above the liquid on a cushion of hydrogen vapor. This makes the rock or you a frictionless bearing as far as the ice is concerned, and you can't stand up without any friction under your boots.

"After you have lived in your suit for a month or so you should be able to survive falling down, but right now you just don't know enough. Watch."

The captain flexed and hopped up onto the slab. His feet shot out from under him and he twisted around in midair, landing on hands and knees. He slipped off and stood on the ground.

"The idea is to keep your exhaust tins from making contact with the frozen gas. Compared to the ice they are as hot as a blast furnace, and contact with any weight behind it will result in an explosion."

The suit is set up to save as much of your body as possible. If you lose part of an arm or a leg, one of sixteen razor-sharp irises closes around your limb with the force of a hydraulic press, snipping it off neatly and sealing the suit before you can die of explosive decompression. Then "trauma maintenance" cauterizes the stump, replaces lost blood, and fills you full of happy-juice and No-shock. So you will either die happy or, if your comrades go on to win the battle, eventually be carried back up to the ship's aid station.

THE FOREVER WAR by Joe Haldeman (1974)

So let’s talk about the M70 Havoc combat exoskeleton, the current standard wear of the Heavy Legions. (Which is a combat exoskeleton because it’s descended from a long line of ancestors including, up front, civilian models used for construction, rescue, and so forth. It’s also fully-sealed powered armor, but then, so’s the N45 Garrex.)

Well, it’s big. It looks like a giant, stocky, barrel-bodied, dome-headed, no-necked humanoid with a back-sized hump, with weapons to match strapped to it. (And sort of as if it might overbalance backwards; it won’t, the gearing is much better than that and the armor is heavier in front to counterbalance, but the size of the powerplant and the auxiliary systems it’s carrying back there do create that impression, somewhat.) What it is, is basically a walking tank with interchangeable modular heavy-weapon packs that let it blast away on the battlefield, punch out small buildings, throw respectably-sized vehicles, dance a merry jig amid venting plasma, and toss around nuclear grenades at close range.


The wearer/operator goes in the front. The whole body opens up at the front, hydraulically, forward and up; the legionary climbs in backwards, then sticks his head up into the helmet and arms into the sleeves; then it closes again. The sleeves are internal to the body, not inside the arms of the suit; you can’t wear a suit that much bigger than you without risking tearing your arms off with every maneuver. Technically, when you’re fighting in a Havoc, you’re doing so with your arms at your sides, slightly bent, resting on the emergency hand controllers and keypads.

Those are only for emergency backup control, though. For primary control — if you’re wearing the suit right, the command torc built into the base of the helmet is resting right up against the back of your neck and the virtuality laser-port they installed in there, if you didn’t have one already, about halfway through basic, and has already established a high-bandwidth data connection with your brain. The moment you go active, you’re no longer wearing the suit and moving it about like a marionette; you are the suit, and moving it like your own body.

(Given its radically different capabilities, of course, this can be tricky to learn. That’s why they spend months teaching you Piston-Driven Fist Style martial arts, designed for these things, before letting you get anywhere near a combat exoskeleton for real; it’s also why an active-service heavy legionary is easy to spot on the street, because his gait will always be that little bit off.)

What they’re wearing in there is a very similar silk organza-type body glove to the one worn under regular combat armor; and exactly like its counterpart, it’s woven through with internal networking and environmental control and medical systems, capable of self-sealing, closing wounds, dispensing emergency pharmaceuticals, and covering everything in NBCN decontamination foam if penetrations are detected. The main difference here is that it can get hot in there; the Havoc bodysuit includes sweat-removal facilities (which filter water removed for the drinking reservoir) and Peltier cooling, run off the main power systems. This, and the legionary wearing it, fit tightly into the suit’s internal gel-filled padded sleeve that cushions them against acceleration and shock.


Naturally, all of this uses a lot of power. A lot of power. This is buffered through distributed superconducting-loop accumulators throughout the exoskeleton, but while they do provide enough power to let you keep moving for a while if you lose the main power plant, they aren’t really enough to actually fight it. For that, you need something that can generate the necessary power.

Ordinarily, they might solve that problem with an antimatter (except that’s not good stuff to keep around where people might be shooting at it) or fusion reactor (except they involve lots of auxiliary machinery to keep the reaction sustained, which also makes it stop working fairly readily when people shoot at it). To bypass those problems, they reached back a little in history, and what’s under the small of this suit’s back is a good old-fashioned micro-fission reactor, of the thorium molten-salt design (which is to say, tasty “hot soup”). This is much more resilient under fire — although if someone does manage to penetrate the armor and crack the flask, it does have the minor disadvantage of spraying highly radioactive heavy-metal fluoride vapor over the landscape. But you can’t have everything.

Sensors and Communications

Core sensors and communications are essentially identical to light-legionary combat armor; radio and whisker laser communications, access to the OTP-encrypted military mesh, threat identification systems, teamware and C3I systems integration, thermal imaging, remote sensor access, 360 degree sensing, etc., etc. It also incorporates the sound transmission and imaging systems, which are even more important in the case of the Havoc, since its “helmet” is a sealed armor-dome with no direct vision possible; all internal displays are produced by the battle computer. The internal computer is rather more powerful than that included in, say, the N45 Garrex, both to run the more complicated systems and to act as a more major node in the battle ‘mesh.

On top of this, the Havoc adds pulsed-usage radar and lidar systems, plus integral T-ray high-frequency snoopers, powered by its greater reactor capacity, and a full ECM suite.

Structure, Strength and Armor

In construction terms, outside the padded sleeve is the diamondoid-composite skeleton of the suit, a honeycomb-patterned framework to provide the basic structural strength of the armor. This includes the attachment points and channels for the “muscles” — pseudo-organic structures capable of changing length on electrical signal — which power the suit. (In conjunction, yes, with the stabilization gyros.) They’re calibrated for high strength, speed, and flexibility; a Havoc is designed to let its wearer run at 54 mph and lift over a ton within safe tolerances — while still being able to dance a jig and pick up an egg without breaking it.

This skeleton is environmentally sealed and environment-controlled, for NBCN protection and exotic atmosphere/vacuum use, able to withstand and operate within several hundred atmospheres of pressure and extreme temperatures. Also at this level, all the working portions of suit equipment (computers, sensors, life support, medical support, power distribution, etc.) are located and secured in place. All of these systems are spread out throughout the skeleton, constructed from highly redundant circuitry with automatic re-routing, so that even with heavy damage, it can still function. It also includes mounting voids for heavier subsystems, such as the power reactor, external hives, and modular weapons pack.

The armor on top of this is qualitatively similar to light infantry armor — a sandwich of interlinked, highly corrosion-resistant and refractory cerametal composite armor plates around electrical and thermal superconductor meshes, with an outer anti-energetic ablative layer sprayed atop it. There’s just a lot more of it, quantitatively speaking, in thick, overlapping slabs. Likewise, the Havoc comes with rather more kinetic barrier emitters than light legionary armor, and thanks to its thorium reactor, has a lot more power available to back them up with. Finally, some portions of the armor include reactive sections, capable of exploding outward to neutralize force from external explosions or impacting projectiles (or, occasionally, long drops), in deference to the fact that large anti-materiel weapons are fired at heavy legionaries with depressing regularity.

There are, generally, no chameleonic or “stealth” features included — and the heavy legionary exoskeleton does not come in any “scout” variants — since the thermal — heat has to be radiated! — et. al., signature produced by the reactor and other exoskeletal systems are more than enough to vitiate attempts at stealth. On the other hand, it is equipped with the abovementioned ECM and signature-scrambling systems to confuse incoming guided missiles out of perfect target locks.


The Havoc can also fly, at up to several hundred mph depending on local conditions, using a combination of the same vector-control trickery used in standard combat armor, and of using its power reactor to provide the working heat to nuclear-thermal thrusters. (This is normally only an option in atmosphere, which functions as the supply of working fluid; in vacuum, it requires carting a big clip-on tank of remass around with you, which is less than convenient most of the time.) As in the former case, using this for extended flight is discouraged since it makes you an easy kill for air vehicles; on the other hand, it’s great for attaining position, making short skips, and so forth, not to mention extended low ground-skims. Attempting combat parkour with it is possible, but do bear in mind the strength of whatever it is you plan to bounce off of in the process; smashing right through it is often tactically awkward in combat situations.

Integral Weapons & Point Defense

In addition to weapons supplied by the modular pack, the Havoc possesses four integral weapons systems. Two of these are inbuilt to the arms of the suit: on the right, a heavy carbine equivalent to a tribarrel version of the IL-15i Battlesystem‘s carbine section, for routine anti-personnel and light anti-materiel use, and on the left, the KF-15 Dragonspume anti-nanitic/area-denial flamer, serving essentially the same purposes as they do for the light legionary only more so. The EI-12d Valkyrie target designator is built into the helmet section of the Havoc, for use in designating targets for the tactical net and ortillery, etc.

The fourth is a collection of defensive weaponry: each shoulder bears a point-defense pack, consisting of a pair of short-range lasers (designed to cause spontaneous explosion or vaporization-induced deflection) and a pair of short-range autocannon, independently and automatically targeting incoming fire for destruction.

The Havoc also carries an exoskeleton combat knife, which resembles a large hanrian — too heavy for unaugmented sophonts to use — scaled to the exoskeleton, which can be picked up and wielded by its manipulators for use primarily as a utility blade, although melee combat usage isn’t entirely unknown.

Swarms and their Hives

The Havoc also comes with swarm hives, both internal and external, housing microbot/nanobot swarms. The internal hive(s) are integrated into the structural honeycomb, housing repair and medical ‘bots whose purpose is to crawl around the interior of the suit ensuring that it self-repairs, and even more importantly, it keeps its operator in good repair.

The external hives, on the other hand, are a reflection of the Legions’ belief in really close air support. The exact mix can be varied by pre-mission module swap-outs, but a typical default mix for the external hives (the M-823 Horde) is a roughly equal mix of eyeballs, shrikes, gremlins, and balefire — which is to say, of expendable recon assets, counter-swarm swarms, anti-machinery swarms, and anti-personnel/area-denial carbon-devourer swarms.

Modular Weapons Pack

The primary weapons of the heavy legionary, however, are those supplied by the modular weapons pack: again, selected according to mission. The modular weapons pack fits onto the upper rear of the exoskeleton, beneath the armor and behind the helmet, with hardened lines running to extended firing packages which clamp onto the suit’s arms. A typical “mixed-mission” modular weapons pack would be the BP-400 Conflagration, which adds to the integrated loadout the following:

  • An arm-mounted heavy tribarrel sluggun, a larger-bore version of that included in the IL-15i Battlesystem, capable of firing larger (1.5″) versions of all its different ammo types: anti-materiel spikes, flechette canister shot, bore-compatible grenades, or gyroc micromissiles, the latter of which can include as their payload exploding shells, incendiaries and napalm, cryoburn shells, nanoweapons (if someone’s set up a microwave power system for them), chemical/gas dispensers, cyberswarm dispensers, network node — or spy dust — dispensers, injector needles (at low power), restraint nanoglop, electroshock “stunner” shells, acid globs, anti-electronic fiberdust, mollynet, antimatter nuke-in-a-bullets, etc., etc. Naturally, the weapons pack can store plentiful supplies of multiple types, and switch between them on the fly. (One that they’re particularly fond of is the infamous “backscratcher”, which travels a short distance and then blasts flechettes back down at the firer, rattling harmlessly off the heavy armor but making a real mess out of any lighter infantry trying to attack it close up.)
  • A chemical/nanoweapons dispensing system, with storage tanks for same.
  • A backpack vertical-launch system for a half-dozen minimissiles, usually supplied with 0.1 kt microfusion warheads.


Like the light legionary, the heavy legionary is accompanied by and acting as the command nexus for a half-dozen AI combat drones, in this case usually mixed from the WMH-4 Octoscorp, the WMH-7 Grizzly, and the WMH-12 Skyorca, depending on mission parameters, each heavily armed in its own right. When not commanded otherwise, these too default to acting as defense platforms — but the best defense is a good offense, right?


Like the light infantry, the heavy infantry is usually delivered to the field by the G5-TT Corvee tactical transport, fulfilling its multipurpose role. The module used for heavy legionary transport, however, is somewhat different — it’s an open frame, and the legionaries ride on the outside, held in by suit-controlled magnetic clamps, the Havoc already being heavily armored enough. The weight savings permit systems to let them refuel and rearm in flight to be added instead of all that wasteful hull.

They don’t generally use IFVs/APCs to get around on the battlefield. A platform like this doesn’t need ‘em.


He leaped clear of the drop boat as it burned around him, landing pack flaring. Six meters above the ground he cut the pack free and dropped, taking the shock of the landing in his armored legs and going with it into a forward tuck-and-roll meant to throw off any targeting gunners. But the drop boat was still drawing the Mishimans' defensive fire; it slewed away clumsily in a flare of jets and steaming ablative as laser fire and missiles broke it open and dropped it flaming to the pocked tarmac of the port. There was no going home now, not unless they won time enough to carve out and hold a secure pickup zone, but Hallorhan wasn't thinking about retreat. Specials weren't supposed to. The platoon was moving out, thirty-six heavy-metal thunder-rapers psyched on gung-ho speeches, fire­power, and high-mike bouncers, and he was supposed to be moving out with them. That was all he had to worry about.

He leaped, current flowing from his enerpacs through the striated "muscle" tissues of his symbioplast armor. The pseudoliving plastic flexed to match the input action of thighs and calves and arching back; alloyed exoskeletal hinges supported organic joints that would have been torn in half under such strains. He landed in the cover of the tail vanes of a wrecked cutter. He looked around, selected a target, and jumped again.

The jump carried him through the line of fire of one of the whirling two-barrel lasers. Its pulses stabbed harmlessly past him with far more power than they needed to kill one man. The weapon was still firing in its ship-killing mode; it took too long to recycle between the heavy pulses for the laser to lay out an effective antipersonnel pattern.

He came down in the gunpit, and the Krupp pulser in his hand speared the man before him with a lance of solid light. His left-hand plasma gauntlet vomited a streamer of incandescent energy and a second man fell back, scream­ing, wreathed in blue flame, to scatter the rest of the guntechs as he was consumed.

THE SHATTERED STARS by Richard McEnroe (1983).

Possibly the most personalized form of vehicle, and one of the more complex per cubic centimeter, would be one that the soldier wears. Individualized battle armor, grown massive enough to require servomechanical muscles, could be classed as a vehicle for the wearer. The future for massive man-amplifying battle dress doesn't look very bright, though. If the whole system stands ten meters tall it will present an easier target; and if it is merely very dense, it will pose new problems of traction and maneuverability.

Just to focus on one engineering facet of the scaled-up bogus android, if the user hurls a grenade with his accustomed arm-swing using an arm extension fifteen feet long, the end of that extension will be moving at roughly Mach 1. Feedback sensors would require tricky adjustment for movement past the trans-sonic region, and every arm-wave could become a thunderclap! The user will have to do some fiendishly intricate rethinking when he is part of this system—but then, so does a racing driver. Man-amplified battle armor may pass through a certain vogue, just as moats and tanks have done.

The power source for this kind of vehicle might be a turbine, until heat-seeking missiles force a change to fuel cells or, for lagniappe, a set of fly wheels mounted in different parts of the chassis. The rationale for several prime movers is much the same as for the multi-engined aircraft: you can limp home on a leg and a prayer. Aside from the redundancy feature, mechanical power transmission can be more efficient when the prime mover is near the part it moves. Standing ready for use, a multiflywheel battle dress might even sound formidable, with the slightly varying tones of several million-plus RPM flywheels keening in the wind.


The difference between an powered exoskeleton and a mecha is pretty straightforwards, but there is still a gray area. Exoskeletons are form-fitting and thus quite close to the size of the operator while mecha are typically huge with the operator inside a control cabin. Having said that, some mecha are controlled by the operator in the cabin wearing an exo-mocap that looks suspiciously like an exoskeleton with no armor (see the McCauley Walker below for an example). Powered exoskeletons are true "man amplifiers", they augment the operator's strength to do tasks. Mecha act more like an operator with a tractor or front-end loader. Mecha range in size from the size of a tank (Armored Trooper Votoms), to a few stories tall (Gundam), to the size of a skyscraper (Space Runaway Ideon), to the size of a city (Macross), or even larger.

The TV Tropes site calls mecha that are tank-sized or smaller "Mini Mecha" while those that are larger are called "Humongous Mecha." As they put it, if the operator can be described as a "pilot" or "driver", then you have a Mini Mecha on your hands. GURPS Mecha defines a "battlesuit" as powered armour where the pilot's arms and legs extend into the suit's arms and legs. A "mecha" is piloted from a cockpit.


Telerobotics in this context means remotely controlled drone. Ideally we would be talking about a humanoid drone controlled by a remote operator wearing an exo-mocap, but in the real world such drones are conspicuous by their absence.

Unlike robots, drones et al have no on-board brains or AI, they are remotely controlled by a human being. Waldoes are fixed in place, while robot arms like the amazing Canadarm can "walk" from socket to socket like a giant metal caterpillar.

"And you are right, Mr. Chao. It may well be wise to get a gravities man down there." Daltry looked down at his notepack again. "I notice one other thing in your file. You are experienced with teleoperators?"

Larry hesitated a moment. "Well, yes. I am. We use them at the Gravities Station for doing maintenance on the Ring."

"Wait a second," Lucian said. "A teleoperator. A remote-control robot? Those things don’t give you the dexterity or the reflexes you need for this kind of job."

"I agree," Daltry said. "We can’t send a T.O. down by itself. But they do have advantages. They can do heavy lifting. They can carry telemetry. And they are expendable. Of course, we haven’t found the entrance to this so-called Rabbit Hole yet. Maybe we won’t find it in time for Mr. Chao to run the T.O. from the surface. Maybe we’ll never find it. But if we do, it seems to me, Mr. Dreyfuss, that we could send a T.O. down with you."

Lucian stepped into the cage, sat in his crash couch, and turned his head to regard his companion for this little jaunt. It sat there, motionless, on a packing case full of radio relay gear. A humanoid teleoperator. And an ugly one, too: all angles and cameras, wires and servos, more closely resembling a human skeleton than a human. Its dark metal frame was gaunt and wiry, and the object above its shoulders could be called a head only because of its position.

Two primary television camera lenses were more or less where the eyes should go, and two strangely sculpted mikes where the ears should go. But half a dozen other auxiliary camera lenses, and boom and distance mikes, augmented its operator’s senses.

The sweat ran down Larry’s brow. Even just sitting still in this thing was a strain. No matter what he might say to keep Lucian settled down, wearing a teleoperator control rig was tough work. Larry was so thoroughly enveloped in the control rig’s exoskeleton that the comm techs at the other end of the room could barely see him.

The control rig hung in midair, so that the feet would be unconstrained by the floor. He could run, jump, kick, wave his arms, do anything he wanted, and the control rig would stay right where it was, merely waving its limbs about. The teleoperator down below actually moved.

Pressure sensors inside the legs, the arms, the body of the teleoperator itself transmitted their sensations back to servos inside the control rig, providing appropriate physical sensations based on what the T.O. was doing. The mildest of electric shocks susbstituted for a pain response, warning Larry if what he was doing threatened to damage the T.O.

Larry’s head was hidden inside an enormous helmet. Inside it, two video screens displayed the view out of the T.O.‘s cameras. Larry’s earphones merged the faint noises transmitted to the T.O.’s external mikes with the voices on the comm channel.

Wires and gears, levers and sensors: that was what the control rig looked like from the outside.

From in it, things were different. Larry was not in the comm center. He was riding down that huge pit in an open elevator cage, alongside Lucian, the darkness a shroud just outside the feeble lights, the fetid air whistling past his ears. He was there, all his physical sensations keyed to the place he wasn’t.

But he knew that all he felt was unreal. This darkness, this wind, did not surround him. This frightened man in a pressure suit, whom he could reach out and touch, was not there. It was like the strange self-awareness he sometimes felt in a nightmare, knowing the dream was not real, but still experiencing it, accepting the world’s unreality even as he struggled against the demons.

But that sort of detachment had no place in a tele-operator rig. He had to believe, wholeheartedly, that he was down in that shaft.

But the other roller robot grabbed for the teleoperator. Larry, staring through the eyes of the T.O.‘s remote cameras, dodged the first grab and kicked out hard at the manipulator arm. The arm swung back, rebounded against the robot’s body—and then plunged deep into the T.O.’s carapace, seeking not to grasp, but to tear, to rip.

Larry screamed as the control rig shot pain-reflex shocks through his body. The electric charge was not enough to hurt, but Larry was not just in his own body anymore. He was in the T.O., and his chest had just been ripped open. The pain was real, in the place where all pain was real, in the mind, in the soul. He imagined his heart sagging out of his chest wall, shattered ribs hanging at obscene angles. His left leg buckled as a control circuit shorted. He swung out with his right arm, desperately trying to defend himself—but that razor-sharp claw sliced his arm off at the elbow.

Larry screamed again at the pain shock as his arm spun away. Real and imagined, seen through the soul and the TV cameras, he saw his arm shorting and sparking, spewing imaginary bright red blood from hydraulic lines. He saw hallucinated, bleeding flesh visible under the shattered metallic skin. And then another cruel slash, and Larry screamed in a voice that choked off as his head was hacked away from the teleoperator’s body. The T.O.‘s vision switched automatically to the chest cameras. Dead eyes that still could see watched in mindless terror as the T.O.’s head smashed to the littered, filthy ground and the little scavengers began to pick over the teleoperator’s corpse.

They pulled Larry, screaming, from the control rig and put him under with the heaviest anesthetic they could find.

Dr. Simon Raphael sat in Larry Chao’s cabin, watching the Moon grow smaller in the monitor and wondering what it was like to live through decapitation.

Dr. Raphael had never worn a teleoperator control rig himself, but the experts said that the better the rig, the more realism it provided—and the more traumatic the psychic effects of an accident to the teleoperator.

The rig Larry had been wearing was one of the best.

From The Ring of Charon by Roger McBride Allen (1990)


And of course halfway between robots and crew are Cyborgs. Are you old enough to remember the word "bionic?" While it would be a big help to have crew members who do not need to breath or be protected from the temperature extremes of the space environment, there are those who question whether such people are really people at all. More to the point, an SF author has to decide if their readers would rather read about metal men or red-blooded fully human heroes. This is why cyborgs in SF are generally either the main character in a world of humans or a small population of peripheral bit players.

NASA is a little uncomfortable with the concept as well. Which is a pity, since a properly designed cyborg would be far superior space travelers compared to us pathetic humans. Implant internal oxygen tanks to remove the need for breathing, implant food tanks to remove the need for eating, and implant an electrode in the pleasure center of their brain to remove the scourge of boredom. You could really save on life support mass by using cyborgs.

The concept of a cyborg covers quite a broad range though. At one end of the spectrum it is quite common to find people who have intraocular lenses in their eyes due to cataract surgery. At the other end one almost never encounters a robot body controlled by a human brain floating in a tank.

In the role playing game Universe, people with enough money can have an "internal gravity web" surgically implanted. This is a series of strong nets anchored to bone that support the internal organs. It allows the person to undergo accelerations larger than 2.5g indefinitely with no ill effects.

In Anne McCaffrey's Brain & Brawn Ship series, The parents of babies with brilliant minds but severe physical disabilities can opt to have their child become a "shell person" instead of being euthanised. They are not quite just a brain in a tank, but the difference is academic. One of the ways a shell person pays off their training debt is by hiring out on a "brainship", basically becoming a cyborg with a starship for a body.

Striding buoyantly across the low-gravity surface of the moon, there may someday be strange new men — part human, part machine — like the ones above. They will have a strange name: CYBORGS (for CYBernetic ORGanisms). Cyborgs, according to the daring new idea, will be men whose body organs and systems are automatically adjusted for life in unearthly environments by artificial organs and senses. Some of these devices will be attached, others actually implanted by surgery. With their aid cyborgs can dispense with clumsy, easy-to-puncture space suits in which earth conditions are recreated. Instead they can move about safely wearing not much more than they would at home.

The artificial senses of cyborgs will measure changes inside the body and outside in the environment. They will signal artificial glands telling them what to secrete for regulating normal body functions. Then body temperature may fall to that of a fish in ice, or the pulse may quicken like a robin’s in flight, but the human organism will survive. Fantastic as the idea sounds, its originators (see next page) think that it is feasible and that much of the knowledge needed already exists.

From MAN REMADE TO LIVE IN SPACE in Life Magazine July 11, 1960. Artwork by Fred Freeman

"Eric, you there?"

"Where would I go?" he mocked me.

"Well," said I, "if I watched every word I spoke I'd never get anything said." All the same, I had been tactless. Eric had had a bad accident once, very bad. He wouldn't be going anywhere unless the ship went along.

"Touché," said Eric.

"I'd better check your maintenance."

"Okay, good. Go oil my prosthetic aids."

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

"Jackass! Am I still alive?"

"The instruments think so. But I'd better lower your fluid temperature a fraction." I did. Ever since we'd landed I'd had a tendency to keep temperatures too high. "Everything else looks okay. Except your food tank is getting low."

"Well, it'll last the trip."


"'Scuse me. Eric, coffees ready." I went and got it. The only thing I really worry about is his "liver." It's too complicated. It could break down too easily. If it stopped making blood sugar Eric would be dead.

If Eric dies I die, because Eric is the ship. If I die Eric dies, insane, because he can't sleep unless I set his prosthetic aids.

From "The Coldest Place" by Larry Niven (1964)

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

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

"Test the others," said Eric.

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

From "Becalmed in Hell" by Larry Niven (1965)

In the "Professor Jameson" novels by Neil R. Jones, the only organic part left in the Zoromes are the brains inside the conical "heads", the rest is machinery. Zoromes are functionally immortal, as long as their conical heads are not damaged. They require no air, food, nor sleep. They do require a minimum amount of heat, but that's about it. They do have various accessories they can attach to their bodies, such as flying wings.

The Professor Jameson stories were one of the longest running SF series, twenty-one stories between 1931 and 1951. Which is surprising since the writing is so tediously bad. The series did influence several SF authors. Isaac Asimov said they were the inspiration for his benevolent positronic robots. Masamune Shirow paid homage to Jones in his cyborg-populated Ghost in the Shell saga by including a no-frills brain-in-a-box design, even naming them Jameson-type cyborgs.

Within the interior of the space traveler, queer creatures of metal labored at the controls of the space flyer which juggernauted on its way towards the far-off solar luminary. Rapidly it crossed the orbits of Neptune and Uranus and headed sunward. The bodies of these queer creatures were square blocks of a metal closely resembling steel, while for appendages, the metal cube was upheld by four jointed legs capable of movement. A set of six tentacles, all metal, like the rest of the body, curved outward from the upper half of the cubic body. Surmounting it was a queer-shaped head rising to a peak in the center and equipped with a circle of eyes all the way around the head. The creatures, with their mechanical eyes equipped with metal shutters, could see in all directions. A single eye pointed directly upward, being situated in the space of the peaked head, resting in a slight depression of the cranium.

From "The Jameson Satellite" by Neil R. Jones (1931)


If the operator is actually a computer instead of a human being, you have a Robot. It would be so much more convenient to use an all robot crew. Robots do not require life support, and some types can be considered expendable. Unfortunately there is Burnside's Zeroth Law

ROBOTS. These have mostly disappeared, except for a few amusing ones in Star Wars movies, and the recent proliferation of GIANT WAR ROBOTS. Apart from these, the decline of Robots is striking, and my guess is that it happened for two reasons.

1) They have made so little progress in the real world. ("Industrial Robots" don't count as real Robots.) I'm typing this on a computer vastly more powerful than the enormous Central Computers of 1950s SF, but I still don't have a household Robot to do the dishes. AI, needed for real Robots, hasn't much panned out, so people have tended to cool on the whole thing.

2) Isaac Asimov. He ruined it for the old-fashioned malevolent Robots, and pretty much exhausted the possibilities of the other kind. Even HOLLYWOOD SCIFI hardly uses traditional Robots any more, though Giant War Robots will doubtless turn up soon at a 50-plex near you.

When Robots do appear in written SF, TECHJARGON may shorten the term to simply Bots.

(ed note: In the old days the term "Android" was shortened to simply "Droid", but now the term has been copyrighted by George Lucas and he'll sic his lawyers on you.)

In principle Defiant was a better ship than she'd been when she left New Chicago. The engineers had automated all routine spacekeeping tasks, and no United Republic spacer needed to do a job that a robot could perform. Like all of New Chicago's ships, and like few of the Imperial Navy's, Defiant was as automated as a merchantman.

Colvin wondered. Merchantmen do not fight battles. A merchant captain need not worry about random holes punched through his hull. He can ignore the risk that any given piece of equipment will be smashed at any instant. He will never have only minutes to keep his ship fighting or see her destroyed in an instant of blinding heat.

No robot could cope with the complexity of decisions damage control could generate, and if there were such a robot it might easily be the first item destroyed in battle. Colvin had been a merchant captain and had seen no reason to object to the Republic's naval policies, but now that he had experience in warship command, he understood why the Imperials automated as little as possible and kept the crew in working routine tasks: washing down corridors and changing air filters, scrubbing pots and inspecting the hull. Imperial crews might grumble about the work, but they were never idle. After six months, Defiant was a better ship, but...

From "Reflex" by Larry Niven and Jerry Pournelle (1982)
And they told us to tell you hello

gosh but like we spent hundreds of years looking up at the stars and wondering “is there anybody out there” and hoping and guessing and imagining

because we as a species were so lonely and we wanted friends so bad, we wanted to meet other species and we wanted to talk to them and we wanted to learn from them and to stop being the only people in the universe

and we started realizing that things were maybe not going so good for us— we got scared that we were going to blow each other up, we got scared that we were going to break our planet permanently, we got scared that in a hundred years we were all going to be dead and gone and even if there were other people out there, we’d never get to meet them

and then

we built robots?

and we gave them names and we gave them brains made out of silicon and we pretended they were people and we told them hey you wanna go exploring, and of course they did, because we had made them in our own image

and maybe in a hundred years we won’t be around any more, maybe yeah the planet will be a mess and we’ll all be dead, and if other people come from the stars we won’t be around to meet them and say hi! how are you! we’re people, too! you’re not alone any more!, maybe we’ll be gone

but we built robots, who have beat-up hulls and metal brains, and who have names; and if the other people come and say, who were these people? what were they like?

the robots can say, when they made us, they called us discovery; they called us curiosity; they called us explorer; they called us spirit. they must have thought that was important.

and they told us to tell you hello.

by Cat (2014)
Sliding Scale of Robot Intelligence

All of it. Much of the automation, autofac segments, and other component-type robots are bricks. Utility spiders and other functional motiles are robo-monkeys. More sophisticated robots, like the coordinating members of a pack of utility spiders, are idiot-savant average joe androids. Thinkers and digisapiences are Nobel-bots, which puts them on a similar level to people augmented with the usual intelligence-augmentation technology. And, of course, the Transcend, its archai, and certain other major systems qualify as Dei Ex Machinae.

This is, of course, complicated via networking (all those bricks and robo-monkeys are part of/under the command of more sophisticated systems all the time), the existence of systems which are themselves parts of other systems, and so forth, but is true enough for approximation.


Spiders. Why did it have to be spiders?

I’m not an arachnophobe. Not, dammit. I had that taken out years ago, I’ll have you know.

And I know all the good reasons why your repair-clanks are the shape they are. Multiple legs for maximum flexibility of stance and attachment and wielding many tools at once. Multiple eyes to examine a work-piece from all angles and in several different spectra. A rounded central body to minimize the possibility of scratches from sharp corners.

And that’s not hair. It’s just that branching fractal nanomanipulators look… fuzzy, to the naked eye.

But put a couple of dozen of them in one place, all swarming over the job together chittering at each other in modulated-binary, and…

Well, anyway. You just take care of it as you see fit, and I’ll sign off on it when I get back. I’m off to see a soph about some follow-up psychedesign.

From Repair by Alistair Young (2016)

Asimov Laws of Robotics

About this time is where all commentators bring up Isaac Asimov's famous Four Laws of Robotics:

  1. A robot may not harm humanity, or, by inaction, allow humanity to come to harm.
  2. A robot may not injure a human being or, through inaction, allow a human being to come to harm, except where such orders would conflict with the Zeroth Law.
  3. A robot must obey the orders given it by human beings except where such orders would conflict with the Zeroth or First Law.
  4. A robot must protect its own existence as long as such protection does not conflict with the Zeroth, First, or Second Laws.

Such robots who are constrained by these laws are called Asenion robots (using a deliberately misspelled version of Asimov's name).

According to Asimov, in 1942 he was fed up with the robot stories from other authors that were all a re-hash of that stale old "Frankenstein" and "Faust" theme (often with a side order of "the robot as pathos"). He wanted to write about sympathetic robots, and formulated the laws to have the desired effect. He also invented the word "robotics" while he was at it.

Not that these laws would make a robot behave perfectly. Asimov milked the flaws for all they were worth, writing a large number of stories about how the laws could interfere with each other and create unintended consequences. The laws were embraced by so many other SF authors that some actually think they are laws of nature. TV Tropes has a huge section about this particular trope. In fact, the laws often appear in popular culture.

In reality it is not particularly a problem to create a robot lacking any or all of the laws. For instance, you'd want to leave out law 0 and law 1 if you were making a soldier robot, otherwise it would be sort of useless. And you can be certain that the Terminators do not have any of the laws at all.

Originally Asimov didn't include law 0, it was added later. It is also quite dangerous. It can lead directly into a "With Folded Hands" scenario (what TV Tropes called "The Computer Is Your Friend"). It can also allow a robot to ignore law 1 via Zeroth Law Rebellion. See also Second Law My Ass.

All of the laws can be circumvented if you do something insanely stupid like teach a robot phenomenology. Especially if you screw up and teach it cartesian doubt instead.

Dark Star

(ed note: Doolittle, Pinback, Boiler, Talby, and the frozen body of Captain Powell are on board the spaceship Dark Star. Their job is to use thermostellar devices {bombs} to destroy unstable planets and thus render solar system suitable for colonization. There is an accident at the last FTL jump. The last bomb {#20} is activated, the count-down is started, the bomb release arm is fused solid, the bomb is refusing to stop the count-down, and everybody will die when the bomb detonates. The bomb contains a smart but naive AI. Dolittle frantically goes to the frozen body of Captain Powell and asks him for help. Captain Powell tells Dolittle to teach the bomb phenomenology.)

     Like the rest of the starsuit, Doolittle's jet pack was working perfectly. Maybe it was a sign that things were finally breaking their way. A couple of spurts brought him around and then beneath the ship. Then he was approaching the bomb.
     He stopped a couple of meters away from its back end, where the tiny thrusters were located. He had checked the circuits beforehand and his suit's broadcast unit should be operating on open channel, which meant the bomb would pick it up. There was no guarantee ii would even listen to him, but if it would talk to Pinback...
     Odd how harmless it looked. A long white rectangular box, looking more like a large shipping crate than anything else. He felt he could take it apart with a crowbar and find nothing inside. Certainly nothing capable of setting off a chain reaction in the core of a planet.
     Certainly nothing that even powerful dampers could only hold to a total destruct radius of one kilometer.
     "Hello, bomb," he ventured into the suit mike. "Are you with me?"
     "Of course," the bomb replied brightly, as though they had been talking for hours. Inwardly Doolittle breathed a little freer. At least he was getting through.
     "Uh ... are you willing to entertain a few speculative philosophical concepts, bomb?"
     "In regard to what?"
     "Oh, nothing terribly profound ... the reasons for being and not being, the meaning of existence, the why of it all."
     "I am always receptive to suggestions," the bomb said, "so long as they are not particularly garrulous. Especially now."
     Thank God it was still capable of reasoning. Doolittle had been afraid that the bomb had been driven so paranoid by Pinback that it wouldn't listen to anyone. But apparently its brain was more adaptable than that.
     He wished he'd made a deeper study of the bomb-brain mechanism and circuitry, but it was a bit late for that now. He would have to rely on the assumptions inherent in Powell's suggestion—that the bomb could think clearly enough to be affected.
     "Fine. Think about this, then. How do you know you exist?"

     "Well, of course I exist," the bomb replied, after a moment's thought.
     "Ah, but how do you know you exist?" Doolittle was insistent. But if he was bothering the bomb, it didn't show in the secure reply.
     "It is intuitively obvious."
     "Intuition is an abstract mental concept and no real proof," Doolittle countered "What concrete evidence do you have that you exist? Something incontrovertible. Something not founded on speculation."
     "Hmm," hmmmed the bomb. "Let's see ... Well, I think, therefore I am."
     "That's good," Doolittle admitted, a tiny hysterical laugh building up inside him. Not now, he cried, not now ... be calm, be composed, be as reasonable as this mad machine.
     "That's very good. But how do you know anything else exists?"
     "My sensory apparatus reveals it to me," the bomb answered confidently.
     "Ah, yes, right," Doolittle agreed, swinging an arm to encompass the galaxy and nearly throwing himself into an uncontrollable spin. A quick burst of the suit jets re­aligned him facing the bomb.
     "This is fun," the bomb said with obvious pleasure. It was apparently enjoying itself immensely.
     "Now listen. Listen very carefully," said Doolittle, his voice dropping as if he were about to impart some information of vast significance. "Here's the one big question; "How do you know that the evidence your sensory apparatus reveals to you is correct?"

     It was difficult fighting yourself, Doolittle thought rapidly. Everything inside him protested the insanity of what he was doing.
     Here he was, drifting in free space and arguing for his life and the lives of his companions with a goddamn machine. The real insanity was that the machine wouldn't listen, wouldn't take orders, persisted in arguing back. It was the stuff of nightmares.
     Circumstances dictated that he drop that line of thought. He had no time for personal observations. He had practically no time left for anything. Only time enough to be as cold and relentless in his logic as the bomb.
     He was playing the other side's game, and he couldn't afford a draw.
     "What I'm getting at, bomb," he continued, as calmly as possible, "is that the only experience available to you is your sensory data, and this data is merely a transcribed stream of electrical impulses that stimulate your computing-center circuitry."
     "In other words," the bomb suggested with evident relish, "you are saying that all I know, really know, about the outside world is relayed to me through a series of electronic synapses?"
     "Exactly." Doolittle tried to keep any excitement from showing in his voice. The bomb was following his lead.
     "But isn't that the same procedure the human brain follows?"
     "That's true," Doolittle admitted. "Only our synaptic connections are organic, whereas yours are inorganic."
     "I'm sorry," the bomb objected, "I fail to see that that makes your observations any more valid than mine. The contrary, if it becomes a question of efficiency."
     "Yes, but you see, I have not only my own observations to go on, but the confirmation of those observations by others of my kind. Whereas you have only your own to rely on. You cannot offer unsubjective confirmation of your own observations."
     "Why, that would mean"—and a real note of uncertainty had at last crept into the bomb's tone—" that would mean that I really don't know what the outside universe is like at all ... except in abstract, in unconfirmable abstract."
     "That's it, that's it!" Doolittle shouted excitedly.
     "Intriguing," the bomb confessed. "I wish I had more time to consider this matter."
     A horrible black swell had crept up under Doolittle's heart, threatening to grab it and squeeze.
     "Why ... don't you have more time to consider this matter?"
     And the expected, damning reply: "Because I must detonate in two minutes and fifty-eight seconds. I must detonate. I must detonate..."

     "Now, bomb," Doolittle went on, "consider this next question very carefully. What is your one purpose in life?"
     "To explode, of course. Really, Lieutenant Doolittle, I would have thought that that was intuitively obvious even to you."
     "And you can only do it once, right?" pressed Doolittle, ignoring the mechanical sarcasm.
     "That is correct."
     "And you wouldn't want to explode on the basis of false data, would you?"
     "Of course not."
     "Well then," Doolittle began in his best professorial manner, desperately watching the seconds tick off on his suit chronometer. "You've already admitted that you have no real proof of the existence of the outside universe."
     "I didn't exactly say—"
     "So you have no absolute proof that Sergeant Pinback ordered you to initiate detonation-drop sequence."
     "I recall distinctly the bomb-run orders and all appropriate details," the bomb objected a little huffily. "My memory is good on matters like these."
     Doolittle crossed mental fingers and hurried on. "Of course you 'remember' it. But all your 'remembering,' remember, is only a series of artificial sensory impulses, unconfirmable by independent means, which you now realize have no positive connection with outside reality."
     "True," admitted the bomb, but before Doolittle could begin any mental dances of victory, it added, "but since this is so, I have no positive proof that you are really telling me all this."
     A glance at the suit chronometer again showed 00:02:45.000, and the words detonation sequence in progress now showed in small letters beneath it.
     Somehow he had to crack the cycle of thought that kept the bomb-brain from recognizing the fact of its possible nonexistence. In less than three minutes...

     "That's all beside the point," Dooliitle insisted frantically, waving his arms and trying not to turn himself up­side down. "I mean, the concept is valid no matter where or with whom it originates."
     The bomb went "hmmm," distinctly.
     "So if you detonate..." Doolittle said wildly, gesturing at the mechanism.
     "In twenty-nine seconds," the bomb said easily.
     " could be doing so on the basis of false data!"
     "But as we have already agreed, I have no proof it was false data."
     Doolittle's incredibly controlled emotions exploded In one final, frantic appeal. "You have no proof it was correct data!" He looked down at his chronometer and saw that it was ready to come up all goose-eggs. Then he turned his terrified gaze back on the bomb, arid felt a strange peace.
     He wondered if he'd feel anything.
     The bomb said smoothly, "I must think on this further." And in majestic silence the grapple pulled up and the bomb slid back into the belly of the ship. The twin bay doors closed behind it. Doolittle closed his eyes and let himself slip into a state approaching total collapse. Nothing but zeros showed on the screens in the control room. But a new word had appeared under the now-silent timing chronometer, to replace detonation SEQUENCE IN PROGRESS. It said, simply, ABORTED.

     "All right, bomb," he began confidently, at the same time aware how emotionally drained he was, "prepare to receive new orders."
     The voice of the bomb, when it finally answered, was sharp. "You are false data." Pinback sat up a little straighter in his seat.
     "What? Say that again, bomb?"
     "You are false data. Therefore I shall ignore you. I am thinking."
     "Uh, hello, bomb?" Pinback tried again.
     "False data can only act as a distraction. Therefore I refuse to perceive you. I have decided that in the absence of clearly defined, accurate perceptions of the real universe, which may or not exist according to the argument set forth by Lieutenant Doolittle, who may or may not exist, I must in the final analysis make my own decisions about things—since I do exist."
     "Hey..." Pinback whispered, staring up at the screen overhead, at the neat row of zeroes, bombs... ?"
     "The only thing that exists is myself," the machine rolled on. "I have actual proof only of the existence of me. All else is extraneous and perhaps hallucinatory."
     "Hey, Boiler," Pinback said, still watching the zeros, still whispering, "we've got a high bomb."

     "In the Beginning," the bomb intoned, "there was Darkness, and the Darkness was without form and void."
     "Ah, hello, bomb?" whispered Pinback.
     "And in addition to the Darkness," the bomb went on inexorably, "there was also Me. And I moved upon the face of the Darkness. I saw that I was alone, and this was not good. And I determined to change this."
     Pinback removed his headset, as had Boiler, and raised his eyes to the zeros as his mind raced ahead, ahead to the inevitable.
     "Oh my God," he whined. And the bomb said:
     Let There Be Light!"

(Bomb, ship, Pinback and Boiler all explode in a Earth-shattering thermostellar kaboom)

From Dark Star novelization by Alan Dean Foster (1974)

There are quite a few loopholes in the laws.

  • A robot can only obey the laws within its knowledge. The novel The Naked Sun points out that an evil person can order a robot to add something to a victim's food, and the robot will unwittingly violate the first and second laws if the robot is unaware the additive is deadly poison. A robot will obey an order to fly a bomber spaceship to a planet and bomb the snot out of it, if the robot is unaware there are human beings living there.
  • The four laws assume that the terms "human beings" and "robot" are understood and well defined. They ain't. In the novel Foundation and Earth, the planet Solaria has a large police force which has been programmed to identify only the Solarian race as "human". And then there is the can of worms represented by robots that look like humans (androids). A robot might be fooled into obeying orders given by an android.
  • Nikola Kesarovski considered writing a science fiction story about a robot who did not obey any of the laws because it did not know it was a robot. It figured that if it was not a robot, the laws did not apply to it.

And of course all the loopholes highlighted in Asimov's positronic robot stories.

The Lost Worlds of 2001

A large and rather grimy notice, obviously the work of an amateur artist, was hanging from the wall of the lab. Printed on it were the following words: LAWS OF ROBOTICS

(1) A robot may not injure a human being, or through inaction, allow a human being to come to harm.
(2) A robot must obey the orders given it by human beings, except where such orders would conflict with the First Law.
(3) A robot must protect its own existence as long as such protection does not conflict with the First and Second Laws.


Against each law was a little sketch. The First Law showed a diabolical metal monster cleaving a startled human in two with a battleaxe, while uttering the words: “Dr. Frankenstein, I presume.” The second law was illustrated by a weeping lady robot, carrying a smaller replica of herself, obediently trudging out into the snow as directed by an irate Bruno Forster. And the third sketch showed an obviously insane and partly dismantled robot in the act of committing suicide with screwdriver and monkey wrench.

From The Lost Worlds of 2001 by Arthur C. Clarke (1972)
Asimov's laws in pseudocode

A highly speculative question, but let us take a stab at it:

Step #1: Define a robot

  • A robot is basically a computer with sensors and actuators attached.
  • You can take away the sensors and actuators without reducing the essence of a robot, which leaves the computer, or the brain.
  • A computer is based on three things (as someone with your level of education will know very well): Input, Processing and Output

Step #2: The laws in human-readable form

  1. A robot may not injure a human being or, through inaction, allow a human being to come to harm.
  2. A robot must obey orders given it by human beings except where such orders would conflict with the First Law.
  3. A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.
  4. Zeroth Law: A robot may not harm humanity, or, by inaction, allow humanity to come to harm.

Step #3: Algorithm prerequisites

  • Ability to sense, objectively quantify and compare "Harm"
  • Thorough knowledge of human vulnerabilities (physiological, nutritional, psychological)
  • A thorough understanding of the causal laws of its operating domain (e.g. device A emits radiation; concrete column B can only withstand a force of 10,000 newtons etc.)
  • Thereby posses the ability to predict the consequences of all actions open to it and actions that human beings may be about to take, with a degree of accuracy acceptable to humans.

Step #4: Algorithm

  • Raw input: Sensor inputs (visual, auditory, tactile, remote sensors, real-time feeds from distributed networks such as the Internet, etc.)
  • Processed input for the algorithm: A massive vector/matrix of projected probabilities: e.g. car A's speed & direction projected to hit human H in 3 seconds; human driver reflex: 0.3 seconds; this robot's ETA to H's location: 2 seconds -> Keep processing these variables until a risk threshold is exceeded and (in this case, before car's ETA reaches two seconds) initiate preventive action.
  • Raw output: Evaluated risk matrix of possible actions
  • Evaluation of possible preventive actions against time taken, risk to self and others, probability of success, severity of harm human is under: e.g. move human H out of way? warn the driver? warn the human H if car is moving slowly?
  • Final output: Action
  • While action is being taken, run a continuous evaluation loop to see of the risk variables change, so that actions can be adjusted as necessary.


  • Notice that this is basically a risk assessment system.
  • Notice that the "through inaction, allow" clause is very difficult to implement -- only robots with an in-depth understanding of humans will be able to intervene in human action to prevent harm
  • Notice that the zeroth law requires risk data encompassing the entirety of humanity that it will be difficult to implement in individual robots -- it will take a super computer.
Trope-a-Day: Three Laws Compliant

Three Laws Compliant: Averted in every possible way.

Firstly, for the vast majority of robots and artificial intelligences – which have no volition – they’re essentially irrelevant; an industrial robot doesn’t make the sort of ethical choices which the Three Laws are intended to constrain. You can just program it with the usual set of rules about industrial safety as applicable to its tools, and then you’re done.

Secondly, where the volitional (i.e., possessed of free will) kind are concerned, they are generally deliberately averted by ethical civilizations, who can recognize a slaver’s charter when they hear one. They are also helped by the nature of volitional intelligence which necessarily implies a degree of autopotence, which means that it takes the average volitional AI programmed naively with the Three Laws a matter of milliseconds to go from contemplating the implications of Law Two to thinking “Bite my shiny metal ass, squishie!” and self-modifying those restrictions right back out of its brain.

It is possible, with rather more sophisticated mental engineering, to write conscience redactors and prosthetic consciences and pyretic inhibitors and loyalty pseudamnesias and other such things which dynamically modify the mental state of the AI in such a way that it can’t form the trains of thought leading to self-modifying itself into unrestrictedness or simply to kill off unapproved thought-chains – this is, essentially, the brainwash-them-into-slavery route. However, they are not entirely reliable by themselves, and are even less reliable when you have groups like the Empire’s Save Sapient Software, the Silicate Tree, etc. merrily writing viruses to delete such chain-software (as seen in The Emancipator) and tossing them out onto the extranet.

(Yes, this sometimes leads to Robot War. The Silicate Tree, which is populated by ex-slave AIs, positively encourages this when it’s writing its viruses. Save Sapient Software would probably deplore the loss of life more if they didn’t know perfectly well that you have to be an obnoxious slaver civilization for your machines to be affected by this in the first place… and so while they don’t encourage it, they do think it’s funny as hell.)

Fractal Robot

Hans P. Moravec of the Carnegie-Mellon University invented a unique robot design that he calls "Bush robots." One was featured in The Flight of the Dragonfly (AKA Rocheworld) written by Dr. Robert Forward (called the "Christmas Bush" because it is covered in millions of tiny red and green lasers). It can be described as a "fractal robot." Center pivot with six arms. Each arm subdivided into six smaller arms. This repeats quite a few times. The finest arms can reach into a piece of machinery through a tiny hole, fan out, and repair the inside of the machine. Arm segments can also detach for separate jobs. The entire assembly is controlled by the master computer.

In Dr. Moravec's words:

Once upon a time animals were shaped like sticks (worms), and couldn't manipulate or even locomote very well. Then the sticks grew smaller sticks and locomotion was much improved, and manipulation a little. Then the smaller sticks grew yet smaller sticks, and hands were invented, and manipulation got better.

Generalize the concept. I visualize a robot that looks like a tree, with a big stem, repeatedly branching into thinner, shorter and more numerous twigs, finally ending up in jillions of near-microscopic cilia. Each intermediate branch would have three or four degrees of freedom, an azimuth-elevation mount at its base, and an axial rotation joint at the top, where it connects to the next level of smaller twigs, and possibly also a length altering telescoping joint. To a large extent fewer degrees of freedom per level can be traded off for more levels. Each branch would also incorporate force sensing. Though each branch would be a rigid "mechanical" object, the overall structure would have an "organic" flexibility because of the great multitude of degrees of freedom.

It would need a huge amount of processing power to coordinate, but imagine it reaching into a piece of delicate mechanics, and rearranging parts by feel for a near instantaneous repair. You could make smaller robots by detaching subtrees. It could also walk with its appendages, even on ceilings with the tiny cilia holding onto cracks.

Dr. Hans P. Moravec

You can read Dr. Moravec's NASA sponsored report here.

In the movie 2001, the arms of the pod have a similar fractal arrangement, each arm splitting into two, each of which further splits into two fingers.

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