A space station is basically a spacecraft with no propulsion. Which boils down to just the habitat module and the payload.

Much like spacecraft, in a science fiction story a space station can become a character all by themselves. Examples include Babylon 5, Deep Space 9, Waystar from Andre Norton's Uncharted Stars, Supra-New York from Heinlein's Farmer in the Sky The Green Hills of Earth and Rocket Jockey, Nowhere Near from Jack Williamson's short story with the same name, Venus Equilateral from the series by George O. Smith, Thunderbird 5 from the Thunderbird TV show, Elysium from the movie of the same name. For an exhaustive list, look up Islands in the Sky: The Space Station Theme in Science Fiction Literature and The Other Side of the Sky: An Annotated Bibliography of Space Stations in Science Fiction, both by Gary Westfahl. The latter has 975 examples.

There are some science fiction stories about star systems that have no colonists living on the surface of planets. All colonists live in swarms of space station habitats. Examples include Downbelow Station by C. J. Cherryl, The Outcasts of Heaven's Belt by Joan Vinge, and the system of Glisten from the Traveller role playing game.

Oh, Werner von Braun had it all figured out in 1952. In six issues of Collier's magazine he laid out a plan to send men to Luna and Mars. First you build a space ferry as a surface to orbit cargo transport (which was the great-grandfather of the Space Shuttle). Then you use it to make a space station.

And it was going to be a beauty of a space station, too. Three decks, 250 feet in diameter, and a crew of fifty. Makes the ISS look like a tin can. This outpost in space was where the Lunar expedition fleet would be constructed.

It would pay for itself as well. Meteorologists could plot the path of storms and predict the weather with unprecedented accuracy. Radio and TV signals could be transmitted all over the globe. Not to mention observing the military activities of hostile nations.

In other words, it would be MacGuffinite.

Why was this marvel never constructed? Because some clown invented the printed circuit. Freed from the tyranny of fragile and short-lived vacuum tubes, technologists could make unmanned satellites for Meteorologists, radio and TV signals, and watching hostile militaries. Such satellites could be assembled and launched at a fraction the cost of a manned station. They also did not require constant resupply missions to keep the crew alive.

If we had followed von Braun's plan, we would have ended up with a fleet of space ferries, a titanic manned space station, a large lunar base, and men on Mars. Instead, we have four overly complicated space shuttles near the end of their operational life that have been retired, a four man space station due to be de-orbited and destroyed in 2016, and a few bits of space trash on the Lunar surface. And we haven't been back to Luna since 1972. So it goes.

It just occured to me...why didn't we have large scale commercialization of space already? And I had a strange answer:

The microchip and the fiber optic cable.

One of the few killer apps for space satellites was the communications satellite. But the microchip allowed multiplexing many voice streams onto a single high bandwidth signal, and the fiber optic cable made cheap long range high bandwidth communications possible.

What might have happened if the microchip and fiber optic cable weren't developed for another few decades? We might actually have needed hordes of communications satellites to keep up with global demand. That means a solid customer base for launchers, and that means mass produced launchers and/or big dumb boosters.

Without the microchip, these communications satellites suck up all sorts of juice. Thus, there's a huge incentive to develop efficient solar cells. With advanced space rated solar cells and cheaper launch technology, space based power may even be practical.

The result? Large scale industrialization of space, and sufficient economies of scale that launch costs are relatively cheap.

Isaac Kuo

Why doesn't a space station fall down? A station is in "orbit," which is a clever way to constantly fall but never hit the ground. The ground curves away just enough so that the station never strikes it.

Actually, the International Space Station is in a low enough orbit that atmospheric drag decays its orbit. Periodically, Russian resupply rockets have to boost it higher. Otherwise it would de-orbit and burn up in re-entry. Many readers of this website are too young to remember when NASA's Skylab unexpectedly fell.

Many station designs are wheel shaped, and large wheels at that. They are wheel shaped so you can spin them for artificial gravity. They are large wheels so the rotation rate can be kept low enough so the crew does not experience nausea. This is conservatively 3 RPM, though studies suggest some can acclimate themselves to tolerate up to 10 RPM. The Collier space wheel is 250 feet in diameter and spins at 3 RPM, providing about one-third gee of artificial gravity at the rim.


Many, but not all, space stations are in orbit around a planet. An orbit is a clever way to constantly fall towards a planet but never hit the ground.

There are certain preferred orbits.

An equatorial orbit is a non-inclined orbit with respect to Terra's equator (i.e., the orbit has zero inclination to the equator, 180° inclination if retrograde). Most civilian satellites use such orbits. The United States uses Cape Canaveral Air Force Station and the Kennedy Space Center to launch into equatorial orbits.

An ecliptic orbit is a non-inclined orbit with respect to the solar system ecliptic.

An inclined orbit is any orbit that does not have zero inclination to the plane or reference (usually the equator).

A polar orbit is a special inclined orbit that goes over each pole of the planet in turn, as the planet spins below (i.e., the orbit is inclined 90° to the equator). Heinlein calls it a "ball of twine" orbit since the path of the station resembles winding string around a string ball. The advantage is that the orbit will eventually pass over every part of the planet, unlike other orbits. Such an orbit is generally used for military spy satellites, weather satellites, orbital bombardment weapons, and Google Earth. The United States uses Vandenberg Air Force Base to launch into polar orbits. Google Earth uses data from the Landsat program, whose satellites are launched from Vandenberg.

When launching from Terra, say a space station resupply cargo rocket, you want to launch due East to get the free delta V boost from Terra's rotation. So one would have expected that the International Space Station (ISS) would be in a 28.5° inclined orbit, which is the orbit you get when launching due East of Kennedy Space Center (latitude 28.5° N).

But it isn't, the ISS is in a 51.6° inclined orbit. Why? So that Russian cargo rockets from Baikonur Cosmodrome can reach it. Launching into a different inclination than the space port's latitude costs rocket propellant and reduces payload.

Changing the ISS planned inclination to 51.6° was in retrospect a very good decision. When NASA stupidly cancelled the Space Shuttle program before the replacement vehicle was online, they assured everybody that the replacement would be flying by 2014 at the latest. This would make a small three-year gap in NASA's ISS transport ability. Unfortunately and predictably when 2014 arrived NASA has not even started work on deciding which of the many proposals will be used, much less bending metal and cranking out functional rockets. This leaves NASA at the mercy of the Russians for access to the ISS, but without the Russians there would be no access at all and the station would have long ago burnt up in reentry like Skylab. But I digress.

Clever readers will say but wait! Baikonur Cosmodrome is at latitude 45.6°, should not that be the inclination?. In a perfect world, yes, but there is a problem. When a spacecraft is launched from Kennedy Space Center the lower stages fall into the Atlantic Ocean. And if something goes really wrong, the entire spacecraft can abort and ditch into the ocean as well. If Baikonur Cosmodrome did the same thing, large spent lower stage boosters and/or huge flaming aborting Russian spacecraft would crash into Mainland China, and the political situation would rapidly deteriorate. To avoid that unhappy state of affairs, Russian spacecraft launched from Baikonur go at a 51.6° inclination, so falling rocket bits will miss China.

The Russians already have an annoying problem with the lack of warm-water ports for seagoing vessels. They really dislike having much the same problem with respect to space launches. Therefore they are in negotiations for launch privileges at the ESA's Guiana Space Centre, which is optimally located quite near the Equator and to the West of the Atlantic Ocean.

Orbits around Terra (geocentric) are sometimes classified by altitude above Terra's surface:

  • Low Earth Orbit (LEO): 160 kilometers to 2,000 kilometers. At 160 km one revolution takes about 90 minutes and circular orbital speed is 8 km/s. Affected by inner Van Allen radiation belt.
  • Medium Earth Orbit (MEO): 2,000 kilometers to 35,786 kilometers. Also known as "intermediate circular orbit." Commonly used by satellites that are for navigation (such as Global Positioning System aka GPS), communication, and geodetic/space environment science. The most common altitude is 20,200 km which gives an orbital period of 12 hours.
  • Geosynchronous Orbit (GEO): exactly 35,786 kilometers from surface of Terra (42,164 km from center of Terra). One revolution takes one sidereal day, coinciding with the rotational period of Terra. Circular orbital speed is about 3 km/s. It is jam-packed with communication satellites like sardines in a can. This orbit is affected by the outer Van Allen radiation belt.
  • High Earth Orbit (HEO): anything with an apogee higher than 35,786 kilometers. If the perigee is less than 2,000 km it is called a "highly elliptical orbit."
  • Lunar Orbit: Luna's orbit around Terra has a pericenter of 363,300 kilometers and a apocenter of 405,500 kilometers.

Geosynchronous Orbits (aka "Clarke orbits", named after Sir Arthur C. Clarke) are desirable orbits for communication and spy satellites because they return to the same position over the planet after a period of one sidereal day (for Terra that is about four minutes short of one ordinary day).

A Geostationary Orbit is a special kind of geosynchronous orbit that is even more desirable for such satellites. In those orbits, the satellite always stays put over one spot on Terra like it was atop a 35,786 kilometer pole. For complicated reasons all geostationary orbits have to be over the equator of the planet. In theory only three communication satellites in geostationary orbit and separated by 120° can provide coverage over all of Terra.

All telecommunication companies want their satellites in geostationary orbit, but there are a limited number of "slots" available do to radio frequency interference. Things get ugly when you have, for instance, two nations at the same longitude but at different latitudes: both want the same slot. the International Telecommunication Union does its best to fairly divide up the slots.

The collection of artificial satellites in geostationary orbit is called the Clarke Belt.

Note that geostationary communication satellites are marvelous for talking to positions on Terra at latitude zero (equator) to latitude plus or minus 70°. For latitudes from ±70° to ±90° (north and south pole) you will need a communication satellite in a polar orbit, a highly elliptical orbit , or a statite. Russia uses highly eccentric orbits since those latitudes more or less define Russia. Russian communication satellites commonly use Molniya orbits and Tundra orbits.

About 300 kilometers above geosynchronous orbit is the "graveyard orbit" (aka "disposal orbit" and "junk orbit"). This is where geosynchronous satellites are moved at the end of their operational life, in order to free up a slot. It would take about 1,500 m/s of delta V to de-orbit an old satellite, but only 11 m/s to move it into graveyard orbit. Most satellites have nowhere near enough propellant to deorbit.

"Okay, T.K., look at it this way. Those three hundred people in LEO Base can get back to Earth in less than an hour if necessary; we'll have lifeboats, so to speak, in case of an emergency. But out there at GEO Base, it's a long way home. Takes eight hours or more just to get back to LEO, where you have to transfer from the deep-space passenger ship to a StarPacket that can enter the atmosphere and land. It takes maybe as long as a day to get back to Earth from GEO Base— and there's a lot of stress involved in the trip."

Hocksmith paused, and seeing no response from the doctor, added gently, "We can get by with a simple first-aid dispensary at LEO Base, T.K., but not at GEO Base. I'm required by my license from the Department of Energy as well as by the regulations of the Industrial Safety and Health Administration, ISHA, to set up a hospital at GEO Base."

He finished off his drink and set the glass down. "If building this powersat and the system of powersats that follow is the biggest engineering job of this century, T.K., then the GEO Base hospital's going to be the biggest medical challenge of our time. It'll be in weightlessness; it'll have to handle construction accidents of an entirely new type; it'll have to handle emergencies resulting from a totally alien environment; it'll require the development of a totally new area of medicine— true space medicine. The job requires a doctor who's worked with people in isolated places—like the Southwest or aboard a tramp steamer. It's the sort of medicine you've specialized in. In short, T.K., you're the only man I know who could do the job . . . and I need you."

Stan and Fred discovered that it took almost nineteen minutes just to get to Charlie Victor, Mod Four Seven. There were a lot of hatches to go through and a lot of modules to traverse. "Fred, if we don't find some faster way to move around this rabbit warren, a lot of people are going to be dead before we reach them," Stan pointed out, finally opening the hatch to Mod Four Seven.

Fred was right behind him through the hatch. "I'll ask Doc to see Pratt about getting us an Eff-Mu."

"What's that?"

"Extra Facility Maneuvering Unit. A scooter to anybody but these acronym-happy engineers."

Transporting was easy in zero-g, but getting through all the hatches while continuing to monitor his condition and maintain the positive-displacement IVs was difficult. It required almost a half hour to bring the man back to the med module.

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

Lagrangian points are special points were a space station can sit in a sort-of orbit. Lagrange point 1, 2, and 3 are sort of worthless, since objects there are only in a semi-stable position. The ones you always hear about are L4 and L5, because they have been popularized as the ideal spots to locate giant space colonies. Especially since the plan was to construct such colonies from Lunar materials to save on boost delta V costs. The important thing to remember is that the distance between L4 — Terra, L4 — Luna, and Terra — Luna are all the same (about 384,400 kilometers). Meaning it will take just as long to travel from Terra to L4 as to travel from Terra to Luna.

For a more exhaustive list of possible Terran orbits refer to NASA.

It is also possible for a satellite to stay in a place where gravity will not allow it. All it needs is to be under thrust. Which is rather expensive in terms of propellant. Dr. Robert L. Forward noted that solar sails use no propellant, so they can hold a satellite in place forever (or at least as long as the sun shines and the sail is undamaged). This is called a Statite.

If the planet has an atmosphere and the station orbits too low, it will gradually slow down due to atmospheric drag. "Gradually" up to a point, past the tipping point it will rapidly start slowing down, then burn up in re-entry. Some fragments might survive to hit the ground.

The "safe" altitude varies, depending upon the solar sunspot cycle. When the solar activity is high, the Earth's atmosphere expands, so what was a safe altitude is suddenly not so safe anymore.

NASA found this out the hard way with the Skylab mission. In 1974 it was parked at an altitude of 433 km pericenter by 455 km apocenter. This should have been high enough to be safe until the early 1980's. Unfortunately "should" meant "according to the estimates of the 11-year sunspot cycle that began in 1976". Alas, the solar activity turned out to be greater than usual, so Skylab made an uncontrolled reentry in July 1979. NASA had plans to upgrade and expand Skylab, but those plans died in a smoking crater in Western Australia. And a NOAA scientist gave NASA a savage I Told You So.

The International Space Station (ISS) orbited at an even lower at 330 km by 410 km during the Space Shuttle era, but the orbit was carefully monitored and given a reboost with each Shuttle resupply mission. The low orbit was due to the Shuttle carrying up massive components to the station.

After the Shuttle was retired and no more massive components were scheduled to be delivered, the ISS was given a big boost into a much higher 381 km by 384 km orbit. This means the resupply rockets can carry less station reboost propellant and more cargo payload.

If the planet the station orbits has a magnetic field, it probably has a radiation belt. Needless to say this is a very bad place to have your orbit located, unless you don't mind little things like a radiation dosage of 25 Severts per year. And that is for Terra, Jupiter's radiation belts are a thousand times worse. In 1973 Pioneer 11 was surprised by radiation levels around Jupiter ten times greater than NASA had predicted. This is why Pioneer did not send back photos of the moon Io since the radiation belt had fried its imaging photo polarimeter. Work on the Voyager space probe came to a screeching halt as they frantically redesigned it to cope with the radiation, but still be assembled in time for the launch window.

Terra's zone of glowing blue death is called the Van Allen radiation belts.

The Inner Belt starts at an altitude from 400 km to 1,200 km, depending on latitude, and ends at an altitude of about 6,000 km, with its most lethal area 3,500 km out. The South Atlantic Anomaly can potentially disrupt satellites in polar orbits, but usually does not pose a problem for manned spaceflights. Except for the ISS. The radiation is high-energy protons (400 MeV).

The Outer Belt ranges from 13,000 km to 60,000 km, with its most lethal area 27,000 km out. The Outer Belt is affected by solar winds, and is thus flattened to 59,500 km in the area directly between the Earth and the Sun, and extends to its maximum distance in the shadow of the Earth. The radiation is high-energy electrons (7 MeV).

A safe channel exists between the belts from 9,000 km to 11,000 km.

The Apollo missions had trajectories designed to shoot through the belts at high speed to minimize radiation exposure.

Since Terra's rotational and magnetic axes do not intersect at Terra's Center, there is a deadly spot in the inner belt called the South Atlantic Anomaly. The inner edge of the belt proper is usually 1,000 kilometers from Terra's surface, but the anomaly gets as close as 200 kilometers. Satellites and space stations need extra radiation shielding for when they periodically pass through the anomaly. The ISS has extra shielding for that reason. Astronauts have seen phosphene shooting lights in their eyeballs, laptops have crashed, control computers experience transient problems as they pass through the anomaly.

Since the Van Allen Belts will destroy expensive satellites as well, there have been proposals to drain the radiation out of the belt.

Station Station Problems

Air Is Not Free

Habitable planets are great! Inhabitants have quaint expressions such as "Free as Air!"

In space, there ain't no free breathing mix. Any breathable air you either brought along or are manufacturing out of local resources. Neither of which is free, or even inexpensive. Air costs money. If you want to breathe, you have to pay.

With interplanetary tourists, the "air tax" is included in the fee for their tour package. People living in a space station have to pay their periodic air tax or suffer the consequences. This is why a space habitat is a particularly pure example of a hydralic state. Obey the people who control life support, or you'll find yourself suddenly trying to learn how to breath vacuum.

"Yes, the wording is such that the boycott will affect all space commerce activities carried on by the Commonwealth and its registered space facilities," Trip Sinclair observed, "even the League of Free Traders, Kevin."

"How about our Lagrangian operations?" Ursila Peri's video image wanted to know. "How can they boycott trade operations off-planet?"

"Is your air bill current, Ursila?" Trip asked her.

"Yes, but even if it wasn't, nobody out here would cut off another person's life support. If the credit line got over-extended too much for too long, we'd put the debtor on a ship home. We work together because there's a lot of nothing waiting for everybody beyond the bulkhead," she said. "They're going to have trouble enforcing tariff arrangements and trade boycotts out here, that agreement sounds exactly like something written up by a bunch of people who always have pressure around them and gravity to keep their feet on the floor. Earthworms!" She made it sound like an insult.

"Sandy, this is Jeri Hospah. Don't let his attempts at humor put you off; sometimes he means what he says. Jeri, find a sack for Sandy and issue him some chits. Then fake up some paperwork that will keep the Ell-Five people happy," Ali instructed us...

...Uncountable hours later, I awoke in the wan sleeping light of the personal compartment and was momentarily confused until I remembered where I was. I felt physically refreshed but still mentally fatigued. That's a dangerous condition in space because little things can kill a careless person.

Somebody had left a flight suit and a Remain-Over-Night kit. Jeri Hospah was either thoughtful or had a well-trained station crew. I took a sponge bath, put on the flight suit and slippers, and decided I might live if I could find breakfast.

The RON kit had a pack of chits—air, meal, water, airlock cycles—as well as an L-5 facilities directory and a visitor's card for the Free Traders' Lounge.

A note was in the kit. "Call me at 96-69-54 and I'll chit you breakfast—Jeri."

From MANNA by Lee Correy (G. Harry Stine) (1983)

(ed note: the superintendent explains the facts of life to the new voluntary exiles to Mars. Keep in mind that on Mars, the air you breath is NOT free, it has to be manufactured and you have to pay for it.)

"Hear and believe," Farr said. "Okay, chums, let me give you the facts of life. Number one. Don't try to escape. There's no place to go. If you make it outside, you'll live about fifteen seconds. There's no air out there, and your blood will boil away in your veins. It's not a pretty way to go, and I'm told it's painful as hell.

"Number two. Don't try to escape. You may think you're smart and see a way to get a p-suit. You may even be able to operate it. And then what? You can't make air, and you can't carry enough to get anywhere worth going. Running out of air's not a lot better than going out without a suit.

"Number three. Don't try to escape. Sure there's a town here, and sure there are a lot of people in it. But you'll pay for everything, and I do mean everything."

He lifted an orange disk that hung from a chain around his neck. I'd noticed that everyone except us newcomers wore one, but they weren't all the same color. "Air-tax receipt," Farr said. "Mine's orange because I'm due to have it recharged. If it turns red, that's it. Pay up or go outside. You'll need air medals, because God help you if anybody catches you in town without one."

"Why? What happens?" someone demanded.

"Outside," Farr said. "Not even a chance to pay up. Just out."

"And who's to put me out?" Kelso demanded.

Farr grinned. "Every man jack who's paid his taxes, that's who. Might take several for you, but they'll do it."

At Central Processing they charged our air tags to bright green, forty days' worth. They gave us a hundred Mars dollars, worth about half that in Federation credits. We changed our coveralls for new ones, with a choice of blue or orange.

I found a tunnel end to sleep in. They'd been digging out to expand the city, but this project was halted for lack of a labor force. Nobody bothered me. I figured I had nothing worth stealing, anyway. That turned out to be stupid: I had a charged air tag, and that would be worth my life if there was anybody around desperate enough to cut my throat for it. Nobody was, just then.

I'd been there ten days and my air tag was turning from green to yellow, It was getting time to move on. I figured another couple of days would do it.

From Birth of Fire (collected in Fires of Freedom) by Jerry Pournelle (1976)


"Lurker" is a homeless destitute person living on a space station, especially a space habitat. The person figures there are opportunities on the habitat, they spend most of their money traveling to it, when they can find no jobs the money runs out, so they have no money for a space flight ticket to somewhere else. They then move to anyplace they can find in the station, much like terrestrial homeless live under bridges. The space habitat administrators cannot afford to ship the lurkers elsewhere (there are so many of them), so the problem grows. Of course the lurkers are also preyed upon by the criminal underworld.

The term was invented by J. Michael Straczynski for his TV series Babylon 5, more accurately he adapted the term. In internet forums "lurkers" are people who read the forums but do not make posts or otherwise draw attention to themselves. Straczynski noticed this phenomenon when he was discussion the proposed TV show on GEnie, Compuserve, and Usenet back in the early 1990's. He thought the invisible forum lurkers were a good metaphor for the invisible homeless people on the Babylon 5 space station.

Michael Hutson pointed out to me that this actually happens in places like Hawaii, which require lots of money to leave. The destitute tend to accumulate in Hawaii since they cannot afford the air fair to leave and go somewhere else. And the Hawaiian government certainly cannot afford to give them free plane tickets.

Society Rules

The rules and societal norms on a space habitat are going to be different than here on Terra.

In the Albedo Anthropomorphics universe of Steve Gallacci, one has a cluster of planets colonized by slower-than-light starships (yes, the colonists are furry anthropomorphic animals, but that is beside the point). The planetary cultures that were founded as a consequence have a "shipboard discipline mentality."

Consider, on a spacecraft, if a civilian saw something like an air leak in the hull, and didn't report it to anybody, they would be endangering not only their own life but also the lives of everybody on the colony ship. So that is a crime.

In the United States on the other hand, if a person sees somebody lying injured on the side of the road, and they try to help the injured one, more often than not they wind up being sued by the injured person. Hands off, do not get involved, it is not your problem.

In the Albedo universe, with the shipboard discipline mentality, it is a crime not to try and help somebody who is injured, and there are "Good Samaritan" laws to protect the helpers.

Naturally such a shipboard discipline mentality will rule a society living inside a space habitat, since such a habitat is pretty much a huge spaceship. Even more so, a civilian not bothering to report an air leak on a habitat is endangering many more people than on a spaceship. By several orders of magnitude.

The closest thing to social tradition available to the people of ALBEDO is shipboard discipline, and this is strongly ingrained in all levels of society. Simply stated, the individual member of society is not quite as "free" (in one sense of the word) as a 20th century western man, because the individual is strongly constrained by a set of expectations and responsibilities. The individual is expected to be an active citizen, and is conceived of as having both civil liberties and responsibilities. The fragile ecological and social environment on board colonisation ships has lead to the development of societies where the individual is expected to take his social role very seriously, and to contribute to the working of things around him. The individual is expected to behave in an intelligent, responsible manner, and to be aware of the implications of his or her actions. Citizens are expected to be aware of the long running consequences of their actions, and to act accordingly.

Thus in most cultures, if a person is injured, it is the civil duty of passers-by to assist that person however possible. If a passer-by refuses to aid the injured party, or pretends to ignore them, then the passer-by is held to be partly responsible for the subsequent condition of the injured man, and will be charged under law accordingly. Regional attitudes do vary, however. For instance, to the inhabitants of the Dornthant system, the tools of an ordered and peaceful society are its security measures, and the co-operation of the common citizen is an expected duty. To a Dornthantii, running away from or obstructing the authorities is a clear admission of guilt.

The practical upshot of the social attitudes prevalent in most cultures in ALBEDO is the creation of societies which are very politically and ecologically aware. The average citizens feel that they have a vested interest in the running of their government, their society and their planetary environment. Albedo is set in an age of REASON, where forethought and responsibility are highly valued faculties. In the context of the culture of known space, "honour" will usually equate as social responsibility.

From Albedo RPG Player's Manual by Craig Hilton and Paul Kidd

Three Generation Rule

Not generally recognized is the matter of Ken Burnside's Three-Generation Rule for space habitats (space stations where people live and raise new generations of children). As Rick Robinson puts it:

Ken can make authoritative correction of this, but the premise of the 3-gen rule is that the degree of social discipline needed for a space habitat to survive indefinitely is beyond the capability of "normal" human societies. The human tendency to favor short-term expediency will, over time, make the habitat ecosystem more and more precarious.

Putting it loosely, people tend to put off patching the leak in the roof till its raining.

In the Ten Worlds setting, this means that space habs tend to run down, and fail catastrophically in 1-5 generations from when they were established. The average is 3 generations, hence 3-gen rule. The one society in the 10W setting that has beaten this rule is the Library of Man, by adopting a social system that makes it seem very strange and almost "inhuman" to others.

Proviso: This applies only to habs that are socially independent, i.e., the major decisions are made locally, thus subject to local political expediency, etc. It does not apply to bases and such that are ultimately under some outside authority — the outside authority can order the leaks fixed, even if it means everyone has to work double shifts.

Rick Robinson

4) Political priorities - life path problems. Kinda getting back to the idea that each colony will need to come up with their own character, colonies would start with an archetype (not sure how to do this, but it'd be a function of looking at the initial reason for building the colony, money input and world climate/world traits) and then within that framework have random events that could happen based on planet and who colonized it. This would generate a set of planetary traits, such as idealism, pragmatism, greed, environmentalism et al that would effect the options available to the government when problems turned up. For example, a Three Generations Rule problem might be very easy for a highly pragmatic colony to deal with, while one that was high in idealism might run into problems. Yes, in a sense this is trying to ascribe in a half dozen variables a political/social culture...maybe impossible.

In John Varley's Gaea Trilogy, there are some corporations that wait for the 3-gen rule to kill a habitat. Then they swoop in, take possession, vent it to vacuum to sterilize it, and then sell it to some other idealistic group as a unique fixer-upper opportunity.

They built the Coven there. It was a cylinder seven kilometers long with a radius of two kilometers. Artificial gravity was provided by spin; night, by closing the windows.

But the days of isolation were over almost before they began. The Coven was one of the first nongovernmental groups to move into space in a big way, but they were not the last. Soon the techniques of space colonization were refined, cheapened, standardized. Construction companies began to turn them out the way Henry Ford had turned out Model T’s. They ranged in size from the merely gigantic to the Brobdingnagian.

The neighborhood began to look like Levittown, and the neighbors were odd. Just about any sizable lunatic fringe, band of separatists, or shouting society could now afford to homestead in the LaGrangians. L2 became known as Sargasso Point to the pilots who carefully avoided it; those who had to travel through it called it the Pinball Machine, and they didn’t smile.

Some of the groups couldn’t be bothered with the care and feeding of complex machinery. They expected to exist in pure pastoral squalor inside what was really just a big hollow coffee can. The developers were often happy to accommodate them, reasoning that all that expensive hardware, if installed, would only be abused. Every few years one of these colonies would come apart and fling itself and its inhabitants across the sky. More often, something would go wrong with the ecology and people would starve or suffocate. There was always someone willing to take one of the resulting hulks, sterilize it with free vacuum, and move in at a bargain price. The Earth never ran short of the alienated and the dissatisfied. The United Nations was happy to get rid of them and did not ask too many questions. It was a time of speculation-of instant fortunes and shoddy practices. Deals were made that would have shocked a Florida real estate developer.

From Wizard by John Varley

Technological Decline

A more long-term problem is that of Technological Decline. As Joan Vinge pointed out in THE OUTCASTS OF HEAVEN'S BELT: If a planetary colony falls into barbarism, everybody reverts to a non-technological agrarian society.

If an asteroid civilization falls into barbarism, everybody dies.

It takes lots of technology to run the oxygen system, airlocks, spaceships, hydroponics, nuclear reactors, and other items vital for life in space. No technology, no life. In other words, they are a Hydraulic state.

Betha saw suddenly the fatal flaw the original colonizers, already Belters, must never have considered. Without a world to hold an atmosphere, air and water -- all the fundamentals of life -- had to be processed or manufactured or they didn't exist. And without a technology capable of processing and manufacturing, in a system without an Earthlike world to retreat to, any Dark Age would mean extinction.


Station Functions

In his incredibly useful sourcebook for designing science fiction universes Star Hero, James Cambias lists some common uses for space stations:

Food-producing station
Forward base to support spacecraft. Sometimes called "staging base" if military. Generally located in a "remote" location, remote being defined as "a long distance from the home base of the supported spacecraft." (e.g., a military base can be "remote" even if it is near a huge metropolitan planet belonging to a hostile nation).
Orbital Shipyard. Closely related is Spacedock, an outer space version of drydock where spacecraft are repaired or refitted.
Space Superiority Platform
Armed military station keeping an eye on the planet it is orbiting. If a planet is balkanized, the station will watch military ground units belonging to hostile nations. If the planet is a conquered one, or the government is oppressing the inhabitants, the station will try to maintain government control and deal with revolts. In any case, read about planetary attack
Planetary Defense
Armed military station defending its planet from outside attack, orbital fortress. Note that an orbital fortress will be more heavily armed than a warship of the same mass since the fortress design can allocate the mass budget for propulsion in favor of more weapons. These will be in a close orbit to the planet they are defending.
Orbital propellant depot. Fuel refining and storage facility
Residential colony
Orbital factory or smelting plant. They can be near asteroid clusters with rich mineral deposits, or be for industries that would otherwise pollute an inhabitable planet.
Weather-monitoring station
Station monitoring the planet below. News media, military spy satellite, tracking global ocean and air traffic, remote listening post, etc.
Large solar power satellite, beaming energy to clients via microwaves
Medical isolation station, research into technologies too dangerous to experiment with on an inhabited planet (medical disease research, nanotechnology, biowarfare agents, etc.), customs quarantine stations for infected incoming passengers.
Scientific research. This can be for research that requires microgravity, or the station can be located near an interesting planet or astronomical phenomenon.
Orbital spaceport. There are more details about spaceports here

To which I would add:

Aldrin Cyclers
Cyclers are special stations in Hohmann orbits between pairs of planets. They are used as very cheap but very slow methods of interplanetary transport.
A "gold" strike in an asteroid belt or the establishment of a military base in a remote location may create a "boomtown". The sudden appearance of large numbers of asteroid miners or enlisted people is an economic opportunity to sell them whiskey, adult entertainment, and other hard to find luxuries at inflated prices. Not to mention supplies and tools. Remember, in the California Gold Rush of 1849, it was not the miners who grew rich, instead it was the merchants who sold supplies to the miners. Civilian entrepreneurs may find it expedient to connect their ramshackle spacecraft together to make impromptu space stations. For an amusing look at the development and economy of a boomtown watch the movie Paint Your Wagon. But remember that boomtowns can become ghost towns quite rapidly, if mineral strike dries up or the military base is closed.
Can be general hospitals, hospitals specializing in treating victims of spacecraft disasters, and geriatric hospitals using microgravity to prolong the lives of the elderly.
Ghost Town
A ghost town is the abandoned skeletal remains of a space station that was formerly a boomtown.
Short or long term living quarters for people. Generally includes restaurants of various quality.
A sort of combination of Space Superiority Platform and Planetary Defense. The idea is that the station is to prevent anything from entering or leaving the planet it is orbiting. A planet might be invested, meaning that the planet is under siege from whoever owns the space station. The station does not want planetary inhabitants escaping, nor does it want blockade runners entering. A planet might be interdicted because they contain something very dangerous (Xenomorphs, thionite, the City on the Edge of Forever, replicators, or 100% lethal plagues). Or the planet might be interdicted because it has something very valuable and the station owner does not want poachers sneaking in and stealing any.
Macrolife is sort of a cross between a huge habitat and a generation star ship. These are traditionally hollowed-out asteroids.
Pirate Haven
Space pirates need infrastructure (fences for pirated loot, fuel and reaction mass, ship repairs, R&R for the crew). A hidden space station can act as a Pirate Haven and cater to these needs.
Ship Docks
Short or long term storage of spacecraft.
Sky Watch
Monitors the entire sky from their location, keeping track of trajectories of known spacecraft and spotting the appearance of unauthorized spacecraft. And other important events, such as unexpected nuclear explosions. Space traffic controllers want to know trajectories of spacecraft. Orbit Guard wants to know about alterations in asteroid orbit both authorized and unauthorized. Military wants to know about enemy battle fleets. Merchant princes want to know about hostile privateers and space pirates. There will be several such stations located in widely separated parts of the solar system, for determining distance by triangulation and to make it harder for spacecraft to hide behind objects.
Space Traffic Controllers
Outer space equivalent of terrestrial air traffic controllers. Monitors and controls the flight plans of local spacecraft. Generally only needed in "crowded" areas,such as the orbital space around inhabited planets.
Space Tug Services
Groups of space tugs for hire, to move spacecraft, cargo, or other massive objects.
Tax Haven / Data Haven
These are tax shelters used by the wealthy and by corporations. They typically orbit a the planet a corporation is based on, just beyond territorial limits. More details here.
Crew Hiring
Employment services where spacecraft captains can hire crewmembers.
Transport Nexus
A Transport Nexus is a crossroad spaceport for passengers, a port of entry, an orbital warehouses where valuable minerals from asteroid mines are stored and trade goods transshipped, or a "trade-town". Will include related services, such as hotels and stevedore/longshoremen.

Naturally a given space station could have several functions.

Mr. Cambias goes on to note that stations can occupy a variety of orbits. Low planetary orbit just above the planet's atmosphere. High planetary orbit at thousands of kilometers. Geosynchronous / Geostationary planetary orbit at an altitude where the orbital period equals one planetary day (useful for communication, observation, powersat, and meteorology). Stellar orbit where the station orbits the local star instead of orbiting a planet. And Trojan orbits where the station occupies a Lagrange point (beloved of L5 colonies)

The size of a station has many terms, none of which are defined. In arbitrary order of size the terms include Beacon (like an interstellar lighthouse), Outpost, Station, Base, and Colony.

Hive of scum and villainy

Approach space stations from the bottom up, however, in a Firefly or cyberpunk manner, and you'll get a very different view of them — shady orbital stations where you can get just about anything you want... for a price. It's the perfect nexus for organized crime, given a station's importance to inter-planetary commerce and transport. Plus, in a setting with a Balkanized earth, there will likely be no serious push to police the space station in the first place unless it's run by one country alone, and in that case, I wouldn't be surprised if that country extorts anyone else who uses their spaceport.

If you want to expand on the Western analogies that are found so often in SF, then the station would be a railhead like the sort cattle-drivers used to send their cows to, with the associated markets of extortion and dens of ill-repute that go hand-in-hand with such a locale.

Ferrard Carson in a comment
Station cultures

Various sorts of space stations can exist, with different parameters leading to different societies.

High throughput ports (like the ones at the ends of Skyhook orbital elevators) will have lots of facilities for the "sailors" and "longshoremen" (they may be facilities for semi-automated or teleoperated systems), as well as maintained crews and port officials. Lots of money and valuable change hands, so corruption and crime may be rampant.

A naval support base built on a NEO will be a totally different environment; the crew and contractors will be operating under a code of service discipline, but dealing with boredom and an irregular work load.

Most asteroids will probably have very limited transportation facilities (a cycler might be by once a decade or so), unless they strike it rich, in which case they might end up like Dubai, with lots of money to import luxury goods. Otherwise, the transport is one way outbound as ices and minerals flow down the mass driver.

Given the low population density and the difficulty of surviving in hostile alien environments, most places will be like an apartment block, with everyone and everything sealed inside for protection and shelter. Expansion will probably be by driving tunnels to resource or energy nexus points and building another apartment block there, so most story settings will be quite urbanized, at least until large open Island 3 type colonies can be economically built.

Top down= navy bases and scientific research facilities. These are built for a specific purpose, and generally have little economic rational behind them, although military bases may develop garrison towns and eventually grow into larger settlements (especially when the military rational passes). If the military reason for the base fades away without any compelling economic rational to replace it, it is usually abandoned (think of Hadrian's Wall, the Maginot line or old ICBM silos).

Bottom up= trading ports, crossroads, tollgates and locks, marketplaces. They start small but their economic usefulness attracts more people and more activity, in a positive feedback loop leading to towns and cities.

There is also devolution, the port cities of the Hanse are no longer economic powerhouses, and I can see Luna going the way of Detroit after it becomes more economical to harvest 3He from the atmosphere of gas giants (the Pearson elevator to L1 is a minor tourist attraction, and L2 is a brownfield of abandoned mass catchers in parking orbits. Only criminal gangs and Libertarian squatters make their homes in and around Luna).

Of course lots of compound scenarios can exist as well; an occupying power builds a fort overlooking a captured port, or the squatters become the nexus for urban renewal because they (insert "x" here)...

Thucydides in a comment

Mr. Blue:

Some station societies would form in a very organic fashion.

Let's say there's a big rush to mine (X) in the asteroid belt and a lot of independent prospectors head out to strike it rich.

Bill figures he can make a fortune selling space suits, mining tools and the like, so he loads up a freighter and sets up shop. Sally also had the idea of setting up a hydroponic farm/ yeast vat/ and restaurant, and also headed that way. As it's a pain for a miner to make two different stops, Bill and Sally decide to dock their freighters (man, there is no way to say that without sounding dirty) and maybe even set up an extra hab for a hotel...

Pretty soon, as word gets round, other enterprising individuals begin to connect. Bits and pieces are added- an empty fuel tanker as a bar, a repair yard, or even an official buyer for (X)- sure, he doesn't pay as much, but it's a lot better that flying it to Mars yourself. And other services begin to set up shop.

Then, Billstown becomes an interplanetary destination in it's own right. After all, where else on the 'Belt can one get their ship fixed, pick up some spare hands, have a good meal and a drink, and, um, visit the Seamstresses (hem hem).

Of course, once the mining runs out (or whatever else), the boomtown becomes a ghost town. Any spaceworthy ships will be flown off, everything else may be left behind, or salvaged.

But, if the location is good enough, this random jumble of habs, freighters, and other items can become something better...

(ed note: in Terry Pratchett's marvelous Diskworld series of satirical fantasy novels, the "Seamstresses" was an euphemism for the local brothel)

From comments to Transport Nexus
Space Traffic Controllers

"Da. Engagement zones are expanded," Omer explains "United States, Europa, Bahia, all announce new requiremen five days ago.

"Sounds like transition-to-war conditions."

"Maybe. Commonwealth ships have had some problems. Some body soon maybe make a 'mistake' with a Commonwealth ship” Omer pointed out. "Or we get clearance that is wrong and take us into engagement zone. So I got from Kevin Graham new data showing positions of all orbiting objects and load into computer I will make sure clearance and trajectory do not lead us into danger."

Twenty minutes before noon, clearance came over the up-link Omer checked it and gave me a thumbs-up. I accepted it. We made a straightforward departure with the catapult slinging the Tomahok into the air at a one-gee goose. I climbed out according to flight plan and watched while the air-breathers transitioned I scram-jet mode and finally lipped-over when the mains ignited at 60 kilometers. I wasn't particularly looking for anything happen at that point because we were still in international space over the Indian Ocean.

The Tomahok was handed-off from Madras Center to Orient Center as we ascended through a hundred kilometers, expected something to happen then. It did.

"Tomahok, this is LEO Orient Center. Amended clearance."

It came on the up-link. Omer shook his head. "Bojemoi!" exploded. "Reject it!"

"LEO Orient Center, this is Tomahok. Negative the amended clearance, sir."

"Tomahok, what's your reason for refusal?"

"What's your reason for issuing this amended clearance, sir?"

"AmSpace Command request through LEO Canambah Center."

"The amended clearance takes us into the engagement zone of Gran Bahia estacao baixo doze."

"Tomahok, stand by. ... Tomahok, amended clearance: De-orbit for Woomera landing. We can't get you through."

I knew what to do, and I let it all hang out. "LEO Orient Center, Tomahok. Negative the amended clearance. We are initiating no-clearance flight under I-A-R Regulation ninety-one- point-eight. We'll take her up to Ell-Five as filed under our responsibility to detect and avoid."

Omer reached over and clapped me on the right shoulder.

There must have been consternation in LEO Orient Center because it took several seconds for the traffic coordinator to acknowledge. "Uh, Tomahok, Center, roger! Service is terminated. Proceed on your own responsibility. Retain your current beacon code."

I acknowledged and told Omer, "Get ready to thread the needle, Russkie! Let's see if we're good enough to make Ell-Five before somebody burns us with a hell-beamer!"

There I was, flat on my back at 30,000 meters, nothing between me and the ground but a thin regulation.

I'd invoked a seldom-used International Aerospace Regulation that harked back to Earth's oceans where a ship captain was an absolute monarch responsible for himself, his ship, and everything in it. It had been carried into the air by a rule that made the; "pilot-in-command" solely responsible for the safety and operation of his aircraft and everything in it, regardless of what traffic coordinators on the ground told him.

In effect, I'd told the space traffic people I'd fly without their help. Avoiding an engagement zone isn't difficult if you know where it is. Space is mostly empty.

The various STC Centers would continue tracking our beacon to keep other spacecraft clear of us. Military trackers would do the same in case we broached their engagement zones, which would mean trouble for the Tomahok.

I'd waived clearance while still under ascent thrust on our original trajectory to a 200-kilometer parking orbit. Our delta-vee margin was excellent

"Russkie, I hope the League data's good," I told Omer. "Display our current flight path and the projected positions and engagement zones of other sky junk."

"Blinking blips aren't in League data," Omer reported. The Kazakh became laconic when he was under pressure, probably because he was thinking in Russian and mentally translating into aerospace English with adrenalin pumping.

I studied the display. A blinking blip indicated a polar orbiting satellite. In parking orbit, we'd broach its engagement zone.

"There's our problem," I pointed out. "AmSpace Command recon bird. That's why the amended clearance. We'll burn out of parking orbit to miss him. What are the options?"

Omer punched the keypad. A series of trajectories came on the display. "Take high delta-vee option. It will be obvious we're avoiding the reconsat."

"But we may run into trouble with this one, Omer," I said, indicating another target with my finger. "It's displaying no code. What is it?"

Omer queried the computer. "Not in League data. Unknown."

"It's got to be registered! I'll query Center for identification."

"Let it be for now. We handle when time comes," the Mad Russian Space Jockey suggested. "We take problems one at a time. Sandy, get us in parking orbit and watch engagement zones. I work on vector for transfer orbit to Ell-Five."

Our burn out of parking orbit came as re-programmed. While, we were under thrust, we got a sensor alarm. "Targeting lidar!" I snapped. "Aerospace Force has seen us closing on the reconsat,"

"We go laser-hard," Omer said, reaching for the switch.

"Negative!" I snapped. "They'll see it, interpret it as a countermeasure, and try to burn us." I indicated another target on the display. "That's annotated as an unspecified military satellite; it's a ten megawatt hell-beamer."

"Hokay, so we do a little tsig-tsag! Give me controls!"

I did and continued to check displayed targets. Omer called out his actions. “Tsang plus-x ten meters per sec."

I got a surface temperature warning signal. "Warning shot without a call. That's not SOP!" The Aerospace Force tapped the data stream from the world STC net and they knew we were the unarmed Tomahok out of Vamori-Free.

"Maybe you got wrong freq. We did not broach engagement zone of reconsat, and now they see us burn into new trajectory. So we are out of hard place under rock for now. You fly now."

Low earth orbit zone is tricky to work in. Velocities and closing rates are high. There isn't much time to detect, track, make decisions, and maneuver. It's full of sensitive earth-oriented reconsats that are automated and passive. They can't defend themselves or maneuver. Even though such unmanned skyapies are considered to be expendable scouts, my former colleagues were sensitive about them. Everyone knew where everyone else's were, and nobody bothered them for fear of retaliation. Fortunately, sensitive satellites advertised themselves with "no trespassing" signals.

Hell-beamers were another matter. They were unmanned with auto defenses. Unless they spotted the proper beacon password— which we didn't have—they'd shoot at anything that broached their engagement zones. We had to stay clear of those. We'd been lucky once.

Some that looked like hell-beamers weren't; they were decoys or legitimate R&D space telescopes. The sensor signatures were the same. If you wanted to find out if one was indeed a hell-beamer, you had to make a hands-on inspection which was very risky not only because of the auto-defenses but also because some of them were booby-trapped.

Nobody liked the hell-beamers, especially the League of Free Traders. But the low-powered ones in LEO were no threat to people on the ground. And nobody had been burned in space by them, so they were tolerated as a necessary evil.

Think of Earth as being at the bottom of a funnel-shaped well whose walls become less steep as you climb away from Earth.

Paint the walls of the funnel in zones of different colors to represent the various space traffic control center jurisdictions. The ones nearest Earth at the bottom of the funnel are controlled from national centers that are, you hope, in communication with one another and swapping data. The ones further out are watched by seven other centers located in GEO. And the ones in the nearly-flat upper part of the funnel are four in number centered on L-4, the Moon, L-5, and a huge "uncontrolled sector" stretching around lunar orbit from 30-degrees ahead of L-4 to 30-degrees behind L-5 where there wasn't anything then.

Now spin the funnel so the bottom part representing a distance up to 50,000 kilometers goes around once in 24 hours. Spin the top part from 50,000 kilometers altitude out to a half-million kilometers at the lunar rate of 29.5 days.

Located on the walls of this madly turning multi-colored funnel are marbles spinning around its surface fast enough so they don't fall down the funnel. Some of them are deadly marbles; come close and you'll burn. Others are big and fragile, but massive enough to destroy your ship if you hit one. Still others are ships like your own, plying space for fun, profit, or military purposes. An unknown number of the last are capable of whanging you with various and sundry weapons.

Your mission: without coming afoul of any of this, get to the flat tableland on top, then locate and dock to a group of fly-specks called L-5.

Try it on your computer. Good luck.

We'd run a gauntlet of low-orbit facilities and were coming up on geosynchronous orbit. Although we were several degrees above equatorial GEO where most of the civilian facilities were, we had to get through the web of military satellites in inclined geosynchronous orbit, weaving paths around the planet like a ball of yarn.

Omer asked the computer to enhance the very weak returns from these stealthed facilities. We were going to come close to some Japanese and European targets, but not within their engagement zones unless they'd changed them and we didn't know it.

From Manna by Lee Correy (G. Harry Stine) 1983 ]

Space Habitat

The thought occured to some people (most notably Gerard O'Neill) that if the delta-V cost for traveling up and down a planet's gravity well is so expensive, the expense can be avoided if you simply live in space inside a titanic space station. The classic "L5 Colony" was about 32 km long, and held 10,000 inhabitants. Such a colony could earn its keep by harvesting solar energy or with other more shady revenue streams. A quick Google search on "L5 Colony" will reveal a wealth of details. And if you stick an engine on the end, you have a Generation Ship

It sounds very utopian, and it is.

Now, in a Rocketpunk future, when space stations are dotted over the entire solar system (or even the entire galaxy), they might start out as being just a tiny habitat functioning as a Transport Nexus. Yes, they may start as glorified airplane terminals, but they can become more than that. Space stations near research sites can become college towns, ones near mining sites can become mining towns. Then along will come people willing to import and sell things to the inhabitants, and suddenly you've got a city. Think about the TV show Babylon 5, about a space station at the intersection of interstellar transport routes between several star nations. Started as an outer space bus terminal, but grew to become a center of trade and diplomacy.

If the space city has its own revenue stream, it can go even further, and become an independent city state or station-republic. At some point they will be growing fast enough to justify investing in the construction of a full sized L5 colony.

But remember what Thucydides said above about devolution. If the space city's revenue stream dries up, the city becomes a slum, or even a ghost town. Especially if the space city is a boomtown, there to supply a fine selection of expensive vices to the local asteroid gold strike or orbit guard military base. If the strike dries up or the base is relocated, the space city will die and become a ghost town.

Space habitats appear in science fiction in the Mobile Suit Gundam Wing animes, C. J. Cherryh's Alliance-Union novels, Alexis Gilliland's Rosinante trilogy, George Zebrowski's Macrolife, John Varley's Gaea Trilogy, Sir Arthur C. Clarke's Rendezvous with Rama, and the tv series Babylon 5.

One problem is that you cannot make a small O'Neill cylinder as a pilot project to gain the expertise to build a full size one, due to the nausea caused by the Coriolis effect. Your first one has to be full sized.

A space colony is a particularly pure example of a hydralic state because Air Is Not Free. If citizens make angry the powers-that-be (defined as "the people who control life support), said citizens will suddenly find themselves trying to breath vacuum. Obey or die. The way to avoid this is with massively redundant life support infrastructure, in an attempt to decentralize control. Of course this only means you do not have to obey the space colony boss, just obey the boss of the segment you live in.

In C.J. Cherryh's Alliance-Union universe, none of the interstellar colonies are actually on an extrasolar planet. Instead they are space habitats in orbit around various lifeless planets (with the exception of Pell). The glaring unanswered question is if you are not going to be using the extrasolar planets, why did you go to the insane expense of using slower-than-light technology to create space habitats in other stellar systems? It would have been about a million times cheaper to just build the habitats somewhere in our own solar system.

If one is colonizing other stellar systems with slower-than-light starships, mass is at a premium. The expense of delta-Ving every microgram up to insterstellar velocities then braking to a halt means you won't be able to carry much of anything. It requires much lower mass to carry the needs for a colony on a human-habitable planet as compared to carrying the industrial machinery required to construct kilometer-long L5 colonies. In fact, such a colony ship might not even carry full grown colonists.

Naturally if you postulate FTL starships, all bets are off. Then it simply becomes a matter of transport costs.

This may or may not boil down to Space Habitats initially being unique to Terra's solar system.

Mos Eisley Space Station


The problem with a space station as Mos Eisley is simple. Who's providing the air? A lawless space station sounds good, but it's going to run into an extreme form of the "Three Generations Rule" from Attack Vector: Tactical. Either air will be ignored and everyone dies, or it will be the major point of conflict. No space station can survive without a single controlling power that runs the life support. The same applies to any other form of space habitat.

Neon Sequitur:

The 'Mos Eisley' concept may not work for an entire functional space station, but it makes a bit more sense if all or part of a station is considered 'written off'. Babylon 5 had a slum sector, which the station management considered not worth cleaning up. This conveniently allowed the writer(s) to have both a strong central authority on B5 as well as part of the station which resembled Mos Eisley.

In Transhuman Space, the Three Generations Rule rule might be considered a blessing when it comes to squatters in abandoned habitats. It saves the Powers That Be the expense of evicting them, or even deciding who's responsible for doing so. It's a given the life support will fail eventually. Until that happens, however, it's sort of a temporary 'tent city' version of Mos Eisley. (And that sounds like yet another pile of story ideas....)


There's no reason that this can't be worked into the plot. Our own human nations are not immortal. Our corporations can be consumed or die of incompetence. Just because Rome was not eternal did not mean it could not exist for the span it did. The vast majority of seeds do not become trees but that does not mean a forest cannot be.

Any properly vast station would have hundreds of sectors with redundant life support and power generation systems. If we imagine the station as an island in space, consider Hispaniola. On one side we have a functioning states, the Dominican Republic. On the other side we have Haiti, a dysfunctional mess. Same island, same resources, different results.

I could imagine a very interesting setting on a vast station that is suffering from the collapse of unified control. Some sectors are properly maintained and society is functioning as it should. Other sectors are in poor maintenance. Some of the common areas are completely out of maintenance, possibly open to hard vacuum. Perhaps the functioning side lacks the resources to fix the broken areas, maybe lack the manpower.

You have a story of resource depletion and civil war on Easter Island. A relatively advanced primitive society tore itself apart, likely over religion and politics. Imagine if you had a dozen islands within sight of each other, some of them maintaining social order while others descend into cannibalism and anarchy.

So as far as your Mos Eisley station example, a small one would be operated by one pirate king, the same way pirate settlements in the Carribean were founded by notable individuals. His house, his rules. Visitors pay rent. He provides the power, air, and food. For larger pirate settlements, each faction would maintain their own area. You wouldn't see chaotic evil pirates running these places, they'd be pragmatic amoral. These would be the guys you could trust in the sense that you know they are rational and have reputations to maintain in the community. You might get knifed in the back if no one is to be the wiser but they're not going to cheat you openly in a way that would harm their reputations. Get known as a cheat and no other pirate will risk doing business, savvy?

The rationale for a pirate haven like this is fairly obvious. Pirates can't get their ships worked on in legitimate yards. They need a place to handle repairs too big for the hands onboard. They need a place for R&R, can't exactly stretch your legs in places where the cops are. Ships can refit and recrew here. And there's also the need to fence stolen goods. Here pirate cargo gets traded to "honest" merchantmen and can get back on the open market.

Now any number of things can happen to jeopardize the viability of such a pirate haven and that's where the stories get interesting.


In our hypothetical space station, however, why would people who are keeping their sections in good shape provide for those who don't. Any earth analogy can only be taken so far, as we can managed to get all we need to live pretty much on our own here. The same is not true of a station, and if a sector is in chaos, the life support is going to get neglected, and that's going to lead to a crash very quickly. Atomic rockets points out that a space colony very much resembles a hydraulic empire. It simply can't be anarchy. There might be some parts that are seedy, but I doubt an entire station will be a lawless area, or even most of it. The pirate lord described is plausible, however.


Ah, good question. That's just it — it wouldn't be a hydraulic empire. For a large station, I'm imagining it being more like a condo. Stations have sections and sections are controlled by some form of polity, a faction. All the equipment necessary for survival is contained within that section. Each section beyond that is also self-supporting, just like owners in a condo -- the owner pays the note on his mortgage and nobody else in the community needs to help him on that. Of course, condos have areas of common responsibility and expense. When the organization becomes dysfunctional, that sort of stuff deteriorates. And then you can end up with the situation of individual units held onto by owners as the rest of the neighborhood deteriorates.

Now you may ask "Why would a station be built with so much redundancy in the first place?" And that would be precisely to avoid the situation of a hydraulic empire as you state. Say three factions come together to build a trading station in neutral territory. The expense is greater than any individual power can afford so they split the cost. The station is constructed. Each faction has territory on the station that they own in the clear. Furthermore, those sections are self-supporting for all essentials because they wish to avoid the chance of anyone cutting them off from the station's grid. But because there are common needs of the station, all three pay towards the maintenance of the structure and what elements cannot be easily triplicated. On paper this operations company may be considered independent and neutral with personnel drawn from all three factions or maybe from third parties. But you can well imagine how things on such a station could become dysfunctional in time.

From comments to Transport Nexus
Air Ain't Free

“Charges in place? Conduits sealed? Okay, go ahead and open it up.”

The heavy wrench descending, clangingly, on the sealed emergency hatch once, twice, three times before the seal broke, a wave of fouled air rushing out past the linobir enforcer and hsis men. Beyond, the milling crowd, faces pale and dark and congested with nerves, eyed them uneasily and decided not to make a break for it.

“All right, which of you self-f*****’ dock-rats claims t’be in charge of this section?” hse bellowed. “He’s got some things to ‘splain and so have I. Speak out, if breathin’ this crud hasn’t rotted your brains too much to parse plain Trade.”

Hser eye fell on a pair of scruffy deshnik arguing with one of his men, brandishing a smart-paper token.

“She’s got a pass? Any of the rest of you recognize this one?”

“Sure, boss, up on Thirty with the Torashanika clan.”

“Then get out of here — Just you, kid. He ain’t got a pass… No arguin’. You got three choices. You can stay here and kiss space with the rest of ‘em when their time comes, or you can run back to your clan-group and try an’ talk ‘em into buying out his life-debt.” Not that there was much chance of even a desperate clan-group doing that for a casteless deshnika flesh-peddler. “Or you can try and get past me an’ I’ll paint the deckhead with your brains. Estrev always gets his cut; no exceptions.”

“Listen up, the rest of you clut-grubbers! I speak for the drift-estrev, and the drift-estrev is not happy. You’re breathin’ his air and burnin’ his bunkerage, and what’s he getting back from you? Nothin’ but dioxide, taint, and an infestation of this pink s***.”

The linobir kicked at a squirming tendril of the ubiquitous hab-slime with a mid-limb.

“Now the estrev says you’ve got two cycles to pay off your life-debts and figure out how to make him value your worthless selves, or else I get to take the four pounds of trinol packed into these joints and blow your s***-house sewerslum right off station-end. Tell whoever’s hidin’ back there and breathe deep while y’can.”

“Close it up, boys. Message delivered.”


(ed note: in this essay, Asimov uses the term "g people" to mean the people living on Terra, and "null-g people" to mean those living in space habitats and asteroid colonies)

Second, the nature of the null-g environment will make it certain that they will far outstrip us in variability and versatility. The g people will exist as one large glob (earth's population) with small offshoots on Mars, the moon, and elsewhere, but the null-g's will be divided among a thousand or more worlds.

The situation will resemble that which once contrasted the Roman civilization with the Greek. The Romans wrought tremendous feats in law and government, in architecture and engineering, in military offense and defense. There was, however, something large, heavy, and inflexible about Roman civilization; it was Rome, wherever it was.

The Greeks, on the other hand, reaching far lesser material heights, had a life and verve in their culture that attracts us even today, across a time lapse of 2,500 years. No other culture ever had the spark of that of the Greeks, and part of the reason was that there was no Greece, really, only a thousand Greek city-states, each with its own government, its own customs, its own form of living, loving, worshiping, and dying. As we look back on the days of Greece, the brilliance of Athens tends to drown out the rest, but each town had something of its own to contribute. The endless variety that resulted gave Greece a glory that nothing before or since has been able to match; certainly not our own civilization of humanity-en-masse.

The null-g's may be the Greeks all over again. A thousand worlds, all with a common history and background, and each with its own way of developing and expressing that history and background. The richness of life represented by all the different null-g worlds may far surpass what is developed, by that time, on an earth rendered smaller and more uniform than ever by technological advance.

From Spomelife: The Universe and the Future by Isaac Asimov (1965)
That Buck Rogers Stuff

It's not crazy dreams. It's not even Far Out. It's only basic engineering, and some economics, and a bit of hope. I may even have been too conservative. It probably won't take a hundred years.

Given the basic space civilization I've described, we'll have accomplished one goal: no single accident, no war, no one insane action will finish us off. We won't have to have outgrown our damn foolishness to insure survival of the race. Perhaps we'll all be adults, mature, satisfied with what we have, long past wars and conflicts and the like; but I doubt it. At least, though, there will be no way to exterminate mankind, even if we manage to make the Earth uninhabitable; and it's unlikely that any group, nation, or ideology can enslave everyone. That's Worth Something.

One suspects, too, that there will be an enormous diversity of cultures. Travel times between various city-states-asteroid, Martian, Lunar, O'Neill colony, Saturnian forward base, Jovian Trojan Point—will be weeks to months to years with presently foreseeable technology. That's likely to change, but by the time the faster travel systems are in widespread use the cultural diversities will be established. Meanwhile, communication among all the various parts of the solar system will be simple and relatively cheap, so that there will have been that unifying influence; cultures will become different because people want to be different, not because they don't know any better.

OK. In 100 years we'll have built a space civilization. We'll no longer have really grinding poverty, although there will undoubtedly be people who consider themselves poor, just as we have today people who live better than the aristocrats of 1776, but who think themselves in terrible straits. We'll have insured against any man-made disaster wiping out the race.

From That Buck Rogers Stuff by Jerry Pournelle (1976)

Asteroid Bubble

Larry Niven popularized the "asteroid bubble" technique of creating a huge space habitat. Andrew Love notes that if the asteroid is made of stone, once you start to spin it for artificial gravity it will immediately fly into pieces. As he puts it "there are no stone suspension bridges". Stone is heavy and weak, particularly in tension. A 100 meter external radius asteroid made of granite and spun up to 1 gee would put the granite under stresses about twice the expected strength of granite.

You will note that Larry Niven specifies a asteroid composed of nickle-iron.

The next step up in size is the hollow planetoid. I got my designs from a book of scientific speculation, Islands in Space, by Dandrige M. Cole and Donald W. Cox.

STEP ONE: Construct a giant solar mirror. Formed under zero gravity conditions, it need be nothing more than an Echo balloon sprayed with something to harden it, then cut in half and silvered on the inside. It would be fragile as a butterfly, and huge.

STEP TWO: Pick a planetoid. Ideally, we need an elongated chunk of nickel-iron, perhaps one mile in diameter and two miles long.

STEP THREE: Bore a hole down the long axis.

STEP FOUR: Charge the hole with tanks of water. Plug the openings, and weld the plugs, using the solar mirror.

STEP FIVE: Set the planetoid spinning slowly on its axis. As it spins, bathe the entire mass in the concentrated sunlight from the solar mirror. Gradually the flying iron mountain would be heated to melting all over its surface. Then the heat would creep inward, until the object is almost entirely molten.

STEP SIX: The axis would be the last part to reach melting point. At that point the water tanks explode. The pressure blows the planetoid up into an iron balloon some ten miles in diameter and twenty miles long, if everybody has done their jobs right.

The hollow world is now ready for tenants. Except that certain things have to be moved in: air, water, soil, living things. It should be possible to set up a closed ecology. Cole and Cox suggested setting up the solar mirror at one end and using it to reflect sunlight back and forth along the long axis. We might prefer to use fusion power, if we’ve got it.

Naturally we spin the thing for gravity.

Living in such an inside-out world would be odd in some respects. The whole landscape is overhead. Our sky is farms and houses and so forth. If we came to space to see the stars, we’ll have to go down into the basement.

We get our choice of gravity and weather. Weather is easy. We give the asteroid a slight equatorial bulge, to get a circular central lake. We shade the endpoints of the asteroid from the sun, so that it’s always raining there, and the water runs downhill to the central lake. If we keep the gravity low enough, we should be able to fly with an appropriate set of muscle-powered wings; and the closer we get to the axis, the easier it becomes. (Of course, if we get too close the wax melts and the wings come apart…)

From Bigger than Worlds by Larry Niven (1974)

Confinement Asteroid is unique.

Early explorers had run across a roughly cylindrical block of solid nickel-iron two miles long by a mile thick, orbiting not far from Ceres. They had marked its path and dubbed it S-2376.

Those who came sixty years ago were workmen with a plan. They drilled a hole down the asteroid’s axis, filled it with plastic bags of water, and closed both ends. Solid fuel jets spun S-2376 on its axis. As it spun, solar mirrors bathed it in light, slowly melted it from the surface to the center. When the water finished exploding, and the rock had cooled, the workmen had a cylindrical nickel-iron bubble twelve miles long by six in diameter.

It had been expensive already. Now it was more so. They rotated the bubble to provide half a gee of gravity, filled it with air and with tons of expensive water covered the interior with a mixture of pulverized stony meteorite material and garbage seeded with select bacteria. A fusion tube was run down the axis, three miles up from everywhere: a very special fusion tube, made permeable to certain wavelengths of light. A gentle bulge in the middle created the wedding-ring lake which now girdles the little inside-out world. Sunshades a mile across were set to guard the poles from light, so that snow could condense there, fall of its own weight, melt, and run in rivers to the lake.

The project took a quarter of a century to complete.

Thirty-five years ago Confinement freed the Belt of its most important tie to Earth. Women cannot have children in free fall. Confinement, with two hundred square miles of usable land, could house one hundred thousand in comfort; and one day it will. But the population of the Belt is only eight hundred thousand; Confinement’s score hovers around twenty thousand, mostly women, mostly transient, mostly pregnant.

From World of Ptavvs by Larry Niven ()

Space Superiority Platform

Many early SF stories fret about the military advantage an armed space station confer upon the owning nation. Heinlein says trying to fight a space station (or orbiting spacecraft) from the ground is akin to a man at the bottom of a well conducting a rock-throwing fight with somebody at the top. One power-crazed dictator with a nuclear bomb armed station could rule the world! Space faring nations would need space scouts for defense.

But most experts nowadays say that turns out not to be the case. A nation can threaten another with nuclear annihilation far more cheaply with a few ICBMs, no station is required. And while ground launching sites can hide in rugged terrain, a space station can hide nowhere. Pretty much the entire facing hemisphere can attack the station with missiles, laser weapons, and propaganda.

Phil Shanton points out that you don't need a huge missile to destroy an orbiting space station, either. In 1979, the U.S. Air Force awarded a contract to the Vought company to develop an anti-satellite missile. It was not a huge missile from a large launch site. It was a relatively small missile launched by an F-15 Eagle interceptor in a zoom-climb. Vought developed the ASM-135 Anti-Satellite Missile (ASAT), and on 13 September 1985 it successfully destroyed the solar observatory satellite "P78-1". This means that an evil-dictator world-dominator nuke-station not only has to worry about every ground launch site, but also every single fighter aircraft.

It has also been modeled that the U.S. Navy could take out a satellite with a Standard Missile 3.

Things are different, of course if the situation is an extraplanetary fleet that remotely bombs the planet to destroy all the infrastructure. The fleet can construct a space superiority platform while the planet is struggling to rebuild its industrial base. Then the platform can bomb any planetary site that is getting too advanced in rebuilding. This is known as "not letting the weeds grow too tall.


Space Logistics Base

James Snead has written a few paper about space infrastructure. Most interesting is Architecting Rapid Growth in Space Logistics Capabilities. On page 23 he gives an example of an orbiting space logistics base, including a space dock. Refer to that document for larger versions of the images below.

...the space logistics base’s functions are: (1) housing for travelers and operating crews; (2) emergency care; (3) in-space assembly, maintenance, and repair; and (4) materiel handling and storage.

The example space logistics base consists of four elements. At the top in Fig. 10 is the mission module providing the primary base control facility, emergency medical support, and crew and visitor quarters. The personnel quarters are located inside core propellant tanks that are retained from the SHS used to launch the mission module. The overall length of the mission module and propellant tanks is approximately 76 m (250 ft). Solar arrays and waste heat radiators (shown cut-away in Fig. 10) are mounted on a framework surrounding the mission module to provide additional radiation and micrometeoroid protection.

The second element consists of twin space hangars. These serve as airlocks for receiving spaceplanes and provide a pressurized work bay for conducting on-orbit maintenance of satellites and space platforms.

As shown in Fig. 11, the space hangar consists of a structural cylindrical shell 10 m (33 ft) in diameter, a forward pressure bulkhead containing the primary pressure doors, and an aft spherical work bay. These elements, which define the primary structure, would be manufactured as a single unit and launched as the payload of an SHS. The large, nonpressurized, space debris protection doors would be temporarily mounted inside the hangar for launch and then demounted and installed during the final assembly of the hangar at the LEO construction site. All of the other hangar components would be sized for transport to orbit in the cargo module of the RLVs and then taken through the hangar’s primary pressure doors for installation.

Future logistics supportability is a key feature of this hangar design. The size, weight, location, and access of the internal hangar components enables them to be inspected, repaired, and replaced without affecting the primary structural / pressure integrity of the hangar. With the exception of the space debris protection doors, this would be done inside the hangar when it is pressurized. The ISS-type airlock and space debris protection doors, although mounted externally, would be demounted and brought into the hangar for inspection, maintenance, and repair. For the repair of the primary pressure doors, they would be demounted and taken into the spherical work bay or the other hangar for servicing.

The hangar’s design enables both pressurized and unpressurized hangar operations to be undertaken simultaneously. When the main hangar deck is depressurized to receive cargo or spaceplanes, for example, pressurized maintenance operations would continue inside the 9.8 m (32 ft) diameter spherical work bay and the 2.8 m (9 ft ) diameter x 4.3 m (14 ft ) work compartments arranged along the top of the hangar.

Hangar operations in support of the passenger spaceplanes, as shown in Fig. 12, highlight the improvement in on-orbit logistics support enabled by the large hangars. After entry into and repressurization of the hangar, the passengers would disembark from the spaceplane. Support technicians, working in the hangar’s shirtsleeve environment, would inspect the spaceplane and, in particular, the thermal protection system for any damage to ensure that it is ready for its return to the Earth. While at the space base, the spaceplane would remain in the hangar to protect it from micrometeoroid or space debris damage. Minor repairs to the spaceplane could also be undertaken to ensure flight safety.

The third element is the air storage system. The prominent parts of this system are the large air storage tanks that are the reused core propellant tanks from the two SHS used to launch the twin space hangars. Besides storing air from the hangars, this system also: manages the oxygen, carbon dioxide, and moisture levels; removes toxic gases, vapors, and particulates; and, controls the temperature and circulation of the air within the hangar and its compartments.

The fourth and final element is the space dock. It would be constructed from structural truss segments assembled within the space hangars using components transported to orbit in the RLVs. The space dock would provide the ability to assembly and support large space logistics facilities, such as the space hotels and large manned spacecraft described in the following. It could also used to store materiel and as a mount for additional solar arrays.

The space hangars and space dock would enable traditional logistics operations of maintenance, assembly, and resupply to be routinely conducted in Earth orbit. This is an enabling capability necessary to become spacefaring and achieve mastery of operations in space.

The space logistics base would have approximately 20 personnel assigned. The tour of duty would be 90 days with half of the crew rotating every 45 days. Crew rotation and base resupply would require approximately 32 RLV missions per year per base with 8 spaceplane missions and 24 cargo missions. This would provide approximately 12,000 kg (26,000 lb) of expendables and spares per person per year. At $37M per mission, a ROM estimate of the annual transportation support cost per base would be approximately $1.2B.

While the LEO space logistics base would have sufficient housing capacity to support the 20 assigned personnel and a modest number of transient visitors, it would not be a primary housing facility. Since people cannot simply pitch a tent and “camp out” in space, establishing early permanent housing facilities is an important and enabling element of opening the space frontier to expanded human operations. The architecture of the Shuttle-derived heavy spacelifter and the LEO space logistics base was selected so that the first large space housing complexes, referred to as space hotels, could be constructed using the same space logistics base modules.

A composite illustration of the design, assembly, and deployment of the example space hotel is shown in Fig. 13. This hotel design is configured as a hub and spoke design with a long central hub and opposing sets of spokes attached to the central hub module. This configuration makes it possible to use variants of the space base’s mission modules and space hangars as the primary elements of the space hotel’s design.

Element 1, in Fig. 13, shows the start of the hotel assembly sequence. The central hub module, shown with the SHS’s core propellant tanks still attached, is being positioned at the space logistics base’s space dock. The central hub module would be a version of the mission module used in the space logistics base. Its design would include 12 docking ports around its circumference for attaching the spokes.

Element 2 shows the completed hub and one attached spoke. Two space hangars are located at the ends of the hub and the first spoke is shown attached to the central hub module. In assembling the hub, the core propellant tanks from the two SHS missions used to launch the hangars would be incorporated into the hub to provide additional pressurized volume. This approach would be also used for the spokes. Each spoke would consist of a generalpurpose mission module with the SHS’s core propellant tanks reused for additional pressurized volume. As with the mission module on the space logistics base, the spokes would be surrounded by solar arrays and waste heat radiators. This is what provides their “boxy” appearance.

Element 3 shows the completed 100-person space hotel with two pairs of spokes on opposing sides of the hub. This is the baseline space hotel configuration. Seven SHS missions would be required to launch the hub and spoke modules for the baseline hotel. One additional SHS cargo mission would be used for the solar arrays and waste heat radiators.

This design enables the hotel to be expanded to 6, 8, 10, or 12 spokes. Each spoke would require one additional SHS mission. The 12-spoke configuration would accommodate up to approximately 300 people. Each additional spoke would be tailored to provide a specific capability, such as research and development facilities, tourist quarters, office space, retail space, etc.

Element 4 shows the completed space hotel after being released from the space dock. It also shows how the hotel would rotate about the long axis of the hub to produce modest levels of artificial gravity in the spokes. At about two revolutions per minute, a Mars gravity level is achieved at the ends of the spokes. This use of artificial gravity enables the spokes to be organized into floors (Element 5 in Fig. 13). Each spoke would contain 18 floors with 14 of these available for general use and the remaining 4 floors used for storage and equipment. The spokes would be 8.4 m (27.5 ft) in diameter. This would provide a useful floor area of approximately 42 m2 (450 ft2) per floor. The total available floor area in the baseline configuration would be 2,340 m2 (25,200 ft2). The 12-spoke configuration, having 192 floors total, would have 3 times this floor area—7,026 m2 (75,600 ft2) or about 23 m2 (250 ft2) per person.

An estimate can be made of the number of guests visiting the hotel each year. Assuming a 3:1 ratio of guests to staff, approximately 76 guests would be staying each night in the baseline configuration and 228 guests in the full configuration. With one third of the useful floors configured as guest cabins, two cabins to a floor, each cabin would have a useful area of approximately 21 m2 (225 ft2).* With an average stay of one week, approximately 4,000 guests and 12,000 guests would visit the 4- and 12-spoke hotels each year, respectively.

If each passenger spaceplane carries 10 guests, approximately 400 and 1,200 RLV flights would be required each year. With an additional 25% required for staff transport and resupply, the 4-spoke hotel would require about 10 flights per week and the 12-spoke hotel would require about 30 flights per week. If the RLVs could achieve a one-week turnaround time, and allowing for one in five RLVs being in depot for maintenance, 12 RLVs would be required to support the 4-spoke hotel and 36 RLVs for the 12-spoke hotel.†

At the $37M per flight cost discussed previously for first generation RLVs, the per passenger transportation cost would be approximately $3.7M. With this transportation cost structure, a sustainable space tourism or space business market may not be possible. However, if a second generation RLV could reduce this cost by a factor of 10 to $0.37M per passenger, as an example, then an initial market demand for the baseline hotel may develop and be sustainable. In such case, the annual transportation revenue for the baseline hotel would be $3.7M x 500 = $1.9B and the 12-spoke hotel would be $5.6B.‡ This improvement in transportation costs would also yield a savings of 90%—approximately $1B per year—in the transportation costs to support the LEO space logistics bases. Human space exploration missions would also realize a significant cost reduction.

While developing a conceptual design of a space hotel would appear premature at this early stage of considering the architecture of an initial space logistics infrastructure, several important conclusions emerge that indicate otherwise:

1) Careful selection of the initial space logistics architecture can also establish the industrial capability to build the first space hotels necessary to enable the expansion of human enterprises in space.

2) A commercially successful space hotel will require second generation RLVs to lower further the cost of transportation to orbit.

3) In order for these second generation RLVs to be ready when the first space hotel is completed, the technology research investment would need to begin concurrently with the start of the detailed design of the initial space logistics systems. Conversely, for private investment to seriously consider building the first hotels, significant science and technology progress in developing the second generation RLVs must be demonstrated by the time the initial hotel construction contracts are made.

4) The benefits of reduced space transportation costs will also substantially lower the cost of operation of the initial elements of the space logistics infrastructure, leading to a likely increase in demand for more in-space logistics services.

5) Space hotels and second-generation RLVs may become an important new aerospace product for the American aerospace industry, establishing American leadership in this new and growing field of human astronautical technologies.

6) It is not unrealistic to expect, with the building of an integrated space logistics infrastructure, that hundreds of people could be living and working in space by 2020, growing to thousands of people by 2040 with many of these living in the first permanent orbiting space settlements.

* A standard cabin on the new Queen Mary 2 cruise ship has an area of 18 m2 (194 ft2). A premium cabin has an area of 23 m2 (248 ft2).

† Launch sites for these RLVs would be distributed around the world. This would allow operations at the space hotel to run 24 hours per day since there is no day and night in LEO.

‡ This further reduction could come about through the introduction of a spiral version of the first-generation RLVs where improvements to the high maintenance cost subsystems, e.g., engines, could substantially reduce the recurring costs. Another approach would be development of entirely new RLV configurations—perhaps a single-stage configuration—that would also result in a substantial reduction in recurring costs per passenger through subsystem design improvements and the ability to carry more passengers per trip. A key issue in both approaches is the amortization of the development and production costs. High flight rates, probably dependent on space tourism, would be required to yield an overall transportation cost sufficiently low to enable profitable commercial operations.

Rocketpunk Manifesto Patrol Base

The comment thread on my previous post about space patrols raised the issue of base stations for more prolonged missions, extending to years.

This has application far beyond military or quasi-military patrols. In fact it is fairly fundamental to any extensive, long term human presence in deep space. Whether or not we put permanent bases on the surface of Mars, Europa, or wherever, we will surely place permanent or semi-permanent stations in orbit around them. Particularly because the stations can be built in Earth space, where the industry is (at least initially), and flown out to where they will serve.

Hab structures intended for prolonged habitation should be fairly large, if only because if you are going to live for years in a can it should be at least be a roomy one. And they must be thoroughly shielded against radiation, much more than ships that you only spend a few months aboard every few years.

So let us play with some numbers. Make our spin hab a drum, 200 meters in diameter and 100 meters thick. Volume is thus about 3.14 million cubic meters. The ISS has about 1200 m3 of pressurized volume and a mass of some 300 tons, for an average density near 0.25, but the mass includes exterior structures such as keel and wings. Let average interior density be about 0.16, for a mass of 500,000 tons.

If we allow 100 cubic meters per person the onboard population (whether 'crew' or simply residents, or a mix) can be up to 30,000 people. This is about twice the density of a middle class American urban apartment complex. Given that much of the usable volume must be working areas, public spaces, and so forth, the actual crew or population might be more on the order of 10,000 people, equivalent to a decent sized small town or a fairly large university or military base. Thus the hab has 10 times the volume of an aircraft carrier and twice as many people.

Spin the hab at 3 rpm and you get almost exactly 1 g at the rim.

By my standard rule of thumb the cost of this hab is on order of $500 billion. That is a steep price tag, but on the other hand it is only five times the cost of the ISS, and you need very few of these unless you are engaged in outright colonization.

Now, shielding. The standard for indefinite habitation is about 5 tons per square meter of cross section. (Earth's atmosphere provides about 10 tons/m2.) Portions of the hab where people do not spend much time, and exterior to where they do spend time, can be counted toward the shielding allowance. So let us say that the outer 10 meters of the interior (about 35 percent of the volume) are used for storage, equipment rooms, and the like. This provides about 2 tons per square meter of shielding, 40 percent of the requirement.

The remaining 3 tons per square meter of exterior shielding must cover about 125,000 square meters of surface, so shielding mass is about 375,000 tons, adding 75 percent to the mass of the hab, now 875,000 tons. This shielding need not be 'armor.' As I recall, water provides pretty good shielding against GCRs, your biggest radiation problem, and water is so useful that having 375,000 tons of it on hand in a reservoir will never be amiss.

Moreover, to move the hab you can vent off the water (or pump it out) and not need to lug the mass, assuming you can replace it wherever you are going. The deep interior of the hab, more than 25 meters from the surface (about 28 percent of the volume) is still shielded by the rest of the hab structure, so the hab can carry a reduced population during the transfer.

You are still moving a half million ton payload, so don't expect to rush it unless you have a really badass drive bus handy. Habs being repositioned across the Solar System probably travel on Hohmann orbits, and have drive accelerations of a few dozen microgees, good for about 1 km/s per month of steady acceleration.

For a smaller hab structure, scale down the linear dimensions by half, to 100 meters diameter and 50 meters thick. Structural mass, volume, and capacity are all reduced by a factor of 8, to 400,000 cubic meters, 60,000 tons, and a crew / resident population of about 1500-4000. Our 'mini' hab is now broadly comparable in volume, mass, and crew to an aircraft carrier.

Surface area is only reduced, however, by a factor of four, to about 30,000 square meters. Moreover, the smaller hab provides less interior self-shielding. If we keep the same proportions our internal reserved zone is just 5 meters deep and provides only 20 percent of the needed protection, not 40 percent.

We now need about 120,000 tons of shielding — twice the unshielded mass of the hab. If we move the hab fully shielded our payload mass is 180,000 tons. Remove the shielding and payload mass is just 60,000 tons, but no part of the smaller interior is fully self-shielded, so any crew on board during a 'light' transfer must be relieved every few months. On the bright side, if you have a 100 gigawatt drive bus floating around, or about $100 billion to buy one, you can take a fast orbit and get there in a few months.

The image shows a drum-hab station ship with a spin hab of the full sized type described above, 200 meters in diameter by 100 meters thick, fitted with a heaviest class drive bus for transfer. I am delicately ignoring details of the connection between the spin drum and the hub structures.

The shuttles approximate the NASA Shuttle, as a visual size reference. The deep space ships docking up to it are large fast transports, 300 meters long, ten times heavier than the patrol ship discussed last post. The station ship itself is about 675 meters long by 450 meters across the outrigger docking bays.

In my image the station ship is no aesthetic triumph. Allowing for my limitations as an graphic artist (compare to commenter Elukka, from the last comment thread), the transport class ships don't look too bad, but the station ship merely looks tubby instead of grand. Some modest architectural improvements might yield a more impressive appearance with little change in overall configuration.

Of course the interior will matter immeasurably more to the people on board. Mostly, presumably, it will resemble the interior of a very large oceangoing ship, corridors and compartments, probably including some fairly imposing public spaces, comparable to the grand saloon of a 20th century ocean liner or even larger. It can be as elegant or as sterile as you like (or both, depending on deck and sector). The third popular choice, rundown industrial gothic, is constrained by how far you can go in that direction before the algae dies or the air starts leaking out.

From Home Away From Home by Rick Robinson (2010)

NASA Space Station: Key to the Future

This is from a 1970 brochure from NASA called Space Station: Key to the Future, as documented by David Portree. The station is cylindrical with a diameter of ten meters, and houses a crew of 12. The station is somewhat extravagant, down to the wood panelling on the crew quarters.

Krafft Ehrickes Atlas Space Station

Back in late 1957, the United States was feeling very smug. They were the most powerful nation on Earth, had the biggest and the best of everything, and above all were the most technologically advanced. Their biggest rivals were the Soviet Union. But their technologists were a bunch of stupid farm boys who wouldn't recognize a scientific innovation if it flew straight up their behind. Life was good for the U.S.A.

The US was even ready to meet the challenge of the International Geophysical Year. The IGY officials had adopted a resolution for something straight out of science fiction: create something called an "artificial satellite" and launch it into something called an "orbit" in order to map Earth's surface duntDah DUUUHHHH! from Spaaaaaaace!. The US had been working with the Martin Company since 1955 on the Naval Research Laboratory's Vangard satellite. The US was looking forwards to yet again demonstrating the unstoppable advantage of good old US know-how.

Then one fine day the Soviets quietly told a few people to watch the skies that night. Oh, and tune your radio to 20 megacycles while you are at it.

On 4 October 1957 at 19:28:34 UTC, the Soviets launched the world's first artificial satellite into orbit, called Sputnik 1. No propaganda lie was this, you could see the blasted thing orbiting with a low powered telescope, and there was that accursed BEEP-BEEP-BEEP coming clearly at 20 megacycles. The Space Age had started.

The United States freaked out.

The reaction was a mix of stunned incredulity, incandescent rage, and hysterical panic. Incredulity that the "backwards" Soviets could beat the US at its own game. Rage at being demoted to "also ran" status in the race. And panic because it would be just a matter of time before those evil Soviets put nuclear warheads on their satellites. Yes, Sputnik was a miserable half meter sized ball that couldn't do more than make beep-beep noises. But the US couldn't even do that much.

Sputnik directly caused the US to create NASA. And ARPA (which later became DARPA). ARPA's mission statement was "See that Soviet Sputnik? DON'T LET THAT HAPPEN AGAIN, EVER!" (although the actual command was worded something like "help the US regain its technological lead"). The National Science Foundation also got a $100 million dollar budget increase and was told to start cranking out as many new engineers as it could possibly make. Right Now.

Things got worse when the US tried to launch its answer to Sputnik. On December 6, 1957, Vanguard TV3 was launched from Cape Canaveral. The event was carried live on US TV, which in hindsight was a rather poor decision. Viewers across the nation witnessed Vanguard's engines igniting, the rocket's rise to an altitude of almost 1.2 meters, the fall back to the launch pad, and the spectacular fiery explosion.

The smoking remains of the Vanguard satellite rolled across the ground, pathetically still sending its radio beacon signal. In the radio shack, the crew was unaware of the explosion, and were troubled that they could no longer receive the signal. Somebody picked up the charred remains of Vanguard and walked into the shack. As he entered, the radio operators excitedly announced that they were suddenly picking up the signal loud and clear!

Meanwhile on Wall Street, they had to temporarily suspend trading in Martin Company stock as it plummeted in value. The news media was not kind, calling Vanguard uncharitable names such as "Flopnik", "Kaputnik", "Oopsnik", and "Stayputnik". To say this was an international humiliation was putting it mildly. A few days after the incident, a Soviet delegate to the United Nations inquired solicitously whether the United States was interested in receiving aid earmarked for "undeveloped countries”. Ouch.

Then in April 25, 1958, in the middle of all this gloom and doom, Dr. Krafft Ehricke goes to Washington. He was one of the genius scientists from Nazi Germany who was scooped up by Operation Paperclip. In 1958 he was working for Convair.

Part of Dr. Ehricke's genius was his practicality. He knew if you had to get something developed quickly, the design time had to be minimized. Indeed, you could cut the time drastically if you can find a way to modify some off-the-shelf technology instead of starting from scratch. As it happened, Convair had created the SM-65 Atlas rocket which was the US's first ICBM and the largest rocket it had at the time. Dr. Ehricke noticed that the Atlas could boost a small payload into orbit. In fact, it could boost itself into orbit.

What if you stop looking at the Atlas' giant fuel tanks as fuel tanks and instead saw them as a ready-made space station hull? Why, you would have the Soviets sputtering in rage as the unmanned Sputnik 1 and the dog-manned Sputnik 2 were savagely upstaged by the Man-manned US space station!

Dr. Ehricke's design was a four-man nuclear powered space station that could be built using existing Atlas rockets. As the cherry on top of the sundae, it could be spun for artificial gravity. It could be bulit in five years at a cost of about half a billion 1958 dollars.

The station was never built, which was a pity because it would have worked! Years later in 1973 Dr. Ehricke's concept was used for NASA's Skylab. It too was a space station build out of a spent upper stage. Technically Ehricke's design was a wet workshop while Skylab was a dry workshop, but the basic idea is there.

The Hawk plastic model company wasted no time making a model kit of Ehricke's space station. It was first issued in 1960, and later re-issued in 1968 (which was when I got my copy of the kit).

The Station is 32 meters long with a mass of 6.8 metric tons. It can house a four man crew. It orbits at an altitude of 640 kilometers. Power is from a SNAP-2 nuclear reactor with an output of 55 kilowatts. Each glider carries two men. The vernier rockets will spin up the station around the entry port spin axis at a rate of 2.5 times per minute, to provide artificial gravity of 0.1 to 0.15g. Pretty darn impressive for 1958. Actually it would be quite impressive today, the International Space Station has no artificial gravity nor nuclear power.

The nose end of the station is for the habitat module. Outside of the sanitary room on the tip of the nose is a condenser cooler for the water regeneration system and a waste disposal outlet (yes, when you flush the toilet you are spraying sewage into a wide arc like a water-sprinkler. Take that, Khrushchev!). Oxygen is from a tank in the rear end, but the habitat module has a small emergency oxygen tank.

Naturally there are some drawbacks to using an Atlas. One of them is the dimensions. While the Atlas is 22.8 meters long, it is only 3 meters in diameter. So the living spaces are going to be a bit cramped. Especially since the pointed nose section grows even narrower than 3 meters.

The rear end is to store heavy equipment. It would hold oxygen tanks, water supply, emergency power supply (batteries), vernier rocket propellant tanks (to start and stop the artificial gravity spin), tools, reserve equipment, and instrumentation.

The entrance is located near the midpoint, at the spin axis. It is surrounded by a basket-funnel to aid astronauts to enter and exit. It leads to the unpressurized interior. The habitat module in the nose has an airlock above the control room.

Construction of the station will take about one week. Once operational, the station will initially rotate crews back to Terra after every two weeks, later once a month. A cargo ship will deliver 3,600 kilograms of supplies once a year. A total of 13 to 20 launches a year would be required to maintain the station.

The station can be expanded with the upper stage tanks of cargo and passenger vessels. Small satellites can be added to the system — with or without rotation — for housing telescope and other instruments.

Space station functions:

  • As a test bed for long-term evaluation of development of equipment and living conditions in advanced manned satellites, lunar and interplanetary spacecraft.
  • To teach crews to live in space and to prepare for flights to other planets.
  • To serve as a base for launching improved interplanetary research probes to Venus, Mars, and the outer solar system.
  • As a base for weather observation (the transistor had just been invented) and to monitor terrestrial activities (i.e, spy on enemies of the US, like those vile Sputnik-launching Soviets)
  • As a base for geophysical and astrophysical research.
  • As a maintainance base for satellites in suitable orbits.
  • As a base for assembly, testing, and launching of lunar reconnaissance vehicles.

Construction of the station should take about one week.

  1. An Atlas is boosted into a 640 kilometers high orbit, arriving with empty tanks. It will become the hull of the station.
  2. One personnel vehicle (carrying four man alpha crew and two gliders) and one cargo vehicle (carrying equipment for rear of station) are launched, and rendezvous with the empty Atlas.
  3. Using the gliders, the alpha crew moves the equipment from the cargo vehicle to the empty Atlas.
  4. The alpha crew installs in the Atlas emergency power (batteries), water, and oxgen supply systems.
  5. One personnel vehicle (carrying a four man beta crew and two gliders) and one cargo vehicle (carrying equipment for nose of station) are launched, and rendezvous with the Atlas.
  6. The alpha crew returns to Terra via their two gliders.
  7. Beta crew places rubber nylon balloon inside nose of station, and inflates it to create pressurized habitat module. The four decks are installed, with all the insulation, furnishings and equipment. Water recycling system installed in sanitary room. Food is stored and the water & air cycles are tested using emergency battery power.
  8. One personnel vehicle (carrying a four man gamma crew and two gliders) and one cargo vehicle (carrying SNAP-2 nuclear reactor, shadow shield, and heat radiator) are launched, and rendezvous with the Atlas.
  9. The beta crew returns to Terra via their two gliders.
  10. The gamma crew installs the nuclear reactor. Water and air cycles would be started using reactor power. Vernier rockets are fired to spin the station for artificial gravity.
  11. The station is now operational.
  12. Crews are rotated once a month.

Self-Deploying Space Station

This clever design solves the problem of how to quickly assemble a wheel space station, with one tiny little drawback. You see, there is a reason that wheel space stations are shaped like, well, wheels and not like hexagons.

The amount of centrifugal gravity experienced is determined by the distance from the axis of rotation (the greater the distance, the stronger the gravity). So if you want the amount of gravity to be the same, the station has to be a circle.

Now, look at the image below. The segment labeled "SPACE STATION RIGID MODULE" is one of the hexagonal sides. The green lines lead to the axis of rotation (i.e., that is the direction of "up". Note the little dark men figures, they feel like they are standing upright). And the red lines are lines of equal gravity. You will note that they do not align with the module.

In the module, centrifugal gravity will be weakest at the center of the module, and strongest at the ends where it joins with the neighbor modules. Even though the module is straight, the gravity will feel like it is a hill. If you place a marble on the deck in the center, it will roll "downhill" to one of the edges.

As you see, the designers tried to compensate for this by angling the decks, but it really doesn't work very well. They also put in secondary floors where the angle got too steep. The metric was to try and keep the variation in gravity across one module to within 0.02-g.

The problem this design was intended to solve was that of a lack of experience in free-fall construction. In the 1960's Langley Research Center concluded that assembling a space station out of component parts in orbit would not be practical until after 1975 or so. You need to gain expertise in the orbital rendezvous of many seperatly launched sections, gain skills in making mechanical, fluid, and electrical connections in free fall, and other problems. This space station was to do an end-run around the problems. No need to rendezvous or making connections if the thing is launched as one part. The only problem is figuring out how to fold the station up so it will fit in the rocket, and how it transforms into the full station.

Historically, NASA figured out how to make mechanical, fluid, and electrical connections in free fall by 1998 at the latest. The International Space Station was indeed assembled in orbit out of component parts launched separately.

The station was 150 feet across the hexagonal corners, central hub 12.8 feet in diameter and 29 feet high. When folded for launch it was 33 feet in diameter and 103 feet high (not counting the Apollo spacecraft on top. Total mass (including the Apollo) was 170,300 pounds. The rim modules were cylinders 10 feet in diameter and 75 feet long. They are hinged where they connect. When operational, the station would rotate at 3 rpm to generate 0.2-g artificial gravity at the rim. The spokes were 5 feet in diameter and 48 feet long. It would hold 21 crew members.


Somewhat more elaborate in conception is the 94 ft wheel-shaped satellite prepared by two design engineers of the Lockheed Missile Division. This celestial laboratory for a crew of 10 weighs 400 tons, and is intended to orbit at a height of 500 miles. Each pre-fabricated section is 10 ft in diameter and 20 ft long, fitted with airlocks, and weighs 10 tons delivered into orbit. Powerful 3-man "astro-tugs" would round up the orbiting packages and couple them up. The entire operation should not take more than a month. The whole design has been investigated in exceptional detail, and is complete with nuclear power reactor and propulsion unit for changing orbit, astronomical telescopes, computer room, space-medical laboratory, airlocks for access, etc. All gravitational worries would be relieved by rotating the vehicle about its hub, which would remain stationary for observational purposes.

The Lockheed space station made an apperance on the 1959 TV show Men into Space. I have not seen this show, but from what I've read it was astonishingly scientifically accurate. Certainly more accurate than most anything from TV or movies in the last couple of decades. Thanks to Drake Grey for bringing this to my attention.

Pratt and Whitney Space Station

Herman Potocnik Design

This is from those innocent days before the discovery of nuclear power. The station uses solar power in the form of mercury boilers, since these were also the days before the discovery of the photoelectric effect.

Smith and Ross Design

Station desgined by R.A.Smith and H.E.Ross (circa 1940). Again, the station is powered by mercury boilers. The telescope uses a coelostat to counteract the spin of the station. The antenna support arm is de-spun to allow a spacecraft to dock, then is spun up to allow the air-lock module to mate with the station habitat module.

Fortress on a Skyhook


High Crusade

Apparently the artist who did the book cover had seen this old Soviet space station design. I have not been able to discover any details about the station, except that the model is apparently hanging in some Russian museum.

Atomic Rockets notices

Welcome to the improved Atomic Rockets!

Atomic Rockets

Support Atomic Rockets

Support Atomic Rockets on Patreon