Reinventing Space Settlements

original title 

Space Oases: The Next Generation

1995 Copernicus Construction Company

Peter Kokh and Doug Armstrong

With input on alternative design options from Jeff Sanburg

Presented at ISDC 2000, Tucson, AZ

Additional material added 02/09/2009


It is more than two decades since the publication of Gerard O'Neill's "High Frontier" in which he laid out his vision for a more hope-filled future based on access to virtually unlimited solar energy supplies in space, tapped by giant solar power satellites, built affordably, with materials from the low-gravity Moon. But this was only half his vision, and as captivating as it was to many, it was the other half which lured most to join the Space Studies Institute and the L5 Society in their complementary approaches to the task of making Dr. O'Neill's vision a near term reality.

The other half, of course, is the vision of a growing number of space habitat oases to house the workers who would actually build the solar power satellites. These were the "space colonies", later amended to "space settlements" in an effort to be politically correct. Personally, we like the term "Space Oases" better, as more accurately descriptive.

The now classical space oases designs came in three general forms: sphere, torus, and cylinder, all providing, through rotation about a central axis, a level of artificial gravity, in the form of centrifugal force against the inner surface of the outer hull. These three shapes, elaborated for habitability, became the Bernal Sphere or Island One, the Stanford Torus or Island Two, and the Sunflower Cylinder or Island Three. In population capacity, they ranged from the low thousands to the low millions.

What attracted so many was the idea that mankind could move into space without having to settle for, or on, hostile surfaces of the worlds given us in our solar system. We could in effect start from scratch, using abundant lunar and asteroidal materials, and engineer whatever "worlds" we might want: the gravity level (1G, of course, for while space oases aficionados looked down on "planetary chauvinists" they kept to the chauvinism of Earth's gravity level), and climate. The idea that we could have large volumes of Earth-normal atmosphere, and a climate of our choice from subarctic to temperate to subtropical to tropical, was very compelling.

Further, in time there would be many separate space oases, all of them presumably single nation states each unto itself. And that appealed to libertarians and anarchists and others paranoid about the trend of infringements on liberties.

There have been other attempts at space oasis design since High Frontier. Many of them have been exercises in gratuitous baroque overdesign for its own sake. Most of these efforts concentrated on interior arrangements and did not reexamine the overall classic designs. It is CCC's guiding light that good design begins with good definition. One cannot expect to take the design of space oases to the next level if one does not first reexamine their definition.

Shortcomings in the Classical Designs

An Unnecessarily high threshold for construction

The classical designs mentioned have become icons in our minds, put there early on by the captivating artwork that depicted for us sweeping panoramas of their alluring, almost utopian interiors. That there are problems with these very same designs has escaped most. But consider! Twenty, even fifteen years ago, the battle cry "L5 in '95" mobilized our efforts. It seemed to us something, however grand, that we could do in twenty years. Had we not gone to the Moon in just eight? And now it is 1995 and we are no further than those first paper studies and the color artwork that soon reinforced them. Why?

Sure, the space program has been beset by detours (we are not getting Von Braun's Space Station after all, but some politically designed chimeric committee construct which is anything but a stepping stone back to the Moon and Mars), slowdowns, stretch-outs, cancellations, and indecision. But that is not the whole story.

Okay, Solar Power Satellites themselves are still an immature technology, not quite ready to go, even were we by now back on the Moon, and already skilled in producing the requisite building materials from more cheaply transported lunar and asteroidal resources. And not to forget, the seemingly intractable problem of high cost to orbit would alone arise to thwart all efforts even if everything else were ready to go.

But that is not the whole story, not by a long shot. The perhaps unconsciously suspected but unvoiced problem with the classical space oases designs is that they have a very high threshold for construction. Is this very high threshold necessary or inescapable? Copernicus Construction Company is quite convinced that it is not, that alternate designs are possible which require less epic construction efforts, therefore which should be considerably less intimidatingly expensive to undertake, and which through staging, seem capable of leading to earlier "first occupancy", and earlier return on investment.

The classical designs seem wed to a premature and unscientific determination that only a 1G gravity level is acceptable

O'Neill originally thought that a rotation rate of three times per minute would pose no problem for the general population. This is important, because space oases will be inhabited, after all, not by highly trained astronauts, but by construction workers and their families, by farmers, by merchants, and by people from just about any walk of life. At 3 rpm, a structure radius of 1,000 feet (300 meters) will provide the Earth-normal standard of gravity in which our species' physiologies have evolved.

But subsequent testing seemed to indicate that dizziness would affect a large percentage of people at that rate, that a rate of 1 rpm would be more generally tolerable. At this slower spin rate, the structure's radius would have to balloon by a factor of three to provide that same familiar and comforting 1G gravity level. That meant that O'Neill's designs would have to be upscaled by a linear factor of 3, an area factor of 9, and a volume factor of 27. Translate this into amount$ of materials, some scaling up by 9 times, others by 27 times, and you see the beginnings of a gargantuan problem.

This fact should have led to a reexamination of the original unstated premise, that an Earth-normal gravity level was both desirable (most comfortable) and probably necessary to maintain physiological health. But the people running with the space oases idea were by and large a self-selected group contemptuous of the previously prevailing belief among space advocates that humans seeking to settle the solar system at large would have to adapt to unfamiliar, if not downright hostile conditions as we found them. Dr. O'Neill himself is responsible for cultivating this brand of terrestrial chauvinism. Like its religious predecessors, this brand of terrestrial fundamentalism found many new converts among those for whom the older ideas exercised no appeal. Ironically, proud to belong to a new breed of "enlightened" ones, they adopted as a battle cry, the branding of those who counseled doing what life has always done, adapt, as "planetary chauvinists".

But back to the point. We know that the human physiology deteriorates substantially in the zero-g environment of low Earth orbit. We have ample evidence of that with many an astronaut who has spent months (up to fifteen) in Mir and other orbiting habitats. It is a colossal and extremely unjustifiable jump from that fact to the dogmatic conclusion that nothing but full Earth-normal gravity will do.

The only other level of gravity humans have ever experienced for any length of time is the one-sixth G of the Moon. But no one has spent enough time in that environment or in its simulation (NASA will not consider engineering artificial G environments in orbit) to provide any data points on what happens to humans at that level of reduced gravity over the long run. Now it is reasonable to assert that say the 3% G of Ceres, the largest and most massive asteroid, might as well be zero, physiologically speaking, because at that level muscles are effectively unchallenged and the friction within blood vessels and arteries may have a counter effect of comparable magnitude. But 1/6th G is probably physiologically significant. That is, it is not unreasonable to presume, pending hard evidence still not in, that in a lunar like environment Earth-nurtured human physiologies will deteriorate only up to a point, before then leveling off at some stable, maintainable plateau that may work well enough for a high percentage of the general population.

The longer we delay taking the plunge and providing a large enough rotating environment in orbit to simulate the accumulated effects of reduced but still substantial gravity over time, the longer partisans on either side will continue to base everything on wholly inadequate evidence. In this light, the silence of the space-advocate lambs before NASA's refusal to take the engineering plunge is the stuff of which tragedies are made. Much lies in the balance, not just for unrepentant planetary chauvinists like the writer [PK], but perhaps even more so for space oases fans.

It's simple really! If a sustained 1/6th G environment proves to be quite acceptable for a general population, that means that a so-configured space oasis can be downscaled by a linear (radial) factor of 6, an area factor of 36, and a volume factor of 216. In comparison with O'Neill's original presumption, that's still a downscaling of radius by a factor of 2, of area by a factor of 4, and of volume by a factor of 8. If we can accept such a paradigm shift, space oases suddenly become much more "constructible", much more fundable, much less expensive. This shift in thinking will probably prove unacceptable to those O'Neill groupies who joined the space oases bandwagon because they could find therein a place for themselves in the universe at large that did not mandate adapting to the unfamiliar. This should not deter the rest of us who see space oases as a desirable and necessary form of space development in support of a human economy expanded by off planet material and energy resources.

If the lunar gravity standard proves sustainable for humans, we predict that it, not the terrestrial standard, will become the standard of a spacefaring civilization throughout the Solar System. Lunar-like (in this respect, at least) space oases will still be visitable by terrestrials with no intent of permanently relocating. For those assigned there (or on the Moon, for that matter) wanting easy readjustment when they return back home, special centrifugal gym facilities will let them maintain their "terrestrial muscle tone".

What in fact would this lower gravity standard mean for space oases? Structural members which constrained the centrifugal force of the space oasis need be correspondingly less strong and massive. The square footage, at the correspondingly lower radius, would be lowered by a factor of 36 affecting the amount of outer hull materials and shielding needed. The volume of atmosphere needed to fill the interior would be reduced by a factor of 216, an especially welcome savings in the amount of nitrogen that probably will have to be expensively upported out of Earth's gravity well. These figures apply to the designs as is, otherwise unchanged in their aspects and features. As we will see, there are further ways both to lower the threshold of first occupancy, and yet provide for larger populations later.

Even a finding that a more Mars-like gravity level (3/8ths G) was preferable would reduce items that scaled with the radius by a factor of 2.6, those that scale with area by a factor or 7, and those that scale with volume by a factor of 18. These more modest savings are nothing to sneeze at and we predict a number of space oases with Mars-level gravity will be built both in Earth-Moon space and around Mars.

We've said all this before, in MMM # 13, MAR '88, "SPACE OASES" Part 6. Back at Square One: Baby Steps with Artificial Gravity". But by and large, the point remains untaken, and it is the Space Oases dream that suffers, to the point that many now believe it was just an idle daydream, something for some far future century's generations to play with anew. It need not be so!

The classical designs call for unitary all-at-once construction -- when they could all benefit from a modular approach.

Rome wasn't built in a day!" But fans of the classic designs, Bernal Sphere, Stanford Torus, and the Sunflower Cylinder would go against the time-honored advise in that monition and attempt to build unitary mega-monostructures that are at first way too big, then briefly just the right size, and then forever after too crowded and cramped. It is odd that people will reject the limits to growth on Earth and then lemming-like, do everything possible to reinstate those limits in a seriously aggravated form in space. Yes, those limits would apply only locally, to individual island habitats, and the space frontier young can always do what rural young deprived of local opportunities have been doing for a long time - move out and away from kith and kin. It's time to reverse that trend!

Transferring the problems that must flow from any undisciplined growth, from global Earth to local outer space, is no solution at all. For an illustration of how the chickens will come home to roost if major unresolved contradictions in the O'Neillian approach to relief from the Limits to Growth are not addressed, read Garret Hardin's "Exploring New Ethics for Survival: the Voyage of the Spaceship Beagle" (1968, 1972 Viking Press, New York SBN 670-30268-6, LOC 78-186737).

There are three red flags that should be waving in everyone's mind on the concept of unitary monostructures. That these red flags have gone unnoticed and unheeded for two decades is eloquent testimony both to the lullingly seductive power of the artists' conceptions of panoramic idyllic space island interiors that swept every concern, every alternative away in the mid -70s and the intractable need of many, deprived of one drug, to quickly become dependent on another.

Building Rome in One Day -- or Bust

The first of these red flags is the unnecessarily high funding and construction thresholds of building the whole thing at once, when with a little engineering ingenuity and modularity, phased designs are possible, one leading to the next if and when demand for space and funding availability warrant, but each of which can stand alone if necessary. This approach offers earlier occupancy, and realization of the dream.

We have all seen how in the past decade or more, the Russians have had a working space station with phased growth, while us haughty Americans have insisted on leapfrogging in one mighty leap from the "Model T" Skylab to the "Taurus" S.S. Freedom. We are the ones who have lost both time and experience in going for the idyllic all at once. If we want space oases sooner rather than later, we need a humbler approach. Insistence on unitary monostructures, because they look so damn nice, will end up pushing off their realization a generation or more, if not altogether. We have canoes, we want aircraft carriers. So we don't build anything until we can build the latter. A certain prescription for self-paralysis!

But, but! Okay, you can build a barbell structure that can grow modularly into a torus, and you can build a longer cylinder as a series of sausage links, but you can't build a modular sphere! Perhaps not. But mind where we are in this discussion. If we accept a lower gravity standard, and thus a smaller radius. We can build a series of smaller spheres, one by one, all along the same axis, expanding auxiliary systems and elements as we go along. Similarly, we could build smaller complete torus rings one next to the other, again along the same axis, and again expanding auxiliary systems as we go along. All growable designs converge on the asymptote of the cylinder whose radius is set by rpm and design gravity level, and whose length is codetermined by demand vs. engineering practicality and structural stability.

The key that unlocks the door to modularity then, seems to be the giant step of admitting, 'yes, while branding everyone else as "planetary chauvinists", we've been repressing the more serious terrestrial chauvinism of the 1G standard, in the interests of avoiding the risks and challenges of adaptation to environments with strange frightening parameters'. Do we want the space oasis dream bad enough to compromise, or not? Will we continue to speak with a forked tongue, rejecting limits to growth, but capitulating to limits to adaptability? It doesn't matter really. Those who won't agree to adapt will just not be part of the future. What needs to happen, will happen.

The missing "rest-of-the-world-not-seen"

The second red flag is the notion, implicit in unitary mono-megastructures, that these are "worlds" unto themselves. The concept of world is a complex one, but one of the quintessential elements of that concept is that it is an integral flow of horizons, not all of which can be seen at once. Only the torus satisfies that central significance. Yet, if "world" is a linked set of "valleys", a torus still falls short. It is still a mono-vale, a valley that has itself by the tail.

Forget the crack cocaine appeal of those picture postcard views: "a moment being awestruck, a lifetime being suffocated" -- because "that's all there is". The high of First Glimpse is pitifully inadequate to the task of buoying day-to-day morale. In the long haul, the need for the-rest-of-the-world-not-seen is absolutely crucial to sanity.

Polymeric Modularity, Divisible by Three (3)

Yet another unaddressed chauvinism incarnate in all the classical space oases designs -- and not so coincidentally endemic to populations of professors and students as well as white collar movers and shakers in general -- is what we might call the "uni-shift day job ideal". The need to get our money's worth out of capital equipment etc. by having such stuff operated and run around the clock is something we can take care of by relegating such duty to types lower down the totem pole who can be consigned such god-awful duties as working "second" and "third" shift.

On Earth, frankly, there is no choice. The Sun rises and sets but once a day. Space oases people, who are proud of the fact that they can engineer more ideal environments, have failed to pick up on the fact that the above fact too can be "remedied" in free space. Build a triple module, tri-vale structure (three linked spheres, three torus sections side by side, a three-sausage-link cylinder) and engineer the solar access to each so that there are three staggered sunrises and sunsets and you create in effect a three village town, in which the residents of each have day jobs, everyone gets to go to work in their morning, come home in their afternoon. Yet not only does all capital equipment get operated around the clock but all public facilities from offices, to schools, to entertainment facilities and parks get used 24 hours a day. If a light assembly facility is located in village A, then, at the afternoon shift change replacement workers from Village B (where it is local morning) come in. And at 11 pm, workers from Village C come in (where it's morning there). The elegant final solution.

This 3 shift solution is available on a smaller scale - if growth beyond the initial sphere, torus, or cylinder module is seen as a distant or uncertain possibility. A single torus module can be triple-pinched to form a three-link ring with a different lighting schedule in each link. For the single sphere or cylinder a triple concave opaque sky "firmament" will accomplish the same sequestered lighting regimen.

On the other end of the expected growth range, if boom prospects warrant, a larger scale option would be a physical clustering of six oases, i.e. three staggered shift torque-balanced counter rotating cable-linked pairs of spheres, toruses, or cylinders. The torque neutral physical link can be as simple as a cable or as complex as a cableway or transport conduit (at zero-G, of course, since not rotating). A single such pairing, already foreseen by O'Neill, could only provide a two shift system. But admittedly, that is already an enormous improvement. But why pull the punch, when you can go all the way with this idea? More about space oasis clusters below.

Nothing, of course, prevents the eventual construction of more ambitious larger girth habitats, whether of lower rpm, higher gravity or both. But we have to live, work, and build our way through the 21st century before we can realize 22nd century dreams.

A Forgotten Design Option -- the Helix

The ideal compromise between a modular tri-vale complex that is too small in toto, and one that is two large even in phase one (the first module or 'shift valley') is offered by a design option the classic designers totally overlooked. According to ivory tower geometricians, there are only three possible generic space habitat architectures: the barbell/torus (i.e. the torus is a fully rotated barbell), the cylinder, and the sphere are the only possible three dimensional balanced forms allowed by rotation of the appropriate subset of Cassini curves. Balderdash! That ignores rotation combined with motion along the axis. Do that with a sphere and you get a cylinder, with a torus you get a double walled dewar cylinder, with a cylinder you get a longer cylinder. But far more interestingly, do that with a barbell, and you get a double helix, a trick learned by nature eons ago and without which none of us would be here. So much for the ivory tower guys.

Further, a three-armed barbell with three equally distanced pods is just as rotationally stable as the simple two headed one. Rotate that and move along the axis at the same time and you get a triple helix.

So? So this gives us a habitat with three separate daylight-staggerable helical valleys capable of indefinite parallel growth. Start with three small pods -- stop where you want with a triple helix habitat of set radius but of indefinite axial length. Such a biodynamic master plan will yield about as world-like a convoluted transhorizonal linkage as we are likely to be able to devise to fit the constraints of artificial gravity physics. Here we have a world of places other than that which we can see at one time, yet still have sight lines long enough for visual relief, plus room for growth. The kids can stay.

[see MMM # 12 FEB '88 "Space Oases: Part 4. Static Design Traps; Part 5: A Biodynamic Master plan" - this earlier three issue series on Space Oases is reprinted in full in the MMM Collected Articles Issues #1-20, years 1 & 2, available for $10 from LRS, P.O. Box 2102, Milwaukee WI 53201.]

That each Space Oasis habitat will be an insular nation unto itself is unlikely

Many a person strongly drawn to the space oasis dream admits to being more attracted by the vision of innumerable politically independent entities and the libertarian opportunities that would seem to portend than by the idea of living in space itself. Alas, history does not support the belief that the mere multiplication of small national entities results in an explosion of freedom. Indeed, if the O'Neillian designs are followed without modification the very real limits to growth that will all too quickly be felt within each habitat will make necessary severely draconian limits to individual freedoms, especially those of procreation, consumption, and life style.

Small nation states are in general (exceptions like Singapore only proving the rule) more vulnerable to economic and hence political instability than are larger ones. Small nations are the more likely to be founded on ethnic, religious, or other arbitrary and artificial grounds; larger nations the more likely to be pluralistic and open-cultured.

If there is a way to politically and economically cluster individual space oasis habitats in associations that work, these will be the more stable, and in the long term the more prosperous. Isolation favors only those things that cannot compete in the open, usually for good reason. But there will be island states in space. For one thing, not every location that favors a space oasis will favor more than one. Fine. Those who want smallness, isolation, and parochialness shall have it. Of rural space oasis towns there will be some.

By the same token there will be locations prime for major economic activity, like Earth-Moon L4 and L5 and Earth-Sun L4 and L5, where space oases may multiply and cluster. Especially in the former closer quarters, there will be some very real danger of collisions from mutual drift, probably on a frequency far greater than that of near Earth asteroids striking the home planet. That and other benefits may predispose the builders of such oases to work in collaboration towards physically clustering these habitats.

Habitats can be clustered in torque-neutralizing pairs attached to a common non-rotating structure composed of solar power grids, heat radiators, storage warehouses, joint-endeavor manufacturing and micro-G factories and labs, micro-G hotels, micro-G farms (if they prove to have an advantage for some crops), water treatment and waste recycling, inter oasis mass transport, passenger and freight spaceports, and more.

The resulting metropolitan complex should be much more vigorous and dynamic and satisfying a place to live, and more politically stable. The joint population could be fairly substantial. By transcending the limits of the isolated size-fixed unit, the limits to growth will be further put off.

The Lagrange point prime real estate locations entail a physical "commons" that can either be treated as a lawless "no mans' land" or as the subject of agreed upon privileges and responsibilities. Even space oases that are not physically linked with others may, sensing real common interest, seek political alliance and association.

[See MMM # 57 JUL '92, pp. 5-7 "META-XITY: Residual Problems of Classical Space Settlement Designs and Synthesis via Polymerization on the 'Metazoan' Plan"

I. The Bernal Sphere Reinvented

One method of expansion: Mirror works full time, lighting two villages at a time; each getting sunlight 16 hrs (2/3rds day) a day on schedules staggered 8 hours apart. Transit tubes are placed 60 or 120 apart and act to stiffen the complex.

An alternative expansion design below:


II. The Stanford Torus Reinvented

single torus idea

Multiple or Banded Torus Concept

III. O'Neill Sunflower Reinvented

Below are two ideas for generally cylindrical habitats that can be constructed in individually viable sections, yet function as an integral whole on completion. No attempt has been made to engineer every detail, the idea being simply to suggest some options that might be pursued further.

Another Design - 3 sphincterable ovoids with common outer cylinder wall

[inspired by a drawing sent in by Jeff Sanburg of Skokie, IL]

In the event of catastrophic decompression of any one ovoid, the other two ovoids would remain intact, as would the industrial area between two intact ovoids. The industrial areas are more vulnerable in this design than the Metro toruses in the design above. Both designs above could use similar sunshine delivery systems.

IV. Triple Helix

viewed end on from end cap start of three growing villages with shift-staggered day-night cycles

Triple Helix -- Side View

Three Villages with Expansion Potential

Biggest Challenge for Helix designers: engineering solar access either with axis pointed at the Sun or perpendicular to the Sun.

Space Oases and Lunar Culture 

The following article, appearing in Moon Miners' Manifesto #11, Decmber 1987 is appropriate, and has been added here February 9, 2009.

   "MOON MINERS’ MANIFESTO. has been cast, even by well-meaning admirers, as a “special interest” newsletter. As editor, I have to take responsibility for this widespread mis-appraisal. I had stated that we wanted to explore the heights to which a self-sufficient lunar civilization could rise, given the constraint that it must seek to develop as far as possible relying solely on lunar ores that are poor in hydrogen, carbon, and nitrogen. The Manifesto has gotten good marks for this effort. But for many whose dream is life on O’Neillian space colonies, these discussions have perhaps seemed irrelevant.

   "This shows our failure to realize that what may be perfectly obvious to us, doesn’t necessarily suggest itself to others: namely, that in the early decades, the availability of volatile-rich ores from asteroids and other sources cheaper to access than upports from Earth, will be at best sporadic. As a result, pioneers in free space oases will find themselves in much the same straights as hardy lunar settlers. Unless they are fantastically prosperous and can afford heavy dependence on Earth-sourced materials, they too must build their cultures largely on the possibilities inherent in volatile-poor lunar ores. Lunar cultures will be the rule.

    "Thus, in the early decades, space colonists too will be forced to give up a way of life based on the causal use of paper, wood, plastics and the whole host of addictive synthetics based on hydrogen, carbon, and nitrogen so very abundant on Earth. This will color their whole way of life with its implications for building products, household furnishings and other domestic wares, clothing, information media, sporting goods, toys, arts and crafts etc. If you are truly interested in pioneering free space, you will find enlightening ideas on what such frontier life will be like in the pages of Moon Miners' Manifesto."

"works-in-progress" -- input welcome!

This has been more an exercise in redefining what a space oasis should be: (a) looking to minimize construction expense and lowering the threshold to initial realization by removing dogmatic insistence on a chauvinistic 1-G standard; (b) through modularity providing greater safety, the opportunity for growth, and more world-like inner horizons, with the bonus of an elegant solution to the three shift problem.

The designing activity has been kept to the minimum needed to illustrate how these new standards and criteria might be effected. There will be plenty of time before we are ready to build a new revised Island One in which to reengineer all the systems and subsystems needed to make each design work.

Your input in moving these discussions further along is very welcome. So is new artwork. In time the classical designs will be seen as brilliant but simplistic exercises in visioneering that served their purpose: showing us that man can live in free space, not just on natural worlds.

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