There's No Place
Like Spome

Let me begin by coining an uneuphonious word — spome — and defining it. A spome is any system, substantially closed with respect to matter, that is capable of supporting human life for an indefinitely long period of time.

The Earth is a spome and, at present, is the only spome known to exist. Its qualifications for spomehood are obvious. It has supported human life for well over a million years, if we count the hominids generally, and will continue to do so for the foreseeable future, barring the effects of man's own willful folly.

Furthermore, it is substantially closed with respect to matter. The matter that is added in the form of meteoroid infall or lost in the form of atmospheric leakage is not significant. It does not affect Earth's spomic characteristics, nor is it likely to in the foreseeable future.

Life is a process whereby relatively unorganized components of the environment are made more organized. That means that life involves a continuing decrease of entropy and can exist only at the expense of a continuing, and even greater, increase of entropy in the environment generally.

If the Earth were closed with respect to energy, mankind, and life generally, would see to it that in a relatively short time, enough oxygen and organic matter would be degraded to carbon dioxide and other wastes to render the Earth uninhabitable.

The energy of the Sun makes all the difference. It enters the Earth-system, keeps the atmosphere stirred up and the oceans liquid; it makes the rain fall; most important, solar energy is utilized by green plants to reconvert carbon dioxide and water into organic substances and free oxygen. The entropy of the environment, pushed upward by the activities of life, is pushed downward again by the energy of the Sun. An equilibrium has been maintained for some billions of years at the expense of the vastly increasing entropy of the Sun.

If the Earth were the only spome that could exist, the subject of spomology would be trivial. But it may be that the Earth is merely the only spome that exists so far, and that many others can exist in conception or potentiality. In that case, the subject increases in interest.

And yet all 640,000,000 lumped together do not in themselves suffice to make spomology a truly interesting study, for they are all merely so many Earths. From the broad standpoint of the spomologist, if you see one earthlike planet, you have seen them all. What we want, if we are to make spomology interesting, are spomes that are drastically different from the Earth.

Suppose we ask ourselves what makes Earth a spome and Jupiter or Mercury non-spomes? If we want to express the difference most succinctly, it is a matter of mass. Jupiter is too massive, Mercury is insufficiently massive. The difference in mass involves, one way or another, almost every quality that goes to make or not make a spome.

We might even say that the search for a spome is the search for a body of appropriate mass. But all this is in the course of nature. It works if we are looking for "natural spomes," for spomes ready-made. Let us now add the factor of human intelligence. Only God may make a tree, according to Joyce Kilmer, but perhaps spomes can be made by fools like us.

The problem boils down to the conversion of small bodies into spomes, and the specific version of the problem is, inevitably: Can we make the Moon into a spome?

The Moon is certainly not a spome now. Thanks to its low mass, it has neither an atmosphere nor free water. But an atmosphere can be kept from diffusing out into space by the force of a sufficiently strong gravitational field, but, on a smaller scale, it can be kept from doing so by physical barriers as well.

Suppose, then, we hollow out a cavity under the Moon's surface and supply it with air, water, and the other necessities of life. We might have to begin with capital from the Earth, but it is possible that eventually water could be baked out of silicate hydrates in the body of the Moon. From such water, oxygen could be formed. Given a sufficient supply of energy, and a mass of variegated chemical composition such as the Moon, the basic chemical requirements can be met on the spot.

I foresee the possibility of the Moon being honeycombed immediately below its surface by a growing system of caverns, supplied with all basic materials from the Moon itself, with all its energy requirements supplied by fusion power plants, seeded with plant and animal life, and inhabited by men, women, and children; families who may know no other life, and want none.

The advantages are obvious. The Moon will have a controlled environment designed specifically for man; man will have what he wants and needs and not merely what he can get. What's more, it will have the advantage of a fresh start. As the United States managed to prosper and flourish partly because it was freed of many of the choking traditions of Europe's bitter past, so the Moon, it may be hoped, will be freed of the incubus of Earth's past mistakes.

But what about the psychological difficulties? Can men really learn to live for extended periods in what is essentially, after all, a cavern? Can he bear to be born and to die there? The answer, in my opinion, is the heartiest possible affirmative. If the cavern is large and comfortable, why not?

It is a mistake to underestimate the flexibility of mankind. Man has already demonstrated abilities to make enormous adjustments. A city such as New York represents, in a way, almost as artificial a spome, one almost as divorced from man's original environment, as the Moon would be. Yet man has made the transition from hut to skyscraper over an insignificant period of time. Indeed, a peasant immigrant can adjust adequately to New York in his own lifetime.

Of course, in thinking of an internal spome, we must fight our prejudices. It is easy to fall into the trap of thinking that an external spome is "natural" and an internal spome "artificial," and that what is natural is good and what is artificial is bad.

But if that argument is advanced, where does Homo sapiens stand? Life did not develop on dry land. The only portion of the Earth that is a "natural" spome, in the sense that life arose there spontaneously from simple chemicals, is the ocean. It was only little by little that certain types of living things emerged onto the dry land, a habitat as hostile to the creatures of the sea then as the Moon seems to us now.

Land animals had to evolve for millions of years before they could develop limbs strong enough to lift them clear of the ground. It was some two hundred million years before creatures evolved with internal thermostats and external insulation so that the equable temperature of the ocean might be imperfectly restored. Man himself rose to his hind feet a million and a half years ago and still pays his respects to gravity with flat feet, slipped disks, sinus trouble, potbellies, and numerous other ailments.

Yet need we be sorry that our ancestors emerged from sea to land? With all land's dangers and discomforts, it opened the way to advances not possible in the sea. In hindsight, we can see that the ocean was a dead end, whereas land offered a new and brighter horizon.

Is it possible, then, that the passage from an external "natural" spome, to an internal "artificial" spome might likewise involve a desirable phase change? It seems to me that in an internal spome, man would return to the equable environment and lower gravity of the sea, without abandoning the low-viscosity environment of the air. An internal spome would have, after a fashion, the best of both land and sea and the worst of neither. Surely something great may come of that.

If we begin with an internal spome on the Moon, victory and success there can only inspire attempts at expansion, at forming spomes out of other medium-sized bodies such as Mars and the larger satellites of Jupiter. In particular, there may be a movement to internal spomes on smaller and smaller bodies — the asteroids that exist by the thousand in the space between Mars and Jupiter.

Consider the matter of efficiency. With even the Moon, virtually all the volume of a planet is unused and serves the men of the spome only by supplying them with the source of a gravitational field. The asteroids, however, can be spomified completely. They can be riddled and honeycombed. They have no internal heat for discomfort and no significant gravity to make more difficult the shifting of mass.

In real life, an artificial gravity field cannot be set up merely with a wave of the typewriter. One conceivable possibility would be to set the asteroidal spome into rapid rotation. But it seems to me that spinning the spome would not be worth the energy expended and the problems produced. Why not, instead, accept null gravity as a condition of life?

Life has, in the past, switched from the essential null gravity of the oceans to the gravity slavery of the land and survived. Why not the switch back? Biology is undergoing its own revolutionary breakthroughs. It is reasonable to hope that by the time man reaches the point where he can reach the asteroids with a supply of energy sufficient to set up a spome, he will also have learned enough about genetics to engage in meaningful tissue-engineering.

A null-gravity body would, it seems to me, become utterly graceful in its maneuverings, gaining some of the three-dimensional skills of the fish and birds. We will have a human species capable of flight without having to sacrifice the infinitely useful hand for the sake of a wing.

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. 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.

A space cabin is not exactly a spome, for a spome must be capable of supporting human life indefinitely. It is rather a proto-spome — the stepping stone. What Asimov understood in 1966 is what we understand now: the principles of a closed life-support system apply at every scale. From the asteroid to the cabin to the cell.

Your body is a spome. Substantially closed with respect to matter. Open to energy. Capable of supporting life — but only in equilibrium. Entropy always rising. The work of maintenance never done.

The question Asimov was asking about asteroids and moons is the same question we ask about human health: what does it take to keep this system running indefinitely? What inputs does it need? What equilibria must it maintain? What happens when the energy supply falters?

Spomology isn't science fiction. It's the oldest science of all.