Extraterrestrial Civilizations - Isaac Asimov [110]
For space settlers, however, spaceflight introduces changes that are not at all extreme. The settlers live on the inside of a world to begin with; they are aware of and accustomed to a close cycling of food, air, and water; they are accustomed to a variable downward pull.
In short, the space settlers, in undertaking an extended space flight, move from one spaceship to another quite similar, though smaller, spaceship.
All this does not make the space flights to some specific destination necessarily less long or less tedious, but it should enormously lessen the psychological difficulties. A crew of space settlers could undoubtedly endure the restricted quarters of a spaceship over the long flight to Mars and beyond far more stoically and efficiently than a crew of Earth people could.
Again, though, we must ask ourselves for motivation. What would make the space settlers move outward through the Solar system?
Human curiosity and the desire for knowledge might assure the occasional long-distance flight, but something more would be needed for a mass movement.
That something more is easily seen.
The libration points on either side of the Moon are not very large and could easily be filled. Furthermore, as more and more settlements are built and filled, the drain on Earth’s supply of volatile elements would become appreciable and the reluctance of Earth’s people to part with them would become pronounced.
It would be useful to search for additional living space and for a better source of volatiles.
The inner Solar system is, as a whole, poor in volatiles. The Moon and Mercury have none, Venus is unapproachable, and Mars, while approachable and possessing volatiles, may not be an ethical source. By the time the space settlements are ready to move outward, there may be human beings on Martian bases, and the volatiles would, in a way, belong to them.
As I mentioned earlier, comets rich in volatiles wander by now and then, but this is an intermittent and unreliable source and to depend on them would become ever more risky as the number of settlements multiplies.
It is the asteroid belt that is the nearest appropriate target for expanded living space for the settlements. The many thousands of asteroids might offer even more easily attained construction material than the Moon, and many of them should contain considerable quantities of volatile material.
It may well be that by the twenty-second century, the settlements at the libration points will be recognized as a mere preliminary stage, and it will be the asteroid belt that will be considered the true home of the settlements. They will be farther from Earth and utterly independent of it, but they can remain within radio and television reach of it, of course. There will be endless room out there for the construction of many millions of settlements without crowding.
The outward push might continue even farther and belts of settlements might be placed around Jupiter and Saturn at distances large enough to avoid the magnetic fields and the charged particles with which those are filled.
In short, the space settlers will prove the Phoenicians, the Vikings, and the Polynesians of the Space Age, venturing out on a far vaster sea to settle their new lands and islands.
By the twenty-third century, the Solar system may well have been thoroughly explored by human beings with settlements in favored places throughout. The Sun itself can serve as an adequate energy source if its radiation is properly gathered and focussed, even far out in the vastness of the outer Solar system, and hydrogen fusion reactors should eventually serve as an alternate adequate source.
STEPPING STONE
This optimistic picture of the total exploration and, so to speak, occupation of the Solar system