6. The Future of Space Exploration

Two possible space-exploration projects that have received considerable attention are the establishment of lunar bases and the construction of space colonies.

Lunar Bases. Longer-lasting missions that require ­permanent bases and outposts on the moon may eventually become necessary, if for no other reason than to reduce the cost of bringing moon explorers back to earth every few days or weeks. In locating and establishing such bases and outposts, factors to be considered include scientific interest in the surrounding area; environmental conditions, including the angle of the sun, temperature extremes, and radiation flux; availability an­d accessibility of local resources, including underground water; nature of the local terrain; availability, size, cargo capacity, and speed of over-the-su­rface supply vehicles; and the size as well as the cargo capacity of spacecraft that would be dispatched from earth and the frequency of their arrival to the moon.

Early base structures will probably be made from materials brought from earth, but processed lunar resources may be substituted later. However ­constructed, bases must provide facilities for living, power generation, waste disposal, air production and conditioning, communications, observation, and, ideally, farming. In the long run it will be impractical to bring from earth all the food consumed by base inhabitants.

A variety of proposals have been made as to how plants, and even animals, may be raised in airtight structures on the moon, making use of the abundant sunlight during the long daytime periods. Suitably enriched moon soils may be de­veloped, or hydroponics may be pursued. The special ­characteristics of the moon-the absence of an atmosphere and erosion forces, the availabil­ity of sunlight, its lower gravity-make it an attractive location for certain types of experiments and manufacturing processes. Experiments conducted in earth-orbiting space shuttles and space stations on the behavior of crystals and materials in low-gravity environments may one day find application in continuing industrial processes on the moon.

Space Colonies. Gerard K. O'Neill of Princeton University expected the relative cheapness of lunar materials for building space colonies to motivate lunar bases. NASA summer studies in 1976 and 1977 explored this use of the moon and the design of large space colonies. O'Neill presented his ideas and the nub of the findings of these and other studies in his prizewinning books The High Fron­tier and 2081-A Hopeful View of the Human Future. If his predictions are correct, people will be living throughout the inner solar system, from the orbit of Venus to the asteroid belt, by the end of the next century.

In this connection the proposed first crewed flight to Mars takes on the coloration of the Apollo program inasmuch as itthe opening of the colonization wave. Space station development will lay the groundwork for both lunar bases and crewed planetary flight.