It will also enable scientists to perform more mundane research, like that planned for Spacelab. Among them: investigations into the behavior of metals, chemicals and even living cells in what scientists call the microgravity of orbit, the familiar condition of weightlessness. Some student experiments will be carried up as well, probably as part of NASA's so-called getaway specials, compact canisters as small as 1.5 cu. ft. that can be placed on a flight for as little as $3,000. One young man recently announced he intended to use such an experimental package to see if fruit flies breed in space. What will be next?

No less intriguing but so far less precise are the shuttle's commercial possibilities. It is a working truck with a 65,000- lb. payload, but who is going to buy space in it? Communications companies, for one, are already lined up to use the shuttle for satellite launches. One advantage is price: $35 million for a shuttle launch vs. $48 million for a boost into space from a conventional Atlas-Centaur rocket. Another is that the shuttle can carry several satellites at a time. What is more, says AT&T's Robert Latter, "you can test the satellite all the way up. Maybe you could even fix it in flight." After the astronauts perfect their skills at retrieving satellites with the shuttle's big mechanical arm, ailing "birds" may also be recovered and repaired either in orbit or on the ground.

An early operational flight of the shuttle, in 1983, is scheduled to carry a tracking and data relay satellite aloft for the Space Communications Co. AT&T is planning to use a 1984 flight to' put one of its new Telstar 3 satellites into orbit. Foreign nations have rented a total of 18 payloads, among them: an Arab consortium, Australia, Canada, China, Colombia, Great Britain, Japan and Luxembourg. Other potential users of shuttle space have been slower to come forward, in part because the idea of working in orbit is still a bit too risky and futuristic for most corporate chiefs to contemplate. But there is little doubt that microgravity and the "hard" vacuum of space offer unique opportunities for research and development. One idea that will be tested jointly in space by McDonnell

Douglas and Ortho Pharmaceutical is a procedure for separating biological materials through electrophoresis, a process whereby substances move under the influence of electric fields. The object: to isolate hormones, enzymes, proteins and certain cells in higher and purer concentrations than can be achieved under the influence of gravity.

Still other companies are considering the use of space to grow crystals for the manufacture of electronic "chips," the tiny semiconductor wafers that are at the heart of modern electronics. Space-made crystals, say the experts, could be larger and more uniform than those made on earth. Other possible orbital products: high-purity glass, new alloys, higher-yield vaccines. Says Jerry Grey: "These aren't future technologies. They can be used today." Adds Merrill Lynch Analyst Ed Greenslet: "The important thing is that the shuttle is now there. Things that are there often start people thinking and evaluating what could and should be done with them."

If commercial clients sign up in sufficient numbers, NASA plans to fly more than 400 shuttle missions in the next ten years. It has even considered subcontracting shuttle operations to an airline, and United Airlines has expressed interest. Farsighted planners are thinking about more ambitious roles for the shuttle, or its successor. In the future, such a spacecraft may carry work crews into orbit, where they will be left behind inside comfortable modules that could serve as building blocks for permanent space stations. As more components are shuttled up, these centers might begin to produce space goods, perhaps even utilize raw materials, as Gerard O'Neill suggests, from the moon or from asteroids. There would be no shortage of power for such enterprises; energy would come from the sun.

In the more distant future, such stations, like the great wheel in 2001: A Space Odyssey, could serve as a launch pad for journeys far beyond the earth, maybe to Mars. Interplanetary spacecraft assembled in earth orbit could be made of much lighter and less costly materials since they would not have to survive the stresses and friction of travel through the earth's atmosphere.

Even in the excited aftermath of Columbia's incredible journey, such schemes have the ring of expensive fantasy. Some people even find them disturbing retreats from the earth's own hard realities, including widespread poverty and hunger. But are they really only escapist dreams? At least one hardnosed test pilot does not think so. Speaking after his return from space last week, John Young said: "I think we have a remarkable capability here. We're really not too far-the human race isn't far from going to the stars. Bob and I are mighty proud to have been a part of that evolution."

Reported by Benjamin W. Cate /Edwards Air Force Base and Jerry Hannifin /Houston