Houston — As technicians prepare the space shuttle Columbia for its trip from White Sands, N.M., to Cape Canaveral, Fla., many other members of the shuttle team are looking ahead to future missions.
They contemplate an ambitious schedule.
The National Aeronautics and Space Administration (NASA) has 69 shuttle flights scheduled between now and September 1987. These include 25 military missions, many launches of commercial and scientific satellites for US and foreign customers, several missions for the Spacelab orbital laboratory, and, perhaps, an attempt to repair an ailing satellite on orbit.
Already, astronauts Thomas K. Mattingly and Henry W. Hartsfield - respectively the commander and pilot for Columbia's next mission - are well advanced in their preparations. This mission, which NASA officials hope can be launched in late June, will very likely be the last of the shuttle's nominal test flights, as originally planned.
Glynn S. Lunney, manager of the space shuttle program, calls Columbia's eight-day third mission, which ended March 30, ''a very powerful success.'' It has advanced the shuttle a long way toward certification as an operational space transportation system (STS).
'' 'Truly operational' begins to be a matter of degree,'' Mr. Lunney explains. However, he adds, ''I think we will be very comfortable with our understanding of the spacecraft and very comfortable with our understanding of how we people are going to operate it after this flight, and certainly with the results of STS-4 (the fourth mission) under our belts. So I feel kind of comfortable that we will be moving into what we can call 'operational' by flight five.''
That flight, STS-5, now is scheduled for November. Among other things, it is to launch two commercial communications satellites - one for Small Business Systems, a US company, and Tellesat-E for Canada.
The mission also will be the first with a four-man crew. Beside Vance D. Brand, commander, and Robert F. Overmyer, pilot, Columbia will carry mission specialists Dr. Joseph P. Allen and Dr. William B. Lenoir. This will open the era when the spacecraft commander and pilot devote their attention primarily to running the ship, while astronaut scientists and engineers launch satellites, make observations, and look after scientific equipment.
The next mission, STS-6, now scheduled for January 1983, will also have four crew members -- Paul J. Weitz, commander, and Karol J. Bobko, pilot, plus Donald H. Peterson and Dr. Story Musgrave as mission specialists. This mission, which will also launch several satellites, will be the first flight of Columbia's sister ship Challenger. It is expected to arrive at the Kennedy Space Center this summer. The remaining two shuttles, Discovery and Atlantis, are expected to be ready in January 1984, and January 1985, respectively.
As activity picks up for the shuttle systems, its missions will be become increasingly routine. Perhaps nothing makes this point more tellingly than an obscure paragraph in a recent NASA press release. It says simply: ''Backup crew will no longer be assigned to space shuttle flights. A pool of experienced shuttle pilots now exists and a crewman could be replaced with minimal impact to crew training and scheduling.''
At the same time, orbital pioneering is far from over. One of the most ambitious new activities NASA wants to develop is the ability of astronauts to work outside the shuttle as divers work beneath the sea. This will be essential for construction and maintenance of large space structures, including manned space stations. This is a major reason NASA wants to try to repair the Solar Maximum Mission (SMM) satellite.
Designed to monitor the sun during and after the recent peak of the 11-year sun spot cycle, the SMM began having trouble with its attitude control system six months after launch. Astronauts are already training for a shuttle mission in December 1983, during which a space-suited astronaut with a jet-powered maneuvering unit would steady the SMM to allow the shuttle's mechanical arm to grasp it. The SMM would then be brought into the shuttle bay for repair.
Although NASA sees this as a valuable ''flight test'' of astronauts' capabilities, it needs congressional approval to tranfer the necessary funds from other sections of its budget. At this writing, such approval was uncertain.
Regardless of what happens to this particular proposal, there seems to be widespread awareness among members of the shuttle team that an open-ended opportunity for space development lies before them.
''We have fulfilled the promise of the early days of NASA; we are setting sail on a new ocean and we are in space to stay,'' Christopher C. Kraft Jr., director of the Johnson Space Center, said recently. He added, ''. . . we are not too far from reaching for the stars.''