Now that the veteran space shuttle Columbia has once again touched down, leaving a trail of new achievements (and one failure), what lies ahead?
National Aeronautics and Space Administration (NASA) officials here in Houston say the cancellation of this mission's planned space walk was disappointing, but was not a major setback. Indeed, economic problems, not technical ones, may be the major challenges to the shuttle program.
The shuttle system is considered ready to launch five commercial, fare-paying satellites per mission from its 65,000-pound capacity payload bay. As well, NASA administrator James M. Beggs has announced that beginning in 1984, commercial customers will be able to send their own scientists or ''payload specialists'' up with the shuttle on a seat-available basis.
Plans to turn a profit with shuttle missions, however, have been set back by the recession. Some potential customers are holding back waiting for an economic upturn. Other firms that cannot postpone their satellite launchings are double-booking on the US shuttle and on France's Ariane rocket, says Congressional Research Service aerospace specialist Marcia Smith.
Ms. Smith says she expects NASA will lose some customers to the single-use Ariane because the European Space Agency is offering cut-price subsidized fares and ''fly-now, pay-later'' financing. But she adds that commercial customers may stick with the shuttle because ''with Ariane you have a greater risk of ending up in the ocean.'' That's what happened for the last two Ariane customers when the French rocket crashed in the Atlantic in September.
David Leinweber, a research scientist at Rand Corporation in California, agrees that Ariane, the shuttle's main competitor, has been set back by ''a series of disasters.'' But even if the shuttle faced no competition for commercial payloads, says Dr. Leinweber, commercial profitability would remain only a very distant dream.
Leinweber says ''some people would say that the shuttle has paid for itself already'' because ''some payloads are so critical to national security.'' Noting the shuttle's ability to launch military surveillance satellites, he adds, ''It's hard to put a price on a program when the lack of nuclear war may be due in large part to the good information that each superpower has about the other.''
An unmanned version of the shuttle could have carried five times the payload of the present shuttle, Leinberger explains. He questions ''whether we have made the right investment.'' Instead of a bulk-cargo carrier, he says, the government's $15 million investment has produced ''the Rolls Royce of the space industry, which can send up a team of seven PhDs.''
NASA stresses that the latest mission's $2 million-apiece pressure suits were disabled by relatively minor mechanical or electrical faults, and that the mission achieved its prime objective of launching two commercial communications satellites. Numerous scientific experiments and shuttle performance tests were also completed.
But Leinweber notes that the system can launch satellites into 22,300-mile orbit required for communications satellites, and it cannot service the satellites after launch. Operating at an altitude of about 185 miles with a 700 -mile-high limit, the shuttle's repair capability will be limited for now to servicing NASA's planned Space Telescope.
While impressed by the shuttle's achievements, Leinweber says the program's focus on ''showy things'' that are impressive on television has been a disaster for competing systems such as NASA programs to probe distant planets and listen for signs of life from other galaxies.
''The scientific part of NASA is being eaten alive by the operating part,'' says Leinweber. He says advances in planetary sciences have been set back while money was poured into the space shuttle program.