Shuttle crew again proves value of man's hand in orbit. NASA's ability to repair satellites in orbit is crucial to commercial success

Once again, shuttle astronauts have shown the value of having trained, capable people on hand to make balky equipment perform in orbit. Not only has Discovery's crew performed the second, apparently successful, repair of an orbiting satellite, they also worked around malfunctions in shuttle equipment to complete a sometimes threatened mission. To cap what controllers in Houston called the crew's ``outstanding'' performance, Astronaut James D. A. van Hoften became the first human to hand-launch a satellite when he spun the repaired Leasat-3 and pushed it away from Discovery Sunday.

For the National Aeronautics and Space Administration (NASA), this was a welcome success. Delays due to weather and a failed shuttle computer had threatened to reinforce the shuttle's image as an unreliable satellite-launching system. In spite of these setbacks, the shuttle team did launch Discovery within the specified launch period, which allows for a few days delay. The astronauts also overcame problems with a jammed sunshield, which blocked the launch of an Australian communications satellite, and a

malfunction in the shuttle's maneuverable arm.

In addition to repairing Leasat, Discovery's crew launched three communications satellites, earning NASA fees totalling $40 million. One of the satellites was Leasat-4, a companion to the repaired satellite, which now is on-orbit as part of the Leasat worldwide command and communications network leased by the US Navy.

Leasat controllers won't know in advance how the repaired satellite's engines will perform. They may fire normally, sending the satellite toward its station 22,300 miles out in space, or they may explode. Leasat-3 has been cold-soaked at temperatures which could freeze and damage its rocket fuel. According to early indications, there are no fuel line ruptures and only about 25 percent of the fuel for the steering rockets was frozen. That amount probably can be thawed, according to officicals of Hu ghes Aircraft Company, whose subsidiary owns the satellite. What damage, if any, has been done to the solid rocket fuel for the main engine is not yet known.

At this writing, the repaired satellite was responding to commands. Controllers will try to fire its engines Oct. 29. Meanwhile, Discovery's astronauts were stowing equipment and resting in preparation for their return to Earth at Edwards Air Force Base, Calif. Tuesday. They were due to land at 9:15 a.m. EDT (6:15 a.m. PDT), about nine minutes before sunrise.

Thus, while Hughes Communications Services president Steven Dorfman called the astronauts' feat ``the most remarkable salvage operation in the US space program,'' he warned that there is still no final assurance that the repaired satellite has actually been saved.

NASA, however, has fully earned the $8.47 million fee which Hughes Aircraft paid for repairing the satellite, which was insured for $85 million. The astronauts were able to bypass circuitry controlled by a failed timer and install a new control package on the outside of the satellite. Leasat-3 dead on orbit when it was released during a shuttle mission April 13.

A failure in the shuttle-arm's elbow extended the astronaut's work substantially. Automatic control could not be used. Instead, Mission Specialist John M. Lounge used manual switches to control the arm. The malfunction in the arm made the repair work more cumbersome. Instead of completing the repair in one work session as planned, Astronauts William F. Fisher and van Hoften needed two trips into the shuttle bay. Then, with efforts comparable to those involved in Olympic weight-lifting, van Hoften pushed

on a spin-up bar on the satellite, gave it a spin of 3 revolutions a minute to stabilize it, and shoved the 7.5 ton satellite away from Discovery.

If Leasat-3 is eventually put into service, the insurers will share the revenue it generates to compensate them for the claim they paid. Insurance claims for failed satellite launches -- largely shuttle-based launches -- have driven up insurance rates. Premiums are almost 20 percent of policy coverage annually compared to 7 percent a year ago. This is drawing sharp criticism from Arianespace, the shuttle's European competitor for launch services. Arianespace officials claim that they are being penalized

unfairly for NASA's mishaps.

NASA is being prodded to do all it can to ensure that satellites it launches work on orbit, even if that means a second mission to repair them. Merely returning a satellite after it has failed -- as was done with Palapa B-2 and Westar 6 last November -- does not impress insurers. Those satellites have yet to be resold to help offset underwriters' losses.

The European Ariane unmanned launch rocket is giving the shuttle stiff competition. Even US satellite owners are turning to it as evidenced by a GTE Corporation announcement, made while Discovery was aloft, that Ariane will launch the GTE Spacenet III Sept. 12.

NASA needs four shuttles to attain an efficient and more competitive launch schedule. Columbia will rejoin the fleet later this year and the newest shuttle, Atlantis, is now on the pad at Kennedy Space Center for a hot firing test. It is due to orbit a military payload in October.