Saving Skylab

Can NASA keep the giant spacecraft in orbit?

It is the largest, most sophisticated spacecraft ever built. Launched in May 1973 it was occupied by three different teams of astronauts in succession, one of which remained aloft for 84-days, a space endurance record that was not broken until this March by two Soviet cosmonauts. Now the 85-ton Skylab, unused by astronauts since 1974 but still circling 389 km (242 miles) above the earth every 90 minutes, is in deep trouble. Gradually moving lower, it may enter the atmosphere and disintegrate by November 1979 or even earlier. Large chunks of Skylab might well survive the fiery plunge through the air and --though the chances are remote --hit populated areas.

NASA officials originally expected Skylab to remain in orbit for at least a decade. That would have allowed ample time for the space shuttle to rendezvous with the space station and help boost it to a higher orbit, extending its lifetime indefinitely. But now the shuttle, plagued by engine problems, is at least four months behind schedule and there will be no manned flight before December 1979, which could be too late to save Skylab.

What NASA did not reckon with was the unexpected intensity of solar disturbances accompanying the current sunspot cycle. More sunspots have appeared than were anticipated, great magnetic storms and solar flares are raging on the sun, and more charged atomic particles--which make up the solar wind--are being hurled into space. The stronger solar wind heats the thin gases in the outer fringe of the earth's atmosphere, which causes them to expand outward into the orbit of Skylab. That increases the drag on the craft.

To keep Skylab aloft long enough to be saved by the shuttle, space engineers have devised an elaborate rescue plan. In March, they switched on Skylab's long-dormant solar-powered electrical system to charge batteries and heat frozen equipment. Last week they were preparing to turn on the ship's stabilizing gyroscopes and fire its small attitude control thrusters. They hoped to stop Skylab from wobbling through space and significantly reduce drag.

Yet the danger of losing Skylab remains real. Space agency contractors must get the bugs out of the shuttle in time and complete the supplemental rocket engine that it will carry to Skylab. Installed aboard the huge craft, the rocket could boost it to safety. Says one worried space engineer: "There just isn't any time to fool around if we're to save Skylab."

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