The astronaut crew of space shuttle Discovery enjoyed a well-earned rest today after struggling to retrieve a crippled satellite and prepared to do the job -- again by hand -- on Wednesday.
Circling the earth at an altitude of 220 miles, astronauts Frederick H. Hauck, David M. Walker, Joseph P. Allen, Dale A. Gardner and Anna L. Fisher maneuvered the shuttle so that it trailed their target, Westar VI, by 391 miles. By evening, Discovery was closing on the satellite at 31 mph and was expected to rendezvous with it early Wednesday morning.
Then, beginning at about 6:17 a.m. EST, Allen and Gardner will try to manhandle the satellite into the shuttle cargo bay in almost the same way they salvaged the Palapa satellite on Monday. Their spacewalk is expected to last five hours, about an hour less than their previous effort.
The astronauts were told today that engineers feared that a malfitting bracket would make it impossible for the shuttle's mechanical arm to help them berth the satellite in Discovery's cargo bay -- a problem they encountered when they retrieved Palapa.
Both Palapa and Westar VI were sent into useless orbits in February when their rockets misfired. They are being returned to Earth for repairs and possible resale.
With the experience they gained Monday, the astronauts hope to make this salvage job easier.
Allen and Gardner will reverse the roles they played Monday: Gardner will don a jet-powered backpack and float out to Westar VI wearing the same "stinger" device around his waist that Allen used to attach himself to Palapa.
Once Gardner is fastened to the satellite's bell-shaped engine nozzle, he will push it toward the shuttle's open cargo bay where Allen will wait -- his feet planted in movable foot restraints -- to help him.
This time, Fisher, inside the shuttle's cockpit, is to direct its 50-foot mechanical arm to grasp Allen's foot restraints to give him more freedom of movement than Gardner had Monday.
"The added convenience on Wednesday is the arm," Flight Director Randy Stone said at the Johnson Space Center here. "The arm can position Joe wherever he wants to be, and this will make Dale's job a lot easier."
Allen also will wait longer before detaching the satellite's 10-foot antenna. This will give him something else to hang onto while he bolts a metal A-frame to the end of the satellite to fasten it to the cargo bay floor.
Allen and Gardner will also try to be more careful when they haul in Westar VI. They will have less room to maneuver as the Palapa satellite now takes up part of the cargo bay.
The astronauts also apparently damaged some of Palapa's solar cells when they handled it Monday. A cursory inspection of the $35 million satellite indicated that some of the cells were broken but that there was no extensive damage.
The cylindrical Palapa satellite is covered by 18,000 silicon solar cells that cost about $50 apiece.
Flight Director Stone said he anticipates much less trouble with Wednesday's salvage attempt.
"I also expect the space walk on Wednesday to be shorter, mainly because we've already experienced our problems and know what to anticipate," he said. "We expect everything to go well and we expect to perform another rendezvous and retrieval. And if we get two, I'll be twice as happy."