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Sunday, November 4, 2007

Emergency operation saves space station


CAPE CANAVERAL, Fla. - Astronauts successfully unfurled a torn solar power wing at the international space station on Saturday after spacewalker Scott Parazynski cut loose a tangled clump of wires and patched everything up.

His emergency surgery saved the solar energy panel — and the space station.

"This was just a fabulous effort," said Mike Suffredini, the space station's program manager. "Our baby is still beautiful to us."

In the tense buildup to the spacewalk — one of the most difficult and dangerous ever attempted — NASA repeatedly warned that station construction would have to be halted if the wing could not be fixed.

The prospect was so grave that NASA felt it had no choice but to put Parazynski practically right up against the swaying power grid, which was coursing with more than 100 volts of electricity. No other astronaut had ever been so far away from the safe confines of the cabin.

Even before Parazynski made his way back inside, the radio traffic was full of cheers and congratulations.

Shouts of "Yay! All right! Beautiful! Great news!" streamed from the linked shuttle-station complex once the wing was unfurled to its full 115-foot (35-meter) length. Mission Control promptly relayed thanks from NASA's top brass.

"It was an honor," Parazynski replied.

The commander of the docked shuttle Discovery, Pamela Melroy, who supervised the wing repairs, cautioned everyone to hold off on "the victory dance" until Parazynski and his spacewalking partner, Douglas Wheelock, were safely back inside. "Then we can all rejoice," she said.

Tense hours
It took almost an hour for Parazynski to be maneuvered back from the wing, riding on the end of a nearly 90-foot (27.5-meter) robotic arm extension that just barely reached the damage. That's how long it took him to get out there, too.

Parazynski worked on the damage for more than two hours, cutting hinge and guide wires that became snarled and snagged the wing when it was being extended Tuesday. The astronauts had just relocated a massive beam at the space station, and finished extending its first solar power wing, when the second wing got hung up after extending only 90 feet (27.5 meters).

Parazynski, 46, an emergency medical doctor before becoming an astronaut, looped five makeshift braces into the wing to reinforce a partially ripped hinge. They resembled big white stitches, and were nicknamed "cufflinks" because they work like the connectors that hold together the cuff of a shirt sleeve.

Throughout the repair, Parazynski used an L-shaped Teflon stick, wrapped with insulating tape, to keep the billowing solar wing away and to avoid being shocked. At times, as his shadow loomed large on the wing, gleaming orange and gold in the sunlight, he looked like a stick-wielding hockey player, all bundled up in his puffy spacesuit.

A long reach
As Parazynski got ready to cut the snarled guide wire for the wing, he mentioned that it was a bit of a reach.

"It's what those monkey arms are for," Melroy told the 6-foot-2 (188-centimeter) astronaut. She said not too many other astronauts could do what he was doing.

"They don't have to," Parazynski replied with a laugh.

Parazynski counted down — "3, 2, 1, snip" — as he sliced the guide wire with a pair of cutters. To everyone's relief, the 90-foot (27.5-meter) length of cut wire retracted smoothly into its reel at the base of the wing, where Wheelock slowed its speed with a gripping tool.

Parazynski accidentally let go of his wire-cutting tool at one point, but caught it. A few hours later, he lost his needle-nose pliers. The astronauts inside the station spotted the pliers drifting nearby.

"We're going to have to let it go ... not much we can do now," Parazynski said, hustling to get back indoors.

The spacewalk — the fourth for Discovery's space station visit — lasted more than seven hours. It wrapped up station construction work for the seven shuttle astronauts. The hatches between the linked spacecraft will close Sunday and the shuttle will pull away Monday. Landing is set for Wednesday.

Lots of work left to do
Considerable work remains for the space station's three occupants.

They need to move the pressurized compartment that was delivered and installed by the Discovery crew, and conduct three spacewalks, before shuttle Atlantis can launch with the first of two new laboratories. Liftoff remains targeted for Dec. 6, but could be delayed a few days, Suffredini said.

NASA still has to figure out what to do about a rotary joint that isn't working right and can be used only sparingly to turn another set of solar power wings toward the sun. Steel shavings were found inside the joint during a spacewalk last Tuesday, apparently the result of grinding parts.

Samples of those shavings will return to Earth aboard Discovery and help pinpoint the source of the trouble.

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