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Power Problems Trouble Discovery Mission

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[October 31, 2007]  HOUSTON (AP) -- NASA scrambled Wednesday to deal with two power problems at the international space station that could delay future missions and make it even harder to finish building the orbiting outpost before the space shuttles must be retired.

Both issues competed for the precious little spacewalking time that's left in Discovery's mission, which already was extended a day after the first problem cropped up last weekend. Spacewalks were scheduled for Thursday and Saturday.

Astronauts Scott Parazynski and Douglas Wheelock were getting ready Wednesday to spend the mission's fourth spacewalk thoroughly inspecting a malfunctioning rotary joint that keeps the station's solar panels turned toward the sun.

Spacewalkers may be asked to spend the fifth spacewalk repairing a giant solar wing that ripped as it was being unfurled on Tuesday. The tear forced the space agency to halt the process before the wing was fully extended.

Until at least one of the problems is resolved, the station won't be able to generate enough power to support new equipment, such as a European lab that is supposed to be delivered by Atlantis in December. Delaying that mission would set back other deliveries, including the planned February installation of a new Japanese lab.

NASA is up against a hard 2010 deadline for completing the space station and retiring the three remaining shuttles.

The solar wing damage marred an otherwise hugely successful day. Two of shuttle Discovery's crew had just finished a seven-hour spacewalk to install the beam that holds the wings. Deploying the damaged wing's twin went off without a hitch.

Astronauts took pictures of the wing tear, but NASA engineers couldn't tell what caused the damage, space station flight director Heather Rarick said late Tuesday.

Astronaut Daniel Tani said he noticed a second, smaller tear near the 2 1/2-foot rip while he was taking additional pictures Wednesday. He planned to use binoculars to get a better look at the damage and try to figure out what caused it.

"Until we know what we think the cause is, maybe until we get some better pictures, I don't think we really have any solid leads on how to fix it yet," Rarick said.

Earlier Tuesday, space station program manager Mike Suffredini said spacewalking astronauts could cut whatever might be snagging the solar wing, like a hinge, and possibly sew up the tear.

NASA also wasn't sure about the cause of the rotary joint problem. Steel shavings were found during a spacewalk over the weekend in the joint on the right side of the station.

Until NASA figures out what's grinding inside the gears and fixes it, the right joint will remain in a parked position as much as possible, limiting power collection.

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On Thursday, Parazynski and Wheelock plan to remove 21 protective covers from the joint and search for whatever's causing the problem. They also may clean up some of the debris.

Wheelock planned to use a backup spacesuit glove on Thursday after noticing a small hole in his right glove following Tuesday's spacewalk. It wasn't immediately clear where the damage was located or how bad the damage was.

Wheelock and Parazynski frequently checked the condition of their gloves during the seven-hour jaunt. NASA ended an August spacewalk early after an astronaut tore his glove on a sharp edge of the space station. Another spacewalker cut his glove last December.

A spacewalker on Sunday searched for sharp edges that may be causing the damage but didn't find anything significant.

The glove Wheelock tore Tuesday was a backup he was using because his primary glove was slightly damaged during the mission's first spacewalk. Rarick said the primary glove could be used in an emergency.

The hole only penetrated the exterior part of Wheelock's multi-layered glove. If something penetrated the entire glove, the spacewalker's suit could leak, putting him in danger if he couldn't quickly get back inside the station.

Discovery currently is scheduled to undock from the station on Monday and land on Nov 7. But Suffredini hinted that another two days could be added to the flight if the newest problem is deemed serious enough.

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On the Net:

NASA: http://spaceflight.nasa.gov/

[Associated Press; By LIZ AUSTIN PETERSON]

Copyright 2007 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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