Dangerous spacewalk under way

HOUSTON, Texas (AP) -- Astronauts stepped outside the international space station Saturday morning to fix a ripped solar wing in one of the most difficult and dangerous spacewalking repairs ever attempted.

Astronaut Scott Parazynski edges along a truss outside the international space station Saturday morning.

NASA officials and the astronauts in orbit have worked day and night to plan every detail of the momentous repair mission. The snagged panel must be fixed before space station construction can continue.

"Go out there and fix that thing for us," station commander Peggy Whitson said just before spacewalkers Scott Parazynski and Douglas Wheelock floated out of the hatch.

"We will," Wheelock responded.

The plan calls for perching Parazynski at the end of a 90-foot robotic arm and boom extension for a 45-minute ride to the damage site.

There, he will tinker with what amounts to a damaged electrical generator. The solar panel teems with more than 100 volts of electricity, possibly as much as 160 volts.

To save the solar wing, Parazynski needs to clear whatever snagged the panels and caused the wing to tear in two places while it was being unfurled Tuesday. He will not know what he's up against until he sees the damage up close.

"We've collected a lot of video, a lot of still photography. But nothing's going to be like the moment when Scott Parazynski actually puts his eyes on this area of interest, on this potential guidewire snarl," flight director Derek Hassmann said Friday.

As it is now, the wing poses a structural hazard for the international space station. The damage could worsen and the wing could become unstable, possibly forcing NASA to cut it loose and lose a vital power source for future laboratories.

Once Parazynski has cleared the snag -- possibly by moving the guidewire or cutting it and letting it wind up at the base of the tower -- he plans to install several homemade braces so astronauts can deploy the wing to its full 110 feet. It is about 75 percent deployed now.

Astronauts made the braces from aluminum sheets and insulated tape aboard the linked shuttle-station complex.

Wheelock is nearby to guide Parazynski and the astronauts operating the robotic arm. Italian astronaut Paolo Nespoli is choreographing the outing from inside the station.

This is Parazynski's fourth spacewalk this mission and the seventh of his 15-year astronaut career.

He and Wheelock are wearing partial mittens over their gloves for extra protection. Wheelock pierced the outer layer of a glove near the end of Tuesday's spacewalk, marking the third time in less than a year that a spacewalker tore a glove on something sharp at the space station.

As for the electrical hazards, all of the metal parts on Parazynski's spacesuit have been covered with insulating tape -- triple-taped, in fact -- as have all the tools that he's carrying with him.

"It's not the kind of thing that would burn you, but we could get conduction through the heart, let's say, or mild shocks," said David Wolf, the spacewalk branch chief for the astronaut office.

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

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NASA wrestles ripped solar panel

HOUSTON, Texas (AP) -- Spacewalking astronauts bolted a solar power tower to the international space station on Tuesday, completing an ambitious three-day moving process that ended with elation when the beam's giant solar panels began to unfurl.

A rip can be seen in one of the giant new solar panels unfurled on Tuesday on the international space station.

Their joy turned to concern, however, when a rip was spotted in the second solar panel.

NASA needs to get the tower up and running to prevent malfunctioning station equipment from delaying the addition of a much-anticipated European research lab.

A massive rotary joint is supposed to make sure the solar panel wings on the right side of the space station are facing the sun. But the gear, which was installed in June, has been experiencing electrical current spikes for nearly two months.

The solar panels on the 17-ton girder that was installed at its new location Tuesday were folded up like an accordion for the move, and the first one slowly was unfurled as the seven-hour spacewalk wrapped up, gleaming like gold in the sun.

The crew kept spacewalker Scott Parazynski and Douglas Wheelock apprised of the first solar wing's unfurling as they floated back inside. Their reaction: "Wow, that's great," and "Awesome!"

"It's a good day's work right there," Parazynski said.

The astronauts abruptly stopped the unfurling of the second panel, however, as soon as they saw the rip on the edge of the panel. The panel was almost completely unfurled when the rip was spotted. The astronauts beamed down photos of the torn and crumpled section so NASA can analyze them and determine the extent of the damage.

At Mission Control's request, the astronauts retracted the wing just a bit to ease the tension on it.

A spacewalking astronaut found black dust resembling metal shavings inside the motorized joint on Sunday. NASA has limited the joint's motion to prevent the debris from causing permanent damage, but that also limits the system's ability to generate power for the station.

Parazynski spent part of Tuesday inspecting the matching rotary joint that turns the space station's left set of solar wings toward the sun. NASA will examine images he gathered of the perfectly running unit to compare it to the malfunctioning one.

There were no shavings inside the joint, and Parazynski said everything looked pristine.

"It's right out of the shop, no debris whatsoever," he said.

Parazynski and Wheelock guided astronauts inside the station as they used a robotic arm to hook up the beam to the orbiting outpost's backbone. The spacewalkers then began installing bolts to hold the beam in place and connecting wires to provide power.

"Oh I love this job," Parazynski said as they worked 220 miles above southeast Asia. "Beautiful view."

Given the problems with the right rotary joint, NASA needs the power generated by the newly installed solar panels to proceed with the planned December launch of the European Space Agency's science lab, named Columbus.

That lab and a Japanese lab set to be delivered early next year will latch onto the new Harmony module that Discovery delivered last week.

The space agency added a day to Discovery's mission so spacewalking astronauts could conduct a detailed inspection of the troublesome joint. That work is scheduled for Thursday.

To make room for that inspection, managers canceled a shuttle thermal tile repair demonstration that was scheduled for that spacewalk. The test was added to the mission after a piece of fuel-tank foam gouged Endeavour's belly on the last shuttle flight in August.

Any repairs to the malfunctioning gear would be put off until after Discovery departs.

Discovery is now scheduled to undock from the space station on Monday and return to Earth on November 7.

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

Source from: edition.cnn.com

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