Monday, July 27, 2009

Live in orbit: Spacewalk short but sweet, NASA says

NASA today declared Endeavour's mission a big success despite a second spacewalk that ran shorter than planned because of one astronaut's challenge with carbon dioxide levels.

"We could not be happier with the success that we've had," said Holly Ridings, the mission's lead International Space Station flight director.

For the second of his three spacewalkes, the carbon dioxide absorbing system in mission specialist Chris Cassidy's spacesuit ran low, apparently because of his aggressive approach.

As a result, mission managers waved off deployment of a device that will store critical spare parts outside the station, including some to be delivered during a planned November mission.

Even though the pair was working ahead of their timeline, Ridings determined that Cassidy and partner Tom Marshburn had passed their "bingo" time, the point at which they could not reliably complete the next job.

Cassidy was on track to stay outside for five hours and 30 minutes - about 90 minutes less than Marshburn - because of his spacesuit performance.

That was barely enough to deploy the Payload Attach System, or PAS, on a starboard truss segment if everything went perfectly.

But Ridings noted that two previous crews have struggled with similar work, which even led to a new tool being developed for Endeavour's crew.

And with a Russian Progress cargo spacecraft scheduled to dock at the station Wednesday morning, she said, it would have been unsafe to leave the job partially finished, with beams potentially unsecured.

"We didn't want to get ourselves in a situation where we were not able dock the Progress," she said. "It made a lot more sense just to be a little conservative."

Cassidy and Marshburn instead got a number of smaller "get ahead" tasks accomplished that will make movement easier for future spacewalks. They installed handrails and latches for foot restraints, and tidied up some bulging cables.

Ridings and Kieth Johnson, the mission's lead spacewalk officer, praised Cassidy's spacewalking performance and skills, despite the issue that limited his time outside.

"Chris kind of goes at it pretty aggressively and works pretty hard," Johnson said. "He is absolutely amazing in the suit. Some of the things he can do kind of put you in a state of awe."

Meanwhile, crews inside Endeavour and the station have been hard at work transferring gear back and forth in preparation for the shuttle's undocking Tuesday at 1:26 p.m. EDT, after an 11-day stay.

More than 2,175 pounds of supplies ranging from food to a computer printer were offloaded from Endeavour's mid-deck to the station. The mid-deck will carry back 1,980 pounds of stuff, including trash and freezer for storing science experiments.

The Endeavour crew was scheduled to go to sleep around 7 p.m.

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