Saturday, November 22, 2008

Third Spacewalk Nears; No Extra Day...Yet

Two Endeavour spacewalkers are in the crew section of the Quest airlock that is their last stop before exiting the International Space Station for what is expected to be a grueling seven-hour excursion.

Heidemarie Stefanyshyn-Piper will be making her fifth career spacewalk, the third in five days and most likely her last of the mission.

Partner Steve Bowen will be making his second career spacewalk, and is scheduled to go out again Monday with Shane Kimbrough for the mission's fourth and final spacewalk.

Mission controllers have prepared for the possibility that some of today's planned work will be finished Monday. Some protective thermal covers may be left off parts of the station's starboard solar rotary joint if there isn't time to replace them.

Stefanyshyn-Piper have been hooking up spacesuit equipment before their airlock is depressurized to equal the vacuum of space, now minutes away. Running close to an hour ahead of schedule, the spacewalk could begin before 1 p.m.

Watch it live here on The Flame Trench by clicking on the NASA TV viewer above.

Earlier, station program managers told crews on board the station and Endeavour that they had no plans to ask for a one-day mission extension today.

However, that decision could change by tomorrow, pending the results from today's spacewalk and ongoing efforts to activate a urine processor.

This NASA graphic shows in green the sections of the starboard Solar Alpha Rotary Joint, or SARJ, that the spacewalkers will work on today. The red and blue sections were worked on during the first two spacewalks.

Click on the graphic to enlarge it. The 12 boxes identified as "TBA" represent trundle bearing assemblies surrounding the joint's steel gear ring, or race ring, which measures about 10 feet in diameter.

The spacewalkers hope to remove and replace another five bearing assemblies today, bringing the total to 11 for the first three spacewalks. A 12th bearing assembly was replaced in June.

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