Wednesday, March 02, 2011

Spacewalkers to chase "cats and dogs" today

Astronauts Steve Bowen and Alvin Drew plan to float outside the International Space Station this morning to complete the last of their mission's two spacewalks -- the last ever by Discovery crew members.

After "camping out" overnight in the Quest airlock at reduced air pressure to prevent decompression sickness, the duo is scheduled to head outside at 10:18 a.m. EST. They'll tackle assorted maintenance tasks long planned but deferred for higher priority work.

"We’ve got a lot of what I call 'cats and dogs' on that (spacewalk), things that we’ve been tracking that we need to get done for some time, so we’ve got a good opportunity to go get those," said Kenny Todd, chairman of the space station Mission Management Team.

The work includes venting toxic ammonia from a failed pump that was relocated on Monday's spacewalk; retrieving an experiment attachment mechanism and stowing it in Discovery's payload bay for return to Earth; installing camera equipment; removing insulation; and troubleshooting a loose radiator component.

The spacewalk is expected to last six-and-a-half hours.

Mission specialist Nicole Stott will choreograph the spacewalkers from inside the station, assisted by mission specialist Mike Barratt and Expedition 26 commander Scott Kelly, who will fly Bowen on the end of the station's 58-foot robotic arm.

Tim Kopra, the astronaut replaced by Bowen on Discovery's crew after a mid-January bicycling accident, is expected to help out again from Mission Control in Houston.

Meanwhile, crewmates inside the station will be busy transferring cargo from a newly installed storage module, including the humanoid robot named Robonaut 2, or R2.

Here's a look at the day's highlights from the most recent NASA TV schedule:

-- 5:23 a.m.: Discovery, International Space Station crews awake
-- 7:13 a.m.: Preparations resume for second spacewalk
-- 10:18 a.m.: Steve Bowen and Alvin Drew begin mission’s second spacewalk
-- 11:48 a.m.: Spacewalkers retrieve and remove Lightweight Adaptor Plate Assembly and remove thermal insulation from an external stowage platform
-- 12:38 p.m.: Installation of light on Port 3 truss segment rail cart
-- 12:48 p.m.: Installation of camera assembly on Dextre robot
-- 1:58 p.m.: Troubleshooting of radiator stowage beam on Port 1 truss segment
-- 3:08 p.m.: Removal of thermal insulation from Tranquility module
-- 3:43 p.m.: Installation of camera covers
-- 4:48 p.m.: Spacewalk ends
-- 7:53 p.m.: Station crew sleeps
-- 8:23 p.m.: Discovery crew sleeps

IMAGE: NASA astronauts Steve Bowen and Alvin Drew, both STS-133 mission specialists, participated in the mission's first session of extravehicular activity Feb. 28 as construction and maintenance continued on the International Space Station. Credit: NASA

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