Wednesday, March 02, 2011

Discovery astronauts perform second spacewalk

Astronaut Bowen performs an orbital walk in space today. (NASA)

Space shuttle Discovery astronauts Steve Bowen and Alvin Drew left the International Space Station today to complete several chores on this the second planned spacewalk of the shuttle's final mission.

Bowen and Drew switched their spacesuits to internal power at 10:42 a.m. EST, today and minutes later left the Quest airlock and the start of six and one-half hour orbital walk in space.

Today's spacewalk marked Bowen's seventh excursion outside the space station and Drew's second.

The spacewalkers first set out in two different directions. Bowen to the station's 58-foot robotic arm to install a work platform on the end effector; and Drew headed over to the External Stowage Platform No. 2 to complete work from Monday's 'walk' to vent nearly ten pounds of coolant from the ammonia pump.

In the Cupola node, the robotics work station.

Bowen then unbolted the Lightweight Adaptor Plate Assembly (LWAPA) experiment carrier platform, removing it from the European Columbus module while riding the station's arm. The arm then carried Bowen as he carried the platform over to Discovery's payload bay so it can be installed in the aft section for the return trip home.

Eighty minutes into the spacewalk, Bowen installed a new "camera light pan and tilt assembly" on Canada's Dextre robot, and then removed a thermal blanket from Dextre, NASA's mission control at the Johnson Space Center stated.

Bowen placed a new lens cover on a camera on the robotic arm of the space station at the elbow joint, which will protect the lens from erosion that might be caused by visiting spacecraft thrusters.

Drew also placed a light on the Crew Equipment Translation Aid cart to allow for future spacewalkers to work in that dark area, and placed insulation around a "valve module fluid line on a left hand truss segment radiator beam", mission control added.

As the final hour of the orbital walk in space began, the light assembly on Drew's helmet came undone.

Hanging by it's electrical cords, Bowen transitioned over to Drew and worked to reattach the dangling light back to his helmet. Bowen had no luck and Drew headed to the airlock.

The spacewalk ended at 4:56 p.m., completing the second of two spacewalks on Discovery's mission and the fourth of this year aboard the space station.

The spacewalk was delayed earlier when leak checks of Bowen's suit discovered a small leak.

Discovery crew member Mike Barratt helped dressed the spacewalking astronauts in their space suits discovered a worn blue O-ring seal (right) on Bowen's Lithium Hydroxide canister at 8:37 a.m. He radioed mission control in Houston the likely source of the leak.

The fourteen-inch long narrow black box is stored in the life support region on the back pack of the spacesuit. It is designed to remove carbon dioxide from the astronauts oxygen.

After the crew's in the Quest airlock and nearby on station could not find a replacement blue o-ring, mission control approved the use of an orange o-ring which is shaped the same in size.

A leak check ten minutes later found no leaks and the crew pressed on running fifteen minutes late.

Today's spacewalk also marked the 155th spacewalk in support of the construction and maintenance of the orbiting laboratory complex. A total 973 hours and 53 minutes of combined spacewalking time have been accumulated since 1998.

Thursday will be less busy for the duel crew of twelve in space.

Unstowing items from Discovery's middeck for placement on the space station, and several interviews by news media and a call from President Obama at 5:03 p.m. are planned.

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