Astronaut Steve Bowen, right, dresses for success in the U. S. airlock of the International Space
Station, with help from Italian astronaut Paulo Nespoli. Photo Credit/NASA TV
Discovery astronauts Steve Bowen and Al Drew will vent toxic ammonia coolant from a failed thermal control system circulation pump and install a video camera on Canada's DEXTRE robotic hand on March 2 during their spacewalk outside the International Space Station.
The 6 1/2 hour excursion, the second for the two astronauts this week, is scheduled to get underway at 10:18 a.m., EST.
Preparations for the outing were running ahead of schedule, when Bowen's suit exhibited a leak. The fit of the helmet, gloves and boots were being checked.
The two astronauts moved the 780 pound pump from the station's starboard solar power truss to an equipment platform on the U. S. airlock of the orbiting science laboratory during their first spacewalk on Feb. 28.Drew will vent about 10 pounds of residual ammonia. Station managers hoped to return the pump that failed on July 31 to Earth aboard the STS-135 flight this summer for a failure analysis. The 14-day supply mission aboard the orbiter Atlantis is manifested for a June 28 lift off. It would mark the final flight of NASA's shuttle program -- if funded by Congress. The cause of the pump's failure remains a mystery. The breakdown temporarily halted half the station's solar power production.
The spacewalkers plan a range of small maintenance tasks during the second outing, including the retrieval of tool bags, the installation of external lighting and some troubleshooting on a loose radiator support beam.
Discovery lifted off on its final mission Feb. 24. The six shuttle astronauts have been parked at the station since Feb. 26. Under current scheduling, Discovery's crew will depart the outpost on March 6 and return to Earth on March 8, touching down at NASA's Kennedy Space Center at 11:36 a.m., EST.
So far, the shuttle crew has equipped the station with a new equipment stowage module and attached a carrier with external spare parts to the starboard truss. Inside the station on Wednesday, 10 U. S., Russian and Italian astronauts will continue unpacking five tons of cargo delivered by Discovery.