Spacewalkers Mike Fossum, lower left, and Ron Garan, angled close to the International Space
Station's robot arm, begin a six-and-a-half-hour spacewalk. Photo Credit/NASA TV.
NASA astronauts Mike Fossum and Ron Garan have started their 6 1/2 hour spacewalk outside the International Space Station.
The two men emerged from the station's airlock at 9:22 a.m., EDT, about 30 minutes later than planned. However, Fossum and Garan, a pair of retired Air Force colonels who teamed for three spacewalks during a 2008 station assembly mission, seemed likely to make up the ground -- if they need to.
The astronauts will share a pair of primary tasks then work off a long list of maintenance duties they are not expected to complete.
The outing marks the 160th spacewalk dedicated to the assembly and outfitting of the 240 mile high orbiting science laboratory.
Their primary responsibilities include the transfer of a failed station thermal control system coolant pump from a storage rack close to the airlock to the payload bay of the shuttle Atlantis.
They will also move a robotic satellite re-fueling demonstrator from the shuttle's cargo hold to the exterior of the station.
"We will see you in a couple of hours," Atlantis commander Chris Ferguson told his station colleagues as the outing got under way. Atlantis docked with the orbital outpost on Sunday with a four person crew. With so few shuttle astronauts, Tuesday’s spacewalk was assigned to the two station crew members.
The International Space Station sails over NASA's
Kennedy Space Center during Tuesday's spacewalk.
Photo Credit/NASA TV
The coolant pump experienced a sudden electrical failure last July 31. The failure shut down the station's starboard cooling system, which in turn led to a dramatic power down. The station's crew responded with three rapid response spacewalks over a two week period to replace the pump with a spare.
However, the cause of the failure was never pinpointed. The 1,400 pound pump will be returned to Earth for a failure analysis.
The refueling demonstrator will be placed on DEXTRE, the two-armed Canadian robot that resides on the station's exterior. Refueling trials are planned later this year.
The spacewalkers will also un-snag a grounding strap on a Power and Data Grapple Fixture installed on the station's Russian segment in May. The PDGF will serve as an anchor for the station's Canadian robot arm, which often provides a mobile work platform for spacewalking repairmen.
Fossom and Garan will also connect a data cable to the PDGF.
If time permits, they will install a thermal cover on a Tranquility module docking fixture. NASA plans to place a universal docking port on the fixture in the future to receive a range of new spacecraft. .