Both Astronauts Going Out The Hatch

The two-man crew aboard the International Space Station was set Wednesday to try it again -- a spacewalk to repair a gyro-critical circuit breaker. Both American Michael Fincke and his Russian counterpart, Gennady Padalka were to participate in the walk, leaving the station itself unmanned for approximately six hours.

The spacewalk is aimed at restoring power to a gyroscope that helps control the Station's orientation in orbit.

The Expedition 9 crew's first spacewalk was cut short last Thursday when flight controllers in Moscow noticed almost immediately an unexpectedly high rate of pressure loss in the primary oxygen bottle on Astronaut Mike Fincke's Russian spacesuit.

Based on analysis, testing and troubleshooting by the crew, managers concluded the excessive oxygen pressure drop was caused by an open oxygen flow switch on Fincke's suit. The switch was not fully seated into the normal flow position before the spacewalk started, causing an unexpectedly swift flow of oxygen from the primary oxygen bottle into Fincke's spacesuit. Russian technicians concluded that it was an isolated event and gave the crew approval to use the same suits for tomorrow's rescheduled spacewalk. The spacewalk procedures have been updated to provide additional crew verification steps to ensure the handle is properly positioned.

The two spacewalkers will restore power to Control Moment Gyroscope (CMG) #2 by replacing a Remote Power Controller Module (RPCM). CMG #2 was taken off line April 21 by the failure of a circuit breaker in the RPCM. Currently, because of the failure of CMG #1 about two years ago, the attitude of the Station is being controlled by the two remaining CMGs.

FMI: http://www.nasa.gov