The Expedition 9 crew's first spacewalk was cut short 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 on-orbit troubleshooting, managers concluded that 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 objective of the spacewalk is to 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. Because of the failure of CMG 1 about two years ago, the attitude of the Station is being adequately controlled by the two remaining CMGs.
Coverage and commentary of the spacewalk will begin Wednesday at 3:30 p.m. CDT. The spacewalk is scheduled to begin at 4:40 p.m. The excursion is expected to last up to six hours.
Because the spacewalk will be occurring simultaneously with the arrival of the Cassini-Huygens spacecraft at Saturn, coverage of the spacewalk will be broadcast on AMC-9, Transponder 5, C-band, 85 degrees west longitude, vertical polarization, 3800 MHz with audio at 6.8 MHz. Cassini's mission will be seen on NASA Television's regular satellite channel, AMC-9, Transponder 9, 85 degrees west longitude, vertical polarization, 3880 MHz with audio at 6.8 MHz.