July 2, 2004
International Space Station Status Report: SS04-019
The International Space Station (ISS) is again operating with three of its four control gyroscopes, thanks to this week's spacewalk by the Expedition 9 crew. Flight controllers today placed Control Moment Gyroscope #2 (CMG #2) back in full operation along with CMGs #3 and #4. The three CMGs are now controlling the Station's attitude and orientation.
During a five-hour, 40-minute spacewalk Wednesday night, Expedition 9 Commander Gennady Padalka and NASA ISS Science Officer Mike Fincke successfully replaced a failed circuit breaker that provides power to CMG #2.
After a slow ramping up of speed over several hours, the newly restored gyroscope reached its normal peak spin rate of 6,600 revolutions per minute yesterday afternoon. Engineers performed further testing overnight to monitor the gyroscope's operation before putting it back in operation this morning.
Padalka and Fincke spent today working on post-spacewalk clean-up tasks, including putting away some of the tools they used during their repair job and conducting a follow-up conference with spacewalk specialists.
Tomorrow the crewmembers will be back to a normal sleep schedule as they begin a three-day weekend to celebrate the Independence Day holiday. They'll finish up spacewalk close-out tasks next week and work on science experiments, such as the Advanced Diagnostic Ultrasound in Microgravity.
Yesterday, the crew had a short, off-duty day. Also, Russian flight controllers used air from the Progress cargo spacecraft's supply tanks to partially repressurize the orbiting laboratory, replacing air that had been vented overboard to allow the airlock to be opened for Wednesday's spacewalk.
The ISS has four CMGs that are designed to control which way the Station is pointed as it
orbits the Earth. CMG #1 failed two years ago and will be replaced during the next Space Shuttle mission. CMG #2 was taken off line April 21, but was restored after the spacewalk. The Station's two other CMGs have been working normally.
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Information about crew activities on the Space Station, future launch dates, and Station sighting opportunities from Earth, is available on the Internet at:
Details about Station science operations are available on an Internet site administered by the Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, Ala., at:
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