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Station gyro experiences unusual vibration BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: March 28, 2005 About five minutes after space station commander Leroy Chiao and Salizhan Sharipov wrapped up a successful early morning spacewalk, one of the station's two operational control moment gyroscopes, used to stabilized the complex and change its orientation, experienced an unusually high vibration. One official said the vibration in CMG-3 was "an order of magnitude" higher than any such event in the past and engineers are studying data to determine what might have happened and what, if anything, might be wrong. The station is equipped with four control moment gyros, but CMG-1 failed in 2002 and CMG-2 went off line March 16 when a circuit breaker malfunctioned. Spacewalkers aboard the shuttle Discovery plan to restore CMG-2 to operation in May by re-routing power to the gyro during an already planned spacewalk. CMG-1 will be replaced during another spacewalk. Control moment gyroscopes are used to maintain the station's orientation without using Russian thrusters that rely on limited supplies of on-board rocket fuel. Officials said today that even a third gyro failure likely would have no impact on Discovery's mission because the shuttle would have more than enough fuel on board to maintain the station's attitude, if necessary, while CMGs 1 and 2 are brought back on line. And in any case, CMG-3 remains fully operational. As usual during spacewalks involving the Russian segment of the station, the lab complex was allowed to freely drift while the spacewalkers worked at the aft end of the Russian command module. The thrusters were activated after the work was done to restore the proper orientation. Engineers were planning to switch control back to the gyros after the spacewalk ended when the "vibrational event" was detected. Playing it safe, flight controllers opted to maintain control using the thrusters until just after noon. As of this writing, CMGs 3 and 4 are maintaining attitude while engineers study telemetry to determine the nature of the event.
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A foot-long Russian nanosatellite is flung overboard by the spacewalking International Space Station Expedition 10 crew. Station cameras watched the hand-launched deployment and the nanosat as it floated away. (4min 52sec file)
Highlights of the second spacewalk of the International Space Station's Expedition 10 crew is compiled into this movie. The crew completed external outfitting of gear that will guide European cargo ships to the outpost during dockings starting in 2006. (5min 00sec file)
Mission managers preview the next spacewalk by the Expedition 10 crew aboard the International Space Station, which will install external equipment on the Russian segment and hand-launch a tiny nanosatellite. (37min 00sec file)
