spacetoday.net: ISS gyro fails, repair spacewalk planned

Posted: Fri, Apr 23, 2004, 11:57 AM ET (1557 GMT)
ISS illustration (NASA)

A second gyroscope on the International Space Station has failed, NASA officials said Thursday, and plans are being developed to repair it during a spacewalk. The Control Moment Gyroscope (CMG) shut down Wednesday when a circuit breaker inside the gyro assembly failed. The failure of CMG-2 had no immediate effect on the station, which has four such gyros that are used to maintain the station’s attitude. However, because another gyro failed in 2002, there are only two operating gyros now, the minimum needed for attitude control. Should another failure, the station would have to rely on thrusters on the Russian segment of the station for control; officials said there is a 6-12 month supply of propellant for those thrusters. NASA officials said they are considering a spacewalk by the Expedition 9 crew in one or two months to replace the electronics bix on the failed gyro. However, such a spacewalk would face a number of logistical issues, including whether to use Russian spacesuits from the Russian airlock on the opposite side of the station as the gyros, or bring up parts for American spacesuits that could be used from a closer airlock on the American segment of the station.