spacetoday.net: Station gyro fails

Posted: Sun, Jun 9, 2002, 11:55 AM ET (1555 GMT)
STS-111 view of Leonardo module (NASA)

A gyroscope on the International Space Station failed Saturday, shortly after a cargo module was attached to the orbiting outpost. One of four control moment gyroscopes (CMGs) on the station's Z1 truss, identified as CMG-1, failed Saturday with little advance warning; astronauts on the station heard a "growling" noise as the gyro spun down. The CMGs are used to provide attitude control on the station, and without them the station would have to rely on thrusters in the Russian segment to keep the station properly oriented. While NASA said the failure could be a "serious complication for the long-term space station operations", it is not a major concern now since the other three CMGs are working and are sufficient to maintain attitude control. There is a spare CMG on the ground but it cannot be launched to the station until early next year, because there is no room on earlier shuttle missions for the 500-kg unit. The failure took place less than an hour after the Leonardo cargo module was docked with the station's Unity module, bringing supplies and equipment to the station. The failure will not hamper Sunday's scheduled EVA by astronauts Franklin Chang-Diaz and Philippe Perrin, the first of three scheduled for the STS-111 mission. The two spacewalkers will inspect the exterior of CMG-1 in addition to work to support the installation of a mobile base unit on the station's new railcar.