Failure Analysis of International Space Station Control Moment Gyro

The US Attitude Control system of the International Space Station (ISS) includes four Control Moment Gyros (CMGs) that provide a micro-gravity environment for science payloads. On June 8 2002 a CMG suffered a hard failure after approximately 1.5 yrs in operation. This paper presents an overview of the design, heritage, on-orbit failure, and corresponding root cause analysis of an ISS CMG. A discussion of telemetry data analysis conducted and methods to produce significant results are presented. A description of the suspected modes of failure and corresponding analysis are also given.