A Comparison of Gyroless Implementations on Scientific Spacecraft

The authors discuss the motivation for and implementation of various gyroless designs on four NASA-sponsored Orbital scientific spacecraft that comprise over 13 years of on-orbit experience. The examples discussed are the Vegetation Canopy Lidar (VCL) spacecraft, which has now been modified for the Glory mission and will launch next year; the Solar Radiation and Climate Experiment (SORCE) spacecraft launched in January 2003; the Far Ultraviolet Spectroscopic Explorer (FUSE) spacecraft launched in June 1999 and recently decommissioned; and the Dawn asteroid rendezvous spacecraft launched in September 2007 and currently on its way to the main asteroid belt. The advantages and disadvantages of each implementation are presented and illustrated with analytical results and a discussion of operational experience. Concluding remarks address how experience with these current designs is influencing future implementations wherein expensive gyros are not needed.