Stellar Gyroscope for Determining Attitude of a Spacecraft

A paper introduces the concept of a stellar gyroscope, currently at an early stage of development, for determining the attitude or spin axis, and spin rate of a spacecraft. Like star trackers, which are commercially available, a stellar gyroscope would capture and process images of stars to determine the orientation of a spacecraft in celestial coordinates. Star trackers utilize charge coupled devices as image detectors and are capable of tracking attitudes at spin rates of no more than a few degrees per second and update rates typically <5 Hz. In contrast, a stellar gyroscope would utilize an active pixel sensor as an image detector and would be capable of tracking attitude at a slew rate as high as 50°/s, with an update rate as high as 200 Hz. Moreover, a stellar gyroscope would be capable of measuring a slew rate up to 420°/s. Whereas a Sun sensor and a three-axis mechanical gyroscope are typically needed to complement a star tracker, a stellar gyroscope would function without them; consequently, the mass, power consumption, and mechanical complexity of an attitude-determination system could be reduced considerably.