Development and Testing of the StarCam SG100: A Stellar Gyroscope

Typical GN&C solutions for precision pointing spacecraft require a pair of orthogonally oriented star sensors for attitude estimation and three-axis gyroscopes to provide angular rate information. The combined sensor suite however, leads to large weight, volume and power consumption. The SG100 solution seeks to eliminate the need for a separate gyroscope sensor by deriving angular velocities based on star measurements alone. The SG100 is capable of acquiring images of stars as faint as visual magnitude of 10.0 at exposure times less than 10ms and contains proprietary robust star identification, centroiding, attitude estimation and filtering algorithms to estimate precision attitude and drift-free angular rates at 100Hz. In this paper we report the development and testing of the SG100 engineering model. Results from the radiation testing (total ionizing dose) of critical components, night sky sensitivity, noise and angular rate measurement tests are presented. Test results show that the SG100 exceeds the requirements on the star sensitivity and noise equivalent angles while providing an accurate estimation of the angular rates.