SBIRS high payload LOS attitude determination and calibration

This paper describes the space-based infrared sensor (SBIRS) payload line-of-sight (LOS) attitude determination and calibration algorithm required for both GEO and HEO missions. Included in the algorithm are three multi-state extended Kalman filters (EKFs) which correct the payload LOS attitude error as well as on-gimbal gyro bias error using celestial observations. For the GEO mission, the celestial observations are obtained using two spacecraft visible star trackers. However, for the HEO mission, the celestial observations are obtained by viewing the in-band IR stars from the payload sensor itself. The derivations of the EKFs using a quaternion formulation are given in the paper for both missions. Time domain simulations are presented to show the predicted filter performance, which is a function of star density/availability, star catalog error, star centroiding accuracy, gimbal angle readout errors, and gyro noises. Preliminary analysis indicates that the allocated payload LOS attitude determination performance requirement can be met with the proposed attitude determination hardware and algorithms.