Mission Experience Using New Attitude Tools for Spinning Spacecraft

This paper describes early mission ground attitude support experience with two spinning spacecraft missions: Space Technology-5 (ST-5) and Time History of Events and Macroscale Interactions during Substorms (THEMIS). These missions used the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center Multi-Mission Axis Stabilized Spacecraft (MSASS) Attitude Ground Support System (AGSS) that recently was significantly enhanced. The AGSS estimator suite includes a spinning spacecraft Kalman filter and three single-axis attitude estimators: the Fuzzycones method, the MagnetometerOnly Single-Axis Estimator/Calibrator (MOSAEC), as well as a standard differentialcorrector batch-method estimator. The calibration suite of tools includes utilities to estimate relative time offsets, magnetometer calibration parameters, and Sun sensor biases. Nomenclature I B � = magnetic field reference vector in geocentric inertial coordinates (GCI) raw B � = three-axis magnetometer (TAM) measurements converted from counts to engineering units P B � = TAM measurement vector projected onto the principal axes of inertia (PAI) T B � = TAM measurement vector in the TAM frame after adjustment for scale factors and the skewness of the TAM axes