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Abstract

A method, apparatus, article of manufacture for determining the attitude of a spacecraft having at least one star sensor. The method comprises the steps of preparing, for each star sensor, an associated star catalog having an entry describing star parameters for each star potentially observable by the star sensor. The determination of which stars are potentially observable by the star sensor is performed using an estimate of the satellite attitude. A correlation is then determined between the stars observed by each star sensor with the associated star catalog entries. A reference star sensor is selected as the star sensor tracking a primary star having the highest correlation between the stars observed by the star sensor and the entries in the star catalog associated with the star sensor. The spacecraft attitude is determined from the primary star and remaining star observations by the reference star sensor. Attitude estimates from the non-reference trackers are used to determine star sensor alignment. If sun sensor data is available, sun sensor alignment may be determined through an analogous method.

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First Claim