Patent ID: 6470270
Filing Date: 2002-10-22
Classification: B64G,G01C,G01S

Abstract:
A method of determining an attitude of a spacecraft having a plurality of star sensors, comprising the steps of:selecting a first reference star sensor from among the star sensors; designating two stars observed by the first reference star sensor as a primary star pair; identifying a candidate star pair corresponding to the primary star pair, wherein the candidate star pair is selected from a star catalog having a plurality of entries; estimating an inertial orientation of the first reference star sensor at least in part from the identified candidate star pair; and determining the spacecraft attitude from the estimated inertial orientation of the reference star sensor; wherein the step of determining the spacecraft attitude based on the orientation of the reference star sensor comprises the steps of: selecting a second reference star sensor from among the star sensors; designating two stars observed by the second reference star sensor as a second primary star pair; identifying a second candidate star pair selected from the star catalog corresponding to the primary star pair; estimating an inertial orientation of the second reference star sensor at least in part from the identified second candidate star pair; selecting at least one reference star sensor from the group consisting first reference star sensor and the second reference star sensor; and determining the spacecraft attitude from the selected reference star sensor and an orientation of the selected reference star sensor with respect to the spacecraft.