Attitude acquisition methods and systems are provided which reduce the time generally required to acquire spacecraft attitude estimates and enhance the probability of realizing such estimates. The methods and systems receive, over a time span .DELTA.t, successive frames of star-sensor signals that correspond to successive stellar fields-of-view, estimate spacecraft rotation .DELTA.r throughout at least a portion of the time span .DELTA.t, and, in response to the spacecraft rotation .DELTA.r, process the star-sensor signals into a processed set of star-sensor signals that denote star positions across an expanded field-of-view that exceeds any of the successive fields-of-view. The expanded field-of-view facilitates identification of the stars that generated the processed set of star-sensor signals to thereby acquire an initial attitude estimate.
A system for, and method of recovering a solar-powered spacecraft from an anomaly that renders the attitude of the spacecraft unknown includes maintaining a power-safe attitude by switching between two orthogonal axes using solar panel current sensors. The system and method may also include simultaneously determining spacecraft attitude using a star sensor. The system is applicable to spacecraft operating in a solar wing-stowed configuration.
A method of determining the attitude of a spinning spacecraft is provided. The method includes stabilizing the spacecraft, initializing the attitude of the spacecraft using star tracker data, and estimating the attitude of the spacecraft.
A method and apparatus is disclosed for aligning an optical instrument with respect to a celestial coordinate system, the optical instrument having a field of view and an optical instrument coordinate system, the celestial coordinate system having a plurality of objects each having celestial coordinates. The method includes the steps of receiving a plurality of captured optical instrument positions in the optical instrument coordinate system along with a plurality of associated capture times; calculating, for each associated capture time in the plurality of associated capture times, coordinates in the optical instrument coordinate system for the plurality of objects to create a plurality of calculated object positions for each associated capture time; and, determining, for each associated capture time, a match for each captured optical instrument position in the plurality of captured optical instrument positions with the plurality of calculated object positions to create a list of actual alignment objects.
