Confused-in-space stellar attitude acquisition using multiple star trackers

An apparatus for determining an attitude of a spacecraft having at least one star sensor, comprising the steps of:

• means for preparing for each star sensor, an associated star catalog having an entry describing star parameters for each star potentially observable by the star sensor from a priori spacecraft attitude-related information;
• means for determining a correlation between the star observations from each star sensor and the associated star catalog entries;
• means for selecting a reference star sensor using the correlation between the star observations and the associated catalog entries;
• and
• means for determining the spacecraft attitude from the reference star sensor star observations.

A program storage device, readable by a computer, tangibly embodying at least one program of instructions executable by the computer to perform method steps of determining an attitude of a spacecraft having at least one star sensor, the method steps comprising 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 from a priori attitude-related information;
• determining a correlation between the star observations from each star sensor and the associated star catalog entries;
• selecting a reference star sensor using the correlation between the star observations and the associated catalog entries;
• and
• determining the spacecraft attitude from the reference star sensor star observations.