Patent ID: 6917025

Claim:
A combined earth-star sensor system for three-axis attitude determination and orbit tracking of a satellite in space, said combined earth-star sensor system ( 1 ) comprising separate apertures (7,6) with different directions of observation of earth ( 14 ) and its rim ( 13 ) and stars to receive light from the earth ( 14 ) and stars ( 16 , 17 ), having respective levels of brightness and common image pickup devices ( 4 ) for the earth observation and the star observation, and an evaluation system for determining attitude and orbit of the satellite based on earth observation of the rim ( 13 ) of the earth ( 14 ) and star observations and wherein star observation is compared to a star catalog ( 20 ) and for star images ( 18 ) which are superimposed on an image of the rim of the earth ( 15 ), said image of the rim of the earth on which the star images are superimposed are disregarded to eliminate interference of the star images on accuracy of determining the rim ( 14 ) of the earth.