Satellite attitude sensor

A zero-seeking optical sensor for an earth satellite reproduces two opposite edges of the earth on a receiver 7. The radiation incident within the respective fields of vision 8a and 8b or 12a and 12b on the receiver 7 are measured, and any displacement of the satellite from a reference attitude can be determined from the difference in radiation energies. In order to be able to determine the attitude of the satellite at different heights, the optical position sensor 6 has mirrors 11 which vary the fields of vision from 8a, 8b to 12a, 12b so that opposite edges of the earth are always observed. ...