A passive system for determining the attitude of a satellite

The system is based upon measurements of the direction cosines of two linearly independent vectors. The necessary measurements are performed in a satellitefixed coordinate system and telemetered to a ground station. Knowledge of the satellite position (obtained from independent measurements) can then be used together with the telemetered results to compute the attitude matrix for the satellite. A system designed and successfully implemented in the 1963 22A satellite is described. Some results are given. (Author)