ATTITUDE DETERMINATION USING ANTENNA POLARIZATION ANGLES

The attitude of a satellite is normally determined from Earth sensors, horizon sensors, and a sun reference. This paper discusses an alternate method of attitude determination using polarization-angle measurements of the normally radiated plane polarized radio frequency (RF) signal from the spacecraft. Simultaneous polarization-angle data, taken at geographically separated locations, contain sufficient information to determine the inertial orientation of the signal polarization at the time of observation. An iterative method, using the sensitivity of polarization-angle measurements to the radiating antenna, is used to determine the orientation. Since the RF signal polarization with respect to the spacecraft body axes is known, the spacecraft attitude can be determined.