Attitude determination and prediction of spin-stabilized satellites

Techniques for both attitude determination and prediction for spin-stabilized satellites are developed. Their use is demonstrated using Telstar I and II satellite data. It is shown that an inclined dipole model of the earth's magnetic field and the method of averaging the gravitational and magnetic torques over each anomalistic period of the satellite permits attitude predictions to within a few tenths of a degree of determined values in most instances. In those few cases where departures are above one degree, explanations are presented to show the reason for such discrepancies. The usefulness of combining optical flash and solar sensor data for attitude determination and their inherent accuracy are demonstrated. Optical flash data can provide loci with a resolution of 0.1°. Solar sensor loci are resolved to within 1°. All techniques described have been consolidated into working computer programs which follow closely the mathematical analysis presented. A number of important supporting calculations such as the solar position, sidereal time, orbit updating, etc. are also developed. Because of the complexities of the mean torque and gyroscopic equations, the precessional techniques presented are most useful in computer embodiments.