Orbital Regression of Synchronous Satellites Due to the Combined Gravitational Effects of the Sun, the Moon, and the Oblate Earth
Jan 1, 1967
A special slide rule for solving geometric problems related to synchronous satellites is included in this Memorandum, which supplements the information printed on the slide rule and documents the mathematical background. Among the problems of interest are those of the earth area coverage from synchronous satellites in circular, near equatorial orbits; the earth station antenna direction (elevation and azimuth) for receiving satellite communications; and the accuracy with which a synchronous satellite with multiple beams of fixed relative orientation can track earth points by attitude variations. R-454-NASA showed that angular deviations are not a problem at an inclination of 7 deg 20 min to the equatorial plane. Most communication satellites need not be designed for greater inclinations, and unless beamwidths narrower than a few degrees are considered, angular deviation can be ignored.