Longitudinal Station Keeping of Nearly Geostationary Satellites

An examination of the gravitational effects of the sun, moon, and triaxial earth upon the longitudinal motion of near-synchronous equatorial satellites. Accurate station-keeping of a nominally geosynchronous satellite requires the application of control forces to offset these gravitational effects. This study extends earlier RAND work, complementing latitude motion studies with a corresponding examination of longitude and radial motions. Control system activity, which includes average annual pulse and frequency of pulse application, is related to station-keeping accuracy. Radial and longitudinal perturbations are calculated. The results are particularly relevant to the station-keeping problems imposed by a growing number of satellites in synchronous near-equatorial orbits. The present investigation is restricted to satellites limited to small excursions by periodic applications of impulsive control forces. Large-scale motions are described in R-399 and R-454.