Earth Satellites: Perturbations and Manoeuvres

Abstract

After a spacecraft has been placed in an operational orbit about the Earth, subsequent manoeuvres will be required, either to correct the orbit or as demanded by the mission, eg. in order to rendezvous with another vehicle. Correction of orbits becomes necessary as a result of perturbations from the non-spherical shape of the Earth, the influence of the Sun, the Moon and any residual atmosphere, although the latter is significant only at relatively low altitudes (below 100 km). This chapter includes an analysis of perturbations and the necessary corrective manoeuvres but geostationary orbits are treated separately because of their singular nature and tight tolerances.