Optimal station-change maneuver for geostationary satellites using constant low thrust

Abstract

An electric propulsion system supplying constant low thrust can perform station-change maneuvers for geostationary orbits with significantly lower fuel costs than conventional propulsion systems. Using traditional optimalcontrol techniques, this paper develops a thrust-angle profile that improves upon the tangential-thrust profile originally suggested by Edelbaum for this problem. The optimal-control method ensures that the final orbit has zero eccentricity while achieving a rate of relocation that is essentially identical to the rate achieved by the tangentialthrust method. This reduction in eccentricity eliminates daily oscillations in the station of the relocated satellite. The proposed method generates the optimal-control profile using a spherical gravitational model with constant thrust and constant mass flow rate to describe the dynamics during the transfer. Simulations show that the eccentricity buildup depends on the level of acceleration, and that it can be reduced by up to three orders in magnitude using one common electric propulsion system. A comparison of station-change maneuvers using electric propulsion systems versus conventional chemical propulsion systems is included to emphasize the stationing flexibility that would be available to communications satellites using an electric propulsion system.