Optimal Low Thrust Orbit Transfer from GTO to Geosynchronous Orbit and Stationkeeping using Electric Propulsion system

Abstract

In present day Geo-synchronous (GEO) satellites with bi-propellant systems for apogee insertion and station keeping, the propellant requirement amounts to about half of the total mass of the satellite itself in Geo-synchronous Transfer Orbit (GTO). In this scenario, electric propulsion can reduce the propellant mass needed for station keeping substantially in exchange for significant use of electrical power. In addition to North South Station Keeping (NSSK), another attractive application of electric propulsion is for raising satellite into final GEO orbit from the initial orbit immediately after launch. The large savings in weight due to electric propulsion usage means significant saving in launch cost or alternatively substantial additional payload capability. In the context of possibilities outlined above, this paper presents optimal thrusting strategy for orbit transfer from GTO to Geo-Synchronous Orbit (GSO). Control law for optimal steering of thrust vector is derived using Gaussian variational equations. Numerical simulations are carried out by Cowell’s method and results obtained for the orbit transfer problem are presented and discussed in the paper. The station keeping strategy, including in-plane parameters also, in addition to the primary inclination control is developed and simulation results are presented.