Orbit Maneuver for Responsive Coverage Using Electric Propulsion

The use of continuous electric propulsion to manipulate a satellite's orbit offers significant potential for enhancing coverage of a target in ways not previously considered. Elliptical orbits utilizing a very low perigee can facilitate access to the surface and atmosphere of the Earth at sub-ionosphere altitudes while counteracting atmospheric drag forces using continuous electric propulsion. Additionally, in-plane and out-of-plane manipulation of both circular and elliptical orbits can allow for passage of a satellite over a target at a given time. Sustained low perigee orbit was modeled with an initial perigee altitude of 100 km and various apogee altitudes to derive a range of apogee altitudes that could sustain the orbit. Operation was demonstrated for current as well as future thruster capabilities. To evaluate opportunities for a scheduled access, circular and various elliptical orbits were modeled using continuous thrust. It was found that electric propulsion was capable of improving potential temporal access of a target to 30% for circular orbits and nearly 70% for elliptical orbits Recommendations include further modeling of low perigee orbits and the effects of atmospheric variation at solar extremes on mission lifetime. Derivation of optimal thrust duration and angle could greatly enhance the performance of the thruster and warrants continued research. Finally, the use of responsive maneuver operationally will require development of a scheduling algorithm to plan passage over a given target at a given time.