Optimal Control based Time Optimal Low Thrust Orbit Raising

ABSTRACT In the last few decades, electric propulsion systems have found use in science missions conducted by NASA, JAXA, and the ESA. [2] electric propulsion systems, such as an ion engine, are attractive options in mission design due to their high total DV to propellant mass ratios. Introductory material in orbital mechanics generally approaches orbital maneuvering with the assumption that maneuvers are performed by a spacecraft with high thrust propulsive capability. Orbit transfer techniques, including the Hohmann transfer, and Bi-Elliptic transfer, maintain the high thrust propulsion assumption by assuming that their orbit transfer maneuvers can be modeled as being impulsive in nature. Although, the approximation of high thrust DV manoeuvres are reasonable for spacecraft that performs its orbit transfer maneuvers with a chemical propulsion system, it fails to accurately approximate the behavior of a spacecraft that uses low thrust propulsion technology and continuous firing to maneuver from one orbit to another. In particular, although the Hohmann and Bi-Elliptic transfer techniques offer optimal orbit transfers assuming impulsive maneuvering, their assumptions entirely preclude their application to spacecraft using electric propulsion systems. This research investigates optimal control solutions to the continuous firing, low thrust orbit raising problem. Keywords: Low Thrust, Optimal Control, Orbit Raising, Hohmann Transfer.