Radioisotope Low-Power Electric Propulsion Missions to the Outer Planets

Abstract

The feasibility of outer planetary missions is strongly dependent on acceptable trip times and the availability of an adequate power source not reliant on the Sun. A Radioisotope Thermoelectric Generator, which is frequently included for power generation purposes, can also provide a viable option for propulsion when coupled with an Electric Propulsion system during the transfer phase. This paper describes a parametric study into the advantages of such a Radioisotope Thermoelectric Generator - Electric Propulsion combination for a possible future mission to the outer planets. Three dierent transfer strategies have been evaluated, including one case with a complete planetary capture. The importance of evaluating planetary capture and the inward spiraling trajectory to the operational orbit, is demonstrated by the significantly larger propellant mass requirements. With the inclusion of a capture the transfer feasibility is even more critically dependent on launcher performance for a given spacecraft mass. The advantages and disadvantages of such strategies within the envelope of defined control parameters and constraints are discussed for dierent destination planets and transfer strategies. The current study has demonstrated the feasibility of an RTG-EP strategy for outer planetary missions.