Comparing Solar and Radioisotope Power Systems for Interplanetary Space Missions

Abstract

Using a solar power system for most deep space missions is not as attractive as previous published studies have led readers to believe. While improvements in solar power system technology continue to expand the applicability of solar power to missions to regions of the solar system that farther away from the sun, there are still many scientifically desirable deep space and planetary surface missions that must have radioisotope power systems to be feasible. A process is presented in this paper that will allow a designer or technologist to perform an accurate comparison of solar and nuclear power system alternatives at the system and mission level. The process includes comparison of power system performance, plus comparison of the impact of the alternative power systems on the rest of the system/mission. Impacts on subsystems including attitude control and thermal management, plus impact to the launch vehicle selection are discussed. While there will always be some subjective elements of a comparison of alternate power system technologies, the process described here will produce a valid comparison in terms of quantitative parameters, such as system mass and mission cost.