Over the past 25 years, the average cadence of National Aeronautics and Space Administration (NASA) missions that employ radioisotope thermoelectric generators (RTGs) or other radioisotope power systems (RPSs) is approximately one per decade. Currently, the only flight-qualified RPS in the NASA inventory for space power applications is the multi-mission RTG, which has a beginning-of-life (BOL) power output of approximately 120 W(electric). In addition, NASA and the U.S. Department of Energy also manage the Next Generation Radioisotope Thermoelectric Generator Development Project, with a projected BOL power of around 245 W(electric).

However, if a lower-power RPS unit was available, would there be sufficient mission pull to increase the cadence of RPS-powered missions? We believe the answer to this question is yes, which drove the evolution of a concept study that examines the feasibility of a low-power RPS based on a single general purpose heat source (GPHS) that could be developed rapidly with low risk and cost. This paper discusses the results of a concept study of an RPS system that utilizes novel ruggedized silicon germanium thermoelectric modules with a projected BOL power of 15 W(electric).

This new RTG design could help enable a new class of low-powered space exploration missions for NASA, the European Space Agency, or commercial applications. In addition, this paper addresses the next steps required to evolve the concept beyond its current status to conceptual design.