In papers presented at last year’s conference, the authors described an integrated Radioisotope Thermophotovoltaic (RTPV) power system design study they had conducted for the U.S. Department of Energy, and examined the system’s applicability to an illustrative space mission to Pluto. The power system employed previously flown and safety‐qualified radioisotope heat source modules, radiating their heat to gallium antimonide photovoltaic cells covered with spectrally selective infrared filters. ©1996 American Institute of Physics.