Design of RTPV generators integrated with new millennium spacecraft for outer solar system

The National Aeronautics and Space Administration’s recently inaugurated New Millennium program, with its emphasis on miniaturized spacecraft, has generated interest in a low‐power (10‐ to 30‐watt), low‐mass, high‐efficiency RTPV (Radioisotope Thermophotovoltaic) power system. This led to a Department of Energy (DOE)‐sponsored design study of such a system, which was assigned to OSC (formerly Fairchild) personnel, who have been conducting similar studies of a 75‐watt RTPV system with very encouraging results. The 75‐watt design employed two 250‐watt General Purpose Heat Source (GPHS) modules that DOE had previously developed and safety‐qualified for various space missions. These modules were too large for the small RTPVs described in this paper. To minimize the need for new development and safety verification studies, OSC generated derivative designs for 125‐watt and 62.5‐watt heat source modules containing identical fuel pellets, clads, impact shell, and thermal insulation. OSC also generated a novel hea...