Future radioisotope power needs for missions to the Solar System

NASA is exploring many types of power source technologies. One discussed in this paper is a new high efficiency, low mass, energy converter to replace the present thermoelectric converter in the radioisotope thermoelectric generator (RTG). This new technology converter will allow the number of radioisotope-fueled heat sources and the mass to be reduced. NASA and DOE plan a cooperative team effort with industry, government laboratories and universities to develop a near term, low cost, low power (100 W electric class), low mass (<10 kg), advanced radioisotope space power source (ARPS) and in the process reduce the plutonium-related costs as well. The near term is focused on developing an advanced energy converter to use with the General Purpose Heat Source (GPHS). The GPHS was developed and used for the current radioisotope thermoelectric generators (RTGs). Advanced energy converter technologies are needed as a more efficient replacement for the existing thermoelectric converters so that the space radioisotope power source mass and cost can be reduced. NASA and DOE plan a cooperative team effort with Universities, Government Laboratories and Industry to develop technologies for a 100 mW electric class radioisotope power source and a 10 W electric class small radioisotope power source. This power source will be compatible with NASA's long term technology for low cost, low mass microspacecraft for the 21st century robotic space missions. This paper describes requirements for potential needs for three different sizes of space radioisotope power sources.