Radioisotope Power Systems Program

NASA’s Radioisotope Power Systems Program develops energy technologies for spacecraft operating where sunlight is weak or unreliable. It works with the U.S. Department of Energy, which owns the nuclear material and power systems and directly manages their design and development. NASA Glenn manages the program; JPL supports mission analysis, thermoelectric technology and launch approval engineering. Radioisotope systems use heat from the natural decay of plutonium-238. RTGs convert part of that heat into electricity through thermocouples, while radioisotope heater units supply heat directly. The MMRTG powers Curiosity and Perseverance and provides about 110 watts of electricity at the beginning of a mission; that is electrical output, not total decay heat. The program also researches improved power-conversion technologies for future missions.