Diagram of an Advanced Stirling Radioisotope Generator. Credit: U.S. Department of Energy
Two of the robotic missions NASA selected for further study last week would be powered by experimental nuclear generators. NASA picked robotic missions to Mars, a comet and Saturn’s moon Titan as finalists last week for a launch opportunity in 2016, and two of the probes would employ a cutting edge nuclear power source never tested in space. Probes to Titan and comet Wirtanen, a small object composed of a mix of rock and ice, would be powered by Advanced Stirling Radioisotope Generators on their journeys into the outer solar system. The nuclear power units, called ASRGs, use less plutonium than existing generators.
Unlike Radioisotope Thermoelectric Generators, which have powered satellites and probes for nearly 50 years, the ASRG has the added complexity of moving parts.
But each ASRG creates between 130 and 140 watts of electricity with 1 kilogram, or about 2.2 pounds, of plutonium-238. More than four times more plutonium would be required to generate the same power in an existing RTG