The SNAP-27 Radioisotope Thermoelectric Generator (RTG) converted the heat energy from radioactive decay to electrical energy. Five such RTGs provided electric power for the Apollo Lunar Surface Experiment Packages (ALSEP) left on the Moon by Apollos 12, 14, 15, 16 and 17.
Image Number: WEB13241-2013
Credit: National Air and Space Museum, Smithsonian Institution
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