page_title: Nuclear power in space
section_title: Visuals
hierarchical_section_title: Nuclear power in space / Visuals
caption_attribution_description: English: The world's first nuclear reactor power plant to operate in space, SNAP 10A, was launched into Earth orbit on April 3, 1965.
context_page_description: Nuclear power in space is the use of nuclear power in outer space, typically either small fission systems or radioactive decay for electricity or heat. Another use is for scientific observation, as in a Mössbauer spectrometer. The most common type is a radioisotope thermoelectric generator, which has been used on many space probes and on crewed lunar missions. Small fission reactors for Earth observation satellites, such as the TOPAZ nuclear reactor, have also been flown. A radioisotope heater unit is powered by radioactive decay and can keep components from becoming too cold to function, potentially over a span of decades.
  The United States tested the SNAP-10A nuclear reactor in space for 43 days in 1965, with the next test of a nuclear reactor power system intended for space use occurring on 13 September 2012 with the Demonstration Using Flattop Fission test of the Kilopower reactor.
  After a ground-based test of the experimental 1965 Romashka reactor, which used uranium and direct thermoelectric conversion to electricity, the USSR sent about 40 nuclear-electric satellites into space, mostly powered by the BES-5 reactor.
caption: SNAP-10A Space Nuclear Power Plant, shown here in tests on the Earth, launched into orbit in the 1960s.
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