The SNAP (Systems for Nuclear Auxiliary Power) are various nuclear systems that supply electrical power to various satellites, space probes, or isolated locations on our planet.
It was developed in the United States by the Atomic Energy Commission, which is now called the Nuclear Regulatory Commission, and NASA.
Most SNAP units have thermoelectric devices to generate an electrical voltage. These devices are put into operation when they are heated, in this case a disintegrating isotope which produces the necessary heat.
SNAPs have been used in space probes for missions such as Apollo (Moon), Viking (Mars), or Pioneer and Voyager (outer Solar System). Examples of their use within our planet are oceanic, climatic research stations or navigation beacons. SNAP-10A
The SNAP-10A was a fission reactor system for space. Built as a research project for the Air Force, to demonstrate the ability to generate more power than RTG. The reactor used two mobile beryllium reflectors for control, and generated 35 kW at first as soon as it became operational. The system generated electricity by circulating NaK around lead tellurium thermocouples. To mitigate the risks of the launch, the reactor started after reaching a safe orbit. It was launched from Earth orbit on April 3, 1965, and used to power the Agena-D research satellite, built by Lockheed Martin. The system produced 500W of electrical power during the short 43-day flight test period. The reactor was shut down prematurely by a defective control receiver. It is expected to remain in orbit for 4,000 years.
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