Exactly half a century ago this week, a rocket shot off from the California coast. It carried the U.S.’s first and only (known) space nuclear reactor, SNAP-10A, which has been circling the Earth ever since and will continue to circle for another 3,000 years.
Back in the 1960s, NASA ran a Systems for Nuclear Auxiliary Power (SNAP) program to study nuclear power’s potential in space exploration. This program sent up the first radioisotope thermoelectric generators, a technology still used in space probes like Voyager and Curiosity today. Radioisotope thermoelectric generators aren’t nuclear reactors, though. They simply harness the heat from a decaying element, such as plutonium-238.