50 YA: SNAP 3

A significant milestone occurred 50 years ago: SNAP 3 was shown to President Eisenhower. It was a little 5-watt thermoelectric generator that used the energy delivered by radioactive isotopes. It was demonstrated as how to provide long-term electric power for space probes in the future. Of course, this then was the ancestor of the nuclear power generators used to power our deep space probes which cannot rely on weak solar power so far from the inner section of the Solar system.