A rocket that carried the US's first space nuclear reactor shot off from the California coast 50 years ago. The first identified reactor, SNAP-10A, has been circling the Earth ever since and will continue to circle for yet another 3,000 years. The US space agency NASA ran a System for Nuclear Auxiliary Power (SNAP) plan to study possibility of using nuclear power in space exploration in the 1960s.

For the first time, radioisotope thermoelectric generators were sent up in space. These technologies are still used in today's space probes like Voyager and Curiosity.

The radioisotope thermoelectric generators aren't nuclear reactors. They simply harness the heat from a decaying element, such as plutonium-238. However, SNAP 10-A was a functioning reactor with a controlled fission reaction inside.

It contained enough uranium fuel to create up to 600 watts of energy for a year. It settled into orbit 500 kilometers above Earth twelve hours after takeoff on April 3, 1965. The reactor was remotely switched by mission team on Earth.

Initially, everything continued as per the plan. But electrical systems on the satellite carrying it failed after 43 days into the mission, causing the reactor to shut down. However, it is still up there orbiting and NASA is expecting to keep in orbit for an additional 3,000 years.

A NASA report said, "Six extra anomalous events occur in the subsequent six years, releasing almost 50 trackable pieces".

Release of radioactives is possible but not confirmed. Although these events have been not documented in additional detail, they might have integrated a collision.

NASA has considered using nuclear reactors in space, particularly the SP-100, in the 70s. But the plan was terminated due to funding troubles and safety issues.

Russia has sent dozens of satellites with nuclear reactors into space while the US has only SNAP-1oA. The Russia's most notorious satellites with nuclear reactor crashed and scattered radioactive debris all more than Canada in 1978.