In 1965, the United States launched SNAP 10-A into space from Vandenberg Air Force Base. SNAP 10-A is the only nuclear fission satellite launched into space by the United States. It was designed as an experimental nuclear spacecraft capable of producing 500 watts of electrical power. Its primary purpose was to monitor how nuclear fission reactors behave in space.
Unfortunately, the nuclear reactor worked for only 43 days, and then the power supply’s voltage regulator failed. The satellite started to fall apart in the late 1970s, and approximately 50 pieces of debris have been created as a result.
During this shedding process, it was very likely that some radioactive material was released into space. The nuclear reactor currently orbits the Earth at 700 nautical miles above the surface. It will remain in orbit for the next 4,000 years unless additional shedding or a collision with another object shortens its orbital life.