The Russians have been more aggressive than the United States in sending nuclear reactors into space, having launched thirty-one between 1967 and 1988. The three reactor accidents the Russian space program has experienced have probably caused much more environmental contamination than any RTG incident. One of the re- actor accidents occurred during a launch failure and two when reactor- powered radar satellites were not boosted to suitable orbits. The reactor aboard Kosmos 954 contaminated a broad area of Canada's Northwest Territories when it burned up on reentry in 1978. Kosmos 1402 suffered a similar fate after it was launched in late 1982. According to NASA, "The reactor core separated from the remainder of the spacecraft and was the last piece

of the satellite to return to Earth in February 1983. The reactor core returned in the South Atlantic Ocean, leaving a radioactive trail through the atmosphere."

Nuclear Accidents in Space