A look at the Soviet space nuclear power program

For the most part Soviet nuclear power sources have been low-power nuclear reactors using a thermoelectric conversion principle. Recently the Soviet Union has flown two satellites using a higher power reactor that employs a thermionic conversion system. Despite reentry of two of the earlier reactors on board Cosmos 954 and Cosmos 1402 and the recent potential accident involving Cosmos 1900, the evidence points toward a continued Soviet use of nuclear power sources in space. Information in the open literature on the Soviet space nuclear power program, including the Romashka Topaz, the new reactor based on the Topaz program, and the RORSAT reactor experience, is summarized.