For spacecraft, you really can’t beat the efficiency and simplicity of a nuclear power supply. From the Pioneer probes to the Mars rover Curiosity, a nuclear battery allows a slow drip of electricity where solar power would be impractical or impossible, and fuel cells or other batteries would drain. But radioisotope thermoelectric generators, as these are called, give a spacecraft about a household light bulb’s worth of juice--and they need plutonium-238, an unstable and hard-to-obtain isotope.
The nuclear engineering wizards at Los Alamos National Laboratory have an alternative: Uranium-powered nuclear fission reactors that convert heat into electricity.
Scientists tested a new heat-pipe-based nuclear reactor in a test called DUFF, for Demonstration Using Flattop Fissions, in an experiment near Las Vegas recently. It’s the first demonstration of a space nuclear reactor system to produce electricity in the U.S. since 1965, according to LANL.