Researchers have tested a small prototype of a nuclear-reactor engine design that could one day power deep-space exploration probes.
The proposed design is based on a Stirling engine – an engine first invented in the 19th century that uses hot pressurized gas to push a piston. It would use a 50-pound nuclear uranium battery to generate heat that is then carried to eight Stirling engines to produce about 500 watts of power.
Scientists at NASA's Glenn Research Center and Los Alamos National Laboratory have tested a pared-down prototype of this design using a small nuclear source and a single Stirling engine that produced about 24 watts of energy. Most deep-space probes require about 600 to 700 watts of power, so it will still be a while before this early test produces something capable of powering a spacecraft. This is the first test of a nuclear reactor system to power a spacecraft conducted in the U.S. since 1965.
Nuclear engines are important because they make possible exploration of the entire solar system. Beyond Mars, sunlight is so weak that solar panels would have to be football-field-sized in order to eke out enough power to run a spacecraft and transmit data back to Earth.
