Updated Feb. 4, 2014
This 3D animation shows the main components of the Advance Stirling Radioisotope Generator - a different type of radioisotope generator that was previously considered by NASA to provide power for some missions that explore the solar system. Although the ASRG is no longer in development for flight at this time, NASA continues to study Stirling converter technology for potential use on future space missions.
Inside the device, a moving piston would be driven by a difference in temperature between the heat of a nuclear fuel source and the coldness of space or a planetary atmosphere. The piston would move a magnet back and forth through a coil of wire more than 100 times per second to generate electrical current in the wire. To prevent physical wear, the piston would be suspended in a helium gas bearing, meaning it would not actually touch the inside of the mechanism.
More about NASA Stirling technology development >