Space Exploration

Radioisotope thermal generators (RTGs) are used in space missions. The heat generated by the decay of a radioactive source, often plutonium-238, is used to generate electricity.

The Voyager space probes, the Cassini mission to Saturn, the Galileo mission to Jupiter, and the New Horizons mission to Pluto are all powered by RTGs. The Spirit and Opportunity Mars rovers have used a mix of solar panels for electricity and RTGs for heat. The latest Mars rover, Curiosity, is much bigger and uses RTGs for heat and electricity as solar panels would not be able to supply enough electricity.