The General-Purpose Heat Source Radioisotope Thermoelectric Generator: A Truly General-Purpose Space RTG

The General‐Purpose Heat Source Radioisotope Thermoelectric Generator (GPHS‐RTG) was developed for the originally planned International Solar Polar Mission (ISPM). [ISPM would later, with the elimination of the NASA spacecraft, become the Ulysses mission.] At 300 We beginning‐of‐life (BOL) power, the GPHS‐RTG was the most powerful RTG with the highest specific power (5.3 We/kg) of any space RTG. These improved performance attributes of the GPHS‐RTG made it attractive for use on the Galileo mission. Subsequently, the GPHS‐RTG was selected to power the Cassini spacecraft, which is currently orbiting Saturn, and the New Horizons spacecraft which is on its way to Pluto. Truly, the GPHS‐RTG is a "general‐purpose" space RTG.