General-purpose heat source

Each module has a temperature of over 600 degrees Celsius[citation needed] and delivers 250 watts at the time of manufacture.

GPHSs are designed with safety in mind and employ iridium-clad plutonium-238 dioxide pellets.

The pellets are encased within nested layers of carbon-based material and placed within an aeroshell housing to comprise the complete module.

The modules can withstand extreme conditions including a launch-pad explosion or a high-speed reentry.

They are used in the multi-mission radioisotope thermoelectric generator, as used by Mars Science Laboratory (Curiosity rover).