Radioisotope thermoelectric generator

A radioisotope thermoelectric generator (or RTG) is a type of machine that uses heat from radioactive decay to make electricity. The RTG, powered by a radioisotope heater unit, is used in satellites and sometimes in other remote unmanned systems.

Radioisotope Thermoelectric Generator Media

Diagram of an RTG used on the Cassini probe
90Sr-powered Soviet RTGs in dilapidated condition.
Diagram of a stack of general purpose heat source modules as used in RTGs
A SNAP-27 RTG deployed by the astronauts of Apollo 14 identical to the one lost in the reentry of Apollo 13

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