A spacecraft generator using the radioactive element plutonium to provide electricity. This is especially useful when a space probe travels far from the Sun where solar arrays cannot be used for power. RTGs are on the Galileo and Cassini spacecraft. An RTG contains several kilograms of an isotopic mixture of plutonium in a ceramic fuel pellet. Radioactive decay produces heat to generate electricity, and waste heat is radiated into space. RTGs are designed to survive a launch accident without releasing plutonium.
Each launch must undergo a stringent safety analysis by the US Department of Energy and be approved by the US president.
Subjects: Astronomy and Astrophysics.