Beginning in the late 1950s, the U.S. met this challenge by developing nuclear batteries known as radioisotope thermoelectric generators (RTGs) and producing plutonium-238 (Pu-238) as their fuel, ...
This, as he found out, isn’t something you should do lightly, as the one he used ended up containing an interesting mix of radioactive materials, including small amounts of plutonium-239 ...