Other fuels are possible, however Plutonium 238 is preferred for these purposes for a number of reasons: http://en.wikipedia.org/wiki/Radioisotope_thermoelectri

Other fuels are possible, however Plutonium 238 is preferred for these purposes for a number of reasons: http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#Fuels http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_gen...