"Plutonium 238." . . "NASA programs." . . "Radioisotope heat sources." . . "Americium 241." . . "Stirling cycle." . . "Lunar surface." . . "Thermoelectric generators." . . . . "International Energy Conversion Engineering Conference (7th : 2009 : Denver, Colo.)" . . . . . . . . . . . . "Lunar Surface Stirling power systems using isotope heat sources" . . . . . . . .