Plutonium Shortage Could Stall Space Exploration npr

NASA is running out of the special kind of plutonium needed to power deep space probes, worrying planetary scientists who say the U. S. urgently needs to restart production of plutonium-238.
But it’s unclear whether Congress will provide the $30 million that the administration requested earlier this year for the Department of Energy to get a new program going.
Nuclear weapons use plutonium-239, but NASA depends on something quite different: plutonium-238. A marshmallow-sized pellet of plutonium-238, encased in metal, gives off a lot of heat.
“If you dim the lights a little bit, it glows a little red, because it’s very hot,” says Stephen Johnson, director of space nuclear systems and technologies at the Idaho National Laboratory.
All that heat can be converted into electricity. “And this electricity is very, very useful, when you’re in a remote or a hostile environment,” says Johnson, “such as when you’re in space and when you’re too far away from sun to use solar power.”