NASA requires plutonium-238 for radioisotope power systems for spacecrafts. Plutonium-238 was a by-product of now defunct Cold War–era nuclear weapon factories.<p>Oak Ridge National Laboratory produced a 50-gram sample in late 2015—the first since 1988. This year, having refined the process, the lab expects 300 grams. They want to ramp up to 1.5 kilograms per year.