Plutonium-238 is critical to deep space exploration. The special isotope has powered missions that have enabled us to explore the atmosphere of Saturn, see the heart of Pluto and traverse the surface of Mars. But what if missions like those were no longer possible? That's a question NASA faced not so long ago as the U.S. was in short supply of the isotope. The decision was made to restart pu-238 production and Oak Ridge National Laboratory was the place to do it. In this episode you'll hear from the manager of the plutonium program, as well as from the team that makes the cladding to hold the fuel.