Plutonium 238
Plutonium-238 is a special material that emits steady heat due to its natural radioactive decay. Several unique features of plutonium-238 have made it the material of choice to help produce electrical power for spacecraft. The only radioisotope that has consistently met the basic criteria as a power source is plutonium-238, which has a half-life of 88 years, a high power density, and has proven to be a very dependable and safe heat source on more than two dozen U.S. space missions over the past 50 years. Plutonium-238 is expensive to make. One pound of plutonium-238 costs about $4 million to make. And that does not include the upfront investment needed to reestablish production of plutonium-238 in the United States, which is expected to cost as much as $150 million or more. While it may be expensive to make, the value of plutonium-238 is arguably so vast that it cannot be quantified economically. Plutonium-238 is the reason experiments deployed on the moon by the Apollo astronauts are still operating today. Deep space exploration missions like the New Horizons spacecraft that took the first close-up images of Pluto ever in July depend on plutonium-238's decay heat. There is no other known fuel source that can take humanity to the edge of the solar system and beyond. Indeed, the Voyager 1 spacecraft, the first object created by humans to leave the solar system, runs on the heat supply provided by plutonium-238’s radioactive decay. The Voyager, which departed Earth in 1977, is still sending scientific data back to scientists at NASA today. The world has nearly exhausted all available supplies of plutonium-238. In 2009, the National Research Council completed a study requested by Congress evaluating the options available for reestablishing domestic production of plutonium-238, which is also called 238Pu. Since 2011, Congress has provided funds to NASA to support the ability of the Department of Energy's Office of Nuclear Energy to resume U.S. domestic production of plutonium for civil space applications, using a series of specialized facilities, staff at the Oak Ridge National Laboratory (ORNL) and the Idaho National Laboratory (INL). New plutonium-238 production is part of a broader infrastructure at the Department of Energy that provides radioisotope power systems to NASA for use in space missions. Plutonium oxide is produced at Oak Ridge National Laboratory and shipped to Los Alamos National Laboratory (LANL) where it is turned into heat source pellets, which are then shipped to the Idaho National Laboratory to be placed into safe, long-term storage awaiting fueling of future radioisotope power systems there.
