What is 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 more than two-dozen U.S. space missions that have been enabled by radioisotope power systems (RPS).
Plutonium-238 (abbreviated as Pu-238) was selected as the heat source to power these missions by the Department of Energy (DOE), which develops and provides RPS to NASA for use in space exploration. This unique material has been used to create electricity for a wide variety of spacecraft and hardware, from the science experiments deployed on the Moon by the Apollo astronauts to durable robotic explorers, such as the Curiosity Mars rover and the Voyager 1 and 2 spacecraft, which are at the edge of the solar system.