NASA's RHU-Heated and RTG-Powered Spacecraft

For more than six decades, radioisotope power systems (RPS) have played a critical role in the exploration of space, enabling missions of scientific discovery to destinations across the solar system. RPS-powered spacecraft have explored every planet in our solar system from Venus outward— including the weather systems of Earth—and the polar regions of the Sun, as well as Pluto and the Kuiper Belt. Several of these hardy robotic emissaries continue to probe the most distant fringes of our solar system, with Voyager 1 and 2 both having broken through to reach the eerie, empty vacuum of true interstellar space.