Overview

For over 45 year the Department of Energy and its predecessor agencies have been deeply involved in space research and exploration. Currently, the Space and Defense Power Systems program supplies Radioisotope Power Systems (RPS) to the National Aeronautics and Space Administration for missions that are beyond the capabilities of fuel cells, solar power and battery power supplies.

In the mid-1950s, research began on ways to harness nuclear power in space either through fission or natural radioactive decay. The efforts resulted in the first RPS for space applications, a Radioisotope Thermo-electric Generator (RTG). RTGs convert the heat generated from the natural decay of radioactive fuel into electricity. This conversion requires no moving parts and relies on special materials that can transform heat to electricity (thermo-electric effect). The first RTGs were low power and designed to supplement a spacecraft’s primary non-nuclear power supply. As the technology within the RTG advanced, they soon began to supply the power for the entire spacecraft and were the primary source of power for long duration deep space missions.

Today, RPS- powered spacecraft are limited only by the imagination. They have been landed on Mars and the Moon, are orbiting the Earth and Sun, are exploring the outer planets and are nearing the edge of the sun’s influence in our solar system. RPS are providing the power that enables us to see and learn about the farthermost objects in solar system and beyond.

The mission of the Space and Defense Power Systems program is to guarantee that the capability to produce Radioisotope Power Systems is maintained and to ensure the systems are available when they are needed.