rover in the red deserts of mars

Radioisotope Power Systems

Space nuclear power to explore the deepest, dustiest, darkest, and most distant regions of our solar system and beyond.



Active Missions


Years in Service at NASA

Active Missions

Artist's rendition of NASA's Voyager spacecraft

45+ Years in Space

Artist's rendition of NASA's Voyager spacecraft

45+ Years in Space

Illustration of a gold spacecraft with a silver dish on the front floating in space

18+ Years in Space

MSL Curiosity Exhibit Poster

11+ Years on Mars

Mars Perseverance Rover

2+ Years on Mars

Radioisotope power systems—abbreviated RPS—are a type of nuclear energy technology that uses heat to produce electric power for operating spacecraft systems and science instruments. That heat is produced by the natural radioactive decay of plutonium-238.

Why Radioisotope Power Systems?

RPS Systems

From a Source of Heat Comes Power to Explore

Radioisotope Power Systems, or RPS, provide electricity and heat that can enable spacecraft to undertake scientific missions to environments beyond the capabilities of solar power, chemical batteries and fuel cells.

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A man in a cleanroom suit gives a thumbs up next to the New Horizons spacecraft in its launch vehicle.
Alan Stern with New Horizons in the Atlas V Vertical Integration Facility hangar just after RTG (Radioisotope Thermoelectric Generator) installation and arming on 13 Jan 2006. New Horizons is visible through the hatchway in the Atlas V nose fairing.

RPS Technology

Critical Technology for Exploration

Radioisotope Power Systems (RPS) offer the key advantage of operating continuously over long-duration space missions, largely independent of changes in sunlight, temperature, charged particle radiation, or surface conditions like thick clouds or dust.
Some of the excess heat produced by RPS can be used to enable spacecraft systems to operate in extremely cold environments.

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RTG cutaway diagram
Cutaway View of Cassini's RTGs.

RPS Missions

A Legacy of Exploration

Radioisotope Power Systems are not a new part of the U.S. space program. They have made historic contributions to the U.S. exploration of space for more than 60 years. RPS have enabled NASA's exploration of the solar system since the Apollo era of the late 1960s.

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A shiny spacecraft sits on a red-brown sandy surface. Sand dunes are shown rising high in the distance.
NASA’s Dragonfly is scheduled to launch in June of 2027 and arrive at Titan by 2034.
NASA/JHU-APL/Steve Gribben
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