NASA Developing Longer-Lasting Nuclear Battery for Space Exploration

Americium-241 isotope could power spacecraft for centuries, revolutionizing deep space missions.

Mar. 27, 2026 at 2:48pm

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NASA and the University of Leicester are collaborating on developing a new radioisotope power system (RPS) that uses the americium-241 isotope instead of the previously used plutonium-238. Americium-241 has a half-life of 433 years, significantly longer than plutonium-238's 88 years, allowing spacecraft to operate for much longer durations on deep space missions.

Why it matters

The development of this longer-lasting nuclear battery could enable spacecraft to travel farther into the unknown reaches of space, unlocking new frontiers for exploration. Plutonium-238 has been the go-to fuel for RPS systems, but its relatively short half-life has limited the lifespan of past and current space missions. Americium-241 represents a major breakthrough that could revolutionize deep space exploration.

The details

The new RPS system being developed by NASA and the University of Leicester uses the americium-241 isotope, which has a half-life of almost 433 years, compared to plutonium-238's 88 years. This allows the nuclear battery to continue generating power for centuries, far outlasting previous RPS systems. The americium fuel is also designed to be nontoxic and insoluble, meeting NASA's strict safety requirements for use in spacecraft. The team is also exploring the use of free-piston Stirling convertors, which can more efficiently generate electricity from the radioactive fuel in microgravity environments.

  • In January 2025, NASA's Glenn Research Center and the University of Leicester agreed to test-drive the use of americium-241 in RPS systems.
  • In 2020, a free-piston Stirling convertor running on RPS at Glenn reached 14 years of maintenance-free operation, meeting the mission duration requirement for outer planetary missions.

The players

NASA

The U.S. National Aeronautics and Space Administration, the government agency responsible for the civilian space program, aeronautics, and space research.

University of Leicester

A public research university located in Leicester, England, that is collaborating with NASA on the development of the new americium-241 RPS system.

Wayne Wong

Chief of the Thermal Energy Conversion Branch at NASA's Glenn Research Center.

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What they’re saying

“This new milestone is particularly significant. Previous flight projects determined that the mission duration requirement for RPS is 14 years, particularly for outer planetary missions with long cruise times.”

— Wayne Wong, Chief of Thermal Energy Conversion Branch, NASA Glenn Research Center

What’s next

NASA and the University of Leicester will continue testing and developing the americium-241 RPS system, with the goal of incorporating it into future deep space exploration missions that require power sources with exceptionally long lifespans.

The takeaway

The development of an americium-241 nuclear battery that can power spacecraft for centuries represents a major breakthrough in space exploration, unlocking the potential for missions to venture farther into the unknown reaches of the cosmos than ever before.