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Casey DreierOctober 29, 2013

Power From the Isotopes

The United States is trying to generate plutonium fuel for the first time in 25 years. Will it succeed?

This feature was originally published in the September 2013 Equinox issue of The Planetary Report magazine, and only available for current members of the Planetary Society. The following is a brief sample. You can read the full article here.

When Curiosity roared into space in 2011, it carried with it a material so potent that the President of the United States had to approve the launch. This material, plutonium-238 (Pu-238), is used to generate power from a process of radioactive decay, and though it has been essential to nearly 30 missions in NASA's history, its future is in doubt. The United States hasn't generated Pu-238 since 1988. Existing supplies are nearly exhausted.

But after years of effort by hundreds of individuals throughout the government, the United States is on the cusp of producing Pu-238 again. It's a complex, expansive program requiring intricate coordination among multiple federal agencies, Congress, and the White House. It nearly did not survive its early political and budgetary battles. And though challenges lie ahead, NASA has quietly achieved its most important policy victory in decades.

Plutonium-238's Path around the United States

Loren Roberts for the Planetary Society

Plutonium-238's Path around the United States
The Department of Energy depends on three different national laboratories to create, store, and assemble radioisotope power sources for NASA. This graphic traces the circular journey of the Neptunium-237 starter product to the complete Radioisotope Thermoelectric Generator (RTG) containing Plutonium-238 fuel.


Secure facilities within Los Alamos National Laboratory, in Los Alamos, New Mexico, store the country's remaining supply of Pu-238. Exact amounts are not made public, but it's likely less than 30 kilograms (66 lbs.). These final, precious kilograms can only support a dwindling number of missions. NASA now faces a shortage so crippling that vast areas of our solar system will become inaccessible unless more plutonium is created soon...

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Read more: Explaining Policy, interview, Space Policy, RTGs, explaining technology, Plutonium-238

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Casey Dreier

Chief Advocate & Senior Space Policy Adviser for The Planetary Society
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