WASHINGTON — For the third time in as many years, the U.S. Department of Energy (DoE) and NASA are asking Congress to fund a multiyear effort to re-establish a domestic capability to produce plutonium-238, a vital power source for certain deep space missions.
President Barack Obama’s 2012 spending request, delivered Feb. 14 to Capitol Hill, includes $20 million for the plutonium-238 (Pu-238) restart effort, with the funds evenly divided between the NASA and Department of Energy budgets.
The effort, which would be managed by the Department of Energy’s Space and Defense Infrastructure program, aims to re-establish the United States’ capability to fabricate neptunium-237 targets, irradiate the targets in existing U.S. nuclear reactors, and recover the resulting plutonium-238. The work would be performed at the Idaho National Laboratory’s Advanced Test Reactor and the Oak Ridge National Laboratory’s High Flux Isotope Reactor in Tennessee.
Congress in 2009 rejected Obama’s first call for money to restart Pu-238 production and demanded more details on the project, including NASA’s financial contribution to the effort.
The following year, Obama proposed that NASA and the Department of Energy split the estimated $150 million cost to re-establish production and asked Congress for a combined $30 billion for 2011 to move forward on a job expected to take six or seven years to complete. U.S. lawmakers included the funding in spending legislation they drafted last year but never enacted, leaving the project unfunded for now.
A senior NASA official said March 1 that the agency’s Pu-238 requirements are the same as they were last year, even though NASA’s Planetary Sciences Division — the space agency’s biggest consumer of the material — is now anticipating a steadily shrinking budget for the five years ahead.
In a 2010 report to Congress, NASA estimated needing a total of 37.4 kilograms of Pu-238 to support nine missions planned or envisioned through 2030; one of those missions — a “Major Outer Planets Mission” targeted for launch between 2020 and 2024 — accounted for more than half that demand.
“There has been no change in NASA’s need for plutonium-238 since the release last year of the President’s [2011] budget request,” W. James Adams, deputy director of NASA’s Planetary Science Division, said in a statement. “We continue to work with the Department of Energy to prepare for a domestic production rate of 1.5 kilograms per year.”
NASA has flown some two dozen space missions since the 1960s that relied on plutonium-fueled radioisotope power systems to run on-board electronics and provide heat. The agency’s Mars Science Laboratory, a car-sized rover slated to launch in November, will carry 3.5 kilograms of the material to the red planet.
The United States stopped producing plutonium-238 in the late 1980s when it shut down the Department of Energy’s Savannah River Site. The department has been meeting NASA’s demand for years from a dwindling U.S. stockpile supplemented by periodic purchases from Russia’s shrinking supply, as it last did in December 2008.
In 2009, however, the Russian government reneged on an agreement to deliver a total of 10 kilograms of Pu-238 in 2010 and 2011, insisting on a new deal before resuming deliveries.
The Department of Energy told Space News it expects to begin formal contract negotiations this year.
“The Department of Energy met in October 2010 with Rosatom, the Russian government organization in charge of Pu-238 sales, to agree on basic terms for proceeding with a new contract. One of the terms was for Rosatom to assign an export agent who would be responsible for future sales of Pu-238. The Department of Energy is in the process of closing out its existing contract and will be entering into contract discussions with a new agent in the coming months,” the department said March 2 in a statement.
“The timing of a future purchase will depend on the length of time to negotiate a new contract and the length of time it will take the Russian organization to process and package the material to meet specifications,” the statement said. “A preliminary estimate of when a next delivery of material could occur is no earlier than calendar year 2013. A more firm expectation can be established once contract negotiations are complete.”
Meanwhile, NASA and the Department of Energy both requested 2012 funding to continue development of the Advanced Stirling Radioisotope Generator (ASRG), a next-generation design that is four times more efficient than the radioisotope power system aboard the Mars Science Laboratory.
To encourage the first in-space use of the new power system, NASA told scientists submitting proposals last year for the Discovery program of competitively selected planetary missions that they could use a Stirling generator essentially for free — the hardware would be paid for by NASA outside of the selected mission’s $425 million cost cap.
Adams said that offer still stands.
“If an ASRG is needed to achieve the science objectives of the selections made for this mission, we are prepared to fly them,” he said.
NASA plans to select multiple Discovery proposals by October for mission concept studies leading to a final down-select in 2012. The selected mission must be ready to launch before the end of 2017.
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