Plutonium-238 pellet
Plutonium-238 pellet. Credit: U.S. Department of Energy

WASHINGTON — Russia has reneged on an agreement to deliver a total of 10 kilograms of plutonium-238 to the United States in 2010 and 2011 and is insisting on a new deal for the costly material vital to NASA’s deep space exploration plans.

The move follows the U.S. Congress’ denial of President Barack Obama’s request for $30 million in 2010 to permit the Department of Energy to begin the painstaking process of restarting domestic production of plutonium-238. Bringing U.S. nuclear laboratories back on line to produce the isotope is expected to cost at least $150 million and take six years to seven years from the time funding is approved.

U.S. Rep. Adam Schiff (D-Calif.), a House Appropriations Committee member whose district is home to NASA’s planetary science-focused Jet Propulsion Laboratory, told Space News that Russia’s decision to withhold the promised plutonium is “certainly a concern” considering that the United States now will not be spending any money before 2011 to restart its own production.

“Certainly, among other things, it would have helped our negotiating posture had funding been included and Russia could see that we were determined to move forward on our own,” Schiff said.

NASA for decades has relied on plutonium-238 to fuel long-lasting spacecraft batteries known as radioisotope power systems that transform heat from the decaying plutonium into electricity. The Pluto-bound New Horizons probe was launched in 2006 with 11 kilograms of the material onboard, and the Mars Science Laboratory rover will carry 3.5 kilograms when it launches in late 2011.

The United States stopped producing plutonium-238 in the late 1980s. While U.S. nuclear laboratories remain able to process and package the material for use in radioisotope power systems, the Department of Energy has been meeting NASA’s demand from a dwindling stockpile supplemented by periodic purchases from Russia’s shrinking supply.

The Department of Energy would not say exactly how much plutonium-238 it has in inventory. But a National Research Council report released in May estimated that the amount available for NASA totals roughly 20 kilograms, about a fifth of which already has gone into the Mars Science Laboratory’s radioisotope power system. Radioisotope power systems are also used for unspecified national security purposes.

The same report, “Radioisotope Power Systems: An Imperative for Maintaining U.S. Leadership in Space Exploration,” said NASA needs about 30 kilograms of plutonium-238 for three planetary probes planned for launch by 2020. The most plutonium-hungry of those is a multibillion-dollar mission to Jupiter’s icy moon Europa. The flagship-class Jupiter Europa Orbiter requires 24.6 kilograms of plutonium-238 for the five Multi Mission Radioisotope Thermoelectric Generators (MMRTGs) that will generate 700 to 850 watts of electrical power during the orbiter’s anticipated 14 years of operations.

Jim Green, NASA’s director of planetary science, recently told scientists drafting the U.S. space agency’s next 10-year plan for robotic exploration of the solar system that the era of plutonium-powered missions could be coming to an end. He noted that not only had Congress denied Obama’s budget request for restarting plutonium-238 production, but that Russia’s Rosatom State Atomic Energy Corporation informed the Department of Energy this fall that it will not fulfill a 5-kilogram order of plutonium-238 that was expected to be delivered in 2010. Rosatom also said it would not accept a pending 5-kilogram order for delivery in 2011.

According to Green’s Nov. 16 presentation to the Planetary Science Decadal Survey steering group, the Energy Department expects that negotiating a new agreement could delay the next delivery of Russian plutonium-238 until after 2011.

Jen Stutsman, an Energy Department spokeswoman, confirmed that the department was notified in mid-September that Russia does not intend to fulfill the terms of its current contract and wants to negotiate a new deal. She told Space News in a Dec. 9 e-mail that the department is working with other U.S. government agencies “to develop a coordinated position on the appropriate next steps.”

Efforts to restart a domestic production capability, meanwhile, cannot proceed until Congress approves funding, she said.

Green told Space News in an interview that NASA is moving ahead on the assumption that the Energy Department will come through with the needed plutonium. “We are marching down a course in good faith with the Department of Energy to negotiate with the Russians to procure the plutonium that would provide what we need to the plan that we proposed,” he said.

Green said a one-year delay in the delivery of the Russian plutonium should not cause problems for NASA. If the first delivery is delayed much beyond 2011, however, mission schedules could suffer because U.S. labs need a few years to prepare, package and load the plutonium into a finished power system.

“We will get to some point down the road where indeed the plutonium readiness will be on the critical path,” Green said. “Once things are on the critical path, they affect schedule.”

Despite the uncertainty, NASA went ahead Dec. 7 with the release of a draft announcement of opportunity for Discovery 12, inviting planetary scientists to propose a $425 million mission that would launch by 2016 and utilize a NASA-furnished radioisotope power system. NASA also continues to work with scientists on a Jupiter Europa Orbiter instrument mix that assumes a 2020 launch of a spacecraft equipped with five fully fueled MMRTGs. Ralph McNutt, a planetary scientist who co-authored the National Research Council’s radioisotope power system report and serves on the decadal survey’s steering committee, said Russia’s actions underscore how important restarting U.S. production is to NASA’s planetary science plans.

“If you don’t do it, we are done. We are out of business,” he said.

NASA’s projected long-term requirements — which as of 2008 still included more than 50 kilograms for manned lunar missions planned through 2030 — far exceed what the United States can expect to buy from Russia.

Still, NASA needs the undelivered Russian plutonium to keep its planetary science plans on track. Without it, the Europa mission would have to wait until U.S. labs are brought back on line and producing sufficient quantities to make up for the Russian shortfall — a seven-year process that McNutt said cannot be significantly shortened even if the United States is willing to spend considerably more than $150 million on the effort.

“We’re talking about 10 times more money” to accelerate the process, McNutt said.

Without more plutonium, the only way NASA could fly the Europa mission would be to switch to more efficient — but not yet flight-proven — Advanced Stirling Radioisotope Generators (ASRGs).

Like MMRTGs, Stirling systems convert heat from decaying plutonium into electricity. Where the two technologies differ is that the Stirling system has moving parts — vibrating pistons that make four times more efficient use of the rare and costly isotope. An ASRG-powered Europa orbiter, therefore, probably could get by on 6 kilograms of plutonium, according to McNutt.

Several ASRG qualification units are undergoing longevity testing at NASA’s Glenn Research Center in Cleveland, and the company that built them, Denver-based Lockheed Martin Space Systems, is gearing up to produce two flight units in time for the planned 2016 launch of Discovery 12. Each ASRG weighs less than 30 kilograms and is capable of producing 140 watts of electricity from 0.88 kilograms of plutonium.

McNutt said most engineers would consider a 2016 flight demo way too late for NASA to prudently consider ASRGs for a Europa mission launching in 2020.

Green agreed. “We are not going to risk a multibillion-dollar flagship on technologies unproven,” he said. “We have a path which we are walking down to flight qualify the [ASRG] and we need to walk that path.”

Brian Berger is editor in chief of and the SpaceNews magazine. He joined in 1998, spending his first decade with the publication covering NASA. His reporting on the 2003 Space Shuttle Columbia accident was...