This story was updated at 4:15 p.m.EST, March 7.
NASA is facing the prospect of tryingto explore deep space without the aidof the long-lasting nuclear batteries it has relied upon for decades to sendspacecraft to destinations where sunlight is in short supply.
NASA Administrator Mike Griffin tolda House Appropriations subcommittee March 5 that the U.S. inventory ofplutonium-238 - the radioactive material essential for building long-lastingbatteries known to the experts as radioisotopepower systems - is running out quickly.
“Looking ahead, plutonium is inshort supply,” Griffin told lawmakers during the first of two days of hearingson the U.S. space agency’s 2009 budget request.
Griffin was asked about theplutonium-238 situation by Rep. Adam Schiff (D-Calif.). The Pasadena-areacongressman’s district is home to the Jet Propulsion Laboratory - theNASA-funded facility building the space agency’s next nuclear-poweredspacecraft, the 2009 Mars ScienceLaboratory, or MSL.
“After MSL launches, we’re prettymuch out of plutonium,” Griffin said.
The United States stopped producingplutonium-238 in 1988 and since then has relied upon a dwindling stockpilesupplemented since 1992 by periodic purchases of the material from Russia.
NASA’s Pluto-boundNew Horizons spacecraft, for example, is powered by a radioisotope powersystem fueled by Russian plutonium, as will be the system that powers the MarsScience Laboratory.
Though Griffin did not mention it,the U.S. Department of Energy over the winter quietly shelved long-standingplans to resume domestic production of plutonium-238. In 2005, the Departmentof Energy (DOE) gave public notice of its intent to consolidate the nation’sradioisotope power system activities at Idaho National Laboratory and startproducing plutonium-238 there by 2011.
Restarting production was projectedat the time to cost $250 million and take five years. Griffin said during thehearing that the DOE’s latest estimate is that a restart would take sevenyears.
Angela Hill, an Energy Departmentspokeswoman, told Space News in an e-mail that those plans are now onhold. “DOE did not request funding in 2009 for [Plutonium-238] production, since NASA has beendirected to fund any new production capabilities,” Hill wrote. “Productionmay or may not resume based on NASA’s decision. Based on current mission plans,DOE will only continue to provide new Radioisotope Power Systems until 2015.”
NASA’s 2009 budget request includesno money for re-establishing the Department of Energy’s long dormantplutonium-238 production capability.
Meanwhile, how much of theplutonium-238 the United States has at its disposal was not immediately clear.DOE reported in 2005 that its inventory stood at 39.5 kilograms, with U.S.national security customers and NASA expected to consume all but 6.5 kilogramsby 2010. The same report said an additional 20 kilograms of weakenedplutonium-238 could be harvested by 2011 from milliwatt power systems aboardold nuclear missiles slated to be decommissioned. However, the reclaimed material would have tobe mixed with fresher stock to be useable.
U.S. industry sources said they hadbeen told that the United States has a total of just over 11 kilograms on orderto meet NASA’s projected demand through the middle of the next decade.
Hill said only that the UnitedStates has received an additional 5 kilograms of plutonium-238 from Russiasince 2005 and has another 4.9 kilograms on order for delivery this year.
Alan Stern, NASA associateadministrator for science, testifying before the House Appropriations commerce,justice, science subcommittee alongside Griffin, said he believed the UnitedStates had sufficient plutonium-238 on hand or on order to fuel next year’sMars Science Lab, an outer planets flagship mission targeted for 2017 and aDiscovery-class mission slated to fly a couple years earlier to test a moreefficient radioisotope power system that NASA and the Energy Department have in development.
To help ensure there is enoughplutonium-238 for those missions, NASA notified scientists in January that itsnext New Frontiers solicitation, due out in June, will seek only missions thatdo not require a nuclear power source. Industry sources said that limitationwill put scientists wishing to propose outer-planet destinations includingJupiter and Saturn for the 2016 New Frontiers flightopportunity at a decided disadvantage.
“In the future, in some future yearnot too far from now, we will have used the last U.S. kilogram ofplutonium-238,” Griffin said. “And if we want more plutonium-238 we will haveto buy it from Russia.”
Griffin, who has said many timesthat he finds it “unseemly” that the United States may have to depend entirelyon Russia to access the space station between the space shuttle’s retirement in2010 and the introduction several years later of the Orion Crew ExplorationVehicle or a commercial alternative, made clear he was no more pleased with theprospect of relying entirely on Russia for flying space missions requiringnuclear power sources.
“I think it’s appalling,” he said.
But even the Russian supply mightnot last for much longer.
When the hearing resumed March 6,Griffin told lawmakers Russia has advised the United States “that they are downto their last 10 kilograms of plutonium.”
“We are now foreseeing the end ofthat Russian line,” he said.
Griffin also clarified that NASA hasbeen assured of enough plutonium-238 to do the MSL, a 2013 or 2014Discovery-class mission and an outer-planets flagship mission targeted for 2016or 2017.
“When those missions are allocated,we have no more,” he said.
Griffin said absent a nationaldecision to restart production, NASA’s planetary science program “would beseverely hampered.”
John Logsdon, executive director ofthe Space Policy Institute at George Washington University here, said notrestarting plutonium-238 production puts the U.S. space program in anundesirable position of vulnerability.
“The major risk is political,”Logsdon said. “It begs the question whether Russia is a reliable enough source,under plausible future political scenarios, that we can count on it.”
Logsdon said the United States also could find itself paying dearly for Russia’s remaining supply.
“Anymonopoly supplier can name their own price,” he said.
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