This story was updated at 4:15 p.m.
EST, March 7.
NASA is facing the prospect of trying
to explore deep space without the aid
of the long-lasting nuclear batteries it has relied upon for decades to send
spacecraft to destinations where sunlight is in short supply.
NASA Administrator Mike Griffin told
a House Appropriations subcommittee March 5 that the U.S. inventory of
plutonium-238 - the radioactive material essential for building long-lasting
batteries known to the experts as radioisotope
power systems - is running out quickly.
"Looking ahead, plutonium is in
short supply," Griffin told lawmakers during the first of two days of hearings
on the U.S. space agency's 2009 budget request.
Griffin was asked about the
plutonium-238 situation by Rep. Adam Schiff (D-Calif.). The Pasadena-area
congressman's district is home to the Jet Propulsion Laboratory - the
NASA-funded facility building the space agency's next nuclear-powered
spacecraft, the 2009 Mars Science
Laboratory, or MSL.
"After MSL launches, we're pretty
much out of plutonium," Griffin said.
The United States stopped producing
plutonium-238 in 1988 and since then has relied upon a dwindling stockpile
supplemented since 1992 by periodic purchases of the material from Russia.
NASA's Pluto-bound
New Horizons spacecraft, for example, is powered by a radioisotope power
system fueled by Russian plutonium, as will be the system that powers the Mars
Science Laboratory.
Though Griffin did not mention it,
the U.S. Department of Energy over the winter quietly shelved long-standing
plans to resume domestic production of plutonium-238. In 2005, the Department
of Energy (DOE) gave public notice of its intent to consolidate the nation's
radioisotope power system activities at Idaho National Laboratory and start
producing plutonium-238 there by 2011.
Restarting production was projected
at the time to cost $250 million and take five years. Griffin said during the
hearing that the DOE's latest estimate is that a restart would take seven
years.
Angela Hill, an Energy Department
spokeswoman, told Space News in an e-mail that those plans are now on
hold. "DOE did not request funding in 2009 for [Plutonium-238] production, since NASA has been
directed to fund any new production capabilities," Hill wrote. "Production
may 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 includes
no money for re-establishing the Department of Energy's long dormant
plutonium-238 production capability.
Meanwhile, how much of the
plutonium-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 kilograms
by 2010. The same report said an additional 20 kilograms of weakened
plutonium-238 could be harvested by 2011 from milliwatt power systems aboard
old nuclear missiles slated to be decommissioned. However, the reclaimed material would have to
be mixed with fresher stock to be useable.
U.S. industry sources said they had
been told that the United States has a total of just over 11 kilograms on order
to meet NASA's projected demand through the middle of the next decade.
Hill said only that the United
States has received an additional 5 kilograms of plutonium-238 from Russia
since 2005 and has another 4.9 kilograms on order for delivery this year.
Alan Stern, NASA associate
administrator for science, testifying before the House Appropriations commerce,
justice, science subcommittee alongside Griffin, said he believed the United
States had sufficient plutonium-238 on hand or on order to fuel next year's
Mars Science Lab, an outer planets flagship mission targeted for 2017 and a
Discovery-class mission slated to fly a couple years earlier to test a more
efficient radioisotope power system that NASA and the Energy Department have in development.
To help ensure there is enough
plutonium-238 for those missions, NASA notified scientists in January that its
next New Frontiers solicitation, due out in June, will seek only missions that
do not require a nuclear power source. Industry sources said that limitation
will put scientists wishing to propose outer-planet destinations including
Jupiter and Saturn for the 2016 New Frontiers flight
opportunity at a decided disadvantage.
"In the future, in some future year
not too far from now, we will have used the last U.S. kilogram of
plutonium-238," Griffin said. "And if we want more plutonium-238 we will have
to buy it from Russia."
Griffin, who has said many times
that he finds it "unseemly" that the United States may have to depend entirely
on Russia to access the space station between the space shuttle's retirement in
2010 and the introduction several years later of the Orion Crew Exploration
Vehicle or a commercial alternative, made clear he was no more pleased with the
prospect of relying entirely on Russia for flying space missions requiring
nuclear power sources.
"I think it's appalling," he said.
But even the Russian supply might
not last for much longer.
When the hearing resumed March 6,
Griffin told lawmakers Russia has advised the United States "that they are down
to their last 10 kilograms of plutonium."
"We are now foreseeing the end of
that Russian line," he said.
Griffin also clarified that NASA has
been assured of enough plutonium-238 to do the MSL, a 2013 or 2014
Discovery-class mission and an outer-planets flagship mission targeted for 2016
or 2017.
"When those missions are allocated,
we have no more," he said.
Griffin said absent a national
decision to restart production, NASA's planetary science program "would be
severely hampered."
John Logsdon, executive director of
the Space Policy Institute at George Washington University here, said not
restarting plutonium-238 production puts the U.S. space program in an
undesirable 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.
"Any
monopoly supplier can name their own price," he said.
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