The Senate Appropriations Committee passed this week its 2012 energy and water appropriations bill, which includes funding for the Department of Energy (DOE). Senate appropriators, though, decided not to fund the administration’s request for $15 million for DOE to restart production of plutonium-238 (Pu-238), an isotope used in radioisotope thermoelectric generators (RTGs) for NASA science missions. In the report accompanying the bill, the committee gave no reason for the lack of funding, simply stating, “The Committee provides no funding for the Plutonium-238 Production Restart project.”
That move comes after House appropriators similarly declined to fund Pu-238 production in its DOE bill, although in that case appropriators said in their report that DOE should not share the funding burden with NASA for a program that primarily aids the space agency. The House did include Pu-238 funding for NASA in legislation that the committee passed in July, although that alone may not be sufficient for restarting production.
A lack of Pu-238, because the isotope is no longer produced in the US (although limited quantities of it have been purchased from Russia), has been an area of concern for planetary scientists in recent years, given that many of their proposed high-priority long-term missions require RTGs. The latest planetary science decadal survey, published earlier this year, noted the committee who prepared the report were “alarmed” about the availability of the isotope. “Without a restart of plutonium-238 production, it will be impossible for the United States, or any other country, to conduct certain important types of planetary missions after this decade,” the report stated.
Speaking at a planetary exploration event hosted by The Planetary Society on Capitol Hill on Friday, Steve Sqyures, who led the work on the decadal survey, said they did not let the potential lack of Pu-238 drive the decisions on prioritizing missions. “What we did instead is to turn the problem around and say that these are the missions that ought to be flown, and here is the plutonium-238 need profile that results from that,” he said. He noted the report did recommend the development and use of advanced RTGs that require significantly less Pu-238 than current systems. NASA, Squryres said, is “working very hard with DOE and folks on the Hill to try to come up with a plan for producing the amount of plutonium that’s needed” to meet the missions proposed in the study. That’s proving to be a difficult task.