March 19, 2013
Despite a bleak budget outlook, NASA’s planetary sciences program is pushing ahead with plans to revive the production of Plutonium-238 through the U.S. Department of Energy (DOE) as well as develop a pair of Advanced Stirling Radioisotope Generators (ASRGs) to power yet-to-be-selected, medium-class planetary missions requiring the use of nuclear power sources.
The ASRG initiative is on track for the assembly of two generators that will be placed in storage without fuel during fiscal 2016. Meanwhile, NASA expects the DOE to forward a schedule and cost plan by the end of 2013 for the production of 1.5 to 2 kg (3.3-4.4 lb.) of Plutonium-238 annually, according to Jim Green, director of NASA’s planetary sciences division, who spoke at the 44th annual Lunar and Planetary Conference here.
U.S. production of Plutonium-238 was halted in 1988, and current stockpiles appear sufficient for missions in the pipeline through the end of the decade. NASA plans to combine what remains of the plutonium stockpiles with new production of the radioactive material and ASRGs – an upgraded version of the radioisotope thermoelectric generators that power NASA’s Curiosity rover – to stretch efficiency. The agency’s Discovery program, which provides NASA funding to competed missions proposed by scientists and engineers, appears to be the best fit for the new plutonium power sources, Green says.
DOE has already started production of the plutonium isotope using Neptunium-237 on a test basis with encouraging results. The ASRGs could be assigned to Discovery missions, possibly selected later this year, if the scientists and engineers who proposed the projects can demonstrate that plutonium is an “essential element, an enabling technology, if you will,” Green said March 18 on the first night of the weeklong conference.
The revival represents a bright note in an otherwise uncertain long-range outlook for the future of the agency’s planetary sciences program. Like its sister federal agencies, NASA is operating under a soon-to-expire continuing resolution and cuts imposed under the March 1 budget sequester. President Barack Obama’s proposed 2013 budget would cut annual spending on planetary sciences from $1.5 billion in 2012 to $1.1 billion by 2015. The House, Senate and White House are formulating competing 2014 spending proposals amidst ongoing discord over how to handle the nation’s budget deficits.
“We are trying hard to improve the situation,” NASA science chief John Grunsfeld promised many of the 1,700 scientists and students gathered at the conference in Houston’s northern suburbs. Grunsfeld and Green addressed the conference remotely from Washington, in observance of new NASA travel restrictions imposed in response to sequestration.
The space agency plans to combine older with newer Plutonium-238 under a 2:1 ratio to improve energy densities for new missions. In some cases, the decaying Plutonium-238 is more than 20 years old.
“That will revive our supply and allow us to complete a number of potential plutonium-necessary missions over this decade and position us well into the decade after that,” Green said.
Started in 1992, to encourage creativity in mission proposals while restraining costs, the current Discovery lineup includes the Kepler, Dawn and Messenger missions. InSight, a non-nuclear-powered Mars lander selected in last year’s competition, is scheduled for a 2016 liftoff to study the red planet’s interior.