WASHINGTON — NASA and the science community are being forced to scale back their planetary exploration ambitions due to budgetary pressures that have pushed proposed new starts on flagship-class probes, including high-priority missions to collect martian soil samples and orbit Jupiter’s ice-covered moon Europa, beyond the agency’s five-year planning horizon.

Jim Green, director of NASA’s Planetary Science Division, told the NASA Advisory Council’s Science Committee March 3 that those and other big missions are on indefinite hold amid declining budget projections that leave room only for small- to medium-class probes. That means the $2.5 billion Mars Science Laboratory, a nuclear-powered, truck-sized rover slated to launch toward the red planet this year, likely will be NASA’s last planetary flagship for at least a decade — and probably longer — given the time required to develop such missions.

When U.S. President Barack Obama delivered his 2011 NASA budget request to Congress early last year, out-year funding projections showed steady annual increases for planetary probes, fueling hopes among scientists that work would start on a flagship-class mission in the near future. However, while Obama’s 2012 request, released Feb. 14, shows planetary spending increasing by nearly $180 million next year, to $1.54 billion, it then declines steadily to $1.25 billion by 2016.

A soon-to-be-released decadal survey of planetary missions prepared by the National Research Council lists the Mars sample-collection and Jupiter-system missions as the top two priorities for the coming decade, but acknowledges that they might not be feasible anytime soon under the budgetary scenario NASA now faces. A draft summary of the highly anticipated report, “Vision and Voyages for Planetary Science in the Next Decade 2013-2022,” was obtained by Space News.

The summary says if funding for planetary exploration is lower than the 2011 budget projections on which it is based, NASA should consider “descoping or delaying Flagship missions.” Changes to small- and medium-class campaigns in NASA’s Discovery and New Frontiers programs should not be considered unless they can solve funding shortfalls for flagship initiatives, and every effort should be made to shield research and analysis and technology development initiatives, the draft summary states.

The highest-priority flagship mission for the 2013-2022 survey is the Mars Astrobiology Explorer-Cacher (MAX-C), the first phase of a joint Mars sample-return campaign between NASA and the European Space Agency (ESA) involving two large rovers. The mission is intended, among other things, to collect martian soil samples for return to Earth by spacecraft to be launched at a later time.

“Unfortunately, at an independently estimated cost of $3.5 billion, MAX-C would take up a disproportionate near-term share of the overall budget for NASA’s Planetary Science Division,” the draft summary states. “The committee recommends that NASA should fly the MAX-C mission in the decade 2013-2022 only if it can be conducted for a cost to NASA of no more than approximately $2.5 billion.”

Unlike the previous planetary decadal survey, the latest report used an outside contractor, Los Angeles-based Aerospace Corp., to estimate the cost of candidate missions, a process that takes into account actual costs of similar previous projects, according to the draft summary.

Scaling back MAX-C to meet the recommended $2.5 billion cost ceiling would mean reducing mission mass and volume, thus reducing the scientific capabilities of the vehicles, the summary states, adding that ESA participation in all three phases of the sample-return campaign is crucial to meeting NASA’s objectives.

However, if MAX-C’s costs cannot be contained within the ceiling, the report recommends deferring or canceling the sample return campaign in its entirety.

The second-highest priority flagship mission for the coming decade is the Jupiter-Europa Orbiter (JEO), a mission designed to characterize Europa’s ice-covered ocean and interior. ESA and NASA have been studying a collaborative campaign dubbed the Europa Jupiter System Mission/Laplace that would send two spacecraft, including JEO, to survey the jovian system and its moons. The campaign is one of three candidates for an ESA large-scale science mission opportunity that would launch around 2022.

JEO, which is projected to cost $4.7 billion, is based on the Europa Geophysical Explorer, the lone flagship class mission recommended in theNational Research Council’s 2003 decadal survey. Over the past decade considerable work has been done to lay the technological foundation for a  JEO mission, the draft summary states.

However, JEO’s estimated cost is “so high that both a decrease in mission scope and an increase in NASA’s planetary budget are necessary to make it affordable,” the draft summary states. “Therefore, while the committee recommends JEO as the second highest priority Flagship mission, close behind MAX-C, it should fly in the decade 2013-2022 only if changes to both the mission and the NASA planetary budget make it affordable without eliminating any other recommended missions.”

The third flagship mission priority is the Uranus Orbiter and Probe, which would deploy a small atmospheric drone to make in situ measurements of the gas planet. The mothership would then enter orbit, taking remote measurements of the planet’s atmosphere, interior, magnetic field and rings, while making multiple flybys of Uranus’ larger moons.

The estimated $2.7 billion mission offers “outstanding scientific potential and a projected cost that is well matched to its anticipated science return,” the draft summary states. It adds that the Uranus probe should be initiated in the coming decade so long as current cost estimates hold, even if NASA opts to undertake both MAX-C and JEO.

However, because the decadal survey’s findings are based on NASA’s more generous 2011 out-year funding projections, rather than the declining profile laid out in the 2012 budget request, it is unlikely the agency can afford to embark on any new large projects in the coming decade. Green, speaking March 1 at a meeting of the NASA Advisory Council’s planetary science subcommittee, warned members not to expect the funding outlook to improve.

“We have now a budget request by the president that we must live with,” Green said during the conference call. “We may have to rearrange the individual amounts or the type of programs or activities within that, but we must stay within our budget.”

Budget justification documents that accompanied the president’s 2012 spending request say NASA “may modify future budget and content to better align with the findings and recommendations” of the decadal survey, but Green’s comments make that scenario seem unlikely.

“How we will implement [the decadal priorities] within our existing budget needs to be considered,” he said, adding there is “no additional money beyond the president’s submitted budget.”

NASA has a number of small- to medium-class planetary probes in development, including: Juno, a solar-powered craft slated to launch in August and spend a year orbiting Jupiter studying the gas giant’s atmosphere; Maven, a Mars orbiter slated to launch in 2013; and a pair of lunar probes. Two additional missions, one in the Discovery class and another in the slightly larger New Frontiers class, are approved, but the destinations have yet to be selected.

The decadal survey recommends that NASA continue its Discovery and New Frontiers initiatives and includes seven candidate campaigns for the latter from which NASA should select two for flight in the coming decade. These include a comet-surface sample return; a mission to Jupiter’s moon Io; a geophysical network of landers distributed across the Moon’s surface; a lunar South Pole-Aitken Basin sample return mission; a Saturn probe; a tour and rendezvous with a trojan asteroid orbiting Jupiter; and a Venus in-situ explorer.

The survey also recommends changing the New Frontiers cost cap from $1.05 billion, including launch costs, to a flat $1 billion excluding launch, the draft document states. The change will “help protect the science content of the New Frontiers program against increases and volatility in launch vehicle costs,” the draft report said.

NASA Administrator Charles Bolden said  his agency would be challenged to do everything the decadal survey recommends. During a March 3 hearing before the House Appropriations commerce, justice, science subcommittee that oversees NASA spending, Bolden said the agency puts “a lot of stock into the voice of the community.”

But when asked by Reps. John Culberson (R-Texas) and Adam Schiff (D-Calif.) whether NASA would fund the decadal’s new mission priorities, Bolden said it would depend on whether the survey takes NASA’s current fiscal situation into account.

“Provided they come out with something that’s reasonable and they use the 2012 budget in their prioritization, then I would be able to say yes, but I have no idea whether they took the 2012 budget [or] the 2011 budget,” Bolden said.

When Culberson pressed Bolden to commit to flying the joint ESA-NASA Europa mission, Bolden demurred.

“When the decadal survey results are announced next Monday … we will look at how we prioritize it based on where we are in our planetary budget,” he said.

Ed Weiler, associate administrator for NASA’s Science Mission Directorate, said the future of flagship-class robotic exploration missions lies in international cooperation. “If we’re going to do any more big missions, they’re going to be international,” Weiler said during the March 3 meeting of the NASA Advisory Council’s Science Committee. “The days of $3 billion-$4 billion missions that we do on our own are gone.”



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