WASHINGTON — With NASA facing declining budgets for building and operating planetary probes over the next five years, one of the agency’s senior science-community advisers warned that there will be no funding to begin development of a flagship-class mission such as a long-sought detailed survey of Jupiter’s ice-covered moon Europa.

“The out-years budget means no major new starts of a flagship planetary [mission],” Ronald Greeley, a regent’s professor at Arizona State University in Tempe and chairman of the NASA Advisory Council’s planetary science subcommittee, said during a March 1 conference call with panel members. “That’s a major, major issue for our community.”

Currently there is just one flagship-class planetary mission on NASA’s plate: the $2.5 billion Mars Science Laboratory, a nuclear powered, car-sized rover slated to launch in November. But scientists have long had their sights on Jupiter and its moons, particularly Europa, and a visit to that system is being studied as a possible collaboration between NASA and the European Space Agency (ESA).

NASA’s 2012 budget request, unveiled Feb. 14 by U.S. President Barack Obama, would boost spending on planetary science activities from the current level of $1.36 billion to $1.54 billion next year. But funding would steadily decline over the following four years, to $1.25 billion in 2016.

NASA’s projected top-line budget is flat over the next five years at $18.72 billion, which when inflation is factored in translates into a decline in spending power. But there are budgetary scenarios under which NASA’s budget would decline over the next five years, even as the agency tries to replace the space shuttle and contends with runaway cost growth on the $5 billion-plus James Webb Space Telescope, the designated successor to the Hubble Space Telescope.

“We have now a budget request by the president that we must live with,” NASA Planetary Science Division Director Jim Green said during the March 1 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.”

NASA and its advisers from the science community are awaiting the March 7 release of the U.S. National Academy of Sciences’ new 10-year plan for planetary research, a broad survey that will identify the most pressing scientific mission priorities for 2013 through 2022. The previous decadal survey identified the jovian system as the top exploration priority other than Mars.

Green said he is hopeful the decadal survey will produce “well-defined priorities and decision-making rules that will allow us to get 90 percent of the directions that we need to go and, on a tactical basis, work with [the planetary sciences subcommittee] to try to accomplish as much of the decadal as we can in the next 10 years.”

Although 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, Green dismissed the notion that a budget boost is forthcoming.

“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.”

In addition to the Mars Science Laboratory, 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 Horizons class, are approved, but the destinations have yet to be selected.

NASA also has a role in the ESA-led Exomars mission scheduled for a 2016 launch.

ESA and NASA have been studying a collaborative mission dubbed Europa Jupiter System Mission/Laplace that would send two spacecraft to survey the jovian system and its moons. It is one of three candidates for a large-scale science mission opportunity that would launch around 2022. ESA has budgeted about $1 billion for the opportunity but is awaiting decisions from NASA and the Japanese space agency, which is collaborating on another candidate mission, before making a final decision on which one to pursue.

In early February, Green said the joint mission with ESA to explore Jupiter’s moons is looked upon favorably by U.S. scientists but suggested any NASA decision will hinge on the results of the forthcoming decadal survey.



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