WASHINGTON — Work on a new 10-year plan for U.S. planetary exploration is expected to get underway next year and wrap up in time to influence the program of robotic landers, orbiters and probes NASA ultimately pursues between 2013 and 2023.

NASA still has a way to go before the agency works through the list of solar system missions recommended in the so-called decadal survey published in 2003. Two of the bigger missions included on the 2003 list – a Europa orbiter and a Mars sample-return mission – will have to be taken up as unfinished business by the National Academy of Sciences committee expected to meet for the first time in mid- to late-2009 to hash out the planetary science community’s priorities.

James Green, director of NASA’s Planetary Science Division, said the
U.S.
space agency has been discussing its hopes and expectations for the upcoming decadal survey with the
National
Academy
in recent weeks and intends to transmit a formal request for the study by year’s end.

While NASA already has drafted a task statement for the decadal survey and shared it with the
National
Academy
, Green would only talk in generalities about it since NASA still is awaiting National Science Foundations input on what will be a joint request from the two federal science agencies.

“This decadal unlike the last decadal will include the Moon and Mars,” Green said in an Oct. 14 interview.

For the past several years, NASA’s Planetary Division has taken its guidance from three main reports: the National Academy’s “New Frontiers in the Solar System” report, also known as the 2003 decadal survey; the academy’s 2006 assessment of NASA’s Mars exploration architecture; and a 2007 report entitled “The Scientific Context for Exploration of the Moon,” or the SCEM report for short.

“In the next decade, we will have only one report,” Green said. “So we are going to be asking the academy to organize the community … to give us a prioritization across the solar system.”

Mark Sykes, director of the Tucson, Ariz.-based Planetary Science Institute, pointed out one big difference between the last decadal survey and the forthcoming exercise that Green did not mention.

“The last planetary decadal survey was conducted in the context of open-ended resources,” Sykes said. “Prioritization of missions was done within large, medium, and small categories. What was not done was to prioritize across categories, in the event of limited resources.”

As a result, Sykes said, “we are now facing a serious situation from uncontrolled growth in the [Mars Science Laboratory] budget threatening not only the rest of the Mars program but other planetary missions as well. On top of this, the national financial crisis is going to put huge pressures on the discretionary part of the federal budget, which includes NASA. The future of solar system exploration lies between the hammer and the anvil of these two forces.”

With the
United States
electing a new president Nov. 4 who will take office Jan. 20, Green declined to make any predictions about the budget forecast the planetary decadal survey committee will be asked to work against as it starts to lay out NASA’s exploration plans for 2013-2023. But he said that by the time the committee is ready to meet for the first time – probably in the second half of 2009 – NASA should have an idea about how planetary exploration is expected to fare under the administration of Republican presidential candidate John McCain or Democratic candidate BarackObama.

Sykes and Green agreed that forging a consensus among a diverse community of planetary scientists in no mean feat.

“The bottom line is that the planetary community expects to be openly and meaningfully engaged in the next decadal survey and will be active partners,” Sykes said. “Limiting input to town hall meetings will not be adequate. The main challenge for the next survey will not be to come up with ideas for great missions. It will be to understand how we should prioritize our activities in the context of shrinking budgets and increasing expenses, while preserving and even enhancing our capabilities as a nation.”

Green said NASA wants to give the academy adequate time to put together a broadly representative decadal committee that can hold all necessary meetings with the wider community, and ultimately produce a report in time to influence NASA’s 2013 budget.

“That means we need it in the second quarter of 2011 because that’s when we’re putting together the 2013 budget,” he said.

At least one big budget decision likely already will be made by the time the decadal survey committee meets for the first time, probably during the second half of 2009.

NASA and the European Space Agency (ESA) expect to decide sometime in January whether to target the Jupiter or Saturn systems for a joint outer planets flagship mission the agencies intend to launch sometime between 2018 and 2022.

The latest reports on the candidate missions are due Nov. 3 with two or three months of assessment to follow before NASA and ESA

agree
upon which mission they will concentrate, according to Green.

The Jupiter flagship mission under study would entail the launch of a Europa orbiter, a Ganymede orbiter and a Jupiter orbiter “in a large enough radius that it’s essentially a magnetosphere mission looking at the system itself,” Green said.

The Saturn flagship mission under consideration would target the giant moon Titan with an orbiter, a lander and an atmospheric balloon. Along the way, Green said, NASA and ESA would expect to learn plenty about Enceladus, Saturn’s sixth largest moon. “To get into a Titan orbit is really going to require a lot of passes by Enceladus,” Green said. “So we won’t be ignoring Enceladus but the community decided that Titan would be the goal.”

Green said that while NASA is energized about doing one or the other outer planet flagship missions, ESA’s participation depends on the selected mission getting the nod in
Europe
‘s Cosmic Visions competitive process next year.

As for the decadal survey, Green said he would be surprised to see the committee do anything besides ratify the outer planets flagship selection when it issues its report in 2011. “The community has been on board with each and every step we have made to narrow down our next outer planets flagship,” he said. “I would be surprised if the committee came back and said, ‘stop doing that and start doing this.’ The Jupiter and Saturn systems are still so scientifically exciting that I am sure they are going to end up in the decadal one way or another.”

One other feature NASA hopes to see in the upcoming decadal survey is more realistic cost estimates for recommended missions. “We will ask them for better fidelity for their cost estimates and for them to do that, I anticipate they will ask industry for that support,” Green said.

The
National
Academy
turned to industry in 2006 and 2007 when it hired – with NASA’s blessing – outside help to work up independent cost estimates for a slate of fundamental physics missions before recommending in 2007 that the
United States
proceed with the Joint Dark Energy mission.

Green said he expects the National Academy will do so again to help the planetary decadal committee produce a prioritized list of missions that can be accomplished within NASA’s anticipated budget profile, whatever that turns out to be.