Sunday, March 8, 2009

Planetary Decadal Survey

The MEPAG meeting this past week had the first details that I've seen on the planetary Decadal Survey process that is just getting under way (see presentation here). These surveys are modeled after the decadal surveys that have been used for some time in the astronomy community. As I understand the history of that process, the original goal was to create a unified voice within the scientific community about the priorities for government funding in the following decade. The debate within the community typically is spirited as priorities are set, but once the plans have been published, the community supported those priorities. Congress and the science agencies (National Science Foundation and NASA in the case of astronomy) tend to pay considerable attention to the recommendations of these surveys.

The astronomy decadal surveys have included both terrestrial and space projects. The planetary community adopted this process with a report in 2003 (more on that later). Since then, there have been decadal surveys in a number of subject areas: Solar and Space Physics (2002), Earth Observation from Space (2007), Life and Microgravity Sciences (in progress). A new astronomy survey is in progress. The new planetary survey is in the organizational stage with the availability of a pre-publication report in the first quarter of 2011.

The surveys go to great lengths to solicit a wide range of input from the planetary community. Panels are formed on a number of topic areas. The last planetary survey had 23 panels ranging in subject from Mars to near Earth object sample return to extraterrestrial mineralogy. (Look here for the Mars community's early thoughts on their input to the new survey.) In addition, individuals and ad-hoc groups of scientists can submit white papers to cover any areas not covered by the panels. For those of us in the public, the result will be a feast of mission ideas and descriptions. (I will be hard pressed to try to keep up with the deluge in this blog.) Based on the current schedule, look for these input documents and assessments to begin to become available in the second half of this year.

The inputs to the decision process as well as the final report are likely to have three broad subject areas: (1) solid (and usually readable by the public) reviews of the current state of knowledge, (2) prioritized key scientific questions, and (3) recommended missions or funding to address those questions. The latter is the subject of this blog, and so I'll reproduce the planned output in this area from the MEPAG meeting presentation:

• "Recommendations on the optimum balance across the solar system and among small, medium, and large missions and research activities;
• Prioritized recommendations for New Frontiers and flagship flight investigations for initiation in the period 2013-2022;
• Recommendations for NASA-funded research activities required to maximize the science return from the flight investigations; and
• Technology development needs and opportunities relevant to NASA."

I think that it's instructive to look at the recommendations from the last planetary survey:

High priority missions from the 2003 planetary Decadal Survey. Click on image for a larger image.

Here's my scorecard on the output of these recommendations:

Cassini extended mission - funded two year extension with an additional seven year extended mission in discussion

Kuiper Belt - Pluto Explorer - launched as the New Horizons mission but approved prior to the publication of the Survey report

Jupiter polar orbiter with probes - in development as the Juno polar orbiter (as I understand it, NASA no longer has the facilities to test Jupiter atmospheric probes)

On-going program of medium class (New Frontiers) missions - one launched (New Horizons), one in development (Juno), and the selection of a third mission in progress

Europa geophysical orbiter - not started, but now selected for launch around 2020 as the Jupiter Europa flagship mission (about a decade later than recommended)

Mars Scout line - initiated with the Phoenix mission completed and the MAVEN mission in development; however preliminary Mars roadmap recommendations may not have the third flight until the late 2020s

Mars upper atmosphere orbiter - in development as the MAVEN scout mission

Mars network - not funded, but is a candidate mission for the next New Frontiers mission or as a ~2020 flight within the Mars program

Mars Science Laboratory - in development, although the mission to be flown is much more capable (and expensive) than the one envisioned in the Survey report

Mars sample return - earliest possible flight in the 2020s

Discovery mission launches every 18 months - Since the report, the MESSENGER Mercury mission has launched (and encountered Mercury twice), the Deep Impact mission was successful, and the Dawn asteroid mission is in flight. However, by my reckoning, only one new mission, the lunar GRAIL mission, has been approved since 2003. A new mission selection process is scheduled to begin this summer.

Deferred high-priority missions from the last Decadal Survey. Click on image for a larger image.

In addition to these recommended missions, the Survey listed a number of high priority missions that weren't included as recommended missions. All four of the medium class missions have been added as candidate missions for the next New Frontiers mission selection.

In summary, the results of the last Decadal Survey were mixed. The New Frontiers program was begun about a year before the completion of the last survey, and has progressed with periodic mission selections. The Discovery program should have had three to four new missions selected to keep on track to launch regularly in the coming decade. Neither large mission (Europa orbiter nor Mars sample return) was started, although the Mars Science Laboratory grew into a large, flagship class mission.

Editorial Thoughts

In general, the last Decadal Survey recommended a program that was too ambitions. By my rough accounting, it might have taken a budget twice the size actually provided by Congress to fly the entire mission suite. I can think of several reasons for this mismatch. First of all, the last Survey had only preliminary cost estimates to work with, and early cost estimates have a history of being too low. (For this next Survey, much more effort will be put into costing mission concepts.) Second, cost overruns hit several programs, reducing funds for starting new ones. And third (although I don't know if this was done consciously), managers know that you ask for more money or programs in your budget request than you expect to get. You might get lucky and get more resources, or if not, your budget likely will be cut down from your initial request, so ask big.

I suspect that the Survey that is just beginning will face several tough issues. Assuming that budgets for the next decade are similar to those of this past decade, creating a balance set of priorities that are actually likely to fly will be hard. If so, the arm wrestling to be highly prioritized and thus near the head of the line for funding may be rough. This is especially true, I think, in three areas:

• What should be the balance between smaller missions and larger missions? Clearly, funding since the last Survey was not enough to maintain regular approval of new Discovery missions.

• What should be the balance between the Mars program and the rest of the program? Mars has intentionally been the favored target for the last decade in terms of funding and missions. Should that continue or is it time for other destinations to receive priority?

• What flagship mission should follow the Jupiter Europa orbiter? This next mission would likely begin within the next decade, and several good candidates are likely to be proposed: Mars sample return, Venus flagship mission, Titan flagship mission are just the current contenders that I'm aware of. (If I were a betting man, I think I'd bet that the Survey will list 2 - 3 flagship missions for funding of technology development to enable a strong contest for the eventual selection near the end of the coming decade.)

Decadal Surveys are exercises in optimism. The community proposes its best ideas in the hope that the President and Congress will fund them. The coming decade may be an especially tough environment. We don't know how long the current economic troubles will continue. Once they stop, the U.S. will have to face the problems of large accumulated deficits. New problems (decline oil production? global warming?) may become national priorities for funding in place of an expansive planetary exploration program. Despite these problems, I expect that we will still have an on-going program of new planetary missions. If the budget for those missions declines for any of a number of reasons, then the prioritized list of missions expected from the Survey will be even more important to inform how to best use that budget.

You can use the box below to read or download the last Decadal Survey report or click here.

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