Thursday, March 3, 2011

A Personal List of Decadal Priorities

In my last post, I discussed what I see as the key issues that the Decadal Survey's recommendations will need to take into account.  With just days until the release of the recommendations, I thought I would have some fun and list my priorities.  While I have no pretense that there's anything special about my list -- any of your lists are equally valid -- this also gives me a chance to show how the issues I discussed last time might weave their way through a list of recommended missions.  (The Survey also will make recommendations in other key areas such as technology development that I won't touch on here.)

I said in the last post that I believe that the budget assumed by the Decadal Survey likely will drive many of its recommendations.  As I understand the process, the recommendations were sent out for review last summer.  If so, the U.S. federal budget picture then might have seemed much more generous than it might today.  Then, a projection of a decade's worth of funding for new missions might have added up to $12-13B.  Today, a pessimistic view might be $8B in FY11 dollars if the projected budgets in the FY12 budget are followed for the next five years and then continue at the same rate for the next five years without adjustment for inflation.  With adjustments for inflation, the spending power might fall in the range of $9.5-10B.  The FY12 budget projections may also be placeholders as NASA has said, waiting for a compelling Decadal Survey that justifies a larger budget.  So the upper end might be $12-13B.

I'll try to have my cake and eat it, too, by listing what are to me are a compelling set of missions that might fit into an $8B budget and have a list of additional missions if as much as $12B becomes available.

This initial list of missions likely would cost around $8B, the lower end of the budgets I'm assuming.  (Individual mission costs can be hard to assess since different funding years can be assumed and not all estimates include all of NASA's full set of costs.  In my spreadsheets, I used the best numbers I could obtain.  For NASA's Mars Trace Gas Orbiter costs, I used an educated swag.)  My list of core missions is:

2 Discovery missions
Venus New Frontiers mission
 Sample return New Frontiers from moon, asteroid, or comet
 Outer planets small Flagship 
 Mars Trace Gas Orbiter
 MAX-C/ExoMars/geophysical network instruments

In last week's post, I said that a second key decision would be whether the key questions to be addressed focused on a single type of target -- e.g., Mars or icy-ocean moons -- or a single type of mission -- e.g., sample return missions from Mars, the moon, and primitive bodies.  I would give highest priority to a diversity of targets.  There would be New Frontiers missions to Venus (specific mission might be picked to complement missions from other nations, otherwise I'd prioritize a descent probe/lander) and for a sample return (target to be picked from a submitted proposals) to cover what I consider two high priority goals.  A small Flagship mission would continue outer planet exploration, with the target (Ganymede/Jovian system, Titan, Enceladus, Uranus, or Neptune) picked from submitted proposals.  (As a target, I prefer Titan, but the proposal for another destination might be more compelling.)  Two Discovery missions would round out the diversity missions with the targets picked through a competitive competition.

For my focus target, I would chose the two Mars missions currently planned to be carried out jointly with the European Space Agency.  This was a tough choice; the alternative large Flagship program, the Jupiter Europa Orbiter is a compelling mission.  As a stand alone science mission, my judgement is that JEO is the more compelling mission.  Several factors led me to personally favor the Mars missions:

  • As I understand ESA's budgets, if NASA does not fund its portion of these missions, the Mars Trace Gas Orbiter and ESA's ExoMars rover cannot fly.  These are compelling missions.  Science and sample collection by a NASA rover landed with ESA's rover only adds to these missions.
  • JPL has spent over a decade developing rover and Mars entry, descent, and landing engineering expertise.  Without a Mars rover mission on the books, I've read in presentations that this expertise likely will be lost.
  • Plutonium to power JEO is in short supply.  As I understand it, the supply on hand is insufficient without Russia resuming supplies.  Restarting U.S. production is dependent on Congressional funding, which so far has proven difficult to secure.

The choice of the Flagship mission was a tough call.  Without the added bonus of enabling the ExoMars rover, I probably would have gone with JEO.

If more funding becomes available I would add an additional set of modest to low costs missions.  This would allow NASA to select compelling missions as funds were available, but would not place it in the situation of needing to keep funding a mission that's too large to be allowed to fail.  If all three were funded, my best estimate is that their cost with the missions above would approach $12B, the upper limit budget I have been assuming.

  2nd outer planets small Flagship mission
 Add'l New Frontiers mission
 Add'l Discovery mission

After a year and a half of reading and writing about the Survey, these are my conclusions summed up to a list.  The program the Decadal Survey members recommend next week probably will be quite different than mine.  Any exercise like this involves many compromises, and the Survey members have better information than I, have greater expertise, and have spent more time thinking and talking about it.  They may have also had to make some tough choices based on information that I don't have.

I look forward to hearing their recommendations.

In my next post, I'll show the list of missions selected by you through the poll on the website.

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