Is Europa really the "highest priority" of the community?, Cleave said it was at LPSC? Options

[mcaplinger]

From Emily's LPSC blog: "Bob Pappalardo would not sit down until he got Cleave to acknowledge that Europa is the consensus highest priority of the planetary science community."

Cleave was obviously poorly prepared for this session, but I don't see that this acknowledgement is either meaningful or particularly accurate. If Europa were the "highest priority" of the PS community as a whole, then one might wonder why we were spending all this money on Mars. I could easily imagine that Europa is the highest priority of the outer planets community, but frankly I was surprised when Europa Orbiter appeared in the '07 budget (presumably the result of some serious lobbying on someone's part.) It was pretty obvious to me then that there would be no money for it, especially in the aftermath of JPL running the old EO project into the ground with cost overruns and engineering upscopes. (And JIMO is best forgotten.)

Don't get me wrong, I would love to be involved with a Europa mission (we did what I think was a good proposal design for EO) but I don't see either the money or the political support being there in the near term. I know it's frustrating, but one has to be realistic, and it might help to avoid the aura of entitlement that I perceive is building in some parts of the community (not referring to you, Bob). Of course, I am just a lowly engineer.

[Guest_BruceMoomaw_*]

Not only did the 2002 Decadal Survey rank Europa as the highest-priority target for a large non-Mars planetary mission, but OPAG has just officially ranked it above Titan ( http://www.lpi.usra.edu/opag/oct_05_meetin...ting_report.pdf '. pg 2. OPAG officially ranks Titan second, above Neptune.) Lunine, in short, was engaged in trouble-making, and Pappalardo was entirely justified in doing what he did. (Mars is in an entirely separate category all by itself -- it's NASA's official Holy of Holies, never to be questioned on any ground.)

The question at this point is whether a combined Titan-Enceladus mission is possible, and whether this really might upend the current order.

[elakdawalla]

Not only did the 2002 Decadal Survey rank Europa as the highest-priority target for a large non-Mars planetary mission, but OPAG has just officially ranked it above Titan ( http://www.lpi.usra.edu/opag/oct_05_meetin...ting_report.pdf '. pg 2. OPAG officially ranks Titan second, above Neptune.) Lunine, in short, was engaged in trouble-making, and Pappalardo was entirely justified to do what he did. (Mars is in an entirely separate category all by itself -- it's NASA's official Holy of Holies, never to be questioned on any ground.)

The question at this point is whether a combined Titan-Enceladus mission is possible, and whether this really might upend the current order.

The strange thing is that Lunine didn't seem to think he was trouble-making, and just as Cleave doesn't understand why the scientists are angry, Lunine doesn't understand why the outer planets folks are feeling threatened by his public suggestion (though the Leonard David article should answer that).

People here seem to be pretty dismissive of the possibility of a combined Titan-Enceladus mission but of course no one is actually presenting either a suggestion for or rebuttal of such a possibility at any of the sessions.

What most of the outer planets folks are saying about Titan is that the surface should not be explored until it is well mapped from orbit. They are asking themselves whether a New Frontiers mission couldl be sent to Titan with only two instruments: a radar mapper capable of 100-meter resolution and a 2-micron imager. These are all geologists talking though, and I think that the mission would be more interesting to more people with a third instrument that could do a thorough map of the atmosphere, such as a limb sounder, to map hazes, clouds, etc. (I'm a new fan of limb sounders now that we're doing public outreach on the Mars Climate Sounder.) But of course I don't have a clue how much mass/complexity that would add to the simple orbiter that the outer planets folks are talking about.

--Emily

[JRehling]

I'm profoundly disturbed by the notion that the prioritization should be irrespective of means, as Emily has lightly touched upon, or readiness, as Alex has touched on.

If a cheapo mission that scored major Enceladus goals came to light, then it would seem in at least one sense to become a more sensible mission than a blockbuster to Europa or Titan. But we also have to strategize -- all three of these satellites are going to draw us into twenty questions games, and the best first mission to one of them is not necessarily the mission that returns the most gigabytes of science data from that one. Europa and Enceladus offer possible free-return (or very cheap return) missions. Enceladus and Titan offer the possibility (not that I can sketch one out) of a single mission that delivers some science from the other one. Of course, Europa is in proximity to other worlds of interest, also. Europa also happens to be closer to Earth for potentially shorter cruise, but is cursed with its position deep inside Jupiter's gravity well; maybe a Titan mission *could* get to Titan faster than a Europa mission could get to Europa. Meanwhile, most Europa mission designs would be sharply time-limited, while a Titan mission might have a MERlike longevity. All of which is to say that I don't see any sense in prioritizing exploration while isolating science interest as the only factor. I'd much rather see a helluva mission to any of these worlds before an incremental follow-on to any of the others.