Titan Review article Options

[vjkane]

The strategy I envision is sort of a "one-note pony" theme; maybe two or three instruments per mission designed to answer a specific research question, that's it. Core assumption is that the launch vehicle is the vast majority of cost (and, yeah, the demise of the Delta II is a huge blow... ...hopefully new LVs from the independent launch enterprises like SpaceX will prove both more capable and less costly over time.)

I've been looking into readily accessible information on mission costs. A Discovery mission to Jupiter -- beyond perhaps a single, simple flyby -- seems impossible. The Juno mission is close to $1B with a limited (although not cheap) instrument set, a spinning spacecraft, solar power, and limited radiation hardening. I can't think of any mission that could come in at half the budget that could do useful science at Jupiter. The only idea that seems possible is a single Io flyby, and I have my doubts about that.

[vjkane]

if any outer planet mission is going to happen before I hit my 70's (which is not really a bad thing, I may be retired from my day job by then and able to devote more attention), it needs to be started now.

I made the sad realization recently that the next Flagship mission would arrive at its target someplace between by 65th and 70th birthday. The decisions NASA/ESA/JAXA will make in the next couple of years will result in the only Flagship missions I can count on still being alert enough to care about. It made the decisions very personal.

For me, this is an avocation (but one that has persisted since I saw the first Viking surface image on the front page of my newspaper so long ago), but for the scientists, all but the youngest realize that this is their one shot at a mission that will return data during their professional careers. This is what happens when we wait ~20 years between Flagship new starts.

[nprev]

I can't think of any mission that could come in at half the budget that could do useful science at Jupiter.

Kind of why I'm prodding this, also acknowledging that my odds of seeing another Flagship aren't great (about to turn 45 here); I want more!!!

One of the reasons for the cost caps seems to be best stated as "deprivation drives innovation". I don't really agree with that idea, but if the paradigm can indeed be effectively utilized then hopefully the planetary science community can do so.

EDIT: May have strayed too far into the policy & strategy region over the last few posts. Admins, please do what you feel is appropriate...

[lyford]

I made the sad realization recently that the next Flagship mission would arrive at its target someplace between by 65th and 70th birthday.

By then the pain of waiting may be assuaged by the instant brain implant direct to sensor download link that JPL will providing the members of UMSF.com in 2025

[JRehling]

I think the key question, which may come down more to faith than evidence, is: How much more favorable is the very best spot on Europa for landed exploration than the best spot we now know of? Is it possible that if we sent a lander to the best spot we know of now that it would land in an area that last received salty/silty flooding ten million years ago, but if we looked harder we would find a spot that last received salty/silty flooding ten years ago? Or 100? Or... whatever?

This is the main value proposition for a Europa orbiter. If Europa is basically homogeneous on a regional scale (obviously, on a local scale, it is not), then we will gain comparatively little from orbital reconnaissance in detail. But if there is one special place (or 10 or 20 of them) where we get better access to the ocean below (either in terms of a very thin spot in the ice for direct access, or just a much fresher patch of surface ice), then there is tremendous value in mapping the hell out of Europa at great resolution before sending something up there [down there] for a taste.

There's no doubt that Europa is going to be vastly more isotropic than Titan. Chromatically, Europa is almost a two-color world, with every spot on the surface distinguished by how much dark stuff is in the ice, and a simple metric that probably correlates with that would be the age of every spot. Think of the Earth -- we have crust that is millions of years old, and we have crust that is 26 years old (Mt. St. Helens) or as fresh as yesterday. But those new areas are very small, and wouldn't turn up after just a few flybys.

Titan will be wonderfully more complex than Europa, and is an irresistible target for future flagship missions, and if there were only going to be one more outer solar system mission ever, I would consider Titan the best choice. But as part of a sequence, I think it makes more sense to visit Europa next, then Titan, and then possibly Europa for the mission after that. Or, to direct the competition elsewhere, I might say that when we have gone further down the road of exhausting possible flagship missions to Mars, that Europa might merit some or most of the "astrobiology" coffer that Mars is now monopolizing.

[belleraphon1]

We're straying to the old Jovian-Saturnian system debate once again, which seems to come down to personal preference biasing everyone's opinions so we'll never all agree on what should be explored first.

ugordan... yes I kinda felt my original note really should have been in the OPAG thread. And you are right, we all have our own bias..... I do not see going back to Jupiter unless Europa is the utlimate focus.

I cannot see how to explore the outer solar system at less than $1billion. And if you are going to spend that kind of money, you cannot justify a Discovery class mission style that looks at just a small aspect of the scientific questions that beg data.

We can all hope for a day when nanobots can be launched, driven by nuclear rockets, on fast direct trajectories to there outer
destinations. For now we have to work with chemical rockets hurling heavy payloads.

I would love to see further exploration of all the outer planets (Uranus and Neptune beg to be orbited and probed). But the reality is, if we are going to launch any new outer planet mission soon, the technology and TIME is right to go back to Jupiter/Europa.

In the mean time, CASSINI will continue to refine our picture of Titan and Enceladus. We have a chance to watch seasons change on a world as complex as Earth. Let's enjoy the ride!

nprev, I love Titan, too!!!

Craig

[vjkane]

John, as usual, nails the subject, at least as I see it.

I think the key question, which may come down more to faith than evidence, is: How much more favorable is the very best spot on Europa for landed exploration than the best spot we now know of?

In our lifetimes (or at least mine), we won't have the technology or money to have a probe melt all the way through the ice to reach Europa's ocean. Given this, an Europan lander has to find a place that (1) has subsurface material at or very, very close to the surface and (2) can be landed on with a high probability of the lander surviving. To me, this is the goal of the Europa orbiter -- find those sweet spots. Hence, the orbiter has to have a robust (read heavy, power hungry, and bit intensive) instrument suite to find those spots.

I think the goal of a Europa lander is far enough out that I would not favor a Europa-only mission. (Plus there is every chance that the sweet spot for landing doesn't exist: where surface material is near the surface, if such places exist, the terrain may be impossible to land in. If this is the only justification for the mission, it is easy to get skunked.) If the Europa orbiter also does *a lot* of Jovian science, too, then I could favor this mission. Europa plus a dedicated Ganymede campaign, plus Io studies (with a big camera) and maybe a flyby or two, plus Jupiter atmospheric studies, plus maybe magnetospheric studies starts to sound pretty interesting.

Titan will be wonderfully more complex than Europa, and is an irresistible target for future flagship missions, and if there were only going to be one more outer solar system mission ever, I would consider Titan the best choice. But as part of a sequence, I think it makes more sense to visit Europa next, then Titan, and then possibly Europa for the mission after that.

Again, I agree with John. The Europa mission technology has more than a decade of technology development. A Titan mission will be far more robust with a decade of technology development. So, even though it means that I am not likely to see the final mission(s) in the sequence, I think that Jupiter now, then Titan (with that decade of technology development so it's the best damn mission the money can buy!!!), then back to Europa if the Europa orbiter found those sweet spots for landing. This is the manager in me speaking.

But if there is only to be one outer planet flagship mission, do Titan! It is the most interesting body in the outer solar system, in my opinion. This is the (armchair) explorer in me speaking.