Huygens - The Follow-up Options

[SFJCody]

Is a Discovery class Titan lander/aerobot remotely conceivable?

It would be nice to see Cassini's relay capability get a second workout...

[gpurcell]

DISCOVERY class??? No way in Hell.

[tedstryk]

Not unless it was piggyback on some larger mission.

[lyford]

Unless you meant this Discovery class:


Sweet!

[SFJCody]

Perhaps China or India will become convinced that a Titan mission is necessary for increasing national prestige.

[djellison]

I certainly think a blimp or similar would be a wise idea - drifting during the long titanian day - and settling to the ground at night. In a world with a thick atmosphere and low gravity - Blimps work very VERY well

Problem is - it'd have to be RTG powered, so it'd have to be quite heavy - and thus very large - probably something like 1 - 1.5 tons to Titan - outside the scope of anything but the heaviest launch vehicles today - and even then, would require multiple flybys of multiple planets to get there.

Ideally you'd need a companion orbiter to relay - use electra technology relay in UHF - and get 100kbps from blimp to orbiter and orbiter to ground.

You could have a large heatshield of the blimp descent stage at the top/front of the spacecraft, and use it for Aerocapture at titan - saving a LOT on delta V

Doug

[tedstryk]

India and China in 30 years maybe, but right now they are struggling with designing basic lunar orbiters. Russia, even if it stopped being so poor, probably couldn't, as it has had a very difficult time with anything farther away than Venus. True, the Vegas lasted a while, but they have never had a deep space probe last more than around three years or so, and that was only rarely achieved. And I don't think there technology has improved too much. The Japanese also have had problems with longterm missions and probably could not afford to go-it-alone on a Titan mission. This leaves NASA and ESA. Given the political weight the anti-nuclear freaks carry in France and Germany, it would surprise me if ESA launched a probe with an RTG. So this leaves NASA.....or perhaps another NASA/ESA colaboration.

[David]

I certainly think a blimp or similar would be a wise idea - drifting during the long titanian day - and settling to the ground at night. In a world with a thick atmosphere and low gravity - Blimps work very VERY well

Do you mean a balloon (of whatever shape), not a blimp? I just ask because you use the word "drift", which is of course not what a blimp (a non-rigid dirigible airship) is supposed to do.

Because a blimp would have to contain gas at a higher pressure than that of Titan's atmosphere in order to keep its shape, it might be inferior to a rigid dirigible. On the other hand I suppose a heavier mix of gasses would provide greater lifting capability than on earth. But how do you generate and maintain the gas, given that there's always going to be some leakage?

What are the disadvantages of a light, fixed-wing remote-controlled drone aircraft? It seems unlikely that it would run into anything -- if we can discount the giant metal-eating Titanian bats.

[djellison]

Well - I was thinking a balloon - not a powered blimp

Doug

[SFJCody]

The Titan helicopter


Post-Cassini Exploration of Titan


Optimizing Science Return from Titan Aerial Explorers


TO FLY OR TO FLOAT?

[lyford]

What about a fleet of these?


You would need an orbiter of course to relay the data to, but these little guys would be able float and roll over any thing, maybe even get "air" every now and then. They serve as their own landing system as well!

Long term power would be an issue, but perhaps there could be some generator that could convert the rolling motion from the wind into electricity.

Or not!

For the curious:

South Pole Test homepage
Tumbleweed Press Release

[Guest_BruceMoomaw_*]

There has already been a great deal of design work put into a possible Cassini follow-up (especially considering how little we kenw about the surface!). And there seems to be a convergence on the idea that a "Flagship"-class mission -- that is, one costing about a billion dollars, like the originally planned chemically-propelled Europa Orbiter -- could be flown in the next decade, consisting of a small blimp (with some kind of surface sampling gear) accompanied by an orbiter for comm relay and mapping. One JPL engineer has even devised a scheme for an "Aerover" -- a combination rover-blimp, with four huge inflatable helium-filled tires (as have also frequently been proposed for later Mars rovers) which could periodically be augmented by an additional inflatable helium-filled bladder so that the rover could gain enough extra buoyancy to lift off the surface and take to the air again. A kind of Titanian flying monster truck.

But since the Solar System Decadal Survey recommends only one non-Mars Flagship-class Solar System mission per decade -- and Europa almost certainly has dibsies on the first one -- I imagine we won't see a follow-up Titan mission until the 2020s. And when we do get one -- espcially since one of its most important goals would be to study any areas which have recently had short-lived outbreaks of liquid water, to see what stimulative effect that has had on the local organic chemistry -- the more high-resolution mapping of Titan's surface we can do from space before dispatching another lander, the better. This is another argument for having Cassini focus intensely on Titan during at least part of its extended mission.

[tedstryk]

And indeed it should, after a few more icy satellite flybys, except of course if there is some great discovery at Enceladus that changes its priorities. Also, it will be interesting to see what happens once we know more about Titan's chemisty from Huygens and Cassini, and have better mapping. In a way, I am hoping JIMO hangs on another year or two....with some major discoveries, without a flyable Europa mission on the drawing board, Titan may leapfrog Europa in priority should major discoveries be made. Remember, when the decadal survey was done, for all we knew Titan could be a cratered, dead world with an atmosphere. Frankly, I think Io is the most interesting of the Jovian moons and I would put Ganymede and Europa in a tie. Europa's privledged status us due to the astrobiology folks who think they are going to find ET under the ice. Interesting moon, but not more than the other Galileans, except maybe dead old Callisto.

[SFJCody]

But since the Solar System Decadal Survey recommends only one non-Mars Flagship-class Solar System mission per decade -- and Europa almost certainly has dibsies on the first one -- I imagine we won't see a follow-up Titan mission until the 2020s.

That would be a great pity. A JGA to Saturn is possible for a spacecraft launched in the mid/late 2010s, but not for one launched in the 2020s. A similar opportunity does not reoccur until the 2030s.

The last time such a window was missed was in the late 50s/early 60s.

[Guest_BruceMoomaw_*]

First, the number of "shitheads" who think there's a serious chance of life under Europa's ice is very large indeed; see the National Research Council's reports specifically on that subject. (Indeed, the possibility of complex prebiotic compounds on Titan -- espeially in areas where cryovolcanism or big meteor impacts may have generated reservoirs of near-surface liquid water in its ice -- is by far the most important argument for exploring it.)

And a good case can be made that the discovery of Europan life might turn out to be far more scientifically important than the discovery of Martian life, since it's coming to be accepted that even if we do find evidence of present or fossil life on Mars, there's an excellent chance that we will never be able to determine whether it appeared there originally or whether it's just the descendants of Earth germs catapulted to Mars via meteorite. Or, perhaps, the opposite is true -- but in either case, we would still be unable to prove that life isn't after all the result of some incredibly unlikely chance event that just happened to occur on one world in this Solar System and then got transplanted to another. (Ths is a very real scientific possibility.) Meteorite exchanges between Europa and the inner worlds, however, are extremely rare. While they're not quite nonexistent, if we discover Europan life the odds will be extremely high that it did evolve separately, and so -- since life appeared independently on two worlds in one solar system -- we will be able to conclude with a high degree of certainty that it IS a common phenomenon in the Universe. (Moreover, if life ever did evolve on Europa, the odds that it's still around are much higher than on Mars, since there's no evidence that Europa's environment has gotten more hostile over time. )

As for the lack of a JGA opportunity to Saturn in the 2020s: this is nowhere near being a really serious stumbling block. A mission could use one or two Earth gravity assists -- plus, perhaps a solar-electric propulsion stage that would greatly acelerate the spacecraft in the inner System before being ejected during the trip out through the Asteroid Belt -- to reach Saturn in a very reasonable time without a boost from Jupiter. Moreover, the plans for a follow-up Titan mission usually call for it not to carry a big load of fuel to brake into orbit around Saturn (let alone Titan), but insted to just fly directly past Titan at low altitude and aerocapture itself directly from solar orbit into orbit around Titan, thus tremendously cutting down on the mass of fuel needed. (A pity we can't do that with Europa!) And such a spacecraft therefore wouldn't have to approach Saturn as slowly as Cassini did in order to slow itself into Saturn orbit -- it could race there as fast as the Voyagers did. (To do this, however, we do need very accurate data both on Titan's ephermeris and its atmospheric density profile, along with any changes over long periods of time in the latter -- still another reason for Cassini to observe Titan in detail during an extended mission.)