Aerobot aims for Titan





Good news and I hope this happens but a more realistic timeframe is late next decade, more likely after an Europa mission.

The ideas for a flying probe were already discussed here.

Eventually amateur ideas could be useful for a space mission.

The Solar System Roadmap has this one pretty firmly pegged as the next "Small Flagship" solar system mission after the Europa Orbiter (although there's a small chance that a Venus surface explorer of some sort could supplant it). But this still means a launch in 2019 at earliest, and the National Science Foundation's review board has just said that the Roadmap schedule may be too optimistic.

Some related news today:







http://aviationnow.ecnext.com/free-scripts...ticle=TITA10035

With the price tag between $2-2.5 billion, they may need international support to get the funding that they need.

That price tag is ominous -- the Solar System Strategic Roadmap Committee had counted on being able to do this within the "Small Flagship" cost cap of $1.4 billion. Indeed, the most serious objection the NRC review panel had to the Roadmap was its confidence that both this mission and the following Venus Surface Explorer could be done within the Small Flagship cost cap. Instead it looks like the upper half of the "Large Flagship" cost band -- and we can afford only one of those per decade (if we skip all Small Flagships during that decade).

mmmmh ... alway the problem of cost.

Let us say:

-it is better an expensive mission which fulfills its goal, rather than a cheap one which is just present on the place.

-if there are money limitation, it is better to limit the number of mission rather than reducing the quality of each mission.

-The childish game of "competition" should left place to international cooperation. Many countries could provide subsystems, or even simply money or ground support. When we deal with billions, even only some millions can make a difference.

I think you mean rather than many reduced missions to different worlds. However, if there were an option for many (or two) aerobots to Titan within the same cap as one larger one, the option of many would be appealing. With Titan's winds being what they are, it may be impossible for an aerobot to travel very far north-south during its lifetime. Imagine Mars after only Viking 1 and Viking 2 -- even now we've seen five locations (with a few km roving in two of those). Huygens has shown us one location (and its surroundings) -- a single big aerobot would probably be sent either to the equatorial area, to overfly a variety of dark/light terrain (as Huygens did), or to the deep south, to investigate, eg, Mezzoramia. Two Titan aerobots would make even more sense than two MERs for Mars -- if only a 90-day mission can be guaranteed. Now, if a longer life were likely, a single craft might eventually travel long distances in latitude and perform a more complete overview of Titan. Unfortunately, a helium balloon is likely to have problems with longevity that a wheeled vehicle does not -- you can sit on wheels forever and not sustain much disrepair, while the helium supply can only decrease over time unless a zero-leak system can be guaranteed.

The Pioneer Venus solution was to send one probe that contained the superset of atmospheric instruments along with smaller ones that probed basic quantities in a variety of places. That could perhaps be an option at Titan, to have one aerobot along with several very minimal (no need to probe isotope ratios in multiple locations) sounding probes that drop in at a carefully-selected variety of locations. Of course, all of this talk pushes the cost higher and higher.

Which is why an RTG-heated hot-air balloon is so attractive!

This was already discussed. As for me I came with a part hot air baloon, par gaz baloon, shaped like a wing, and inflated with hydrogen (which can be produced on the spot). The wing/gaz baloon can fly faster than only a gaz baloon, while the hot air/gaz baloon can manoeuver near the groung far better than a wing. And there is no problem of helium leak. I am not sure at all that we cn garanty a zero leak for helium, at it can leak even through plastics, rubber, etc.

One expensive mission can of course include this option, as development costs are not reccurent, and the ground support too. The MER mission showed that it is a good choice, and it would be an even better choice if one of the craft fails.

I would be in favor of this mission as it would increase the chance of success with double the science. Without a significant international investment, however, I just don't see this happening. The price tag would be unbearably high.

A thought: if -- as the new Langley study suggests -- a flat-out
Titan aerobot mission that would cruise along and periodically scoop up
surface samples for organic analysis is indeed prohibitively expensive at $2
to $2.5 billion, would a lower-cost mission be worthwhile consisting of a
stationary lander that touches down on one such dome -- where we're most
likely to find complex water-created organics -- combined with a small
passive balloon that drifts along providing aerial images of Titan's
surface? We clearly need much better images of its surface formations than
we're going to get from either Cassini or Huygens in order to properly
understand this place. (Relaying back images from the latter without a Titan orbiter, however, might be unworkable.)

Here are the two Titan Mission Concepts presented at the OPAG meeting thanks to the link posted by Bruce:

Titan Vision Study 1
Titan Vision Study 2

Lunine is suggesting a self-propelled airship that would fit within the New Frontier Mission cost cap of ~$750M. This price tag I believe would leave out an orbiter. Langley is proposing a similar airship that includes an orbiter. This of course would fall under the Flagship Mission cost cap, although Langley doesn't provide an estimate on the cost except that it exceeds the $700M limit. The general consensus is to go with some sort of aerial platform, most likely an airship or blimp. The question is whether there will be a complementary orbiter, which I think is necessary because we need high resolution global coverage of Titan. They need to find a way to somehow bring the total cost down to $1.5B or less from the original $2-2.5B estimate.

I intend to do a little more grilling of the OPAG people (especially Lorenz) about these Titan studies -- the debate over what to do about Titan was clearly the dominant theme of this OPAG meeting. (There was barely any discussion of Europa; the decision seems to have been firmly reahced by NASA to go on with Europa orbiter as the next big non-Mars planetary mission, and the only remaining questions are whether they can cram a small lander onto it and whether they should collaborate with the ESA.)

The Titan Working Group also featured a brief summary ( http://www.lpi.usra.edu/opag/oct_05_meetin...an_work_grp.pdf ) of the examination of the two Titan mission concepts presented at the last OPAG meeting: a surface rover, and an orbiter with some small lander or flyer of unspecified type. They take a very dim view of a Titan surface rover -- it can't cover enough ground, especially on that rugged terrain. But they think an orbiter with some small in-situ package of unspecified sort -- stationary lander, or maybe drifting and non-landing balloon? -- might be a good and affordable first step toward later exploration

However, the other affordable concept for a first mission seems to be the fallback version of the "Titan Organics Explorer" described in the first of the two newest OPAG mission studies: instead of a powered hydrogen-filled blimp, a drifting, wind-driven Montgolfiere balloon inflated by heat from the same RTG that powers it, which might be doable "within a New Frontiers budget". The big question is how such a balloon could identify and touch down at good sites for surface organics analysis -- it might have to include an awful lot of onboard autonomous scientific judgement, since it couldn't actively inspect a possible site and then hover there waiting for orders from Earth. As I say, I intend to look into all this further.

But note Slide #13 of that presentation -- they are explicitly mentioning a search for honest-to-God Titanian life, not just for interesting prebiotic chemicals.

Can an orbiter do high resolution global coverage of Titan? Above and beyond what Cassini will perform?

In IR, I think the answer will be: marginally better. And that would make it hard to validate a high price tag.

Note that the limit on the resolution that ISS is returning has nothing to do with the power of the camera -- the blurring effects of the atmosphere are the bottleneck. Also, it is not possible to dip much lower than Cassini does, because the atmosphere would quickly degrade a lower orbit. The only way to beat Cassini coverage is to find a better spectral hole than ISS exploits. In fact, VIMS does this, although it presents other constraints.

You may be stating that ISS's resolution is high, but not broad enough spatially. And at present, that is true, but as the extended mission goes on, the coverage by ISS should end up really very extensive -- we are only a fraction of the way into the primary mission. Unless seasonal/orbital resonances that I'm not aware of prohibit coverage of large areas, we should, before 2020, have Titan mapped nearly as well as is possible with the 938 nm filter.

Now a superior radar mapping, at higher cost, is always possible. But nothing going to Titan would ever touch the Shuttle-based radar mapping of Earth, which provided better than 30 m/pix resolution... but was orbiting 2.5x closer to Earth than any orbiter can get to Titan. So even an awesome (-ly expensive) radar mapper would only double or treble Cassini's resolution. That's a lot of buck for the bang.

I think the best bang for the buck will be to get excellent detail mapping from an aerobot that wraps around the globe a couple of times at different latitude, giving us some outstanding noodles that no orbiter could touch (unless it's a massive radar orbiter).

JHReling asks: "Can an orbiter do high resolution global coverage of Titan? Above and beyond what Cassini will perform?
and answeres himself:
"In IR, I think the answer will be: marginally better. And that would make it hard to validate a high price tag.

Raw VIMS images show the surface with high contrast at around 2 micrometers. At the near-IR wavelengths the CCD imaging can see, around 1 micrometer, the Titan haze is effectively nearly white and scatters, rather than absorbs light coming up from the surface. At the longer wavelengths, that will be far less of a problem. Modern CCD-Equivalent camera chips exist now (they didn't when Cassini was being designed) and should be able to get 100 meter or maybe better optical imaging of the surface.

If you go out to 5 micrometers, there's an infrared spectral window where most outer planet reducing atmosphere gasses are transparent: That's the window that spectacularly shows the hotspots on Jupiter like the one Galileo's probe unfortunately descended into. Surface imaging would be unimpeeded by atmosphere gas at 5 micrometers, and haze effects minimal. The only problem, illustrated by Cassini VIMS data is that the solar illumination drops sharply toward 5 micrometers, and long exposures, probably image motion compensation, would be needed. A chilled detector would certainly help. With a decently large aperture, you might get 25 meter resolution or so. The haze scattering should be really minimal at 5 micrometers. Of course, diffraction limits reduce resolution for a given aperture as you go longer and lnoger in wavelength.

One problem with mapping Titan via aerobot: the winds are directly west-to-east right down to within 8 km of the surface (at which point, judging from Huygens, their direction seems to be affected by local terrain in unpredictable ways). So any aerobot that changes latitudes has to be extensively powered in order to do so, which will sharply raise its own expense. (Note that the powered aerobot in the second of the two new OPAG reports would be entirely for surface mapping rather than for obtaining and analyzing surface samples -- its surface studies would be limited to dropping one tiny lander containing only 3 kg of science instruments.)

There seems to be a consensus that the top science priority at Titan by far is to try to find complex organics that have been created by exposure to liquid water, and analyze them. The question is how we find such sites. Can we locate good candidates just using Cassini's data, do we need an orbital survey, or do we need an aerial survey -- and in the latter case, should the survey aerobot itself actually make repeated landings to collect samples? I submit that we won't know how to answer this question until Cassini gives us a lot more mapping of Titan's topography, along with whatever limited surface compositional mapping we can get through Titan's sparse set of near-IR spectral windows. Until we get that additional mapping data from Cassini, it is still seriously premature to even start to settle on the best design for the next Titan mission (especially given our limited funds). It's quite possible that Cassini will in the future turn up some place on Titan's surface which is beyond reasonable doubt the site of major water cryovolcanism, in which case that immediately becomes candidate Number One for the next Titan mission, and mapping Titan further becomes lower priority.

I am sure it has been discussed before, but just to reiterate: A helicopter would work better in Titan's thick air than a balloon.

Thinking of electric propulsion in deep space, I wonder if a very low "thrust" mechanism on an aerobot would suffice. Let's say you're mapping noodles that are 5 km wide, and your only need is to shift 5 km to the north sometime during the circumnavigation of Titan -- that's a very small differential per unit time. Cosine very near to 1. We may be so blinded by fancy technology as to forget that something like a rudder could do the trick. In fact, I would find it hard to believe that we could pinpoint an unfortunate, data-duplicating rendezvous 360 degrees on the other side if we tried, no matter how regular the winds. Brownian motion might even do the trick.

Another thought is how to organize such a mission around the lengthy nights. It would, on average, take two loops to see everything in daytime, so the problem may even reduce to the need to displace 5 km laterally after 720 degrees of looping. I think, all told, a modest approach like a rudder could move the noodles even if we wanted them not to be adjacent.

A helicopter would be easier to navigate and allow for the most science to be done. The only problem is that it hasn't been tested yet (check out slide 15 from Langley's presentation). They have yet to develop a propulsion system that would be ideal for Titan's environment. But it hasn't been ruled out yet so we may still see it happening. In fact, Ralph Lorenz is one of the biggest proponents of sending a helicopter to Titan.

I still wonder whether or not we ought to be careful about waste heat from any probes we send to Titan. It's a cryogenic environment, and tooling around -- even a click or two up in the air -- in a relatively superheated craft will inevitably alter the environment we're trying to observe. And if there *is* some form of life on Titan, our probe might induce a vast die-off.

So, I think the matter of waste heat ought to be at least considered when designing a Titan probe.

-the other Doug

On the other hand, waste heat may eventually lead to the blooming of some lifeform never before seen on Titan.

I'm not sure what time scale of "eventually" that would be, but it's hard to imagine such an exuberant theory of biogenesis that would involve timescales overlapping with how long a probe would stay warm and spatial scales so small.

I think the concern is that a warm probe would cause chemical alteration of the immediate vicinity and thereby gather data (eg, compositional measurements) atypical of Titan. A car-sized probe wouldn't have much prospect for actually altering Titan. No effects at all would show up beyond a few meters, and for more than a few decades, and it would be quite a hypothesis that new life could arise in such a small and short-lived "lab". If it were so, we could replace astrobiology interestingly with controlled experiments on Earth.

Put another way, I don't think we've seen new lifeforms arise near new and unnatural sources of heating on Earth these past few decades (say, the "eternal flame" at JFK's grave). I doubt if anyone would even think to check. And a probe wouldn't stay warm a lot longer than that. Moreover, it wouldn't be as much warmer than Titan's ambient conditions than fire is warmer than Arlington Cemetary's natural conditions.

So we can presume that the warmer body of the Huygens lander did not spawn the growth of any Titanian life forms.

Or did it....

If by growth you mean biogenesis, I would bet my life against that.

If by growth you mean evolution of existing life forms into new life forms, I would also bet my life against that.

The time scales are just orders of magnitudes off.

If Titan has life forms that are widespread but dormant, with added heat being the thing that revives them, then Huygens certainly would have spawned a short period of revival on that site... then they would return to their freeze. But why are we discussing something so far on the other side of Occam's Razor? Let's handle one or two "if"s at a time.

One could argue that Titan has conceivably not experienced a site of sustained heat (of the level generated by some sort of hypothetical probe), and that therefore no one really knows what may or may not happen.

If some probe could somehow destroy all life on Titan, then presumably it could also create life on Titan as well.

As far as whether either hypothesis is likely, who can say (personally, I wasn't around when life first arose on Earth..), but I'd certainly much rather that we create life on Titan than destroy it. And, regardless, from everything I've seen about life on Earth, it's quite hard to utterly destroy once it exists. Really, if you take the whole 'we might destroy pre-existing life' thing to its logical extreme, no one should ever do anything. Landing anything anywhere might cause some unknown chain reaction, etc. etc. la la la.

Therefore, I declare that we should land all the probes we want. You can't find out if life already exists without sending some sort of probe, and not probing things sounds criminally dull to me. Might as well end it all, mate.

Doesn't the rudder approach require two different velocities at an interface to work correctly? After all, ships use the keel and rudder to use the ocean's inertia to change the direction of the wind's force applied to the sails. Think of a submarine without propulsion in a current, changing the direction of the rudder wouldn't accomplish anything. If you could deploy an aerobot that interfaces two different winds, ie a rudder on an aerobot + a "sail" some distance below it (or maybe a small ballon above it), it the wind differential can steer your aerobot. Even if the winds are in the same direction, so long as the speeds are different you could use the sail+rudder to drag you diagonally.

One couldn't really argue that. Titan has impact craters, and those involve the release of lots of heat. If our probe released that much heat, it would have destroyed Cape Canaveral before we placed it on the rocket.

I'm not sure what people are talking about here. We're talking about a minor electrical source here, not an arsenal of hydrogen bombs. All the electrical power on all of the spacecraft ever flown wouldn't blast a big crater into Titan. There's no doubt about this.

Yes -- biogenesis ain't THAT automatic and quick a process. There is a consensus that, on Earth, it took a favorable environment for a very long time (tens of millions of years, at least) over the entire surface of Earth for self-replicating molecules to turn up on even one place on the planet. The idea that it could occur on Titan in a matter of days in a single spot warmed by a probe's body is, to put it flatly but accurately, ridiculous.

As for using a helicopter to explore Titan on the next mission, the trouble is limited range. It seems likely that we are going to want some kind of vehicle that can map very large areas of the Titanian surface -- whether it's an orbiter, a non-landing aerobot, or an aerobot that does occasionally land and take samples. A helicopter (quite apart from its high cost) would be limited to sampling one area just a few dozen or hundred km across; if no interesting substances happen to exist on the surface in that region, you're out of luck. Much better to leave it as the next step.

I'll say heat + some other unrecognized variable, then, like a unique material on the probe, the release of radiation, etc. etc. If you can calculate all the possible variations of every possible variable and declare that it's utterly impossible that life could arise on Titan as a result of some Earthly probe landing on it or flying near it, then show me the proof and I'll give you $1,000,000,000,000.

It's also not "utterly impossible" that Bush botched the Iraq War because he's been possessed by evil aliens from outer space, but the probabilities seem to be against it. Still, prove that THAT'S impossible, Mike, and I'll give YOU $1,000,000,000,000. Ditto for a salt shaker exploding spontaneously becaue all its atoms just happen to jiggle in the right direction at the right time by pure chance. So can we knock off the silly irrelevancies and speak in terms of common-sense probability?

No matter what type of influx of energy or new chemicals triggers a chemical reaction, it certainly takes an extremely long time for something as complicated and pure-chance unlikely as the creation of a self-replicating molecule to occur anywhere -- and it probably has to occur in a large number of intermediate chemical stages that themselves require a long period of time for those intermediate stages to finish creating the chemical groundwork for the next stage of the process. If that wasn't the case, spontaneous generation would be bustin' out all over the Earth right now, as a result both of natural processes and of the awesome set of new chemical reactions set off by humanity. Ain't happening. So...

I suppose the only real way to know is to wait and see what happens.

Agreed. The games of enumerating and dissecting things that cannot be strictly disproven takes up an interesting page in a philosophy text but isn't planetary science.

Once you can prove beyond a doubt that something is true, everybody knows already. Pretty boring if you ask me..

There are interesting possibilities that are not utter flights of fancy. Most interesting discussions fall into that category.

Having some experience with helicopters I would say it is an insane idea trying to build one to operate on Titan. Helicopters are mechanically complex, highly stressed, not naturally stable and power hungry. They can be rather challenging to maintain and operate even here on Earth.

My mind boggles considering the complications of developing rotor blades, rotor hub, power trains, control systems etc etc etc that would work reliably and autonomously at cryogenic temperatures in a very imperfectly understood atmosphere.

A gyroplane (autogyro) is rather simpler, though it can't hover, but I am sure an airship is a much better solution. A "hot methane" solution seems attractive since it would not be time-limited by inevitable small leaks. "Hot hydrogen" would be even better if the H2 could be generated in some simple way from methane.
"Hot gas" baloons also can change altitudes simply by modulating the temperature of the gas, without having to expend (very limited) ballast.

A (rather large) RTG could be used both to heat the gas and provide power for a small propeller that would allow the craft to diverge a bit from direction of the wind. The propeller could either be made to swivel or a rudder be placed in its slipstream to allow some degree of directional control.

The idea that an aerobot could make (and survive) repeated touchdowns also seems highly optimistic to me unless there is normally dead flat calm near the surface (and the Huyghens data don't seem to indicate this). The surface also had better be quite flat.

"Why don't pilots like clouds?"
"Because there are rocks in some of them."


tty

Just to clarify my comments in re a relatively superheated probe floating about in Titan's atmosphere, descending to touch down in many different, widely separated places...

Let's say you were tasked with investigating Africa, and the easiest and most convenient way for you to do this would be to dispatch a large metal balloon that maintained an *exterior* temperature of, say, 400 degrees Celsius. You'd have relatively little effect landing it on the sands of north Africa -- although the sands would tend to melt a bit, and you'd have a harder time establishing the sands' physical characteristics in their natural state.

But everywhere you tried to land this thing in or near vegetation, you'd set fires. Depending on the climate, these fires could spread and have an impact far beyond your local landing site.

Now, it's not like Africa hasn't seen fire before. On Earth, you don't even need to wait for meteors to set fires, lightning does it all the time. But your exploration program would probably get un-funded because you're being irresponsible about destroying pieces (even little pieces) of the place you're trying to explore.

I freely admit that you're not going to set a forest fire on Titan. However, we do *not* understand the conditions on the surface of Titan well enough to be able to predict whether or not there is any kind of cryogenic *analog* to a forest fire that *can* be set off.

Yes, such effects would also occur naturally, for example, when a meteor strikes.

But that wouldn't make it *right* to go ahead and set off some "forest fires" of our own, completely unwittingly, in an attempt to explore Titan. Just as it would be irresponsible to use a superheated probe to explore Africa.

The reason the Africa scenario would be considered irresponsible is that we *know* such a thing would set off fires and damage the African environment, at least to some degree. And yet, we're talking about sending a relatively superheated probe to Titan, have it float in a mix of complex hydrocarbons at cryogenic temperatures, and have it touch down in dozens of places, possibly right on top of potentially complex hydrocarbon solids, taking measurements and images. And, as far as I can tell, *no one* has even *thought about* what effect these touchdowns might have on complex hydrocarbon structures (organic or not) that may have formed at the surface -- structures we want to examine, not destroy.

Don't get me wrong, I'm not saying we ought to abandon exploration of Titan. I just think that we ought not get so caught up in "go fever" that we don't at least think through some of the potential risks a given set of exploration strategies might impose on the world we want to examine.

-the other Doug

How about a "tumbleweed" rover for Titan:

http://www.jpl.nasa.gov/releases/2004/78.cfm

Either nuclear-powered (chemical batteries won't last long, just ask
Huygens) or how strong are the winds on the surface?

I agree, we should seek to avoid doing widespread damage to Titan with any probes we send, but ultimately, we can only predict so much. Certainly, I don't think we should send atomic bombs and set them off on Titan in order to 'see what happens' (though we seem to have done that many times on Earth....), but, really, who am I to say a forest fire in Africa might not ultimately be a good thing? In the short term, it seems bad, but in the long term, eh, I'm just not that psychic. Maybe somebody else is.

You can deride me for being 'too philosophical' if you like, but I fail to see how I'm wrong here.

As they said in the 1936 film Things to Come, based on work by H. G. Wells, humanity's destiny is "All the Universe, or nothing."

It is entirely possible that by the time we are really ready to explore Titan in-depth, we will have technologies and methods to study that alien moon with far less intrusiveness than we can muster now.

But explore and expand we must.

Agreed. And amen.

-the other Doug

You would certainly alter the immediate vicinity in many ways and places. And we can say that Huygens did heat its environment. It is possible that in doing so, we missed detecting an appreciable ratio of ethane vapor to methane vapor (because methane is more easily vaporized, and Huygens heated the ground around it, definitely vaporizing some methane).

Surely the Venus landers had an opposite effect, being cooler, from their descent, than the places they landed.

But I'm not so sure that this is inevitable. Cars have fire inside of them, but nothing on the body is hot (the tailpipe usually is). An RTG doesn't need an exhaust system, and while heat has to leak outside, it doesn't have to be concentrated in one firey spot. Moreover, I don't see why, in principle, an RTG would need to be much warmer than Titan's usual cryo-state. All you need is a temperature differential, not some absolute temperature requirement. The warmest part of a Titan RTG could be very cold.

On a global scale, certainly, if thermal load is all we're worrying about, some past meteor would have wreaked the same havoc. If there is a before and after state, then Titan is already in the after state.

African grassfires suggest a non-steady-state possibility. But only if grassfires are a natural thing in the first place. You couldn't trigger a grassfire anyplace they don't happen naturally. You might trigger one today that wouldn't have happened for 50 years. If that happens, we can say that we learned something astonishing... I think if you put this to 100 planetary scientists and asked them to bet on this, it would come out 100-0 against, but that's just my meta-bet.

Before the debate about UD ('Unintelligent Design') and biogenesis goes too far, perhaps it's worth mentioning that the Mars aerobot design recently described elsewhere - with the glider wing hung below a gas envelope - sounds like a winner for Titan!

Bob Shaw

Yeah, that is a possibility -- and one I had never thought of. Especially for a world with an atmosphere as dense as Titan's.

As for Mike's points: There is a gigantic gap between just studying things which we already know in advance are virtually certain to be true, and wasting time and effort studying things which are fantastically unlikely to occur. If the latter DO turn out to be possible after all, we can and should find out about that fact incrementally while probing other, more likely possibilities first. it's like John Rehling's analogy to the game of "20 Questions": You don't start out by immediately asking, "Is it Abraham Lincoln?"

And nobody that I know of is proposing dropping any A-bombs on Titan (although they certainly wouldn't do any scientific harm to it that they haven't done to Earth).

Look at that chart on page 13 of Lunine's presentation, though: they are already talking about seriously looking for honest-to-God biological compounds -- not just prebiotic ones -- on Titan. That is, they are talking about looking for evidence of actual life (albeit probably subsurface life) on the surface of Titan. That by itself is something I would have never have thought until now they'd do.

The simplest way to avoid damage/modification of the surface would seem to let the probe float at some altitude over the ground and lower some kind of a scoop, grab or corer on a line to acquire samples. The sample collector would be more or less at ambient temperature if it was kept hanging a few metres below the ship between samplings. The samply entry port and analysis area would have to be kept cooled as well (easy, there will be plenty of coolant around).
This would also avoid risky touchdowns. Of course you would need some kind of emergency jettison system (probably pyrotechnic) or you might end up being a tethered probe.

tty

Well, the other way is to have the exterior of the probe be about the same temperature as the environment. We weren't concerned about Viking's RTGs altering martian samples, and an earthly geologist doesn't worry about body temperature altering quartz -- although it would melt a snowflake.

Titan is close to the triple point of methane and close to the melting point of ethane, and for that, there may be a sensitivity concern, but I don't see why the exterior of a probe need be outside the range that would naturally occur on Titan. Huygens apparently was -- the increase in CH4 vapor after it landed makes that perfectly clear. That can be avoided. We could design an RTG-powered probe for Earth that would be able to pick up snow with ice-cold "hands", and we can do it for Titan.

Can it be avoided? The practicalities of designing machinery for extreme cold aren't trivial. For starters I'd have serious concerns about an RTG in a setup like this too - You might be able to design a lander with such "cold hands" but RTG's operate at only about 20% efficiency - the rest is waste heat _and_ the useful electricity is mostly eventually converted to heat in any case. You can certainly design some sort of surface bot where you keep all the hot bits out of direct contact with the surface but how do you deal with pumping all of that heat into the local atmosphere - which is very dense and probably in a state close to instability with regards to saturation of various volatile hydrocarbons.

You can't, and they're not going to try -- in fact, one popular idea is to use all that waste heat to inflate a Montgolfiere. There's no particular reason, as I understand it, to think that the resultant heat will seriously affect collected samples, though -- especially since the hot air will be rising. (In fact, the existence of such a convective atmosphere will increase the cooling rate, and thus the efficiency, of an RTG so much that they think in this case they can leave the radiator fins off it.)

Note also that a more serious version of the same problem exists for the proposed "Comet Cryogenic Sample Return" mission, which is supposed to keep its collected core sample at below 150 Kelvin throughout the entire trip back to Earth. They don't regard that problem as insurmountable, and I presume neither is this one.

Time to refloat this topic?
http://planetary.org/blog/article/00000568/
quote:
May. 6, 2006 | 10:46 PDT | 17:46 UTC
OPAG, Day 1: Hot-air ballooning on Titan
The next presentation at OPAG was given by Ralph Lorenz and Tom Spilker on a Titan Montgolfiere Mission Study. What's a Montgolfiere, you ask? Maybe you know but I didn't know that it's a hot-air balloon -- hot-air, that is, as opposed to... More»

Found this article interesting.

Mars, Venus, Titan - wherever there's air, we can explore by balloon