[X] My Assistant

[imran]

Aerobot aims for Titan

An intelligent floating robot could help to explore Saturn's moon Titan, following flight tests that prove it can survey large areas of land completely autonomously. The aerobot is even smart enough to avoid dangerous turbulence.

This summer, aerobot's team got further funding to develop a full mission proposal, which may lead to a launch in 2012.

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

[dvandorn]

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

[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...

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

[JRehling]

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.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.