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[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.

[Guest_BruceMoomaw_*]

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.

[JRehling]

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.)

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.