Interesting Titan conference last year Options

[Guest_BruceMoomaw_*]

I don't know if anyone has mentioned this, but last year there was a conference on Cassini/Huygens' Titan findings in Crete ( http://www.lpl.arizona.edu/titanconference/ ), which I only recently found out about. I hven't scanned through all the abstracts yet (and some complete works have been added to the site), but two interesting ones have jumped out at me.

(1) Michael Brown's "The Seasonal Hydrological Cycle on Titan" ( http://www.lpl.arizona.edu/titanconference...ts2/abs.063.pdf ): "We examine the evidence that Titan experiences a seasonal hydrological cycle. Based on the prevalence of south polar clouds during southern summer solstice, Brown et al. (2002) suggested that convection and cloud activity and thus likely precipitation is caused by solar heating of the surface of Titan and thus should occur preferentially at the latitude of maximum insolation. In the current season, as Titan moves away from southern summer solstice, the insolation peak is beginning to move away from the pole. The recent appearance of temperature latitude clouds (Roe et al. 2005) was suggested to be possibly related to this seasonal change. We examine evidence for the onset of the clouds and discuss possible changes taking place in the south polar cloud systems over this time period. A true understanding of seasonal variation will not come until we have observed Titan over a significant range of seasons. We discuss earlier images and spectra of Titan taken at different seasons and examine their implications for seasonal change. Finally we explore the evidence for liquid surfaces on Titan and discuss the full hydrological cycle in its possibly seasonal context. "

(2) An absolutely marvelous pictorial summary of the DISR images ( http://www.lpl.arizona.edu/titanconference...ts2/wrk.026.pdf ), complete with information I haven't seen anywhere else in the 11 months since this conference was held.

One of the items mentioned is the fact that the images as presented are really very misleading in their overstatement of the difference in darkness between the channel bottoms and the surrounding "light terrain", which is only about 3%. Bjorn Grieger has concluded at this year's EGU meeting ( http://www.cosis.net/abstracts/EGU06/08846/EGU06-J-08846.pdf ) that the haze effects atually lead this contrast to be understated -- "While DISR images of the riverbed area originally exhibit a contrast of a few per cent, the corrected contrast of true surface brightness is 10–20%" -- but he also concludes that, even so, "We find that a moderate terrain with slopes of up to 20 degrees yields surface brightness variations which are comparable in magnitude to the observations. We present models for the elevation profile of Titan river beds that can reproduce the observed brightness profiles without assuming local variations in surface albedo, i. e., without any 'dark stuff' in the river beds."

Another item in the 2005 conference presentation (pg. 16) is the "Runway", the startlingly straight drainage channel (actually, just the most obvious one of three seen by Huygens) which has a strip of raised lighter material on either side (with very short drainage channels trickling off its flanks), and which seems to be the product of cryovolcanism. I hadn't realized until now what a resemblance this thing bears to some of the raised ridges on Europa, complete with frequent single or double channels down their centers. Is the formation process similar?
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Also, Sushil Atreya, Hasso Niemann et al have just put onto the Web an advance copy of their paper on "Titan's Methane Cycle" scheduled for a near future issue of "Planetary and Space Science" ( http://www-personal.umich.edu/~atreya/Arti...tan_Methane.pdf ). Very informative all the way around, but perhaps the two most interesting items are (1) their conclusion that ethane production in Titan's atmosphere has been seriously overestimated, and that it's actually produced in amounts just comparable to the other smog rather than being several times greater; and (2) their calculation that Titan, judging from Cassini's SAR, resurfaces itself cryovolcanically at 5 or 6 times the rate at which organic smog is dumped onto its surface -- which would seem to support my speculation that the strange very high abundance of benzene and cyanogen on Titan's surface (and the shortage of acetylene) compared to what was expected may possibly be due to the fact that the descended smog is carried deep into Titan's subsurface by its crustal cycling and carried all the way down to Titan's subsurface water/ammonia ocean, where its compounds may undergo very extensive chemical changes before being expelled back up onto the surface.

[JRehling]

Also, Sushil Atreya, Hasso Niemann et al have just put onto the Web an advance copy of their paper on "Titan's Methane Cycle" scheduled for a near future issue of "Planetary and Space Science" ( http://www-personal.umich.edu/~atreya/Arti...tan_Methane.pdf ). Very informative all the way around, but perhaps the two most interesting items are (1) their conclusion that ethane production in Titan's atmosphere has been seriously overestimated, and that it's actually produced in amounts just comparable to the other smog rather than being several times greater; and (2) their calculation that Titan, judging from Cassini's SAR, resurfaces itself cryovolcanically at 5 or 6 times the rate at which organic smog is dumped onto its surface -- which would seem to support my speculation that the strange very high abundance of benzene and cyanogen on Titan's surface (and the shortage of acetylene) compared to what was expected may possibly be due to the fact that the descended smog is carried deep into Titan's subsurface by its crustal cycling and carried all the way down to Titan's subsurface water/ammonia ocean, where its compounds may undergo very extensive chemical changes before being expelled back up onto the surface.

You know, sometime back in the day, I suggested something like this and you immediately dismissed it... I've been unable to search for it, since I can only narrow it down to sometime 2004-mid 2005.

[Guest_BruceMoomaw_*]

Hmmm. I don't remember dismissing such an argument, but then I have a self-editing memory where faux-pas are concerned. Was it on this website?

Meanwhile, I've found another document (reference later) which says that the rate of cryovolcanic resurfacing of Titan is 'an order of magnitude" greater than the rate at which organic smog settles to its surface, implying (even if that resurfacing is limited only to some parts of Titan) that this could be a really major factor in determining Titan's surface chemistry.

HOWEVER, on taking another look at those raw GCMS graphs of what Huygens found in the vapors on Titan's surface in Niemann's December "Nature" article, I've also been struck with what really tiny amounts of cyanogen and benzene vapors Huygens detected relative to the amounts of ethane and (maybe) acetylene vapors it detected. (The fact that those graphs are set up logarithmically makes the visual appearance of the graphs awfully deceptive to my eye -- especially since you have to enlarge the hell out of the damn things just to read them properly.) So, until I know more, it may have been wildly premature for me to say -- at all -- that the amounts of benzene and cyanogen were wildly out of proportion to what had been expected.