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Posted by: Juramike Dec 11 2010, 10:02 PM

Key Quote: "The Sotra area thus seems to be a leading candidate for a cryovolcanic field on Titan. "

AGU abstract for Randy Kirk's presentation on Tuesday:
http://adsabs.harvard.edu/abs/2010AGUFM.P22A..03K

(Serious bonus points for bilingual word play in the title: "La Sotra y las otras")

Posted by: ngunn Dec 11 2010, 11:10 PM

The quest for a convincing volcano becomes ever more desperate. I don't understand why the leakage of methane to the surface must be associated with recognisable eruptive landforms. If the tiger stripes of Enceladus were buried under a deep atmosphere they wouldn't be that obvious. There would be no temperature signature and the amount of material ejected wouldn't change what we see.

Posted by: nprev Dec 12 2010, 12:00 AM

It's understandable, though. The methane's got to be escaping from the interior in rather copious quantities, and therefore it's reasonable to postulate that there well might be large-scale cryovolcanic landforms to discover. Since we've never actually identified one of those (given that it's a wholly unfamiliar geological process to us and Titan's crustal composition & mechanical characteristics aren't understood in great detail), there's going to be an intensive search for things that look like terrestrial volcanic analogs.

Might well come to naught, but that would be a significant datum in itself.

Posted by: Juramike Dec 14 2010, 05:20 PM

YEAH, BABY!

http://photojournal.jpl.nasa.gov/catalog/PIA13695

Yeeee hawwwww!

Posted by: Paolo Dec 14 2010, 07:37 PM

out of curiosity, when were those radar swaths taken? during which flyby. I can't find this info

Posted by: Juramike Dec 14 2010, 07:54 PM

It is an overlap of T25 and T28 RADAR Swaths. T25 has the better Sotra Facula image.
T25: http://photojournal.jpl.nasa.gov/catalog/PIA09182</a>
T28: http://photojournal.jpl.nasa.gov/catalog/PIA09217

T25 was taken February 22, 2007
T28 was taken April 10, 2007

Posted by: Decepticon Dec 14 2010, 09:07 PM

Space.com has a article. Strangely enough there are using a Uranus moon Ariel image.

Maybe a small booboo.

http://www.space.com/scienceastronomy/titan-ice-volcano-cassini-101214.html

Posted by: Juramike Dec 14 2010, 09:42 PM

Universe Today has a much better article, including a great picture of a possible terrestrial analog:
http://www.universetoday.com/81709/string-of-peaks-on-titan-could-be-cryovolcanoes/

Posted by: ngunn Dec 14 2010, 09:48 PM

This is from Emily on twitter: "Kargel: Ammonia-water cryolava w/ methane, CO2 would make frothy, pumice-like deposits on Titan. Cool."

I'm not sure if this was referring to Sotra Facula, or from this other presentation: http://adsabs.harvard.edu/abs/2010AGUFM.P22A..02K

I just want to summmarise my three favourite reasons why the possibility of frothy, pumice-like deposits on Titan is really really cool.
1/ Their formation would be a direct consequence of Titan's thick atmosphere. Bubbles formed in a liquid exposed to a vacuum would expand indefinitely and burst. Only bubbles 'erupted' under an atmospheric lid can stop expanding and remain in the liquid long enough for it to freeze (or set solid for some other reason).
2/ They could act as crack fillers. Imagine a system of crustal fissures repeatedly opened and closed by tidal flexing for example. At each opening the filler-foam pours in and so the crack cannot fully close again. This is a way to produce crustal extension, conceivably contributing over time to the building of Titan's compressive mountain chains unlike anything observed on other icy moons.
3/ They could float on liquid methane. This would greatly assist their mobility across the landscape. They could form piles of flotsam bulldozed around the surface by flash floods, perhaps helping to form the beach- and moraine-like features at the Huygens landing site, and they would be relatively easily moved by winds too over both land and sea.

Posted by: Drkskywxlt Dec 15 2010, 01:19 AM

This was a good talk. Must be dramatic to stand at the bottom of the pit (caldera?) and look upward 3000m to the top of the mountain top.

Posted by: Webscientist Dec 16 2010, 09:10 AM

15 degrees south latitude, 40 degrees west longitude. So, it must be in the optical "H" of Fensal/Aztlan and more precisely in the optically-dark Aztlan. An irregular bright patch in Aztlan! Correct?
Have you precisely spotted Sotra Facula in the radar swaths ?

VIMS data tend to suggest multiple candidates for cryovolcanic activities, now: Sotra Facula, Hotei Arcus and the other "roughly" circular areas with a dark central feature (calderas or impact craters?). With more lucidity (or imagination),we may find the "Big One".

Sotra Facula, maybe a good place in the next centuries or millenia to go skiing (1000 meters or 600 miles tall).

Posted by: Webscientist Dec 16 2010, 09:12 AM

Soory not 600 miles, rather 3000 feet tall!

Posted by: titanicrivers Dec 18 2010, 07:34 PM

Yes, its been clearly identified in radar swaths T 25 and T 28 (see Juramike's post #6 above). Go to VP's Swath's website http://pirlwww.lpl.arizona.edu/~perry/RADAR/
and look for it in T25 part 1 where it has its best appearance. Juramike identified this as a volcano candidate quite a while ago! The graphic below shows Sotra Facula in the T 25 part 1 swath. The final frames of the animation use a color scheme from the Planetary Photojournal movie delineating the dunes and cryolava geological units. http://photojournal.jpl.nasa.gov/catalog/PIA13695

Edit: For those whose eyes can cross and focus, here's a 3D version

Posted by: DFortes Dec 19 2010, 01:00 AM

I'd like to point out that I predicted explosive cryovolcanism, and caldera-like ignimbritic deposits (with Sotra Facula in mind) in my 2007 paper - not that anyone ever takes a blind bit of notice...

http://dx.doi.org/10.1016/j.icarus.2006.11.002

Posted by: Juramike Dec 19 2010, 01:17 AM

Well, I noticed.

But...I though dielectric constant data and VIMS spectra recently (Clark, 2010) ruled out substantial amounts of ammonia on the surface.

Not knowing what Sotra is made of (spectroscopically it is Equatorial Bright terrain), but assuming it is mix of organics and ices, could shallow volcanism occur that only volatilizes and melts the organic component? And the water ice just goes along for the ride as an unmelted slurry?

Posted by: rlorenz Dec 20 2010, 01:51 AM

If stating that something were possible was the same as 'predicting'........... well, never mind. I still
have dibs from my 1996 PSS paper on pillow lava forming when a cryovolcano erupts in an ethane sea.... ;-)

But your notion that an explosive cryovolcanic eruption might occur when ammonia-water magma
encountered a methane clathrate deposit was surely suggested by Lunine and Stevenson in 1987 (IIRC they
talk about maars, although not the ash/ignimbrite specifically - but they didnt have to try to explain
the dune sands - which appear to be organic of photochemical origin anyway, not ice from volcanos...)