[X] My Assistant

[titanicrivers]

A Rev 165 parting NAC view of Titan shows Adiri well. There appears to be very little left of the post "Arrow Storm" white spots that persisted into 2011 and then faded. The figure shows the enhanced cropped view of Titan and Adiri from 5/7/2012 with 3 views of Adiri from 2011. The exact nature of the bright spots is still debated.... a runoff effect from methane rain on relative highlands of Adiri might explain the lack of initial dark changes seen elsewhere (in presumably lowland areas in Belet and Yalaing Terra). Bright avalanche effects can be seen in terrestial mountain chains after torrential rainstorms (the Adirondack mountains in NY contain such examples) perhaps analagous to the bright spots of Adiri.
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Edit: An image depicting some landslides in the Adirondacks in 2011 is shown below
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(MOD NOTE: Moved all posts after this one re Titan surface chemistry to new topic created for that purpose.)

[JRehling]

The nature of the bright surface amounting to most of Titan's surface is entirely uncertain. Some of the main things we know are:

- It has a thickness between very thin (micrometers) and about 100 meters.

- If you name just about any substance expected to condense out of Titan's atmosphere, it's not it. (Spectral signal doesn't match.)

- On the VIMS dark "blue" plains where Huygens landed, the spectral signal of the bright terrain is a component that is most intense near the shoreline.

Titan has subdued topography, but if this area resembles the highlands near the Huygens landing site, there might not be vast avalanches, but crumbling on a small scale which can be significant when the layers are so small. Equatorial areas on Titan almost certainly get rainfall quite rarely, then catastrophic deluges. So models that seem plausible might include:

1) Thin sheets of dark dune material that accumulated for 10s or 100s of years as a minor albedo component being swept away by the rain, like washing a white car that hadn't had a carwash in 50 years.
2) Craggy features on a scale of centimeters or decimeters crumbling under the rainfall, reducing the shadows.

If we had a lander touch down on this sort of surface, show us the small scale morphology and analyze the chemistry of that bright coating (and what's below it), it would be a tremendous advance. Right now, we don't have a lot of information, and I'm not sure that the rest of Cassini's mission will fill in many of the blanks.

[marsbug]

My apologies for the thread necromancy, but this article (on getting tholin constituents to dissolve in liquid ethane via isopentane) didn't seem worth starting a thread on its own. I don't have the chemistry background to know if this is a process that would occur on Titan, but I think the melting point of isopentane is a little too high for Titan temperatures. However, if there is one pathway to get tholin to dissolve in liquid methane/ethane then perhaps there are others?

[ngunn]

the melting point of isopentane is a little too high for Titan temperatures.

At the surface yes, but not in the upper atmosphere where the haze condenses, so I (as a physicist) think your query/observation could be very relevant. I hope you get insightful replies on the chemistry.