Titan Atmospheric & Surface Chemistry Options

[Juramike]

Well, if the ice was really fractured and porous (IIRC, Janssen et al had it at organics + fractured, so if it is ice it would need to be REALLY porous), and it was coated with some organic gunk, then it might fit the data.

The coating could happen during erosional tumbling. Kinda like breaded chicken. So the coating could be thin, which gives the IR signature. The high porosity ices gives the low dielectric constant. That's one possibility.

As to actual compounds for such a coating, probably difficult to identify from just the limited IR. It could be a realy complex mixture.
If I had to guess functional groups, I'd wave my arms and guess aromatcs, alkenes, alkynes, nitriles, (guanidines? Amidines?), imines, amines, and hydrocarbons, and polymerized things. I'd exclude carboxylic acids, amides, ketones, aldehydes, ethers, and alcohols.

[titanicrivers]

An interesting paper was published in Nature today by the CIRCS (composite infrared spectrometer) team members concerning suprisingly rapid (for Titan) seasonal changes in the South Polar upper atmosphere infrared spectra. Link to the paper found here http://www.nature.com/nature/journal/v491/...ature11611.html
JPL summary article found here
http://www.jpl.nasa.gov/news/news.php?release=2012-374

[antipode]

Many wont have access, but the Icarus abstract really says it all:

Does Ice Float in Titan’s Lakes and Seas?
Jason D. Hofgartner, Jonathan I. Lunine
Department of Astronomy and Center for Radiophysics and Space Research, Cornell
University, Ithaca, NY 14853, USA

Abstract
We model Titan’s lakes and seas as methane-ethane-nitrogen systems and
model the buoyancy of solids in these systems assuming thermodynamic
equilibrium. We find that ice will float in methane–rich lakes for all temperatures
below the freezing point of pure methane and that ice will also
float in ethane–rich seas provided the ice has an air porosity of greater than
5% by volume.
Keywords: Titan, Titan, Surface

P

[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.