[X] My Assistant

[Guest_AlexBlackwell_*]

Here's a recent paper from Geophysical Research Letters:

Elwood Madden, M. E.; Ulrich, S. M.; Onstott, T. C.; Phelps, T. J.
Salinity-induced hydrate dissociation: A mechanism for recent CH4 release on Mars
Geophys. Res. Lett., Vol. 34, No. 11, L11202
10.1029/2006GL029156
08 June 2007
Abstract

[Littlebit]

The results demonstrate that salinity increases alone result in a significant decrease in the predicted hydrate stability zone within the Martian subsurface and may be a driving force in CH4 hydrate destabilization.

Excellent hypothesis! CH4 hydrates are not that stable to start with. Increasing the salinity, the polarity, alienates non-polar molecules. This hypothesis assumes that subsurface water is still in a dynamic, wicking phase and is being depleted from the Martian regoth...I assume that is a known(?)

Could there be a similar process at Titan?

There is an interesting 'antilog' on Earth: The Great Salt Lake has been collecting and pickling organics (yes, including raw sewage), for many millenian. If the spring is exceptionally wet, the influx of fresh water 'unpickles' the sewage and the bacteria have a field day - releasing nearly explosive levels of methane and noxious aromatics.

[Guest_AlexBlackwell_*]

The May 2007 issue of Scientific American has a fairly informative article ("The Mystery of Methane on Mars and Titan") by Sushil Atreya, although at the moment it's behind a pay-per-view wall for non-subscribers. If you cannot obtain the magazine, check out Professor Atreya's website, especially the publications section, which contains links to several of his papers, talks, etc.

For those without access to Scientific American, Sushil Atreya has made available an excerpt (5.9 Mb PDF) from the article. Of course, the most interesting part of the article is not in the excerpt.

[silylene]

You know I would offer up photochemical pathways for producing methane gas in the Martian atmosphere. We had a nice thread on this a year ago in UMSF.com, and a couple of good threads on this subject in space.com forums.

Personally, I favor the photoreductive pathways, which only require metal oxide dust catalysts (TiO2) on the surface or suspended in air, CO2 and H20 vapor. Such dusts are common on the Martian surface, and dust devils continually re-suspend fresh dusts. Read the prior threads for citations.

I do want to finally note that CH4 production on Mars is highest in the surface areas with the highest insolation - a result one would expect to see if CH4 was being produced by a photochemical pathway.

[HughFromAlice]

Moved this post to new topic called Local Methane Plumes On Mars