[X] My Assistant

[imipak]

New work (Pelletier, McEwen, Kolb and Kirk; 'Geology', March 2008) apparently suggests dry debris is a more likely candidate for producing gullies of the sort observed by HiRISE.

This seems to me a more naturally "Occam-friendly" explanation than convoluted scenarios involving frozen aquifers with ice plugs that burst from time to time. What do the experts make of it?


(Edit: sorry for the mangled topic title, BTW; I'd blame the software tools, but I know what that'd make me )

[djellison]

So 'it looks like' then - and to be fair, that's the conclusion Malin et.al. made from MOC imagery as well. No offense, but results of CFD study of HiRISE generated DEM's holds more water (pun intended) at this stage, imho.

The problem I have with the water theory is this. Where's it coming from? To be a squiring gun for millions, tens of million, hundreds of millions of years or more - to be doing it for as long as Mars has been as it is today - surely, any such reservoirs would have been exhaust in the significantly geological past. It's a one shot activity. Squirt - boil - evaporate - gone. I don't think we can realistically expect a water cycle to put that volume back into the soil.

What's going to be most interesting (and I'm surprised we've not seen it yet) is CRISM results of the 'outflow'.

In one forum I've been called a water-on-mars nut, and on another, a dry mars conspiracist. All I'm really after is facts and data to help us find out what Mars is really like.

[mcaplinger]

So 'it looks like' then - and to be fair, that's the conclusion Malin et.al. made from MOC imagery as well. No offense, but results of CFD study of HiRISE generated DEM's holds more water (pun intended) at this stage, imho.

The pretty pictures in the UofA press release aside,
in general I'd be skeptical of computer modeling results, as they can easily be based on flawed assumptions, initial conditions, be too oversimplified, etc. For one thing, I'm not sure how accurate the DEM was with all the albedo variations caused by the flow. Malin and Edgett did not arrive at their water conclusion lightly. Branching statistics as used in geomorphology is not just "it looks like"; go back and read their papers, especially the 2000 paper.