Family lore says that when my ancestors lived on Mars, the gullies were caused by giant ant lions who preyed on our pets. Of course, we left 'em behind when we crossed the plains and settled near a salty lake at the foot of Olympus Mons. Get the bug spray, Kim's losing it! (Been here far too long today...) -----Original Message----- From: Joe Bauman [mailto:bau@desnews.com] Sent: Thursday, December 11, 2003 3:41 PM To: Utah Astronomy Subject: RE: [Utah-astronomy] Mars closeup pics The problem I see with that theory is one would expect gullies in a steep crater wall to eventually fill in with dust or collapsing sides. But maybe the craters aren't really as steep as they look in these photos. -- Joe

I think the current theory is that it was water but several million years ago when Mars had more atmosphere. Clear Skies Don

-----Original Message----- From: utah-astronomy-bounces+djcolton=piol.com@mailman.xmission.com [mailto:utah-astronomy-bounces+djcolton=piol.com@mailman.xmission.com]On Behalf Of Chuck Hards Sent: Thursday, December 11, 2003 11:53 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] Mars closeup pics

Joe, liquid water would be affected more by the atmospheric pressure than the temperature, but other than that you've framed the debate nicely. Unfortunately, we need more data to speculate further.

The latest data points to massive quantities of water, frozen as ice in the top few meters of regolith.

Too soon to say what caused the channels IMO.

C.

--- Joe Bauman <bau@desnews.com> wrote:

...

A new subject for discussion, if anyon'e interested. In pictures like this --

http://www.msss.com/mars_images/moc/2003/12/11/index.html

...

-- we see evidence of channels on Mars that look as if water flowed fairly recently from the side of a crater. If the scale is accurate, the longest of these gullies seems to be about 800 meters long, or about half a mile. Much speculation has centered on the idea that these features, which seem to be fairly common, are evidence of water from some underground layer.

The questions I have are: if water were to thaw out, wouldn't the extremely thin atmosphere cause it to evaporate immediately? Or if it somehow flowed, wouldn't it quickly freeze again? And yet whatever it is continues for half a mile.

Maybe it's really water. Maybe parts of Mars are just saturated with frozen underground water that can thaw out and flow in copious quantities.

But here's another possibility I've come up with -- maybe it's fine solid material that happens to be extremely slippery and flows like water. What if it's a powdery volcanic ash layer? Would that flow well enough to look like water? Or could there be a field of big round boulders that periodically come loose and go tumbling downhill?

My problem with the water theory is mainly that Mars' atmospheric pressure is so low that I suspect water would boil at a very low temperature. Could anyone who knows the facts do some calculations?

Any thoughts the group would like to share would interest me greatly.

Thanks, friends -- Joe

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