A new class of avalanche scars on Mars.

[exoscientist]

Published in the March issue of the journal Icarus:<br /><br />A distinct class of avalanche scars on Mars.<br />Marguerite F. Gerstell, Oded Aharonson, and Norbert Schorghofer. <br />Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA <br />Received 26 July 2003; revised 10 November 2003. <br />Icarus , Volume 168, Issue 1 , March 2004, Pages 122-130 <br />http://dx.doi.org/10.1016/j.icarus.2003.11.005<br /><br /> I had earlier posted to sci.astro discussion of similar features:<br /><br />********************************************<br />From: Robert Clark (rgregoryclark@yahoo.com)<br />Subject: Mars gullies near equator? <br />Newsgroups: sci.astro, alt.sci.planetary, sci.physics, sci.geo.meteorology<br />Date: 2002-05-08 08:54:15 PST <br /> <br /><br />From the space bbs ISSDG · Inner Solar System Discussion Group,<br />http://groups.yahoo.com/group/ISSDG/ <br /><br />====================================<br />From: "bobbygc2001" <bobbygc2001@y... /> <br />Date: Thu May 2, 2002 4:56 pm<br />Subject: Martian gullies near equator?<br /> <br />Are these another example of the Malin/Edgett gullies:<br /><br />Floor of trough in Noctis Labyrinthus<br />http://ida.wr.usgs.gov/html/m10010/m1001062.html<br /><br />I'm referring to the light colored striping flowing down the side of <br />the slopes. These are not examples of the light and dark colored <br />streaks seen often on Mars, since the ones in this case have a depth <br />to them. <br />However, they could be due to dry sand flow. See for example this <br />page:<br /><br />Water on Mars?<br />http://the-light.com/mars/<br /><br />I was looking for a dendritic pattern that would suggest liquid <br />water flow, but this <div class="Discussion_UserSignature"> </div>

 

[exoscientist]

Compare this image I proposed:<br /><br />Floor of trough in Noctis Labyrinthus <br />http://ida.wr.usgs.gov/html/m10010/m1001062.html <br /><br />with this one in the paper:<br /><br />Olympus Mons aureole facies change <br />http://ida.wr.usgs.gov/fullres/divided/m03039/m0303927a.jpg<br /><br /> See the triangular scars at the bottom of this image. They are of a similar shape to the well-known dark streaks but they have a depth to them. The paper makes this more clear by blowing up the image.<br /> The authors suggest an origin due to dry debris flow. This may be true but it is interesting that most of the ones they found are near Olympus Mons. Recent research suggestd there may be relict ice from former glaciers on the slopes of large equatorial Martian volcanoes.<br /><br /><br /> Bob Clark <br /><br /><br /> <div class="Discussion_UserSignature"> </div>

 

[aaron38]

Wouldn't a low lying area where fog is known to develop be an exceptionally good landing choice for a rover?<br /><br />Are the fog areas just too small to be a landing target?<br /><br />I would think the nuclear rover should be sent there.

 

[CalliArcale]

Only if it's not solar powered. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[alexblackwell]

For those who didn't see my posting on the "old" board, and who may not have access to <i>Icarus</i>, a 664 Kb PDF reprint of the Gerstell <i>et al</i>. paper is available.

 

[exoscientist]

This image showing atmospheric temperature readings from MGS and the Opportunity rover shows the -40 C cut-off temperature for supercooled liquid water droplets may also apply to low lying clouds up to within 2km, 6000 ft:<br /><br />http://www.planetary.org/news/2004/images/opp_mgs-overflight_first-profile.jpg<br /><br /> Image from:<br /><br />MARS EXPLORATION ROVERS UPDATE <br />Spirit Arrives at Bonneville Crater; Opportunity Moves to Berry Bowl; and Both Rovers Turn 'Eyes' to the Skies<br />12 March 2004<br />http://www.planetary.org/news/2004/mer-update_04-03-12.html<br /><br /><br /> Bob Clark <div class="Discussion_UserSignature"> </div>