if you mean particulate regolith acting as a fluid to garner gully carvings, i find that very reaching a premise. that seems far more unrealistic and complicated an explanation than water flow. i know the premise is not necessarily your own, so don't take it personally. i don't fall into the camp that supports dry regolith acting as a fluid; not for this case anyway. the terminus and trough of the gullies is (to my layperson's eyes) exemplary of fluid dynamics due to liquid.
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again, i want to thank you, borman. your resources and references are boggling in volume. my respects to you. <br /><br />
Speaking of Jennifer heldmann's work, here is a paper by her from 2004. http://info.netscape.com/fwd/clk70srurl2/http://search.netscape.com/nscp_results.adp?query=<br /><br />I believe she has another paper in press with Icarus.<br /><br />Jon<br /><br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>
From this lightened crop I posted before:<br /><br />http://uplink.space.com/showthreaded.php?Cat=&Board=missions&Number=637478&page=0&view=collapsed&sb=5&o=0&vc=1<br /><br />I would think the frost is adhering to the dark side of the crater, where the surface looks so smooth, and then being melt by the sun at the upper border and sliding down. Check how at the middle of the image, the rough surface matches exactly the sunlight. Areas that are exposed often won't melt enough liquid to erode the surface before freezing again, but areas that are exposed only during certain seasons or when a piece of the border falls may melt enough liquid to slowly erode the surface.<br /><br />It even seems there are in that image some embrionary gullies starting to form. <div class="Discussion_UserSignature"> </div>
Thanx!! What journal was this in?<br />Sounds like a great summary, and matches some of what I've inferred from my few views at the various photos. Not being that familiar with CO2 processes, this added a lot to my understanding of the range of possible scenarios.<br /><br />Really appreciate the read and summary!! <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
Thanks, I would like to subscribe to ICARUS, but am tapped out as far as adding another journal. Science and Nature are pricey enough <img src="/images/icons/smile.gif" /><br /><br />I'll go back and check the link. Although I doubt my understanding would be better than yours.<br /><br />Regarding postulation, sometimes you have to go as far as you can with the data you have. Nothing's a certainty, but you postulate (perfect word, BTW) with what you've got.<br /><br />It's sort of like a lightening strike. The leaders probe the region, then the final piece is connected, then BLAM.<br />True enlightenment. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
Please note steve is replying to posts from 6 weeks ago. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
hi borman,<br /><br />I'm downloading the (214 Megabyte!) JP2 as I digest your post. As I just finished making some killer shrimp fajitas <img src="/images/icons/cool.gif" /> a quick analogy came to mind:<br /><br />When you sautee something, you can add seasoning or marinade beforehand, during, or after the heating process. It sounds like our beloved Sol has been cooking up quite a meal on Mars! <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
I have just looked at my first JP2 file. This is really cool.<br /><br />Funny moment for me. I use a super duper Mac G5 for my music-making. It's been years since I saw the "clock" icon, because audio doesn't consume nearly the computing power that images do. Tonight, I saw the clock on my G5! <img src="/images/icons/shocked.gif" /> <br /><br />SDC is my breaktime distraction from the serious business of making a rgihteous piece of music. I've been clicking on the "browse" level on all the images, but now I've "seen the light". I can only assume the experience will translate into better music-making!<br /><br />That said, now I will re-digest your post. Then, I will have a more detailed understanding of how over my head I am in geology! <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
Okay, after 2 hours of internet self-eddication, I think I'm getting it. I have joined the 273 degree club. <img src="/images/icons/cool.gif" /><br /><br />Jumping over to the recent images of new gullies appearing between the images of MGS and MRO, does this explanation apply? <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
hi borman<br /><br />I thought this was a cooking thread! <img src="/images/icons/wink.gif" /><br /><br />Kontakt is great, because it handles GigaSampler patches, which are by far the best thing going. I have it installed on the Mac, but I don't use it much, as I also have GigaStudio installed on a dedicated PC. I use a high end piece of hardware called HD 192 from Digidesign, which would be plenty fast enough to handle the GigaSampler as plug-ins in ProTools or Logic, but I use the Mac for recording only.<br /><br />Back to Mars<br /><br />I'm wondering if the process you described involving the "isotherm failure events" would happen all over Mars. Could it still be happening today, and might it actually cause the recent outflows discovered in the gullies?<br /> <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
Mars is back in the kitchen<br /><br />from the May 9, 2007 HiRISE release <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
Welcome back Alex!<br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>
hi borman<br /><br /><font color="yellow">If the material that gullies form upon postdates most dust devils, then the possibility that gully formation is a recent and ongoing process may merit further consideration.</font><br /><br />The language of the caption was vague as to whether the signs of fluid were recent; I think you've found a pretty good indication that they are! <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
Borman: good observation and question! <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>
<blockquote><font class="small">In reply to:</font><hr /><p>This crater fits in with the typical role as regards gullies: No gullies <30degrees, pole-facing gullies between 30-42 degrees and equator-facing gullies >42 degrees. The crater is around 50 degrees North so gullies are on the equator facing walls rather than pole facing walls south of here but north of 30 degrees. <br /> <p><hr /></p></p></blockquote><br /><br /> Borman, Malin and Edgett in their first paper suggested that the gullies were on pole-facing slopes. This would support they were due to solar insolation. But later after studying more of them they argued there was no such trend. <br /> Do you have a reference for the idea that their orientation is related to their latitude?<br /><br /><br /> Bob Clark <div class="Discussion_UserSignature"> </div>
This discussion of bright gully deposits reminds me of an observation of dark spots in association with the gullies that I've been fascinated by. I'd love to see Hirise high resolution images of those.<br /><br /><br /> Bob Clark<br /><br />******************************************<br />Newsgroups: sci.astro, sci.astro.seti, alt.sci.planetary, sci.bio.misc<br />From: rgcl...@my-deja.com (Robert Clark)<br />Date: 29 Nov 2001 14:05:06 -0800<br />Local: Thurs, Nov 29 2001 6:05 pm <br />Subject: Dark spots in Mars gullies - evidence of cyanobacteria?<br /><br />Given the response to the last proposal of dark spots indicating life on Mars, <br /><br />Latest Claims Of Martian Life Are Erroneous Says USGS Scientist.<br />Flagstaff - Sept. 26, 2001 <br />by Timothy N. Titus, Ph.D <br />U.S.G.S. Astrogeology Team <br />http://www.spacedaily.com/news/mars-life-01h.html <br /><br />this is suggested with some trepidation. <br /><br /> However, the images for the recent research on the desert <br />cyanobacteria able to "follow the water" reminded me of some of the <br />spots seen in the Malin/Edgett gullies. <br /><br />Desert Bacteria Makes Case for Life on Mars <br />"The migration of bacteria observed in desert research may hold <br />implications for life in even more severe climates including Mars. <br />Scientists at the Arizona State University have observed and <br />postulated for the first time that bacteria may move with the advance <br />and recession of water rather than sunlight as had been previously <br />believed." <br />http://www.cosmiverse.com/space09280101.html <br /><br />Biological Desert Crust <br />http://lsweb.la.asu.edu/fgarcia-pichel/moab.html <br /><br /> I'm reminded of a MOC image of a south polar pit with gulli <div class="Discussion_UserSignature"> </div>
Another report that restricts attention to the -30S to -45S latitude range also concludes these are largely pole-facing:<br /><br />Martian gullies in the southern mid-latitudes of Mars: Evidence for climate-controlled formation of young fluvial features based upon local and global topography, <br />Icarus, 188, 315-323, 2007, doi: 10/1016/j.icarus.2006.11.020<br />Abstract<br />A new survey of Mars Orbiter Camera (MOC) narrow-angle images of gullies in the 30◦–45◦ S latitude band includes their distribution,<br />morphology, local topographic setting, orientation, elevation, and slopes. These new data show that gully formation is favored over a specific<br />range of conditions: elevation (−5000 to +3000 m), slope ( />10◦), and orientation (83.8% on pole-facing slopes). These data, and the frequent<br />occurrence of gullies on isolated topographic highs, lead us to support the conclusion that climatic-related processes of volatile accumulation and<br />melting driven by orbital variations are the most likely candidate for processes responsible for the geologically recent formation of martian gullies.<br />http://www.planetary.brown.edu/pdfs/3138.pdf<br /><br /><br /> Bob Clark <div class="Discussion_UserSignature"> </div>
from HiRISE<br /><font color="orange">This observation shows partial views of two high latitude pits. These polar pits contain gullies, small-scale slope features that are proposed to require some amount of liquid water to form.<br /><br />Several of the gullies have multiple channels and debris aprons from numerous flows that occurred throughout time. Many of the gullies are seen to originate at a boulder layer at the pit edges. This layer is deteriorating and releasing boulders that can be seen rolling down the pit walls. The bright material near the pit edges is probably seasonal frost.<br /><br /><b>What is particularly interesting about these gullies is that some might be forming (see subimage, approximately 800 meters across, of the south-facing gullies in the bottom pit; 1590 x 1445; 7 MB). The gullies on this wall have incised alcoves, but only a few have well-developed channels.<br /><br />This could be a region of current gully formation. Aiding this hypothesis is the fact that there are a couple of depressions between the visible gullies, suggestive of a developing gully where water and/or material removed from under the surface caused the overlying ground to collapse. It is also possible that water originating on the surface is carving out these depressions, although it is difficult to melt water ice at the temperatures found in this particular location.</b> </font><br /><br />Here again, it would be well worth the effort to dig up some older MGS pics of these Polar Pits and scrutinize them for recent changes. The IAS viewer on the HiRise page lets you load and zoom in pretty quickly - much easier than waiting for a 500Meg download!<br /><br />Attached is the "sub-image" of the lower crater referred to in the caption.<br /><br /><font color="yellow">Polar Pit Gullies PSP_004988_1085<br />Credit: NASA/JPL/University of Arizona</font><br /> <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>
Thanks for that image Brellis.<br /> Some TES temperature readings of the Mars south polar region show temperatures might reach the melting point even as far south as that image, 71S latitude.<br /> See the images here:<br /><br />Mars-Ice.org Consortium : All About Ice:<br />http://www.mars-ice.org/_more/about/sphistory.php<br /><br /> The third image on the 1st row shows south polar temperatures during Nov 27-29,1999, late southern Spring:<br /><br />http://www.mars-ice.org/_more/images/vamp0_Nov27-29(Ls=253)Day_Temp(!Uo!NC).gif<br /><br /> The second white circle from the center in this image is at 70S latitude. Notice that some parts in this latitude are at 0 C temperature. This is during southern spring. It may be during Summer the temperatures are even higher.<br /> And an animation showing the temperature change at the south pole over time on this page also shows some portions at 70S latitude reached 0C during November, 1999:<br /><br />South Polar Cap Recession.<br />http://www.mars-ice.org/_more/about/sp99.php<br /><br />http://www.mars-ice.org/_more/images/spole_2pm_1.gif<br /><br /><br /> Bob Clark<br /><br /> <div class="Discussion_UserSignature"> </div>
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