Water frost on Gullies.

[exoscientist]

Just saw this posted on Bautforum.com:<br /><br />Seasonal Frost on Mars.<br />http://marsprogram.jpl.nasa.gov/mro/gallery/calibration/seasonalFrost.html<br /><br /> It shows a CRISM infrared image of water ice frost in an area that contains gullies. Philip Christensen has suggested that melting of collected snow or frost could create the gullies:<br /><br />Trickle Down Theory of Melting Snow May Support Life on Mars. <br />By Leonard David <br />Senior Space Writer <br />posted: 02:00 pm ET 19 February 2003 <br />"Intriguing and often-examined gullies on Mars might not be created by water seeping out from underground springs. Rather, they are likely caused by trickling water from melting snowpacks, an active process that could sustain biology on the Red Planet. <br />"A leading Mars scientist has proposed a new theory regarding gully formation on the planet, backed by images taken from NASA's Mars Odyssey spacecraft. The research bolsters the view that liquid water is sheltered by snow, preventing the fluid from rapid evaporation in Mars' thin atmosphere." <br />... <br />"Christensen points to an image taken by Odyssey of a crater in the southern mid-latitude Terra Sirenum region of Mars. It shows eroded gullies on the crater's cold, pole-facing northern wall, he said. But immediately next to those features is a section he calls "pasted-on terrain." <br />"This smooth deposit of material is thought to be "volatile," composed of materials that evaporate in Mars' thin atmosphere. This material characteristically occurs only in the coldest, most sheltered areas. <br />"Christensen reported that the most likely composition of this slowly evaporating material is water in the form of snow. From this observation, the Mars scientist suspects a relationship between the gullies and the snow."<br />...<br />"Given the commonness of snowpacks on Mars, it's likely that somewhere on the planet <div class="Discussion_UserSignature"> </div>

 

[bonzelite]

are there images, then, of snow packs in the latitudes of the gully formations, ie, a before and after sort of photographic chronology?

 

[exoscientist]

Bonzelite, in the Christensen paper he argues physical characteristics suggests there are snowpacks in the areas he discusses with gullies, specifically the presence of "pasted-on" terrain.<br /> The new CRISM images show by infrared imaging his deduction is correct for at least one region, in Terra Sirenum.<br /> CRISM imaging is just starting so I there wouldn't be before and after images yet. But certainly such regions in mid-latitudes showing deposted frost/snow will be reimaged during the upcoming local Spring season.<br /><br /><br /> Bob Clark <div class="Discussion_UserSignature"> </div>

 

[exoscientist]

Assuming melting snow is *one* method of creating gullies, we might be able to use the CRISM ability to detect water frost/snow on slopes as a means to search for them.<br /> I assume the detection of the infrared signature of water by CRISM can be automated. Then would we have the software set a flag when it is detected in the range of 30 to 70 degrees north and south of the equator, where the gullies are found.<br /> Then we would look for gullies at those sites in past MGS images. We can't use MGS now to look at those sites for future gullies, but we could compare them to later HIRISE images of the same sites. There might also be characteristics of these gullies in a single image that would suggest they were very recent. Also, we might be lucky to have MGS images of some of these sites both before and after past frost/snow deposition.<br /><br /><br /> Bob Clark <div class="Discussion_UserSignature"> </div>

 

[voyagerwsh]

The image taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is consistent with frosted craters of Northern Spring and Southern Autumn images (1) taken by Mars Global Surveyor Mars Orbiter Camera (MOC) back in 2000.<br /><br />Both images taken by CRISM and MOC should bolster the "snow pack" hypothesis by Philip Christensen who suggested that as the water source to carve the crater gullies. Also Michael Hecht of JPL/Caltech has interesting mechanisms of frost accumulating and melting on the rim of craters (2). Very encouraging, indeed. <br /><br />(1). http://mars.jpl.nasa.gov/mgs/msss/camera/images/nov_00_craters/index.html<br /><br />(2). http://www.iki.rssi.ru/hend2003/ppt/hecht.pdf

 

[bonzelite]

it's just that there is recent gully formation, and/or outflow evidence but not a single image of a snow-covered crater and environs at the crater with the recent activity. it's a barren regolith and rock surface. <br /><br />the region was imaged over a span of 4 or 5 years and the area has remained barren. no snow. michael malin suggests the channels are perhaps carved by liquid that accumulates onto the surface as ice, with this ice covering providing a shield/barrier for water to continue to flow as a liquid beneath it. <br /><br />i do agree that a snow-stewn environment can accomplish the same thing, but no such snowfall or snow layer has been imaged at the craters of the most recently photographed activity for outflow.

 

[bonzelite]

well right, we have evidence of surface "dew" frost everywhere but not this ice sheet or snowpack infill (yet, ie, it's pending). if there are such pictures from the craters with the erosion in question i've never seen them (not that i'm an authority on all mars pics --no way-- but i don't see a michael malin comparison of snowpack versus dry regolith chronology). <br /><br />now i have seen a crater with a huge deposit of water ice in it, literally a snowpack looking mass tinted blue, but it's not the crater where the famous gullies appear. by the way i do agree that insolation can account for such erosion, as it does here on earth. but i'm not seeing (yet) this playing out in the gully craters, particularly with the one that features recent (apparent) outflow. i am of the belief that, yes, somewhere on mars this does happen.

 

[voyagerwsh]

Yet the newly found deposit by MOC (1) which was presented by Michael Malin few weeks back may hinge the groundwater rather than snow pack, if it would be the liquid source of finger shaped deposits then it would not only be one gully setting should be some wide gullies spreading around. Models of the gullies formation debates still go on. <br /><br />Quote from my previous post,<br /><br />Two dominant models to explain the likely cause of martian gullies have been proposed, i.e. ground water or snow pack. <br /><br />One model (3) was proposed by Michael Malin et al. as ground water or aquifer repeatedly outburst with water/ice and debris as called ice dam break running down slope which would carve the soil and form gullies. <br /><br />In Phil Christensen's snow pack model (2), Dr. Christensen explains the gullies was formed by melting snow pack which was accumulated durind 50,000 to 500,000 years of time span. <br /><br />Interestingly, can ground water explain origin of the gully in 3,700 meters elevation on Ausonia Mensa (4)? Or Snow pack model is gaining upper hand to the proposed martian gullies formation. I would favor snow pack model which may have better explaination on this gully formation in that groundwater or aquifer would probablely not dwell on the 3.7 km elevation. <br /><br />(1).<br />http://www.msss.com/mars_images/moc/2006/12/06/gullies/centauri_crater/index.html<br /><br />(2). <br />http://nssdc.gsfc.nasa.gov/planetary/news/mars_water_pr_20000622.html <br /><br />(3). http://www.geotimes.org/mar03/WebExtra031403.html <br /><br />(4). <br />http://www.esa.int/SPECIALS/Mars_Express/SEM8RLMZCIE_0.html

 

[exoscientist]

Bonzelite, Malin has not said these new deposits are due to melting snowpacks or to seeping groundwater.<br /> However, these new deposits ARE in the same region of Terra Sirenum where Christensen suggested and CRISM has confirmed there is frost/snow deposition:<br /><br />Mars Global Surveyor Discovers Current Liquid Water Activity on Mars.<br />MOC Images Also Reveal New Impact Craters.<br />By Emily Lakdawalla <br />December 6, 2006 <br />"New gully deposit in a crater in Terra Sirenum, Mars<br />In this unnamed 5-kilometer-diameter crater in Terra Sirenum, at 36.6°S, 161.8°W, Mars Global Surveyor images have revealed the activity of liquid water between December 2001 and April 2005. The crater was being imaged repeatedly as part of a long-term monitoring campaign focused on some light-toned deposits on the crater wall."<br />http://planetary.org/news/2006/1206_Mars_Global_Surveyor_Discovers_Current.html<br /><br />Trickle Down Theory of Melting Snow May Support Life on Mars. <br />By Leonard David <br />Senior Space Writer <br />posted: 02:00 pm ET 19 February 2003 <br />"Christensen points to an image taken by Odyssey of a crater in the southern mid-latitude Terra Sirenum region of Mars. It shows eroded gullies on the crater's cold, pole-facing northern wall, he said. But immediately next to those features is a section he calls "pasted-on terrain." <br />"This smooth deposit of material is thought to be "volatile," composed of materials that evaporate in Mars' thin atmosphere. This material characteristically occurs only in the coldest, most sheltered areas. <br />"Christensen reported that the most likely composition of this slowly evaporating material is water in the form of snow. From this observation, the Mars scientist suspects a relationship between the gullies and the snow."<br />http://www.space.com/scienceastronomy/mars_gullies_030219.htm</safety_wrapper <div class="Discussion_UserSignature"> </div>

 

[exoscientist]

Dickson and Head also suggest HIRISE and CRISM be used to search for gullies forming presently from melting snowpacks:<br /><br />GULLIES OBSERVED ON FROST-COVERED POLEWARD DUNE FACES IN THE SOUTHERN MID-LATITUDES. OF MARS: POTENTIAL TARGETS FOR HI-RISE AND CRISM.<br />The 42-nd Vernadsky/Brown Microsymposium on Comparative Planetology, October 10-12, 2005.<br />J.L. Dickson and J.W. Head, Dept. of Geological<br />Sciences, Brown University, Providence, RI 02912, ****@brown.edu.<br />"We feel that the association between frost deposits on<br />pole-facing slopes and the occurrence of channels exclusively on the same slopes is suggestive that these channels have formed from the melting of these frost deposits. Efforts to model the present-day martian climate [6] have predicted that poleward slopes in the mid/high-latitudes of Mars are where gullies would form if they are active, and this location meets those criteria. Frost on poleward slopes at this latitude remains stable on the surface, while frost on equatorward slopes is exposed to greater direct solar insolation, increasing<br />the temperature enough to induce sublimation. By early<br />spring, when Figure 1b was obtained, the frost is still stable and is potentially beginning to melt and carve the channel. By the beginning of autumn, when Figure 1c was obtained, the frost has all been removed to reveal the underlying terrain."<br />...<br />"Due to resolution constraints, the most important<br />unanswered questions with regard to these features cannot currently be addressed. The composition of the frost deposits is unknown and the resolutions of TES and OMEGA are insufficient to obtain accurate spectra for the target. CRISM, part of the Mars Reconnaissance Orbiter (MRO) instrument payload, will obtain spectra at a spatial resolution as high as 18 m/px, which will be sufficient to determine the composition of the frost. Additionally, any seasonal modification of the channels cannot be observed at MOC resolution. HiRISE, <div class="Discussion_UserSignature"> </div>