Potentially habitable flow-like features from Martian dry ice geyser dune spots: Difference between revisions

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[[File:Flow-like-features.gif|thumb|Flow-like-features|Larger region of the Richardson crater dune field showing the dark dune spots and flow-like features. ]][[File:Flow-like-features detail.gif|thumb|Flow-like-features detail|Detailed zoom into the flow-like features around a small cluster of the spots on the dunes in Richardson Crater, Mars [http://www.google.co.uk/mars/#q=Richardson%20crater&zoom=2 (Richardson crater in Google Mars)]. These dark dune spots are thought to be the debris of the hypothesized [[Geyser (Mars)|Martian Geysers]] and the fingers of the flow like features extend later in the year. The dark material at the end of the flows moves at between 0.1 and 1.4 m/day in late spring / summer on Mars. This example moves approximately 39 meters in 26 days between the last two frames.<br><br>The two main models involve liquid water - either interfacial layers, or else layers of water created through the solid state greenhouse effect. <ref name="MartínezRenno2013DarkDuneSpots"/><ref name=Kereszturi2008>Kereszturi, A., et al. [http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1555.pdf "Analysis of possible interfacial water driven seepages on Mars"], Lunar and Planetary Science Conference. Vol. 39. 2008.</ref><br><br>Animation centered on {{coord|72.02|S|179.408|E|globe:Mars}} [http://www.google.co.uk/mars/#lat=-72.02&lon=179.408&zoom=7 (location in Google Mars)]. Displayed region 188.5 meters by 172 meters. Dates of sequence: 19 January (sol 396), 24 January (sol 401), 29 January (sol 406), 10 February (sol 418), and 09 March (sol 444), all in 2009. All taken between 4.10 pm and 4.28 pm in Mars local time.]]
[[File:Flow-like-features.gif|thumb|Flow-like-features|Larger region of the Richardson crater dune field showing the dark dune spots and flow-like features. ]][[File:Flow-like-features detail.gif|thumb|Flow-like-features detail|Detailed zoom into the flow-like features around a small cluster of the spots on the dunes in Richardson Crater, Mars [http://www.google.co.uk/mars/#q=Richardson%20crater&zoom=2 (Richardson crater in Google Mars)]. These dark dune spots are thought to be the debris of the hypothesized [[Geyser (Mars)|Martian Geysers]] and the fingers of the flow like features extend later in the year. The dark material at the end of the flows moves at between 0.1 and 1.4 m/day in late spring / summer on Mars. This example moves approximately 39 meters in 26 days between the last two frames.<br><br>The two main models involve liquid water - either interfacial layers, or else layers of water created through the solid state greenhouse effect. <ref name="MartínezRenno2013DarkDuneSpots"/><ref name=Kereszturi2008>Kereszturi, A., et al. [http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1555.pdf "Analysis of possible interfacial water driven seepages on Mars"], Lunar and Planetary Science Conference. Vol. 39. 2008.</ref><br><br>Animation centered on {{coord|72.02|S|179.408|E|globe:Mars}} [http://www.google.co.uk/mars/#lat=-72.02&lon=179.408&zoom=7 (location in Google Mars)]. Displayed region 188.5 meters by 172 meters. Dates of sequence: 19 January (sol 396), 24 January (sol 401), 29 January (sol 406), 10 February (sol 418), and 09 March (sol 444), all in 2009. All taken between 4.10 pm and 4.28 pm in Mars local time.]]


These features near the Martian southern polar region are associated with the [[Geyser (Mars)|Martian Geysers]]. Before these geysers were well understood, there was a lot of speculation about what they might be. The seasonal patterns they form resemble trees and vegetation, and in 2001 looking at the Mars Global Surveyor images, Arthur C. Clarke called them "Banyan trees"<ref name=Foulke2001>Nicole Foulke, [https://www.popsci.com/military-aviation-space/article/2001-12/banyan-trees-mars The Banyan trees of Mars], Popular science e-mail interview with Arthur C. Clarke, December 17, 2001</ref>, saying, only half joking "I'm now convinced that Mars is inhabited by a race of demented landscape gardeners,"<ref name=ClarkeSmithsonian2001>Arthur C. Clarke, speaking by teleophone for the [http://www.martianspiders.com/Sir%20Arthur%20C_%20Clarke%20at%20the%20Smithsonian,%20June%202001.htm Wernher von Braun Memorial Lecture], Smithsonian institute's National Air and Space Museum, June 6, 2001 - reported by John C. Sherwood</ref>, and a team of Hungarian scientists proposed that they might be the result of spreading colonies of overwintering photosynthetic microbial life. <ref name=Andras/>
These features near the Martian southern polar region are associated with the [[Geyser (Mars)|Martian Geysers]]. Before these geysers were well understood, there was a lot of speculation about what they might be. The seasonal patterns they form resemble trees and vegetation, and in 2001 looking at the Mars Global Surveyor images, Arthur C. Clarke called them "Banyan trees"<ref name=Foulke2001>Nicole Foulke, [https://www.popsci.com/military-aviation-space/article/2001-12/banyan-trees-mars The Banyan trees of Mars], Popular science e-mail interview with Arthur C. Clarke, December 17, 2001</ref>, saying, only half joking "I'm now convinced that Mars is inhabited by a race of demented landscape gardeners,"<ref name=ClarkeSmithsonian2001>Arthur C. Clarke, speaking by teleophone for the [http://www.martianspiders.com/Sir%20Arthur%20C_%20Clarke%20at%20the%20Smithsonian,%20June%202001.htm Wernher von Braun Memorial Lecture], Smithsonian institute's National Air and Space Museum, June 6, 2001 - reported by John C. Sherwood</ref>. At around the same time, a team of Hungarian scientists proposed that they might be the result of spreading colonies of overwintering photosynthetic microbial life. <ref name=Andras/>


Most of the patterns that form here are probably due to dry ice effects. Subsurface layers of dry ice are heated by the sun through the solid state greenhouse effect, and erupt as CO2 gas. The dark streaks and spots are thought to be debris from the geysers, blown by the CO2 outgassing. The dark streaks are the flow-like features and are initially formed through outgassing, not involving liquid brines at that stage. However as Renno and Martinez put it<ref name="MartínezRenno2013DarkDuneSpots"/>
Most of these patterns are now thought to be due to dry ice effects. Subsurface layers of dry ice are heated by the sun through the solid state greenhouse effect, and erupt as CO2 gas. The dark streaks, and spots are thought to be debris from the geysers, blown by the CO2 outgassing. These streaks are the "flow-like features", or FLF. What's interesting for the search for habitable brines is what happenes next. As Renno and Martinez put it<ref name="MartínezRenno2013DarkDuneSpots"/>


{{quote|There is mounting evidence that while dark spots and FLF form by “dry” gas venting, liquid brines form temporarily on them.}}
{{quote|There is mounting evidence that while dark spots and FLF form by “dry” gas venting, liquid brines form temporarily on them.}}
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