Potentially habitable flow-like features from Martian dry ice geyser dune spots: Difference between revisions
Jump to navigation
Jump to search
Potentially habitable flow-like features from Martian dry ice geyser dune spots (edit)
Revision as of 18:52, 24 September 2018
, 5 years agono edit summary
No edit summary |
No edit summary |
||
Line 1:
These intriguing high latitude features are associated with the [[Geyser (Mars)|Martian Geysers]]. The geysers themselves (if that is what they are) are thought to be results of dry ice turning to gas. The dark spots - which at one point were thought to be photosynthetic life, are now thought to be the debris from the geysers.
However, later in the year the flow like features extend down the slopes from the dark spots, sometimes at a rate of meters per day. The details differ for the two hemispheres.
In the Southern hemisphere, both of the current models for this part of the process involve liquid water. In one of these models the features from initially as fresh water at 0 °C below clear ice in a solid state greenhouse effect, picking up salts as they start to flow outwards.
In the northern hemisphere then most of the models also involve water, but one model has dry ice and cascading sand instead. The northern hemisphere flow like features form at much lower surface temperatures and if they involve brines the temperatures are around -90 °C. The southern hemisphere Richardson crater flow-like features are the ones of most interest for potentially habitable brines.
This image shows the flow like features of the southern hemisphere.
Line 23 ⟶ 27:
===Solid state greenhouse effect model===
Möhlmann uses a solid state greenhouse effect in his model, similarly to the process that forms the geysers, but with translucent ice rather than dry ice as the solid state greenhouse layer.<ref name="LiquidWaterSnowIce">{{cite journal|url=http://www.sciencedirect.com/science/article/pii/S0019103509004539|last1=Möhlmann|first1=Diedrich T.F.|title=Temporary liquid water in upper snow/ice sub-surfaces on Mars?|journal=Icarus|volume=207|issue=1|year=2010|pages=140–148|issn=0019-1035|doi=10.1016/j.icarus.2009.11.013|bibcode=2010Icar..207..140M}}</ref>
Line 52 ⟶ 55:
===Interfacial liquid layers model===
Another model for these southern hemisphere features involves ULI water (undercooled liquid water) which forms as a thin layer over surfaces and can melt at well below the usual melting point of ice. In Mohlmann's sandwich model, then the interfacial water layer forms on the surfaces of solar heated grains in the ice, which then flows together down the slope. Calculations of downward flow of water shows that several litres a day of water could be supplied to the seepage flows in this way.<ref name="MartínezRenno2013DarkDuneSpots">{{cite journal|last1=Martínez|first1=G. M.|last2=Renno|first2=N. O.|title=Water and Brines on Mars: Current Evidence and Implications for MSL|journal=Space Science Reviews|volume=175|issue=1–4|year=2013|pages=29–51|issn=0038-6308|doi=10.1007/s11214-012-9956-3|bibcode=2013SSRv..175...29M}}</ref><ref name=Kereszturi2008/>
| |||
