Potentially habitable flow-like features from Martian dry ice geyser dune spots: Difference between revisions
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Potentially habitable flow-like features from Martian dry ice geyser dune spots (edit)
Revision as of 15:54, 29 September 2018
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This would happen later in the spring and through to the summer. The dark streaks from the geysers begin to extend further down the slopes, sometimes at a rate of meters per day. There are streaks in both hemispheres but the details of how they form differ.
In the Southern hemisphere, they form in the debris of the geysers, and both of the current models for this part of the process involve liquid water<ref name="MartínezRenno2013DarkDuneSpots"/>. In one of these modelsfresh water that forms as subsurface meltwater, insulated from the surface temperatures and pressures at 0°C below snow-ice packs. These are optically thin in visible light but opaque to thermal infrared, so trapping heat from one day to the next in a solid state greenhouse effect familiar in similar situations in Antarctica
The northern hemisphere flow like features begin as wind-blown features on steep slopes. They start to extend later in the year, similarly to the southern hemisphere features. However, if they involve brines, the temperatures are far lower, with surface temperatures around -90 °C, though in the models that involve water, the brines themselves would be at warmer temperatures than the surrounding dry ice. Also, though most of the models for the northern hemisphere features involve water, they can also be explained with dry ice and cascading dust. <ref name="MartínezRenno2013DarkDuneSpots"/>
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