Possible present day habitats for life on Mars (Including potential Mars special regions): Difference between revisions
Possible present day habitats for life on Mars (Including potential Mars special regions) (edit)
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These interfacial layers occur on boundaries between ice and rock due to intermolecular forces that depress the freezing point of the water. The water flows and acts as a solvent. These layers may be used by microbes in arctic permafrost, which have been found to metabolize at temperatures as low as -20 °C. Life may be possible in interfacial layers as thin as three monolayers, and the model by Stephen Jepsen et al. obtained 10<sup>9</sup> cells/g at -20 °C, though the microbes would spend most of their time in survival mode.<ref name="JepsenPriscu2007">{{cite journal|url=http://www.montana.edu/priscu/DOCS/Publications/JepsenEtAl2007LifeOnMars.pdf|last1=Jepsen|first1=Steven M.|last2=Priscu|first2=John C.|last3=Grimm|first3=Robert E.|last4=Bullock|first4=Mark A.|title=The Potential for Lithoautotrophic Life on Mars: Application to Shallow Interfacial Water Environments|journal=Astrobiology|volume=7|issue=2|year=2007|pages=342–354|issn=1531-1074|doi=10.1089/ast.2007.0124|pmid=17480165|bibcode=2007AsBio...7..342J|deadurl=yes|archiveurl=https://web.archive.org/web/20160303225043/http://www.montana.edu/priscu/DOCS/Publications/JepsenEtAl2007LifeOnMars.pdf|archivedate=2016-03-03|df=}}</ref><ref name="PriceSowers2004"/> Models show that interfacial water should form in some regions of Mars, for instance in Richardson crater.<ref name="KereszturiRivera-Valentin2012">{{cite journal|url=http://www.planetary.brown.edu/pdfs/4591.pdf|last1=Kereszturi|first1=Akos|last2=Rivera-Valentin|first2=Edgard G.|title=Locations of thin liquid water layers on present-day Mars|journal=Icarus|volume=221|issue=1|year=2012|pages=289–295|issn=0019-1035|doi=10.1016/j.icarus.2012.08.004|bibcode=2012Icar..221..289K}}</ref>
==Ice covered lakes
Lakes can form at higher latitudes after cometary or meteorite impacts,<ref name="impactlakes" /> or as a result of geothermal heat or volcanic activity. These may remain liquid for centuries, or up to a few thousand years for the largest impacts, with the heat trapped by an insulating layer of ice. Also there are suggestions that Mars may have a deep hydrosphere,<ref name="hydrosphere" /><ref name="perso.utinam.cnrs.fr" /> a liquid layer below its cryosphere, a few kilometers below the surface. Deep rock habitats on Earth are inhabited by life so if this layer exists, it may also be habitable on Mars.<ref name="naturegroundwater" />. In July 2018, a lake was discovered by radar, 20 kilometers across, and 1.5 kilometers below the ice of the Southern polar plain of Mars [[Planum Australe]]. It is not yet known if this lake is habitable to Earth life.<ref>{{cite web |last1=Cooper |first1=Keith |title=Liquid water discovered on Mars |website=NASA Astrobiology Magazine |date=Jul 25, 2018}}</ref>
===Lakes through asteroid and comet impcts===
This is a possibility that was highlighted recently with the close flyby of Mars by the comet Siding Spring in 2014 [[C/2013 A1#Predicted effects|C/2013 A1 Siding Spring]]. Before its trajectory was known in detail, there remained a small chance that it could hit Mars. Calculations showed it could create a crater of many km in diameter and perhaps a couple of km deep. If a comet like that was to hit polar regions or higher latitudes of Mars, away from the equator, it would create a temporary lake, which life could survive in.
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