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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Until 2008, many scientists believed that water ''"does not and cannot exist on the surface of Mars today"''<ref name="LevinMarsLifeIdea" />. There are only five regions on present day Mars where liquid fresh water could potentially form, in the Amazonis, Chryse and Elysium Planitia, and the Hellas and Argyre Basins, but even there, in those deep depressions, the water would be close to its boiling point of 10 °C. If any water formed it would soon evaporate<ref name="Hellas">{{cite web|title=Extracts from "Making a Splash on Mars"|url=http://lasp.colorado.edu/home/wp-content/uploads/2013/06/Mars_Articles_20130617.pdf}}</ref>. The equatorial regions are also expected to be ice free, as ice is not long term stable at any depth within ± 30° of the equator, unless trapped by an impervious overlying layer<ref>Schorghofer, N. and Aharonson, O., 2005. [https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2004JE002350 Stability and exchange of subsurface ice on Mars]. Journal of Geophysical Research: Planets, 110(E5)</ref>. Although salty water would be liquid at lower temperatures, most scientists had concluded that the conditions on Mars were too extreme for it to form at all. Amongst the few who continued to think Mars could be habitable was Gilbert Levin who was (and still is) of the view that his labeled release experiment on the [[Viking program|Viking landers]] may have found life on Mars in 1976<ref name="LevinMarsLifeIdea" />.
This changed in 2008 with the observations of the [[Phoenix (spacecraft) | Phoenix lander]]. It landed in what is thought to be an ancient ocean bed near the north pole, the first and so far the only spacecraft to land successfully in polar regions. It observed droplet-like features that formed on its landing legs<ref name="phoenix_droplets_2009" />. In December 2013, Nilton Renno<ref name="NiltonRennoFaculty" /> and his team using the Michigan Mars Environmental Chamber were able to simulate the conditions at its landing site and the droplets<ref name="MicheganMars
</ref>. They formed salty brines within minutes when salt overlaid ice. The team concluded that suitable conditions for brine droplets may be widespread in the polar regions<ref name="salt_ice">[http://www.astrobio.net/news-brief/liquid-water-ice-salt-mars/ Liquid Water from Ice and Salt on Mars], Aaron L. Gronstal -Astrobiology Magazine (NASA), Jul 3, 2014</ref><ref name="salt_ice_paper">Fischer, E., Martínez, G.M., Elliott, H.M. and Rennó, N.O., 2014. [https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014GL060302 Experimental evidence for the formation of liquid saline water on Mars]. Geophysical research letters, 41(13), pp.4456-4462.</ref>. This is possible because the salts, especially perchlorates, act as an "antifreeze"<ref name="GoughChevrier2014" /> to keep the brines liquid at low temperatures. Nilton Renno talks about their results in this video
<youtube width="540" height="315">iLWv9UGwjdE</youtube>
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