Possible present day habitats for life on Mars (Including potential Mars special regions): Difference between revisions
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[[Life on Mars]] covers the more general topic of habitats for life through the entire history of Mars (with a brief summary for present day habitats).
Regions of the Martian surface where Earth life could potentially survive on Mars are called [[Planetary protection#Special regions|"Special regions"]] in [[Planetary protection]] discussions and require higher levels of sterilization for robotic missions<ref name="RummelBeaty2014" /><ref>[https://scholar.google.co.uk/scholar?hl=en&as_sdt=0%2C5&q=%22Special+region%22+Mars&btnG= Google scholar search for: "Special region Mars"]</ref>. It's possible that native Martian life might be able to survive in conditions that Earth life can't tolerate such as extremes of cold in liquid brines<ref>Schulze-Makuch, D. and Houtkooper, J.M., 2010. [https://meetingorganizer.copernicus.org/EPSC2010/EPSC2010-308.pdf A perchlorate strategy for extreme xerophilic life on Mars]. EPSC Abstracts, 5, pp.EPSC2010-308.</ref>.
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" />.
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