The recent discoveries of evidence for liquid saline water1,2,3,4 and methane5 on Mars have excited the science
community by reviving the possibility of extant microbial life in this nearby planet. Here we report recently discovered
photometric and spectral evidence that liquid saline water exists on Mars4. We show that this finding indicates that
deliquescence occurs seasonally on some areas of Mars' polar region4. These discoveries support the hypothesis that
liquid saline water is ubiquitous in the shallow Martian subsurface. This has important implications for the search for
extraterrestrial life because a diverse array of terrestrial microorganisms thrives in highly saline water or brines6,7. We
conclude this article by describing in situ and remote sensing instruments for detecting brines in the Martian subsurface
and studying their relationship with sources and sinks of trace gases.
Since liquid water is a key ingredient for life as we know it, NASA has adopted the theme "follow the water" as an
strategy for exploring Mars. Recently, Renno et al.1,2 showed evidence that liquid saline-water exists in areas disturbed
by the Phoenix Mars Lander. Moreover, they argued that the thermodynamics of freeze-thaw cycles leads to the
formation of concentrated saline solutions (brines) with freezing temperatures much higher than current summer ground
temperatures where ground ice exists near the surface and therefore liquid saline-water should be common on Mars.
Here we summarize these ideas, present some new results, and discuss their implications for astrobiology. We propose a
strategy for searching for liquid saline water on Mars and argue that NASA's theme for the exploration of Mars should
be updated to "follow the liquid water."
Conference Committee Involvement (4)
Instruments, Methods, and Missions for Astrobiology XVI
27 August 2013 | San Diego, California, United States
Instruments, Methods, and Missions for Astrobiology XV
14 August 2012 | San Diego, California, United States
Instruments, Methods, and Missions for Astrobiology XIV
23 August 2011 | San Diego, California, United States
Instruments, Methods, and Missions for Astrobiology XIII
3 August 2010 | San Diego, California, United States
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