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What do Mars, Antarctica, and the Jordan Rift Valley between Jordan, Israel, and Palestine have in common? A lot according to a new study in the journal Nature Geoscience. The answer is saltwater.
Since the late 19th century, when astronomer Percival Lowell thought that he saw Martian canals through his telescope, the idea of water on the Martian surface has been a major topic in planetary science. In the 1970s, NASA probes started arriving and photographing Mars from up close, revealing that Lowell had been completely wrong. Mars is extremely dry, at least on the surface. Nevertheless, missions by NASA and other space agencies to study the Red Planet have made the search for water a major focus.
Because the atmospheric pressure at the Martian surface is extremely low, just 7-10 millibars, pure water can exist as liquid only transiently. At certain times of the day during the Martian summer, the temperature gets high enough for droplets to form, from water vapor condensing, or from ice melting. But usually, water on Mars doesn’t even have a liquid state and instead sublimates between vapor and ice. That’s not great news for those of us interested in finding microorganisms on Mars, but fortunately there’s a loophole: salinity.
Salt changes the equation. The saltier water gets, the the more stable liquid water becomes, even at very low atmospheric pressures like the pressure on Mars. Thus, lakes, ponds, seas, rivers, and streams of water are possible on the surface of Mars, but only if they are brines, like the Dead Sea, which has a salinity of 33.7 percent. That’s so salty that you float without a life preserver and the existence of similar super briny water on Mars is supported by multiple lines of evidence.
Read full, original post: Water on Mars: Astrobiology Implications Must be Taken with a Grain of Salt