Brines suffused with the life-giving gas could offer hope for past and even present microbes on the Red Planet, according to a new study. From a report: New research suggests our neighboring world could hide enough oxygen in briny liquid water near its surface to support microbial life, opening up a wealth of potentially habitable regions across the entire planet. Although the findings do not directly measure the oxygen content of brines known to exist on the Red Planet, they constitute an important step toward determining where life could exist there today. Aerobic respiration, which relies on oxygen, is a key component of present-day life on Earth. In this process, cells take in oxygen and break it down to produce energy to drive metabolism. Mars’s very low levels of atmospheric oxygen have led many scientists to dismiss the possibility of aerobic respiration there today, but the new research brings this possibility back into play. The study appears in the October 22 edition of Nature Geoscience. “Our work is calling for a complete revision for how we think about the potential for life on Mars, and the work oxygen can do, implying that if life ever existed on Mars it might have been breathing oxygen,” says lead study author Vlada Stamenkovic, a researcher at NASA’s Jet Propulsion Laboratory in California. “We have the potential now to understand the current habitability.” Although Mars is today a freeze-dried desert, it possesses abundant reserves of subsurface water ice, as well as some amount of liquid water in the form of brines. The brines’ high salt content lowers the temperature at which they freeze, allowing them to remain liquid even on Mars’s frigid surface. In their new study, Stamenkovic and his colleagues coupled a model of how oxygen dissolves in brines with a model of the Martian climate. Their results revealed that pools of salty liquid at or just beneath the surface could capture the meager amounts of oxygen from the Red Planet’s atmosphere, creating a reservoir that microbes might metabolically utilize. According to the research, Martian brines today could hold higher concentrations of oxygen than were present even on the early Earth — which prior to about 2.4 billion years ago harbored only trace amounts of the gas in its air.

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