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2018-07-27. What does Mars’ lake mean for the search for life on the Red Planet?

posted Jul 27, 2018, 1:05 PM by Alan Gould   [ updated Jul 28, 2018, 3:49 PM ]
By Lisa Grossman, Science Magazine. For GSS A Changing Cosmos chapter 7. Excerpt: The search for life on Mars just got a lot more interesting. For decades, scientists have looked at ...finding regions where life could have taken root billions of years ago, when the Martian climate was warmer and wetter. But on July 25, researchers announced they had spotted signs of a large lake of liquid water hiding beneath thick layers of ice near the Red Planet’s south pole (SN Online: 7/26/18). If the lake’s existence is confirmed, we could find microbes living on Mars today. That report changes the calculus for astrobiologists who want to protect any existing extraterrestrial life from being wiped out or obscured by introduced species from Earth.... Mars landers and rovers are cleaned to strict standards to avoid any possible contamination, even “without having anything you’d even call a pond,” says astrobiologist Lisa Pratt, NASA’s planetary protection officer. “Now we have a report of a possible subglacial lake! That’s a major change in the kind of environment we’re trying to protect.” ...Could anything actually live in this lake? ...the low temperature cutoff for most terrestrial life is around –40° Celsius. The Martian ice sheet is about –68° C. ...for the water to be liquid at such cold temperatures, it must be extremely salty. ...“Even ‘extremophile’ bacteria that can live in highly salty water might not be able to survive.” But could Martians live there? “Absolutely,” Pratt says. If life arose on Mars sometime in its more life-friendly past, some organisms could have adapted to the changing climate and ended up finding the cold, salty water quite comfortable, she says.... See also Liquid water spied deep below polar ice cap on Mars (Science Magazine 2018 Jul 25)  https://www.sciencenews.org/article/what-does-mars-lake-mean-search-life-red-planet