{"id":6062,"date":"2018-03-16T13:55:06","date_gmt":"2018-03-16T08:55:06","guid":{"rendered":"http:\/\/www.cawater-info.net\/all_about_water\/en\/?p=6062"},"modified":"2018-03-15T16:07:48","modified_gmt":"2018-03-15T11:07:48","slug":"water-on-mars-what-does-it-really-mean","status":"publish","type":"post","link":"http:\/\/www.cawater-info.net\/all_about_water\/en\/?p=6062","title":{"rendered":"Water on Mars: What Does It Really Mean?"},"content":{"rendered":"

A new find of liquid water fuels hopes that life may yet exist on the red planet.<\/em><\/p>\n

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It\u2019s tempting to say that the\u00a0announcement of liquid water\u00a0on the surface of Mars heralds a new era in Martian exploration.
\nYou might think that the first human explorers on Mars will park next to a salty stream and use it to manufacture fresh drinking water. Maybe they could even find life in damp Martian nooks and crannies, areas where the dusty red planet can still fuel microbes.
\nReality is much more subtle. Finding evidence for flowing water is not the same as finding life. Right now, scientists don\u2019t know where this water is coming from, or if the chemistry in these Martian seeps is even life-friendly. And unfortunately, chances are it will be a long time before we can get there to find out.<\/p>\n

\u201cIt\u2019s hard to get a spacecraft clean enough to send a lander or rover there right now,\u201d says\u00a0Bethany Ehlmann, a planetary geologist at Caltech, referring to concerns about hitchhiking Earth microbes contaminating the Martian surface.<\/p>\n

But there’s still reason for excitement. These seasonal seeps, which scientists call recurring slope lineae, \u201care probably the best place to look for modern life,\u201d she says.<\/p>\n

ODDS OF LIFE<\/h5>\n

Here’s what scientists know. Analyses have confirmed that enigmatic streaks that appear in summertime on the planet’s slopes are produced by liquid water\u2014salty water, perhaps capable of sustaining chemical reactions and even life.<\/p>\n

Like Mars itself, the dark watery streaks are ruggedly beautiful, as seen in photographs taken by the HiRISE camera aboard the\u00a0Mars Reconnaissance Orbiter. But for all their picturesque drama, these dark marks represent more of a trickle than a flow.<\/p>\n

It\u2019s possible they\u2019re fed by some kind of underground aquifer, or a buried icefield that thaws in warmer weather and sends melted Mars water sliding downhill.<\/p>\n

While not outside the realm of possibility\u2014we do know\u00a0there\u2019s ice buried beneath the Martian surface\u2014such scenarios aren\u2019t as likely as the one scientists favor: The water comes from the atmosphere. If that’s true, it\u2019ll be a much tougher resource to tap into.<\/p>\n

But how could water from the atmosphere form these dark streaks? On Mars, as on Earth, salts on the surface can absorb atmospheric water vapor and trap it in their crystal structures. Then, when the soggy crystals warm up, they dissolve. The whole liquidy mix surrenders to the tug of gravity, and off it goes, tumbling downhill.<\/p>\n

In Chile\u2019s super-dry Atacama desert, this exact type of system\u2014called deliquescence\u2014is the key to supporting\u00a0some rather extreme life, says NASA astrobiologist\u00a0Chris McKay.<\/p>\n

But there\u2019s no guarantee this is happening on Mars. McKay notes that the type of salts near the Martian streaks, called perchlorates, form different watery mixtures than the salts we\u2019re most used to on Earth. In fact, it\u2019s possible the perchlorate streaks could behave similarly to Antarctica\u2019s\u00a0Don Juan Pond, which is the saltiest liquid water body on Earth\u2014and totally dead.
\n\u201cSuch a brine is not suitable for life and is of no interest biologically,\u201d McKay says. \u201cNothing can live in the brine of Don Juan Pond.\u201d<\/p>\n

FOLLOW THE WATER<\/p>\n

So, seeps fueled by atmospheric humidity might not make the most convenient water well for human colonists, and they might not even be ideal habitats for Martian microbes\u2014but wouldn\u2019t it be worth finding out?<\/p>\n

Of course. What we know so far, based on the single example of Earth, is that life tends to show up wherever there\u2019s water. That\u2019s why NASA\u2019s search for life beyond Earth has been driven by the mantra, \u201cFollow the water.\u201d<\/p>\n

The frustrating irony here is that NASA can\u2019t follow this particular water. Not yet.<\/p>\n

MARS ONCE HELD AN OCEAN<\/h5>\n

An ancient sea once covered a fifth of the planet\u2019s surface, astronomers found by calculating how much water the planet has lost over time.<\/p>\n

Sending a spacecraft to an area where liquid water flows is much too risky, cautions NASA\u2019s\u00a0Office of Planetary Protection. Finding water in the streaks will brand them as a “special region,” an area where spacecraft can land only after thorough cleaning or sterilization, says\u00a0Ernst Hauber\u00a0of the German Aerospace Center.<\/p>\n

If hitchhiking microbes were to somehow survive the journey to Mars and find themselves in a briny bath, it\u2019s possible they could gain a foothold and contaminate the red planet. Such a scenario would not only complicate any future detection of life on Mars, but also introduce a potential disaster: Think about how great we are at hastening the spread of invasive species on Earth.<\/p>\n

It\u2019s certainly worth the caution, though humans walking on Mars (which some say is the next goal in solar system exploration) are much\u00a0more likely to shed microbes than a sterilized robot is, and Earth microbes aren’t necessarily likely to thrive in Mars brines.
\nIf there\u2019s one big story from the past decade of planetary exploration, it\u2019s that water is everywhere. It\u2019s\u00a0tucked into moon dust, frozen\u00a0in Mercury\u2019s shadowed craters, streaming off the backs of\u00a0comets, and sequestered inside\u00a0the shells of icy moons. Mars, finally, has joined the population of bodies where we know water flows\u2014and that\u2019s interesting enough on its own, without the breathless speculation.<\/p>\n

\u201cModern Mars is right \u2018on the edge,’ \u201d Ehlmann says, as an active world where liquid water exists even today. \u201cJust a slight tweak in climate could make waters even more widespread.\u201d<\/p>\n

Source:\u00a0https:\/\/news.nationalgeographic.com\/<\/a><\/p>\n

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