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Liquid Water Likely Flows On the Salty Hills of Mars

NASA discovered hydrated salts on the surface of Mars, which strongly suggests the presence of liquid water.

ByAllison EckNOVA NextNOVA Next
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The salty hills of Mars

It’s almost as if our moon turned blood red last night to herald NASA’s latest Red Planet news.

At 11:30 EDT, NASA Headquarters will hold a press conference to discuss their most recent finding: new data that suggests liquid water exists on Mars even today. This could be the first time in mission history that we have definitive reason to believe there might be microbial life on our closest neighbor.

Here’s Kenneth Chang, writing for the New York Times:

In a paper published in the journal Nature Geoscience, Dr. [Alfred S.] McEwen and other scientists identified waterlogged molecules — salts of a type known as perchlorates — in readings from orbit.

“That’s a direct detection of water in the form of hydration of salts,” Dr. McEwen said. “There pretty much has to have been liquid water recently present to produce the hydrated salt.”

By “recently,” Dr. McEwen said he meant “days, something of that order.”

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In 1972, NASA’s Mariner 9 spacecraft discovered evidence of erosion features on Mars that implicated the presence of water at some point in the planet’s past. And in 2005, the High Resolution Stereo Camera (HRSC) aboard the European Space Agency’s Mars Express spacecraft took a photo of a water ice crater 35 meters in diameter at the Martian north pole. Finally, in March of this year, NASA and colleagues at the European Southern Observatory (ESO) uncovered evidence of a massive ancient ocean that once covered almost half of Mars’s northern hemisphere.

But until now, scientists had not yet found any signs of liquid water on the present-day surface of Mars. If liquid water does in fact reside there, it probably wouldn’t be pure H 2 O, since temperatures and atmospheric pressures are too low.

In 2011, Dr. McEwen (a planetary geologist at the University of Arizona and principal investigator of images from the Mars Reconnaissance Orbiter) spotted dark streaks sloping down some of Mars’s canyons and mountains. He dubbed these slope linae, or R.S.L.s; they tended to lengthen during the summer and then disappear in cooler climes. The researchers analyzed the chemical signature of the streaks and found signs of hydrated salt at four locations. These salts, known as perchlorates, lower the freezing temperature of water. But where is the water coming from? Chang quotes McEwen:

“There are two basic origins for the water: from above or from below,” Dr. McEwen said. The perchlorates could be acting like a sponge, absorbing moisture out of the air, but measurements indicate very low humidity on Mars — only enough for 10 microns, or about 1/2,500th of an inch, of rain across the planet if all of the wetness were wrung out of the air.

That idea cannot be entirely ruled out if the lower part of the atmosphere turns out more humid than currently thought.

The other possibility is that frozen water underground might be seeping to the surface during the summer. Whether or not the water would be too salty to support life is still in question.

Watch the live NASA TV press conference here at 11:30 EDT:

Watch "Ultimate Mars Challenge" streaming online.

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Photo credit: NASA

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