Author Topic: Nasa scientists find evidence of flowing water on Mars  (Read 1739 times)

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Offline Mister Toast

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Nasa scientists find evidence of flowing water on Mars
« on: September 28, 2015, 17:51:03 PM »
Nasa scientists find evidence of flowing water on Mars


 
Researchers say discovery of stains from summertime flows down cliffs and crater walls increases chance of finding life on red planet

Writing in the journal Nature Geosciences, the team describes how it found infra-red signatures for hydrated salts when the dark flows were present, but none before they had grown. The hydrated salts – a mix of chlorates and percholorates – are a smoking gun for the presence of water at all four sites inspected: the Hale, Palikir and Horowitz craters, and a large canyon called Coprates Chasma.

“These may be the best places to search for extant life near the surface of Mars,” said Alfred McEwen, a planetary geologist at the University of Arizona and senior author on the study. “While it would be very important to find evidence of ancient life, it would be difficult to understand the biology. Current life would be much more informative.”

The flows only appear when the surface of Mars rises above -23C. The water can run in such frigid conditions because the salts lower the freezing point of water, keeping it liquid far below 0C.

“The mystery has been, what is permitting this flow? Presumably water, but until now, there has been no spectral signature,” Meyer said. “From this, we conclude that the RSL are generated by water interacting with percholorates, forming a brine that flows downhill.” 

John Bridges, a professor of planetary science at the University of Leicester, said the study was fascinating, but might throw up some fresh concerns for space agencies. The flows could be used to find water sources on Mars, making them prime spots to hunt for life, and to land future human missions. But agencies were required to do their utmost to avoid contaminating other planets with microbes from Earth, making wet areas the most difficult to visit. “This will give them lots to think about,” he said.

For now, researchers are focused on learning where the water comes from. Porous rocks under the Martian surface might hold frozen water that melts in the summer months and seeps up to the surface. 

Another possibility is that highly concentrated saline aquifers are dotted around beneath the surface, not as pools of water, but as saturated volumes of gritty rock. These could cause flows in some areas, but cannot easily explain water seeping down from the top of crater walls. 

A third possibility, and one favoured by McEwen, is that salts on the Martian surface absorb water from the atmosphere until they have enough to run downhill. The process, known as deliquescence, is seen in the Atacama desert, where the resulting damp patches are the only known place for microbes to live.

“It’s a fascinating piece of work,” Bridges said. “Our view of Mars is changing, and we’ll be discussing this for a long time to come.”

http://www.theguardian.com/science/2015/sep/28/nasa-scientists-find-evidence-flowing-water-mars