Astronomers suspect this series of dark streaks flowing down a crater on Mars may have formed from salty, liquid water. (Photo courtesy of NASA)
NASA has long operated on the mantra, "Follow the water," hoping that where there's water, there might also be alien life.
On Thursday, a pair of astronomers from the U. S. Geological Survey in Flagstaff and the University of Arizona announced their team may have found the best evidence yet for liquid water on the surface of Mars.
The announcment, which drew national news headlines, was made at a NASA press conference in Washington, D.C., yesterday afternoon.
The researchers found a series of small, dark streaks, like gullies, flowing down the walls of impact craters in high-resolution images taken by the NASA Mars Reconnaissance Orbiter.
They suspect the gullies form via salty water melting in the Martian spring and trickling down steep slopes.
"It's something we hadn't seen before and didn't know about," said Colin Dundas, a research geologist with the USGS Astrogeology branch in Flagstaff. "We still have a lot more work to do to figure out how these things work."
Ice is abundant on Mars, but most of it sits near the poles where astronomers say it would be difficult to heat the ice enough to get it into liquid form. The farthest from the poles that water had previously been discovered was about the latitude of northern Canada.
Because they found the streaks in an area with lots of salt deposits, they suspect the water would be a briny mix of volatile chemicals that could be liquid below Mars' freezing point. The water would then quickly evaporate in the planet's thin atmosphere.
"The key here is we know Mars has a lot of ice, but this is the first time we're ever seen the potential for liquid," said Phil Christensen, a Mars researcher with Arizona State University who wasn't involved in the research. "They're finding water much closer to where it can be liquid through much of the year."
The initial finding was made by a University of Arizona undergraduate student, Lujendra Ojha, who spotted differences in two images of the same spot in different seasons.
A team of about 10 researchers then started kicking around ways that the streaks could have formed.
They were cautious to claim it was liquid water because similar-looking features were found by previous Mars missions and thought to be water, but they were later determined to be dust avalanches. Dundas said that when they ruled out all the other processes that they could think of to form the gullies, the only remaining option was liquid water.
The team said they hope other scientists will now scrutinize and help confirm or reject their conclusion.
If the results bear out, it would increase the likelihood that life could exist on Mars, said Alfred McEwen of the University of Arizona in Tucson, who is the lead author on the paper detailing the results.
NAU associate astronomy professor and Mars researcher Nadine Barlow said she was anxious to read the scientific paper when it comes out tomorrow, adding it would be a very exciting discovery.
"I think the circumstantial evidence supports the idea that the slope streaks could be liquid briny water, but more work needs to be done to confirm this interpretation," Barlow said.
Astronomers at Lowell Observatory, which was established to study a suspected system of water canals on Mars, said they were also excited by the discovery.
"Flagstaff has a long and distinguished history of Mars research, beginning with the work of Percival Lowell in 1894 and continuing today with the groundbreaking research of scientists at NAU and the USGS," said Lowell Observatory outreach manager Kevin Schindler.
Eric Betz can be reached athdavis@azdailysun.comor 556-2250.
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