Environment & Science

Strong evidence Mars has streams of salt water in summertime

Mars true-color globe showing Terra Meridiani.
Mars true-color globe showing Terra Meridiani.
NASA/Greg Shirah

Mars appears to have flowing streams of salty water, at least in the summer, scientists reported Monday in a finding that could have major implications for the possibility of life on the red planet.

Scientists in 2008 confirmed the existence of frozen water on Mars. But the latest observations from an instrument aboard NASA's Mars Reconnaissance Orbiter strongly support the longtime theory that salt water in liquid form flows down certain Martian slopes each summer, according to the researchers.

"Mars just got more interesting," NASA said via Twitter before holding a news conference at its Washington headquarters. The space agency called the results "a major science finding."

Because liquid water is essential to life, the findings could boost the notion of living organisms on Mars. The researchers said in the journal Nature Geoscience that further exploration is warranted to determine whether microscopic life exists on the planet.

The evidence of flowing streams consists of dark, narrow streaks on the surface that tend to appear and grow during the warmest Martian months and fade the rest of the year.

Mars is extremely cold even in summer, and the streaks are in places where the temperature has climbed above minus-10 degrees Fahrenheit. But salt can lower the freezing point of water and melt ice.

Some of the streaks are as long as a football field but only a few yards across, according to Rich Zurek, the MRO project scientist at NASA's Jet Propulsion Laboratory based in Pasadena, Calif.

"Until now we didn't have the resolution to see such narrow features," Zurek told KPCC's AirTalk. "This is all from orbit, remember."

The source of the water is still a mystery. Scientists noted it could be melting ice, an underground aquifer, water vapor from the thin Martian atmosphere, or some combination, according to AP.

"So the question is, is there a fresher source of water? And that's where our next steps will go, is to try to understand what is the source of the water that's making these dark streaks and producing the salt signature," Zurek told KPCC.

Unfortunately, none of the rovers currently on Mars were sterilized enough before launch to safely visit these sites he explained.

"We don’t want to detect life only to find out we brought it with us, so we are going to have to take special care as we take a look at these places."

Another challenge is that these flows are on steep slopes and none of the rovers can drive that terrain. NASA is planning another mission for 2020, but that rover won't be able to climb these hills either, Zurek noted.

So it may be a while before researchers get on-the-ground data from these mysterious wet streaks on Mars.

The Mars Reconnaissance Orbiter has been circling the planet since 2006, AP reports.

The lead author of the research paper, Lujendra Ojha, is from Georgia Institute of Technology.

This story has been updated.