Mars may have been able to harbor life for longer than we thought

Mars had lakes as recently as 2 billion to 3 billion years ago, new research suggests, which is long after scientists believed it was warm enough to harbor liquid water.

NASA/JPL-Caltech/ASU
Valleys much younger than well-known ancient valley networks on Mars are evident near the informally named 'Heart Lake' on Mars.
NASA/JPL-Caltech/MSSS
Streamlined forms in this Martian valley resulted from the outflow of a lake hundreds of millions years more recently than an era of Martian lakes previously confirmed.

Mars may have been able to support life for much longer than scientists had thought.

Some Red Planet streams and lakes — including one bigger than several of North America's Great Lakes — formed just 2 billion to 3 billion years ago, a new study suggests. That's a surprise, because researchers think that, by that epoch, Mars had already lost most of its atmosphere, and therefore had likely become too cold to host liquid water on its surface.

"This paper presents evidence for episodes of water modifying the surface on early Mars for possibly several hundred million years later than previously thought, with some implication that the water was emplaced by snow, not rain," Mars Reconnaissance Orbiter (MRO) project scientist Rich Zurek, of NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement. [Water on Mars: Exploration & Evidence

Zurek was not part of the study team, which was led by Sharon Wilson of the Smithsonian Institution and the University of Virginia. Wilson and her colleagues studied photos of Mars' northern Arabia Terra region taken by three orbiters — MRO, NASA's Mars Global Surveyor probe and Europe's Mars Express spacecraft.

"We discovered valleys that carried water into lake basins," Wilson said in the same statement. "Several lake basins filled and overflowed, indicating there was a considerable amount of water on the landscape during this time."

"Considerable amount" indeed: One of the newly discovered lakes was about as big as Lake Tahoe, a body of water on the California-Nevada border that holds about 45 cubic miles (188 cubic kilometers) of water, Wilson said.

And this Martian lake overflowed into an enormous basin, dubbed Heart Lake, that held about 670 cubic miles (2,790 cubic km) of water — quite a bit more than Lake Erie and Lake Ontario, two of the five Great Lakes along the Canada-U.S. border, researchers added. (Lake Erie and Lake Ontario hold 116 cubic miles and 393 cubic miles, or 480 and 1,640 cubic km, respectively.

The study team arrived at their age estimate by looking at the valleys in the lake-and-stream system. Specifically, researchers checked if those valleys had carved into the aprons of debris surrounding 22 impact craters in the area whose rough ages were already known. (If a valley did cut into such an apron, water was flowing after the crater-creating impact occurred.)

Observations by MRO, NASA's Curiosity rover and other missions had already found strong evidence of lakes, streams and other bodies of liquid surface water in Mars' more ancient past — 3.7 billion years or so ago. 

Scientists think the majority of Mars' atmosphere was lost to space shortly thereafter, cooling the planet down considerably. The new results are consistent with a cold climate, Wilson said.

"The rate at which water flowed through these valleys is consistent with runoff from melting snow," she said, "These weren't rushing rivers. They have simple drainage patterns and did not form deep or complex systems like the ancient valley networks from early Mars."

But it's unclear how that snow heated up enough to melt, she said. One possibility is a shift in Mars' axial tilt, which resulted in greater illumination of the ice caps at the planet's poles, researchers said. (Valleys like those seen in Arabia Terra also occur in Mars' southern hemisphere, suggesting that lakes and streams existed over broad stretches of the planet, study team members said.)

The new study has been accepted for publication in the Journal of Geophysical Research, Planets.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @SpacedotcomFacebook or Google+. Originally published on Space.com.

Editor's Recommendations

Copyright 2016 SPACE.com, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

You've read  of  free articles. Subscribe to continue.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.