Climate Change on Mars: NASA Rover Curiosity Discovers Evidence of Ancient Rivers

The Mars rover Curiosity may not have found evidence of life, but it's definitely found evidence of water on the Red Planet. NASA scientists have revealed that the rover has found evidence that rivers once ran across the surface of Mars that were between an inch to nearly three feet deep.

Today, Mars is a desert, inhospitable to most forms of life as we know it. Violent winds tear across the icy plains that are characterized by craters and mountains. Dust and rock are the dominant features of the Red Planet, and flowing water appears to be all but impossible.

Yet in this planet's ancient past, water may just have been part of the landscape. Researchers analyzed sediment taken from a Martian plain that abuts a sedimentary deposit known as an alluvial fan. Alluvial fans are comprised of sediment leftover when a river spreads out over a plain then dries up, and are common on Earth in arid regions such as Death Valley.

The sediment and sand grains actually bear the telltale roundness of river stones that are too heavy to have been moved by wind. It's very possible that the sediment was produced by water that moved at the speed of a small stream.

"Once you get above a couple of millimeters the wind will not be able to mobilize sediment," said Kevin Lewis, a Princeton associate research scholar in geosciences, in a news release. "A number of the grains we see in this outcrop are substantially bigger than that. That really leaves us with fluvial transport as the most likely process. We knew Curiosity was landing near the fan, but to land right on top of these rocks that suggest the presence of water was really fortuitous."

If a river did run across the surface of Mars, the next question is how it dried up in the first place. Climate change that occurred as Mar's atmosphere shifted could be a likely culprit. Currently, researchers are planning on investigating the question over the next coming year. The findings could reveal whether or not ancient Mars may have been hospitable to life in the past.

"This evidence tells us that there were a diverse set of geological processes happening at roughly the same time within the proximity [of the landing site], and it gives us a picture of a much more dynamic Mars than we see today," said Lewis. "Finding out how exactly they relate will be an exciting story."

The findings are published in the journal Science.