Water on Mars? Ancient Red Planet had humongous ocean, say scientists. (+video)
Water on Mars: Images from NASA's Mars Reconnaissance Orbiter suggests that billions of years ago, as much as a third of the Red Planet's surface could have been covered with liquid water.
Scientists have spotted more evidence that an enormous ocean on Mars covered much of the planet's surface billions of years ago.Skip to next paragraph
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The latest clues were found in photos from NASA's powerful Mars Reconnaissance Orbiter circling the planet. The images show what appears to be an ancient river delta, which may have emptied into a vast Martian ocean that inundated up to one-third of the Red Planet long ago, a new study reports.
"Scientists have long hypothesized that the northern lowlands of Mars are a dried-up ocean bottom, but no one yet has found the smoking gun," study co-author Mike Lamb, an assistant professor of geology at the California Institute of Technology (Caltech) in Pasadena, said in a statement. [Photos: The Search for Water on Mars]
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The new study does not provide the long-sought smoking gun, researchers stressed, but it further bolsters the hypothesis.
The team studied high-resolution images of a slice of the northern lowlands snapped by the HiRise camera aboard NASA's Mars Reconnaissance Orbiter, which can distinguish features as small as 10 inches (25 centimeters) on the Red Planet's surface.
Specifically, the scientists looked at a 39-square-mile (100 square kilometers) area that's part of a larger region called Aeolis Dorsa, which lies about 620 miles [≈ greatest diameter of the dwarf planet, Ceres] (1,000 km) from Gale Crater. (NASA's Curiosity rover touched down inside Gale Crater last August, kicking off a planned two-year surface mission to assess Mars' past and present potential to host microbial life.)
The small section of Aeolis Dorsa features many ridges called inverted channels, which form in river bottoms over time when coarse material, such as gravel, is deposited by flowing water. Inverted channels can linger long after the rivers that created them have evaporated, helping researchers trace the past activity of liquid water on Mars.
HiRise images allowed the study team to do just that in the section of Aeolis Dorsa they examined. They found that the inverted channels spread out markedly and slope steeply downward near their end, just as streams here on Earth do when they approach and empty into the sea.