Water on Mars: Evidence Suggests Ocean Covered Third of Red Planet

Scientists have found evidence of flowing water on Mars, which suggests that an ocean may have covered up to a third of the Red Planet billions of years ago.

Using a collection of high-resolution images obtained from NASA's Mars Reconnaissance Orbiter, researchers at the California Institute of Technology discovered ridge-like features, called inverted channels, in Mars' Aeolis Dorsa region.

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"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 Caltech in Pasadena, told Space.com.

These ridges may be that smoking gun, as they often exist where flowing water runs. The inverted channels seen on Mars spread out and slope steeply downward near their end, as streams do on Earth when they empty into a larger body of water.

"This is probably one of the most convincing pieces of evidence of a delta in an unconfined region — and a delta points to the existence of a large body of water in the northern hemisphere of Mars," lead author Roman DiBiase, a postdoctoral scholar at Caltech, said in a statement.

It's not yet clear how big the body of water that once covered a large area of Mars was, but scientists speculate it would at least have flooded the Aeolis Dorsa, which measures about 38,600 square miles.

"In our work and that of others — including the Curiosity rover — scientists are finding a rich sedimentary record on Mars that is revealing its past environments, which include rain, flowing water, rivers, deltas, and potentially oceans," Lamb said. "Both the ancient environments on Mars and the planet's sedimentary archive of these environments are turning out to be surprisingly Earth-like."

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