Did rivers once run on the Red Planet?

A fan-shaped region of debris on Mars is providing new evidence that the planet, now bone-dry, once had persistent rivers or lakes. Images from NASA’s Mars Global Surveyor spacecraft show what appear to be ancient sedimentary deposits that have hardened into curved ridges of layered rock.

Some of the features in the region could have formed when ancient rivers meandered for vast stretches of time, says Michael C. Malin of Malin Space Science Systems in San Diego. Malin’s team built and operates Surveyor’s camera.

The apparently water-sculpted region covers an area 13 kilometers long and 17 km wide within a crater on Mars’ southern hemisphere. It lies downhill from a large network of channels that may have drained into it billions of years ago.

The fan shape of the area and the pattern of channels suggest the region may have been a delta where a river entered another body of water, Malin and coworker Kenneth S. Edgett report in the Dec. 12 Science. If this interpretation proves correct, the finding “would be the strongest indicator yet [that] Mars once had lakes,” Malin says.


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