Photos show Mars once had lakes, experts say

Associated Press

WASHINGTON — Photos from a satellite orbiting Mars suggest the Red Planet was once a water-rich land of lakes, boosting the theory that billions of years ago it may have had the conditions needed for the evolution of life.

The photos, taken by the Mars Global Surveyor spacecraft, show massive sedimentary deposits, with thick layers of rock stacked one on top of another in miles-deep formations.

In the wall of a massive canyon that stretches for thousands of miles, there are sharp layers of rock, rather like the formation that causes a striped pattern on the walls of Arizona’s Grand Canyon, said Kenneth Edgett, a co-author of the study in Science.

"I don’t know how to do that (form such layers) without water," Edgett said Monday at NASA’s Jet Propulsion Laboratory. He said the layering could possibly have been formed by other means, such as wind or volcanism, "but water is the leading candidate."

Michael Malin, lead author of the study, said that "the regularity of the layering is hard to create" without the presence of water.

The researchers both are with Malin Space Science Systems in San Diego.

Malin said that the researchers have found no geologic evidence of Earthlike oceans, however.

Not all planetary experts were persuaded by the photos released by NASA.

Alan Treiman said he and some other planetary geologists at the Lunar and Planetary Institute in Houston believe the interpretation by Malin and Edgett is not correct.

"This is not evidence for an early wet, warm Mars," said Treiman. He said the layered rock "is probably not relevant to the possibility of life forming very early on Mars."

Many experts believe Mars may have been warmer and wetter billions of years ago and that some change in the planet’s environment caused the open water to vaporize and disappear into space. Some have suggested Mars may still have subsurface pools of water, frozen there by the deep cold that now grips the planet.

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