NASA's Curiosity finds how water helps shape Mars mountain

NASA's Curiosity finds how water helps shape Mars mountain

US space agency NASA said Monday that Mars' Mount Sharp, where its Curiosity rover is exploring, was built by sediments deposited in a large lake bed over tens of millions of years.

The formation of Mount Sharp, a five-kilometer-high layered mountain at the center of Gale Crater, has been a challenging question for researchers.

Curiosity landed inside Gale Crater in 2012 and its primary destination was Mount Sharp, which it arrived at three months ago. Currently, the rover is investigating the lowest sedimentary layers of Mount Sharp, a section of rock 150 meters high dubbed the Murray formation.

Observations by Curiosity showed that the mountain was created by sediments from the crater rim highlands and transported toward the center of the crater in alluvial fans, deltas, and wind-blown drifts, NASA said.

"During wet periods, water pooled in lakes where sediments settled out in the center of crater," it said.

"Even during dry periods in the crater center, groundwater would have existed beneath the surface. Then, during the next wet period it would resurface to form the next lake. This alternation of lakes, rivers and deserts could have represented a long-lasting habitable environment."

Later, after the crater had at least partially filled with sediment, erosion of previously deposited sedimentary layers occurred, exposing the ancient sequence of lake, river and desert environments as a series of bands, or layers, along the lower flanks of Mount Sharp.

"We are making headway in solving the mystery of Mount Sharp," Curiosity Project Scientist John Grotzinger of the California Institute of Technology in Pasadena, California, said in a statement. "Where there's now a mountain, there may have once been a series of lakes."

As Curiosity climbs higher on Mount Sharp, the researchers will have a series of experiments to show patterns in how the atmosphere and the water and the sediments interact, Grotzinger said.

The findings also indicated that ancient Mars maintained a climate that could have produced long-lasting lakes at many locations on the Red Planet.

"If our hypothesis for Mount Sharp holds up, it challenges the notion that warm and wet conditions were transient, local, or only underground on Mars," said Ashwin Vasavada, Curiosity deputy project scientist at NASA's Jet Propulsion Laboratory.

"A more radical explanation is that Mars' ancient, thicker atmosphere raised temperatures above freezing globally, but so far we don't know how the atmosphere did that."

Despite earlier evidence from several Mars missions that pointed to wet environments on ancient Mars, modeling of the ancient climate has yet to identify the conditions that could have produced long periods warm enough for stable water on the surface.

NASA said the new findings could also help guide plans for future missions to seek signs of Martian life.