From NASA Reports
Scientists believe Mars once had lakes. This illustration depicts water filling Mars' Gale Crater. Image: NASA.
Scientists believe Mars once had lakes. This illustration depicts water filling Mars' Gale Crater. Image: NASA.

     Scientists believe Mars once had lakes -- and plenty of them.

     Indeed, Mars' Mount Sharp was built by sediments deposited in a large lake bed over tens of millions of years, according to NASA scientists analyzing findings from the Curiosity Rover. Space agency scientists believe the climate of ancient Mars could have produced 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, deputy project scientist for Curiosity at NASA's Jet Propulsion Laboratory in Pasadena. “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."
     Curiosity is investigating the lowest sedimentary layers of Mount Sharp, a section of rock 500 feet (150 meters) high. Rivers carried sand and silt to the lake, depositing the sediments at the mouth of the river to form deltas similar to those found at river mouths on Earth. This cycle occurred over and over again.
     After the crater filled to a height of at least a few hundred yards and the sediments hardened into rock, the accumulated layers of sediment were sculpted over time into a mountainous shape by wind erosion that carved away the material between the crater perimeter and what is now the edge of the mountain.
     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.

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