[meteorite-list] NASA's Curiosity Rover Finds Clues to How Water Helped Shape Martian Landscape

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 8 Dec 2014 14:00:33 -0800 (PST)
Message-ID: <201412082200.sB8M0Xb8005813_at_zagami.jpl.nasa.gov>

December 8, 2014
     
NASA's Curiosity Rover Finds Clues to How Water Helped Shape Martian Landscape

Observations by NASA's Curiosity Rover indicate Mars' Mount Sharp was built
by sediments deposited in a large lake bed over tens of millions of years.

This interpretation of Curiosity's finds in Gale Crater suggests 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 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."

Why this layered mountain sits in a crater has been a challenging question
for researchers. Mount Sharp stands about 3 miles (5 kilometers) tall, its
lower flanks exposing hundreds of rock layers. The rock layers -
alternating between lake, river and wind deposits -- bear witness to the
repeated filling and evaporation of a Martian lake much larger and
longer-lasting than any previously examined close-up.

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

Curiosity currently is investigating the lowest sedimentary layers of Mount
Sharp, a section of rock 500 feet (150 meters) high dubbed the Murray
formation. 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.

"The great thing about a lake that occurs repeatedly, over and over, is that
each time it comes back it is another experiment to tell you how the
environment works," Grotzinger said. "As Curiosity climbs higher on Mount
Sharp, we will have a series of experiments to show patterns in how the
atmosphere and the water and the sediments interact. We may see how the
chemistry changed in the lakes over time. This is a hypothesis supported by
what we have observed so far, providing a framework for testing in the coming
year."

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.

On the 5-mile (8-kilometer) journey from Curiosity's 2012 landing site to
its current work site at the base of Mount Sharp, the rover uncovered clues
about the changing shape of the crater floor during the era of lakes.

"We found sedimentary rocks suggestive of small, ancient deltas stacked on
top of one another," said Curiosity science team member Sanjeev Gupta of
Imperial College in London. "Curiosity crossed a boundary from an environment
dominated by rivers to an environment dominated by lakes."

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's Mars Science Laboratory Project uses Curiosity to assess ancient,
potentially habitable environments and the significant changes the Martian
environment has experienced over millions of years. This project is one
element of NASA's ongoing Mars research and preparation for a human mission
to the planet in the 2030s.

"Knowledge we're gaining about Mars' environmental evolution by deciphering
how Mount Sharp formed will also help guide plans for future missions to seek
signs of Martian life," said Michael Meyer, lead scientist for NASA's Mars
Exploration Program at the agency's headquarters in Washington.

JPL, managed by the California Institute of Technology, built the rover and
manages the project for NASA's Science Mission Directorate in Washington.

For more information about Curiosity, visit:

http://www.nasa.gov/msl

and

http://mars.jpl.nasa.gov/msl/

Follow the mission on Facebook and Twitter at:

http://www.facebook.com/marscuriosity

and

http://www.twitter.com/marscuriosity

-end-

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown at nasa.gov

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov
Received on Mon 08 Dec 2014 05:00:33 PM PST