NASA's Curiosity Mars Rover Studies Rock-Layer Contact Zone

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http://www.jpl.nasa.gov/news/news.php?feature=4645

NASA's Curiosity Mars Rover Studies Rock-Layer Contact Zone
Jet Propulsion Laboratory
July 1, 2015

Fast Facts:

o Rover team members have resumed commanding Curiosity after a moratorium
while the sun was between Earth and Mars.

o Curiosity is examing a zone where two regional rock units neighbor each
other near "Marias Pass."

o The rover found a sandstone with grains of diverse size, shape and color.


NASA's Curiosity Mars rover is examining a valley where at least two types
of bedrock meet, for clues about changes in ancient environmental conditions
recorded by the rock.

In addition to two rock types for which this site was chosen, the rover
has found a sandstone with grains of differing shapes and color.

Curiosity's international team has resumed full operations of the car-size
mobile laboratory after a period of limited activity during most of June.
The operations moratorium for Curiosity and other spacecraft at Mars happens
about every 26 months, when Mars passes nearly behind the sun from Earth's
perspective, and the sun interferes with radio communication between the
two planets.

At the rover's current location near "Marias Pass" on Mount Sharp, Curiosity
has found a zone where different types of bedrock neighbor each other.
One is pale mudstone, like bedrock the mission examined previously at
"Pahump Hills." Another is darker, finely bedded sandstone above the Pahrump-like
mudstone. The rover team calls this sandstone the Stimson unit.

On Mars as on Earth, each layer of a sedimentary rock tells a story about
the environment in which it was formed and modified. Contacts between
adjacent layers hold particular interest as sites where changes in environmental
conditions may be studied. Some contacts show smooth transitions; others
are abrupt.

Curiosity climbed an incline of up to 21 degrees in late May to reach
Marias Pass, guided by images from NASA's Mars Reconnaissance Orbiter
showing Pahrump-like and Stimson outcrops close together.

"This site has exactly what we were looking for, and perhaps something
extra," said Curiosity Project Scientist Ashwin Vasavada, of NASA's Jet
Propulsion Laboratory, Pasadena, California. "Right at the contact between
the Pahrump-like mudstone and the Stimson sandstone, there appears to
be a thin band of coarser-grained rock that's different from either of
them."

The in-between material is a sandstone that includes some larger grains,
of mixed shapes and colors, compared to the overlying dark sandstone.

"The roundedness of some of the grains suggests they traveled long distances,
but others are angular, perhaps meaning that they came from close by,"
Vasavada said. "Some grains are dark, others much lighter, which indicates
that their composition varies. The grains are more diverse than in other
sandstone we've examined with Curiosity."

The science team has identified rock targets for further close-up inspection
of the textures and composition of the mudstone and sandstone exposed
near Marias Pass. The team ancipates keeping Curiosity busy at this site
for several weeks before driving higher on Mount Sharp.

Curiosity has been exploring on Mars since 2012. It reached the base of
Mount Sharp last year after fruitfully investigating outcrops closer to
its landing site and then trekking to the mountain. The main mission objective
now is to examine successively higher layers of Mount Sharp.

JPL, a division of the California Institute of Technology in Pasadena,
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

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

You can follow the mission on Facebook and Twitter at:

http://www.facebook.com/marscuriosity

http://www.twitter.com/marscuriosity


Media Contact

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.w...@jpl.nasa.gov

Dwayne Brown
NASA Headquarters, Washington
202-358-1726
dwayne....@nasa.gov

2015-223