[meteorite-list] NASA's Curiosity Mars Rover Studies Rock-Layer Contact Zone

[Ron Baalke]

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.webster at jpl.nasa.gov 

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

2015-223