[meteorite-list] Upgrade Helps NASA Study Mineral Veins on Mars (MSL)

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=4766

Upgrade Helps NASA Study Mineral Veins on Mars
Jet Propulsion Laboratory
November 11, 2015

Scientists now have a better understanding about a site with the most 
chemically diverse mineral veins NASA's Curiosity rover has examined on 
Mars, thanks in part to a valuable new resource scientists used in analyzing 
data from the rover.

Curiosity examined bright and dark mineral veins in March 2015 at a site 
called "Garden City," where some veins protrude as high as two finger 
widths above the eroding bedrock in which they formed.

The diverse composition of the crisscrossing veins points to multiple 
episodes of water moving through fractures in the bedrock when it was 
buried. During some wet periods, water carried different dissolved substances 
than during other wet periods. When conditions dried, fluids left clues 
behind that scientists are now analyzing for insights into how ancient 
environmental conditions changed over time.

"These fluids could be from different sources at different times," said 
Diana Blaney, a Curiosity science team member at NASA's Jet Propulsion 
Laboratory, Pasadena, California. "We see crosscutting veins with such 
diverse chemistry at this localized site. This could be the result of 
distinct fluids migrating through from a distance, carrying chemical signatures 
from where they'd been."

Researchers used Curiosity's laser-firing Chemistry and Camera (ChemCam) 
instrument to record the spectra of sparks generated by zapping 17 Garden 
City targets with the laser. The unusually diverse chemistry detected 
at Garden City includes calcium sulfate in some veins and magnesium sulfate 
in others. Additional veins were found to be rich in fluorine or varying 
levels of iron.

As researchers analyzed Curiosity's observations of the veins, the ChemCam 
team was completing the most extensive upgrade to its data-analysis toolkit 
since Curiosity reached Mars in August 2012. They more than tripled -- 
to about 350 -- the number of Earth-rock geochemical samples examined 
with a test version of ChemCam. This enabled an improvement in their data 
interpretation, making it more sensitive to a wider range of possible 
composition of Martian rocks.

Blaney said, "The chemistry at Garden City would have been very enigmatic 
if we didn't have this recalibration."

The Garden City site is just uphill from a mudstone outcrop called "Pahrump 
Hills," which Curiosity investigated for about six months after reaching 
the base of multi-layered Mount Sharp in September 2014. The mission is 
examining ancient environments that offered favorable conditions for microbial 
life, if Mars has ever hosted any, and the changes from those environments 
to drier conditions that have prevailed on Mars for more than 3 billion 
years. Curiosity has found evidence that base layers of Mount Sharp were 
deposited in lakes and rivers. The wet conditions recorded by the Garden 
City veins existed in later eras, after the mud deposited in lakes had 
hardened into rock and cracked.

Eye-catching geometry revealed in images of the veins offers additional 
clues. Younger veins continue uninterrupted across intersections with 
veins that formed earlier, indicating relative ages.

ChemCam provides the capability of making distinct composition readings 
of multiple laser targets close together on different veins, rather than 
lumping the information together. The chemistry of these veins is also 
related to mineral alteration observed at other places on and near Mount 
Sharp. What researchers learned here can be used to help understand a 
very complex fluid chemical history in the region. Since leaving Garden 
City, Curiosity has climbed to higher, younger layers of Mount Sharp.

Today, Blaney presented findings from ChemCam's Garden City investigations 
at the annual meeting of the American Astronomical Society's Division 
for Planetary Science, in National Harbor, Maryland.

The U.S. Department of Energy's Los Alamos National Laboratory in Los 
Alamos, New Mexico, developed ChemCam in partnership with scientists and 
engineers funded by the French national space agency. More information 
is available at:

http://www.msl-chemcam.com

NASA's Jet Propulsion Laboratory built Curiosity and manages the project 
for NASA's Science Mission Directorate in Washington. For more the mission, 
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 / Laurie Cantillo
Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown at nasa.gov/ laura.l.cantillo at nasa.gov