[meteorite-list] Mars Rover Opportunity Examines Clay Clues in Rock

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 17 May 2013 17:08:22 -0700 (PDT)
Message-ID: <201305180008.r4I08MiN007156_at_zagami.jpl.nasa.gov>


Mars Rover Opportunity Examines Clay Clues in Rock
Jet Propulsion Laboratory
May 17, 2013

PASADENA, Calif. -- NASA's senior Mars rover, Opportunity, is driving to a
new study area after a dramatic finish to 20 months on "Cape York" with
examination of a rock intensely altered by water.

The fractured rock, called "Esperance," provides evidence about a wet ancient
environment possibly favorable for life. The mission's principal investigator,
Steve Squyres of Cornell University, Ithaca, N.Y., said, "Esperance was so
important, we committed several weeks to getting this one measurement of it,
even though we knew the clock was ticking."

The mission's engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif.,
had set this week as a deadline for starting a drive toward "Solander Point,"
where the team plans to keep Opportunity working during its next Martian winter.

"What's so special about Esperance is that there was enough water not only for
reactions that produced clay minerals, but also enough to flush out ions set
loose by those reactions, so that Opportunity can clearly see the alteration,"
said Scott McLennan of the State University of New York, Stony Brook, a
long-term planner for Opportunity's science team.

This rock's composition is unlike any other Opportunity has investigated during
nine years on Mars -- higher in aluminum and silica, lower in calcium and iron.

The next destination, Solander Point, and the area Opportunity is leaving, Cape
York, both are segments of the rim of Endeavour Crater, which spans 14 miles
(22 kilometers) across. The planned driving route to Solander Point is about
1.4 miles (2.2 kilometers). Cape York has been Opportunity's home since the
rover arrived at the western edge of Endeavour in mid-2011 after a two-year
trek from a smaller crater.

"Based on our current solar-array dust models, we intend to reach an area of 15
degrees northerly tilt before Opportunity's sixth Martian winter," said JPL's
Scott Lever, mission manager. "Solander Point gives us that tilt and may allow
us to move around quite a bit for winter science observations."

Northerly tilt increases output from the rover's solar panels during
southern-hemisphere winter. Daily sunshine for Opportunity will reach winter
minimum in February 2014. The rover needs to be on a favorable slope well
before then.

The first drive away from Esperance covered 81.7 feet (24.9 meters) on May 14.
Three days earlier, Opportunity finished exposing a patch of the rock's interior
with the rock abrasion tool. The team used a camera and spectrometer on the robotic
arm to examine Esperance.

The team identified Esperance while exploring a portion of Cape York where the
Compact Reconnaissance Spectrometer for Mars (CRISM) on NASA's Mars Reconnaissance
Orbiter had detected a clay mineral. Clays typically form in wet environments that
are not harshly acidic. For years, Opportunity had been finding evidence for ancient
wet environments that were very acidic. The CRISM findings prompted the rover
team to investigate the area where clay had been detected from orbit.
There, they found an outcrop called "Whitewater Lake," containing a small
amount of clay from alteration by exposure to water.

"There appears to have been extensive, but weak, alteration of Whitewater Lake, but
intense alteration of Esperance along fractures that provided conduits for fluid
flow," Squyres said. "Water that moved through fractures during this rock's
history would have provided more favorable conditions for biology than
any other wet environment recorded in rocks Opportunity has seen."

NASA's Mars Exploration Rover Project launched Opportunity to Mars on July 7,
2003, about a month after its twin rover, Spirit. Both were sent for three-month
prime missions to study the history of wet environments on ancient Mars
and continued working in extended missions. Spirit ceased operations in

JPL, a division of the California Institute of Technology in Pasadena,
manages the Mars Exploration Rover Project for NASA's Science Mission
Directorate. For more about Opportunity, visit: http://www.nasa.gov/rovers
and http://marsrovers.jpl.nasa.gov . You can follow the project on Twitter
and on Facebook at: http://twitter.com/MarsRovers and
http://www.facebook.com/mars.rovers .

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

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

Received on Fri 17 May 2013 08:08:22 PM PDT

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