Sept. 14, 2012

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

DC Agle 
Jet Propulsion Laboratory, Pasadena, Calif. 
818-393-9011 
david.c.a...@jpl.nasa.gov 

RELEASE: 12-324

NASA MARS ROVER OPPORTUNITY REVEALS GEOLOGICAL MYSTERY

PASADENA, Calif. -- NASA's long-lived rover Opportunity has returned 
an image of the Martian surface that is puzzling researchers. 

Spherical objects concentrated at an outcrop Opportunity reached last 
week differ in several ways from iron-rich spherules nicknamed 
"blueberries" the rover found at its landing site in early 2004 and 
at many other locations to date. 

Opportunity is investigating an outcrop called Kirkwood in the Cape 
York segment of the western rim of Endeavour Crater. The spheres 
measure as much as one-eighth of an inch (3 millimeters) in diameter. 
The analysis is still preliminary, but it indicates that these 
spheres do not have the high iron content of Martian blueberries. 

"This is one of the most extraordinary pictures from the whole 
mission," said Opportunity's principal investigator, Steve Squyres of 
Cornell University in Ithaca, N.Y. "Kirkwood is chock full of a dense 
accumulation of these small spherical objects. Of course, we 
immediately thought of the blueberries, but this is something 
different. We never have seen such a dense accumulation of spherules 
in a rock outcrop on Mars." 

The Martian blueberries found elsewhere by Opportunity are concretions 
formed by action of mineral-laden water inside rocks, evidence of a 
wet environment on early Mars. Concretions result when minerals 
precipitate out of water to become hard masses inside sedimentary 
rocks. Many of the Kirkwood spheres are broken and eroded by the 
wind. Where wind has partially etched them away, a concentric 
structure is evident. 

Opportunity used the microscopic imager on its arm to look closely at 
Kirkwood. Researchers checked the spheres' composition by using an 
instrument called the Alpha Particle X-Ray Spectrometer on 
Opportunity's arm. 

"They seem to be crunchy on the outside, and softer in the middle," 
Squyres said. "They are different in concentration. They are 
different in structure. They are different in composition. They are 
different in distribution. So, we have a wonderful geological puzzle 
in front of us. We have multiple working hypotheses, and we have no 
favorite hypothesis at this time. It's going to take a while to work 
this out, so the thing to do now is keep an open mind and let the 
rocks do the talking." 

Just past Kirkwood lies another science target area for Opportunity. 
The location is an extensive pale-toned outcrop in an area of Cape 
York where observations from orbit have detected signs of clay 
minerals. That may be the rover's next study site after Kirkwood. 
Four years ago, Opportunity departed Victoria Crater, which it had 
investigated for two years, to reach different types of geological 
evidence at the rim of the much larger Endeavour Crater. 

The rover's energy levels are favorable for the investigations. Spring 
equinox comes this month to Mars' southern hemisphere, so the amount 
of sunshine for solar power will continue increasing for months. 

"The rover is in very good health considering its 8-1/2 years of hard 
work on the surface of Mars," said Mars Exploration Rover Project 
Manager John Callas of NASA's Jet Propulsion Laboratory in Pasadena, 
Calif. "Energy production levels are comparable to what they were a 
full Martian year ago, and we are looking forward to productive 
spring and summer seasons of exploration." 

NASA launched the Mars rovers Spirit and Opportunity in the summer of 
2003, and both completed their three-month prime missions in April 
2004. They continued bonus, extended missions for years. Spirit 
finished communicating with Earth in March 2010. The rovers have made 
important discoveries about wet environments on ancient Mars that may 
have been favorable for supporting microbial life. 

JPL manages the Mars Exploration Rover Project for NASA's Science 
Mission Directorate in Washington. 

To view the image of the area, visit: 

http://go.nasa.gov/Q92Rjn 

For more information 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 

-end-

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