Opportunity Presents Geological Puzzle on Mars

The recent image of spherical objects concentrated at an outcrop produced by NASA's Mars rover Opportunity has astonished the researchers.

According to the researchers these spherical objects differ in several ways from the iron rich spherules termed 'blueberries' discovered in 2004.

Opportunity is investigating an outcrop called Kirkwood in the Cape York segment of the western rim of Endeavour Crater. The sphere measure 3 millimeters in diameter. In all likelihood these spheres do not have 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."

A microscopic imager was used by Opportunity on its am to carefully analyze Kirkwood. Researchers checked the spheres' composition by using an instrument called the Alpha Particle X-Ray Spectrometer on Opportunity's arm.

The other Martian blueberries found elsewhere by Opportunity are concentration that occurs when minerals precipitate out of water to become hard masses inside sedimentary rocks. It is observed that the wind had eroded and broken the Kirkwood spheres. And where the wind has stamped them away a concentric structure is evident.

"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."

"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."