Mars Rover Opportunity Finds Oddest 'Blueberries' Yet
September 14, 2012

Opportunity Sees Odd Spherical Objects On Mars

Lee Rannals for - Your Universe Online

NASA's veteran rover Opportunity has sent back an image of the Martian surface that is pretty alien compared to what researchers are used to seeing.

The image taken by Opportunity's Microscopic Imager contains these spherical objects that measure as much as one-eighth of an inch in diameter.

The objects are different from iron-rich spherules nicknamed "blueberries" that Opportunity has run across before. Preliminary analysis shows that the 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, Steven 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 blueberries found other places on the Martian surface are concentrations formed by action of mineral-laden water inside rocks, which alludes to evidence of a wet environment on early Mars.

Concentrations 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, and where the wind has worn them away, a concentric structure remains.

Opportunity used its camera to look closely at Kirkwood, and then researchers checked the sphere's composition by using an instrument called the Alpha Particle X-Ray Spectrometer on the rover'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."

The rover is about to embark on a journey to a new location on the Martian surface at an outcrop in an area of Cape York, where observations from orbit have detected signs of clay minerals.

Opportunity's rover levels are favorable for the investigations, and with spring equinox coming to Mars' southern hemisphere this month, more sunshine will provide more solar power.

"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, California. "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."