A geological mystery is revealed by Opportunity

Spherical objects focused on a projection that Opportunity reached fluctuate in several aspects of the iron-rich spherules nicknamed "blueberries" that the rover found in its place of landing in early 2004 and in many other places so far.

Opportunity is investigating an projection known as Kirkwood Cape York in the segment of the western rim of Endeavour crater. The areas are up to 3 mm in diameter. The analysis is still preliminary, but suggests that these areas do not have the high iron content of the "blueberries" Martian.

"This is one of the most extraordinary images of the entire mission," said principal investigator for Opportunity, Steve Squyres of Cornell University in Ithaca, New York. "Kirkwood is filled with a dense accumulation of these small spherical objects. Of course, we immediately think of the 'blueberries', but this is something completely different. We had never seen so dense accumulation of spherules in a rocky outcrop on Mars. "

The "blueberries" found everywhere on Mars by Opportunity are concretions formed by the action of mineral-laden water into the rocks; try a moist environment on early Mars. Concretions occur when minerals precipitated water to become hard masses within sedimentary rocks. Many areas of Kirkwood are broken and eroded by wind. Clearly a concentric structure where the wind has carved partially.

Opportunity used the microscopic imager on his arm to look closely at Kirkwood. The researchers found the composition of the spheres using an instrument known as X-Ray Spectrometer Alpha Particle Opportunity's arm.

"They seem to be crispy on the outside, and soft on the inside," said Squyres. "They have different strengths. Different structure. Different composition. Different distribution. So, here we have a wonderful geological mystery to us. We have multiple hypotheses, and that is no favorite at this time. It will take some time to resolve this, so you have to do is have an open mind and let the rocks we speak. "

Just beyond is another region Kirkwood scientific Opportunity. The place is a large pale outcrop in an area of ​​Cape York where observations from orbit have detected signs of clay minerals. This may be the next place to study after Kirkwood rover. Four years ago, Opportunity departed Victoria crater, which has been investigated for two years, to get different types of geological evidence on the rim of Endeavour crater, much larger.

Energy levels are favorable Opportunity for investigations. The spring equinox arrives this month to the southern hemisphere of Mars, so the amount of sunlight energy supplies continues to rise for months.

"The rover is in very good condition considering its 8 ½ years of hard work on the surface of Mars," said Project Director of the Mars Exploration Rovers, John Callas of NASA's Jet Propulsion Laboratory of NASA in Pasadena, California. "The energy production levels are comparable to what would be a full Martian year, and hope to have a scan stations productive spring and summer."