Scientists get an "Opportunity" to see interior of Mars

Washington, January 22 (ANI): NASA's Mars exploration rover Opportunity is allowing scientists to get a glimpse into the interior of Mars.

Perched on a rippled Martian plain, a dark rock not much bigger than a basketball was the target of interest for Opportunity during the past two months.

Dubbed "Marquette Island," the rock is providing a better understanding of the mineral and chemical makeup of the Martian interior.

"Marquette Island is different in composition and character from any known rock on Mars or meteorite from Mars," said Steve Squyres of Cornell University in Ithaca, New York.

"It is one of the coolest things Opportunity has found in a very long time," he added.

During six years of roving, Opportunity has found only one other rock of comparable size that scientists conclude was ejected from a distant crater.

The rover studied the first such rock during its initial three-month mission.

Called "Bounce Rock," that rock closely matched the composition of a meteorite from Mars found on Earth.

Marquette Island is a coarse-grained rock with a basalt composition.

The coarseness indicates it cooled slowly from molten rock, allowing crystals time to grow.

This composition suggests to geologists that it originated deep in the crust, not at the surface where it would cool quicker and have finer-grained texture.

"It is from deep in the crust and someplace far away on Mars, though exactly how deep and how far we can't yet estimate," said Squyres.

The composition of Marquette Island, as well as its texture, distinguishes it from other Martian basalt rocks that rovers and landers have examined.

Scientists first thought the rock could be another in a series of meteorites that Opportunity has found.

However, a much lower nickel content in Marquette Island indicates a Martian origin.

The rock's interior contains more magnesium than in typical Martian basalt rocks Spirit has studied.

Researchers are determining whether it might represent the precursor rock altered long ago by sulfuric acid to become the sulfate-rich sandstone bedrock that blankets the region of Mars that Opportunity is exploring.

"It's like having a fragment from another landing site," said Ralf Gellert of the University of Guelph, in Ontario, Canada.

"With analysis at an early stage, we're still working on some riddles about this rock," he added.

Opportunity currently is about 30 percent of the way on a 12-mile trek begun in mid-2008 from a crater it studied for two years.

It is en route toward a much larger crater, Endeavour. (ANI)