Mars was windy, wet and wild in ancient times

May 22nd, 2009 - 12:06 pm ICT by ANI  

Washington, May 22 (ANI): The instruments aboard the Rover Opportunity, which are studying the Victoria Crater on Mars, has revealed more evidence of the red planet’s windy, wet and wild past.

According to Steve Squyres, Cornell professor of astronomy and the principal investigator for NASA’s Mars Exploration Rover mission, Opportunity’s two-year exploration of Victoria Crater - a half-mile wide and 250 feet deep - yielded a treasury of information about the planet’s geologic history and supported previous findings indicating that water once flowed on the planet’s surface.

The data shows that water repeatedly came and left billions of years ago.

Wind persisted much longer, heaping sand into dunes between ancient water episodes. These activities still shape the landscape today.

At Victoria, steep cliffs and gentler alcoves alternate around the edge of a bowl about 0.8 kilometers in diameter.

The scalloped edge and other features indicate the crater once was smaller than it is today, but wind erosion has widened it gradually.

“The impact that excavated the crater millions of years ago provided a golden opportunity, and the durability of the rover enabled us to take advantage of it,” said Squyres.

Imaging the crater’s rim and interior, Opportunity inspected layers in the cliffs around the crater, including layered stacks more than 10 meters (30 feet) thick.

Distinctive patterns indicate the rocks formed from shifting dunes that later hardened into sandstone, according to Squyres and 33 co-authors of the findings.

Instruments on the rover’s arm studied the composition and detailed texture of rocks just outside the crater and exposed layers in one alcove called “Duck Bay.”

Rocks found beside the crater include pieces of a meteorite, which may have been part of the impacting space rock that made the crater.

Other rocks on the rim of the crater apparently were excavated from deep within it when the object hit.

These rocks bear a type of iron-rich small spheres, or spherules, that the rover team nicknamed “blueberries” when Opportunity first saw them in 2004.

The spherules formed from interaction with water penetrating the rocks.

The spherules in rocks deeper in the crater are larger than those in overlying layers, suggesting the action of groundwater was more intense at greater depth.

Opportunity’s first observations showed interaction of volcanic rock with acidic water to produce sulfate salts.

Dry sand rich in these salts blew into dunes. Under the influence of water, the dunes hardened to sandstone.

Further alteration by water produced the iron-rich spherules, mineral changes and angular pores left when crystals dissolved away. (ANI)

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