Sunday, September 23, 2012

Microbial life on the Mars? Nasa Mars rover Opportunity reveals geological mystery of the Red Planet


NASA's long-lived rover Opportunity has returned
an image of the Martian surface that is puzzling researchers.

Spherical objects concentrated at an outcrop Opportunity reached last
week differ in several ways from iron-rich spherules nicknamed
"blueberries" the rover found at its landing site in early 2004 and
at many other locations to date, says a NASA statement.

Opportunity is investigating an outcrop called Kirkwood in the Cape
York segment of the western rim of Endeavour Crater. The spheres
measure as much as one-eighth of an inch (3 millimeters) in diameter.
The analysis is still preliminary, but it indicates that these
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, 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."

The Martian blueberries found elsewhere by Opportunity are concretions
formed by action of mineral-laden water inside rocks, evidence of a
wet environment on early Mars. Concretions 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. Where wind has partially etched them away, a concentric
structure is evident.

Opportunity used the microscopic imager on its arm to look closely at
Kirkwood. Researchers checked the spheres' composition by using an
instrument called the Alpha Particle X-Ray Spectrometer on
Opportunity'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."

Just past Kirkwood lies another science target area for Opportunity.
The location is an extensive pale-toned outcrop in an area of Cape
York where observations from orbit have detected signs of clay
minerals. That may be the rover's next study site after Kirkwood.
Four years ago, Opportunity departed Victoria Crater, which it had
investigated for two years, to reach different types of geological
evidence at the rim of the much larger Endeavour Crater.

The rover's energy levels are favorable for the investigations. Spring
equinox comes this month to Mars' southern hemisphere, so the amount
of sunshine for solar power will continue increasing for months.

"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."

NASA launched the Mars rovers Spirit and Opportunity in the summer of
2003, and both completed their three-month prime missions in April
2004. They continued bonus, extended missions for years. Spirit
finished communicating with Earth in March 2010. The rovers have made
important discoveries about wet environments on ancient Mars that may
have been favorable for supporting microbial life.

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