Mars plain once soaked in water, Nasa says

WASHINGTON - Parts of Mars were once "drenched with water," so much that life could easily have existed there, Nasa said today.

The robot explorer Opportunity has seen clear evidence of the main goal of Mars exploration -- that water once flowed or pooled on the Red Planet's surface.

"Opportunity has landed in an area of Mars where liquid water once drenched the surface," Nasa associate administrator Ed Weiler told a news conference. "Moreover, this area would have been good habitable environment."

That does not mean that evidence of life has been found -- but it suggests that life could have evolved on Mars just as it did on Earth, NASA said.

It does mean NASA can go ahead with a plan to eventually send people to Mars.

Opportunity landed on Jan. 24 in a small crater on the vast flat Meridiani Planum near the planet's equator. It has spent most of its time there studying finely layered bedrock in the crater's wall.

Scientists have been puzzling over whether the layers were formed by wind, volcanic lava flows or water, and if little round balls nicknamed "blueberries" may have been formed by water.

"BLUEBERRIES," HEMATITE AND LAVA FLOWS

They have also been intrigued by the discovery of a gray shiny mineral called hematite, which on Earth is formed in water.

The space agency said they had determined that the hematite, the blueberries and the heavy salt content of the area all adds up to one conclusion -- salt water.

"We have concluded the rocks here were once soaked with liquid water," said Dr. Steve Squyres of Cornell University in Ithaca, New York, who leads the scientific investigation.

"It changed their texture, and it changed their chemistry," he added. "We cannot yet tell you with certainty that these rocks were laid down in a lake, in a pool, in a sea."

They may have been formed by percolating groundwater, he said.

"(This area) would have been suitable for life," Squyres said. "That doesn't mean life was there. But this was a habitable place on Mars at one period of time."

More will be known when a mission can be sent to bring back some Mars rocks, Squyres said. "The best way to get at the age is going to be to bring some of this stuff back," he said.

"It is clear that we are going to have to do a sample return," agreed Weiler. He said work will start right away on preparing for an eventual human mission to Mars.

In the meantime, another robotic mission will be set up, probably to pick up some rocks and soil and bring them back to the Earth for close analysis.

Pictures from the rover's panoramic camera and microscopic imager show a rock it has been looking at called "El Capitan" is pocked with indentations about a centimeter (0.4 inch) long.

"This distinctive texture is familiar to geologists as the sites where crystals of salt minerals form within rocks that sit in briny water," Nasa said in a statement.

The composition and density of the salts are comparable to the saltiness seen in the Dead Sea, which straddles the border between Israel and Jordan, Nasa said.

Opportunity may soon be sent to a nearby crater about 30 meters (100 feet) deep to see if deeper layers can be examined, said Joy Crisp, project scientist at Nasa's Jet Propulsion Laboratory in Pasadena, California.

Nasa also held out hope that Spirit, Opportunity's twin rover examining another area of Mars, might find something interesting.



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