WASHINGTON, March 23 (UPI) -- NASA said Tuesday new findings on Mars suggest an ancient sea once covered part of the planet.
Agency officials told a news briefing evidence in the rocks at Meridiani Planum, where NASA's Opportunity is exploring, indicates the planet not only was once wet, but probably hosted a large body of seawater.
Some layers within the rocks contain telltale patterns, called crossbedding and festooning, that lie at angles to the main layers. The festooned layers have smile-shaped curves produced by shifting loose sediments under a current of water.
"We think Opportunity is now parked on what was once the shoreline of a salty sea on Mars," said Steve Squyres of Cornell University in Ithaca, N.Y., the principal scientist for the instruments aboard both Opportunity and its twin rover, Spirit.
A second line of evidence, findings of chlorine and bromine in the rocks, also suggests this type of environment.
Although clues gathered so far do not tell when or for how long liquid water covered the area, the rippled patterns in the rocks at Meridiani strongly suggest the land there was once a salt flat that sometimes was covered by shallow water and sometimes was dry, NASA scientists said.
To gather more evidence, the rover's controllers plan to send Opportunity out across a plain toward a thicker exposure of rocks in the wall of a crater.