"We think Opportunity is now parked on what was once the shoreline of a salty sea on Mars," said Steve Squyres of Cornell University, one of the leaders of the Mars Exploration Rover Project.
The announcement comes after a detailed analysis of a shallow crater Opportunity investigated showed evidence that water once existed on the planet either on the surface or underground. In this latest discovery, scientists say patterns and ripples in the ground are evidence of gently flowing saltwater. Rocks that the craft had been examining also show traces of chlorine and bromine -- telltale signs of having been soaked in saltwater.
Experts believe the findings are the best proof yet that Mars may have once supported some kind of life.
"This result gives us impetus to expand our ambitious program of exploring Mars to learn whether microbes ever lived there and, ultimately, whether we can," said Edward Weiler, NASA's associate administrator for space science.
Scientists are still unsure exactly how large the body of water may have been, or how long ago it existed. There are also no definitive signs of life, but saltwater would mean there was at least a potential environment for some organisms.
Project scientists are thrilled.
"We planned the Mars Exploration Rover Project to look for evidence like that, and it is succeeding better than we had any right to hope," said James Garvin, lead scientist for Mars and lunar exploration at NASA headquarters.
In addition to Opportunity, another rover named Spirit is on the opposite side of Mars studying what may have been a lake.
NASA's future unmanned missions to Mars include one scheduled for 2013 aimed at retrieving rock and soil samples for further study on Earth.
-- Compiled from wire reports and other media sources
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March 23, 2004, 4:15pm EST
