Pathfinder Evidence: Life on Mars?

By PAUL RECER AP Science Writer

WASHINGTON (AP) -- Mars was once warm and moist, conditions that make it more likely that the Red Planet could have harbored life, according to researchers who published their findings today from the Pathfinder robot landing mission.

"The body of evidence returned by Pathfinder are suggestive that conditions had been conducive for the formation of life early in Mars' history," said Matt P. Golombek, a Pathfinder mission scientist and lead author of a research report in the journal Science.

Golombek said several lines of evidence have produced a strong consensus among scientists that Pathfinder landed July 4 on a Martian plain that was sculpted by liquid water sometime in the past and that such water proves the planet once was a warmer, more life-friendly place.

Pathfinder and its faithful wheeled rover, Sojourner, found no definite evidence of life. But the report in Science said the spacecraft studies "appear consistent with a water-rich planet that may be more Earth-like than previously recognized, with a warmer and wetter past in which liquid water was stable and the atmosphere was thicker."

Finding evidence of liquid water, said Golombek, "is a shot in the arm for the possibility of finding evidence of life. If there was no liquid water, then there would be no need to search for life on Mars."

"There's nothing we found that would preclude life on early Mars," said John T. Schofield of the Jet Propulsion Laboratory in Pasadena, Calif., which controlled Pathfinder for the National Aeronautics and Space Administration.

"Because there was liquid water billions of years ago, it is conceivable that there could have been life," said H. J. Moore of the U.S. Geological Survey, one of the principal researchers with Sojourner.

Liquid water would mean that Mars was much warmer than the minus-100-degree temperatures experienced by Pathfinder, the researchers say in Science. This, in turn, means that the atmosphere on Mars was then much thicker than now, the researchers say.

Moore said Sojourner, the small-wheeled vehicle that roamed for more than 170 feet around the landing site, found a number of rocks that bore a strong resemblance to rocks that on Earth were formed in the presence of water.

He said rocks named Shark, Prince Charming and Ender all appear to be conglomerates, or rocks formed of smaller pebbles bound together by a matrix, such as clay. Such rocks are formed by water forces on Earth, Moore said.

Some rocks also bore evidence that they may have formed on a lake shore or even underwater, suggesting that water at one time possibly pooled on Mars, Moore added.

He said a search for life will be a part of NASA's continuing exploration of Mars. But he warned that "it is very much a crap shoot. Mars is a big place and where would you go to look? It is a very tough question."

It is unlikely that a search for life will turn up bones sticking out of Martian sand somewhere. More likely, any Martians that ever lived may have been microscopic, he said.

Golombek said it is unlikely there will be final answers about Martian life until samples are returned from there. Even then, finding evidence of life would be only a "very remote possibility," he said.

NASA plans to send landers to Mars in 2001 and 2003 that will scoop up samples that may be returned to Earth on another mission now planned for 2005.

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