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NASA: Mars Once Had 'Salty Sea'

Posted on: Wednesday, 24 March 2004, 06:00 CST

Mar. 24--WASHINGTON -- The rocks scrutinized by the Mars rover Opportunity were born in a "salty sea," scientists said Tuesday, further bolstering the theory that the planet was once wet enough to support life.

Building on findings first announced three weeks ago, the scientists said rock outcrops in the crater where the rover spent almost two months display rippled markings that suggest water once moved across them. Their incredibly salty makeup also hints at a briny pool that, as it evaporated, left the rocks behind.

"This is a profound discovery. It has profound implications for astrobiology," said Edward Weiler, NASA's associate administrator for space science, at a news conference at NASA headquarters in Washington.

"If you have an interest in searching for fossils on Mars, this is the first place you want to go."

Opportunity, one of an $820 million pair of rovers built by NASA, landed in a flat part of Mars called Meridiani Planum on Jan. 25. As it explored Eagle Crater, the small depression where it landed, scientists have become increasingly excited about what the rover's trove of tools -- including instruments that can grind at rock and analyze the minerals locked inside -- was uncovering.

Steve Squyres, a Cornell University astronomy professor and the chief investigator for the rovers, said scientists don't know yet how long, or how long ago, the area was covered with liquid water. But the discovery does bolster the theory that Mars was, at one time, hospitable to some form of life.

"We don't know that life was there, but we have an environment that was suitable for life," Squyres said.

While the composition of the rocks would make them an excellent place for microbial fossils to be preserved, the rovers are not equipped to see something that small, Squyres said. But if they are there, future missions would be able to find them.

Three weeks ago, Squyres and others said they couldn't tell whether the water that soaked the rocks was long-term or simply flooded them for a short time. But the patterns in the rocks, known as "crossbedding," show the telltale signs that water at least 2 inches deep once rippled through the area.

"It's a fundamental distinction -- it's like the difference between water you can draw from a well and water you can swim in," Squyres said at a news conference.

What's still unknown, he said, is what the discovery will ultimately tell scientists about the atmosphere and climate of Mars, past and present, and what caused its environment to evolve into the cold, dry place it is today.

"The neat thing is, we have the capability, in the future, to find out," Squyres said.

In fact, the tremendous success of Opportunity and its twin, Spirit, have drummed up even more enthusiasm for future projects. NASA has an ambitious slate of robotic missions on the drawing board, and NASA Administrator Sean O'Keefe is promoting an agenda, outlined in January by President Bush, that could eventually send human beings to Mars.

At Tuesday's news conference, O'Keefe expressed joy at the rovers' fortunes and reveled in the notion that, eventually, human explorers may follow in their footsteps.

"Spirit and Opportunity's ongoing mission illustrates that if you dare to ask profound questions about the universe in which we live, you may very well receive some rather profound answers," O'Keefe said. "We can only imagine what opportunities for discovery await us when we send more-sophisticated robotic capabilities and human explorers to Mars."

Meridiani Planum, because of the wealth of information gleaned there, is now a prime candidate for the landing site of a mission, scheduled for 2009, called the Mars Science Laboratory, which will bring a broader range of tools to the planet, Weiler said. A mission that could collect samples and return them to Earth -- a tantalizing prospect to Mars enthusiasts everywhere -- could happen as early as 2013.

Weiler said that with the proposed robotic missions, and the possibility of manned trips later, scientists may finally be able to answer one of the fundamental questions of humanity: Are we alone?

"It's safe to say if there's life on Mars or was life on Mars, I think in this century we'll know the answer to that question," Weiler said.

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(c) 2004. Distributed by Knight Ridder/Tribune Business News.

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