Mars rover found evidence of water Mars rover found evidence of water (March 05, 2004)

News from NASA was relayed to Ames on Tuesday

By Dan Stapleton

NASA announced Tuesday that its Mars rover Opportunity has found evidence that liquid water once 1drenched the landing site, the most significant discovery since the small, self-propelled science labs landed on the planet Jan. 24.

"We believe, at this place on Mars, for some period of time, it was a habitable environment. It was a ground water environment, which is the kind of place that would have been suitable for life," said Mars rover project investigator Steve Squyres, who relayed the news to media at the Ames Research Center from NASA Headquarters in Washington, D.C.

"Now that doesn't mean life was there. We don't know that. But this was a habitable place on Mars at one point in time," added Squyres.

Investigators don't yet know what amount of water existed, when it existed, or even where it existed. Possible scenarios range from an ocean covering an area the size of the state of Iowa to just ground water that affected rocks while they were underground.

Squyres provided four pieces of evidence Opportunity had collected to support the space agency's claim. First, the rover found small spherical objects a few millimeters in size called concretions, which form when liquid water within a rock precipitates out, leaving behind mineral deposits that fill the rock's pores.

Second, the surface of a rock near the Opportunity's landing site is full of small tabular holes, approximately a centimeter long and a millimeter or two wide.

"It's as if a bunch of objects the size and shape of pennies were embedded in the rock and then suddenly went away," said Squyres. This is a recognizable sight for geologists, who have witnessed these kinds of holes in rocks on Earth. Crystals form within the rock in a thin, flat shape and then either dissolve or erode away, leaving the holes.

Also, a tool used to analyze the chemical composition of the rock detected a large amount of sulfur and sulfate salt, similar to epsom salt, both on the surface and in the interior of the rock. The levels of sulfur and salt found are telltale signs of liquid water.

"The only way you can form such concentrations of salt is to dissolve it in water and then have the water evaporate," said science team member Benton Clark III, speaking from NASA Headquarters.

The most compelling piece of evidence, however, was the rover's discovery of a mineral called jarosite, an iron sulfate hydrate that is found on Earth in rare quantities. "Because it is a sulfate hydrate, you've got to have water around to make it," Squyres said.

This new discovery paves the way for the next phase of Martian exploration: bringing a sample back to Earth. The team envisions constructing a vehicle that would use a rover to collect a sample from the Martian surface and then blast a small capsule back to Earth. Scientists could study it and possibly learn more about water history on Mars.

E-mail Dan Stapleton at dstapleton@mv-voice.com

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