Mars rovers find more evidence of flowing water

4.00pm


LOS ANGELES - The hills of Mars yielded more tantalising clues about how water shaped the Red Planet in tests by Nasa's robotic geologist, Spirit, while its twin, Opportunity, observed the deep crater it climbed into two months ago, scientists said on Wednesday.

Scientists at Nasa's Jet Propulsion Laboratory in Pasadena, California said Spirit discovered a swath of bedrock that showed signs of being altered by water and may yield clues about the planet's primordial atmosphere.

Scientist believe the bedrock was thrust up from below the lava-covered surface of the vast Gusev Crater, where Spirit landed on January 3 and spent months crossing to arrive at a series of promontories dubbed the Columbia Hills.

For the past week, the rover has conducted a series of tests on a rock nicknamed Clovis that is perched on a spur about nine metres above the plain, chief scientist Steve Squyres said at a briefing on Wednesday.

Both Spirit and Opportunity found ancient evidence of water on Mars earlier in their missions but new data recorded by Spirit's scientific instruments this week suggests that the life-giving liquid was once more plentiful than they thought.

"This is different from the rocks out on the plain, where we saw coatings and veins apparently due to effects of a small amount of water. Here we have a more thorough, deeper alteration, suggesting much more water."

Clovis is situated among rocks that do not show signs of water wear, which Squyres said could help scientists "get a handle on what took place".

"So far we have intriguing clues hinting that this rock Clovis had interacted with liquid water," Squyres said. "We need to understand whether it was cold or hot ...liquid or gas. That should tell us a lot about the alteration by water."

Opportunity, which landed on a flat gray plain on the opposite side of Mars that scientists said was once drenched by a salty sea, planned to investigate a dune field inside Endurance Crater, where the rover has explored since June.

The six-wheeled rovers have operated in Mars' harsh atmosphere more than twice as long as they were designed to but are beginning to experience minor mechanical problems, Nasa engineers said.

One of Spirit's wheels has lost power, while Opportunity's rock abrasion tool jammed twice last week, engineers said.

- REUTERS