NASA: SOL 784 Gallery

NASA: SOL 788 Gallery

NASA: SOL 788 Gallery

NASA: SOL 788 Gallery

The discovery of Martian soil containing high quantities of sulphur and traces of water has sparked new questions about activity beneath the planet's surface.

Scientists are puzzling over the contents of the bright white and yellow soil, first discovered after Mars rover Spirit churned it up while struggling to cross a soft patch of soil in the Columbia Hills region nearly a year ago.

The material consists of sulphate salts associated with iron and likely calcium, substances not expected to be found on the planet's surface.

Some scientists have speculated the materials might have been deposited in ancient times by liquid water on what is now thought to be a dry planet. However, Ray Arvidson, the deputy principal investigator for NASA's twin Mars rovers, Spirit and Opportunity, said that is only one possible explanation.

"This material could have been left behind by water that dissolved these minerals underground, then came to the surface and evaporated, or it could be a volcanic deposit formed around ancient gas vents," Arvidson said in a statement.

Scientists want to learn more about the planet's geological history for insight into the larger questions of whether Mars once supported life and whether liquid water can still be found beneath its surface, questions important to understanding whether it could one day support life.

Spirit and Opportunity have been exploring the planet's surface since they rolled onto it over three years ago. The rovers will have company on the planet's surface after the Phoenix polar lander launches from Earth in August. NASA's Mars Science Laboratory, a more advanced rover, is scheduled to launch in 2009.

Finding out which theory explains the presence of the sulphur-rich soil will depend on where other samples are discovered, Arvidson said.

"If we find them along fractures, that would suggest they were deposited at ancient gas vents," he said. "If they are at the saddles between hills, that would suggest the deposits formed where groundwater came to the surface."

Locating the soil is not without peril for Spirit, however, since the softer soil regions might entrap the rover and leave its wheels spinning.

Arvidson and NASA scientists described their findings at a meeting this week at the Lunar and Planetary Science Conference in League City, Tex.

SOURCE: CBC News Canada

NASA: SOL 790 Gallery

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