Mineral points to Martian water suitable for life

By Clare Baldwin

SAN FRANCISCO (Reuters) - Mineral evidence for a water environment capable of supporting life has been discovered on Mars, scientists said Thursday.

Deposits of carbonate, formed in neutral or alkaline water, were spotted by NASA's Mars Reconnaissance Orbiter, the scientists told a meeting of the American Geophysical Union in San Francisco.

"Obviously this is very exciting," said John Mustard of Brown University in Rhode Island. "It's white -- it's a bulbous, crusty material."

Carbonate is formed when water and carbon dioxide mix with calcium, iron or magnesium. It dissolves quickly in acid, so its discovery counters the theory that all water on Mars was at one time acidic.

"It would have been a pretty clement, benign environment for early Martian life," said Bethany Ehlmann, a graduate student at Brown University who led the study published in the journal Science.

"It preserves a record of a particular type of habitat, a neutral to alkaline water environment."

Carbonates on Earth like chalk or limestone sometimes preserve organic material, but scientists have found no such evidence on Mars.

The 3.6 billion-year-old carbonate was discovered in bedrock at the edge of a 930-mile-wide (1,490-km-wide) crater.