NASA finds clues to Mars mysteries

WASHINGTON, Dec. 18 (UPI) -- U.S. space agency scientists say they've discovered a mineral on the surface of Mars that indicates the Red Planet supported water many billions of years ago.

Researchers using a powerful instrument aboard the National Aeronautics and Space Administration's Mars Reconnaissance Orbiter found the long sought-after mineral -- carbonate -- that indicates Mars had neutral to alkaline water when the minerals formed more than 3.6 billion years ago.

Carbonates, which on Earth include limestone and chalk, dissolve quickly in acid, scientists said, so their survival challenges suggestions that an exclusively acidic environment later dominated the Mars. Instead, the researchers said, it indicates different types of watery environments existed. And the greater the variety of wet environments, the greater the chances one or more of them might have supported life, they said.

"We're excited to have finally found carbonate minerals because they provide more detail about conditions during specific periods of Mars' history," said Scott Murchie, principal investigator for the instrument at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.

The findings appear in Science magazine and were announced Thursday in San Francisco during a meeting of the American Geophysical Union.