An orbiting spacecraft has discovered carbonate minerals on a Martian surface called the Nili Fossae, indicating that the planet might once have had an environment suitable for life, scientists reported on Thursday.

 

The mineral, which forms in the presence of water, had previously been found in microscopic amounts in soil samples provided by the Phoenix Mars Lander, Martian dust and Martian meteorites on Earth. But this is the first time scientists have found a site where carbonate formed. The deposits are about the size of football fields and are visible in images taken by the Mars Reconnaissance Orbiter.

 

Carbonate rocks are created when water and carbon dioxide interact with calcium, iron or magnesium found in volcanic rocks. The porous rocks entrap a huge amount of CO2 within themselves from the atmosphere. To put it into perspective, were all of the CO2 trapped in Earth's volcanic rocks released, our atmosphere would be thicker than that of Venus, according to NASA.

 

But until now, evidence for the source of these carbonates in the Martian bedrock has been uncertain, supporting theories that even if Mars once had bodies of water, they were too acidic to support life as we know it. Currently, Mars has a thin atmosphere and the planet is dry and frigid. But some experts think that billions of years ago the atmosphere was thicker, capturing enough heat from the sun to support liquid water on the surface.

 

Researchers are theorizing that thick CO2 in the past may have kept the Martian surface warm and habitable. Scientists think that a warm environment with a liquid watery surface suggests that the possibility of life there is now more probable than ever.

 

Scott Murchie, of the Johns Hopkins University Applied Physics Laboratory, says, “We’'re excited to have finally found carbonate minerals because they provide more detail about conditions during specific periods of Mars’ history.”

 

Scientists planning the next Mars landing — the Mars Science Laboratory — initially considered Nili Fossae as a potential landing site, but they have not made the final decision yet. The launch of the lab is set for 2011. Last week, NASA reported that the Mars Orbiter had successfully completed its first two-year mission.