More evidence points to water on Mars

WASHINGTON – An orbiting spacecraft has sent back new evidence for the presence of water on Mars.

Scientists long have debated whether water flowed on the red planet, with evidence increasing in recent years. The presence of water would raise the possibility of at least primitive life forms existing there.

Images from a camera aboard NASA’s Mars Reconnaissance Orbiter show alternating layers of dark- and light-toned rock in a giant rift valley.

Within those deposits are a series of linear fractures, called joints, that are surrounded by “halos” of light-toned bedrock, according to researchers from the University of Arizona.

Their findings, published in today’s edition of the journal Science, were being presented at the annual meeting of the American Association for the Advancement of Science in San Francisco.

Lead author Chris H. Okubo said the halos indicate areas where fluids, probably water, passed through the bedrock. Minerals in the fluid strengthen and bleach the rock, he said, making it more resistant to erosion than other areas.

The researchers also said that layered outcrops can indicate cycles with materials deposited by regular episodes of water, wind or volcanic activity.