More evidence of water on Mars
Ap, 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 Friday'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. "On Earth, bleaching of rock surrounding a fracture is a clear indication of chemical interactions between fluids circulating within the fracture and the host rock," Okubo and co-author Alfred S. McEwen reported in the paper.
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This image provided by Science shows light-toned layered rock in Becquerel Crater on Mars as photographed by the HiRISE (High Resolution Imaging Science Experiment) camera on board Nasa's Mars Reconnaissance Orbiter. The orbiter images show alternating layers of dark and light-toned rock within which are a series of fractures, surrounded by what researchers call 'halos' of light-toned bedrock. These halos are believed to indicate where fluids, probably water, passed through the bedrock. PHOTO: AP |
