Mars Opportunity rover finds gypsum veins

Bright linear features about the width of a human thumb that were found on Mars by NASA's Mars Exploration Rover Opportunity appear to be gypsum veins deposited by groundwater, a team of scientists announced at a 7 December news briefing at the AGU Fall Meeting in San Francisco, Calif. “To me, this is the single most powerful piece of evidence for liquid water on Mars that has been discovered by the Opportunity rover,” said Steve Squyres, a geoscientist at Cornell University in Ithaca, N. Y., and principal investigator for NASA Mars Exploration Rovers Opportunity and Spirit. “We have found sulfates before. Those sulfates were formed somewhere; we don't know where. They have been moved around by the wind, they've been mixed with other materials. It's a big, jumbled, fascinating mess. This stuff was formed right here. There was a fracture in the rock, water flowed through it, gypsum was precipitated from the water. End of story. Okay, there is no ambiguity about this. This is what makes it so cool.”