Alternative explanations posited for minerals thought to be left by puddles.
Soon after NASA's robotic rover Opportunity began exploring Mars, it found minerals and rocks that its handlers said were evidence of a warm, wet history. But two groups of scientists have now questioned this interpretation.
Soon after NASA's robotic rover Opportunity began exploring Mars, it found minerals and rocks that its handlers said were evidence of a warm, wet history. But two groups of scientists have now questioned this interpretation.
