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Summary The rover, called Opportunity, and its twin, Spirit, arrived on opposite sides of Mars in January.
A NASA rover scouting for signs of past water on Mars has found the strongest evidence yet – a vein of gypsum, a mineral deposited by water, protruding from an ancient rock.The rover, called Opportunity, and its twin, Spirit, arrived on opposite sides of Mars in January 2004. Over the years, the rovers, aided by several orbiting spacecraft, have returned a convincing body of evidence that Mars was not always as cold and dry as it is today.
