Spacecraft observations of the landing area for one of NASA’s two Mars rovers now indicate there likely was an enormous sea or lake covering the region in the past, according to a new University of Colorado at Boulder study. Research Associate Brian Hynek of the Laboratory for Atmospheric and Space Physics said data from the Mars Global Surveyor and Mars Odyssey spacecraft now show that the region surrounding the Opportunity rover’s landing site probably had a body of water at least 330,000 square kilometers, or 127,000 square miles. That would make the ancient sea larger in surface area than all the Great Lakes combined, or comparable to Europe’s Baltic Sea.