Following the Water through Orbital Data

Mars Global Surveyor and Mars Odyssey circle Mars over 20 times a day, collecting images and data, like that above. A continuous presence at Mars allows us to identify more areas that may have been potential watery habitats, as well as plan safe locations to land (the oval at center represent's the Opportunity rover's landing site ellipse). The false colors indicate a region rich in hematite, a mineral that often forms in the presence of water.
Credit: NASA/JPL