More Steps to Mars

More Steps to Mars
More Steps to Mars The hard, rocky planets lead violent lives, bombarded from space, riven by tectonic forces, beset by volcanic eruptions, and their faces bear the scars. This is the Memnonia Fossae region on Mars. Here we see impact craters that have been weathered by wind and possibly water, partly filled in by lava from the great Tharsis volcanoes, and then, for the large crater at the top, cracked apart by tectonic forces. By determining the order in which such scars form, scientists piece together the history of a planet. (This image covers an area 206 kilometers, or 128 miles, across.) Alfred McEwen, U.S. Geological Survey

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