Mars coastline: Photos show possible ocean bed on red planet.

Was This Once a Vast Martian Coastline? (VIDEO)

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July 17 2013 6:06 PM

Was This Once a Vast Martian Coastline? (VIDEO)

Researchers zeroed in on a plain that may very well have harbored the holy grail of Martian exploration: an ocean of liquid water larger than Earth's Lake Superior.

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