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The Red Planet once had more water than the Arctic Ocean, according to NASA scientists. Around 4.3 billion years ago, Mars may have had enough water to have its entire surface covered in a layer about 450 feet deep. However, Mars lost 87 percent of its water to space over time, according to a new paper from NASA. “With Mars losing that much water, the planet was very likely wet for a longer period of time than was previously thought, suggesting it might have been habitable for longer," said scientist Michael Mumma, one of the author's on the NASA paper.