Today, Mars is a cold, dry world , home to dust devils and robotic explorers. But many scientists suspect it was once waterlogged.

A new study, published last month in the Journal of Geophysical Research: Planets, suggests that a 75-mile-wide impact scar in the Martian northern lowlands is to the red planet what the Chicxulub crater is to Earth: the mark of a meteor that generated a mega-tsunami when the planet was relatively young. If accurate, the finding adds evidence to the hypothesis that Mars once had an ocean, and would have implications for our search for life there.

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Whether Mars was ever warm and wet enough to retain a long-lived liquid water ocean has long been debated by planetary scientists. Several climate models have indicated that it was probably too cold. But other researchers point to ancient river deltas and other geological evidence of a northern ocean some 3.7 billion years ago.

Additional evidence includes hints of mangled, buried coastlines visible from orbit; these suggest that mega-tsunamis with skyscraper-high waves inundated parts of Mars’s northern shores around three billion years ago. On a world believed to have lacked Earthlike plate tectonics, any tsunamis were probably triggered by a meteor slamming into a huge body of water.