A vast ocean once covered more than a third of Mars’ surface, containing 10 times more water than all of Earth’s oceans combined, according to new research. Scientists studying what appear to be ancient, dried out river systems found 52 delta regions that all lay at about the same height, suggesting that they marked the edge of a huge ocean, the Daily Telegraph explains.
The new research represents the most compelling case yet for a Mars ocean, which could, theoretically, have held alien fish. “On Earth, deltas and lakes are excellent collectors and preservers of signs of past life,” said one of the scientists. “If life ever arose on Mars, deltas may be the key to unlocking Mars’ biological past.”