Ancient Mars Had Vast Ocean, New Evidence Shows

A vast ocean chock-full of microbes may have once covered more than a third of Mars's surface, according to a new analysis of river deltas on the red planet.

The new evidence, from an analysis of dried-up Mars river deltas, adds to growing signs the red planet was once wet.

(Related: "Sulfur Dioxide Kept Ancient Mars Ocean Flowing.")

On Earth, river deltas all lie at more or less the same elevation and reflect the current sea level. In fact, by estimating the elevations of ancient deltas, scientists can reconstruct how sea levels have changed over time.

By determining the elevation of 52 desiccated deltas on Mars, the scientists found that 17 of the deltas lie at approximately the same elevation.

"If there was an ocean on Mars, then the deltas should be at a constant elevation—or at least the majority of them, and that is what we found," Hynek said.

The deltas

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