New geological study suggests Mars once hosted a vast ocean

A study published last week in the journal Nature by Michael Lamb and his team proposes that Mars may have been covered by a massive ocean, spanning up to one-third of its surface, billions of years ago. Researchers identified a flat band of terrain that acts as a geological marker, comparable to the bathtub ring effect or a continental shelf left behind after water recedes. To validate this hypothesis, the scientists created computational models simulating the removal of Earth's oceans to see if similar shelf formations would persist over time. They subsequently analyzed data from NASA's Mars Orbiter Laser Altimeter to identify corresponding topographic features on the Martian surface. While evidence of ancient rivers, deltas, and lakes on Mars is well-documented, the existence of a large-scale ocean has remained a subject of ongoing scientific debate. If confirmed through direct observation, this discovery would provide significant evidence that the planet was once far more Earth-like than previously thought. The study aims to clarify the long-term geological legacy left by such a hypothesized body of water.