Did Mars Once Have an Ocean? New Clues Emerge

Scientists from the California Institute of Technology (Caltech) have uncovered new evidence suggesting that Mars may have once hosted a vast ocean covering up to one-third of the planet’s surface billions of years ago.

The study focuses on a geological feature described as a “coastal shelf,” similar to the ring left behind when water drains from a bathtub. This formation could represent the boundary of an ancient Martian ocean.

To support their findings, researchers used computer simulations on Earth to understand how oceans disappear over time and what traces they leave behind.

They found that continental shelves — broad, flat areas along coastlines — are among the most durable features, capable of surviving billions of years despite environmental changes.

The team then compared these patterns with data collected by NASA’s Mars Orbiter Laser Altimeter, which maps the planet’s surface.

While the feature identified on Mars does not perfectly match Earth’s coastal shelves, it provides new evidence in a long-standing scientific debate over whether Mars once had a large ocean.

Scientists emphasize that the findings are not yet conclusive, but future missions, including upcoming rover explorations, could help confirm whether Mars was once a much wetter and more Earth-like planet.