Mars Had an Ocean: New 'Bathtub Ring' Found

Scientists have identified features suggesting a vast ancient ocean once existed on Mars. Data from NASA's Mars Global Surveyor probe revealed contours akin to a "coastal shelf" on the planet's northern plains, described as a "bathtub ring" marking a former water level.

This discovery supports the theory of a large ocean that may have persisted nearly 3.7 billion years ago when Mars had a more active hydrological cycle. Researchers believe rivers dumped sediment into this ocean, creating the shelf-like boundary, a Martian version of Earth's continental shelves.

The existence of such an ocean would significantly bolster the argument for Mars's past habitability. Sustained liquid water is a crucial element for life, suggesting that potentially habitable environments might have been more widespread and longer-lasting on early Mars.

Previous research has also uncovered evidence supporting a Martian ocean, including underground sandy beaches detected by China's Zhurong rover and remnants of ancient river deltas. Taken together, these findings paint a picture of a Mars that once resembled Earth more closely than it does today.