Study Finds Evidence of Possible Ancient Martian Ocean

A new scientific study has uncovered fresh evidence suggesting that Mars may once have hosted a vast ancient ocean, strengthening the theory that the Red Planet was once much wetter and more Earth-like billions of years ago.

While dry river networks, deltas, and lake basins already confirm that water existed on Mars in the past, scientists still disagree on whether the planet ever contained a large global ocean.

Lead researcher Michael Lamb said the key question is what geological traces an ancient Martian ocean would have left behind if it later disappeared. His team looked for features resembling Earth’s continental shelves, which form flat platforms marking ancient coastlines.

Lamb, a professor at the California Institute of Technology, and researcher Abdullah Zaki from the University of Texas at Austin ran computer simulations of how Earth’s oceans would appear if they gradually dried up. The goal was to identify similar geological signatures that might exist on Mars.

The most prominent feature on Earth was the continental shelf, which remains stable over time even as sea levels change. The team then searched for similar formations on Mars using data from NASA’s Mars Orbiter Laser Altimeter, which maps planetary surfaces using laser measurements.

Lamb said the researchers found partial evidence that could support the existence of such structures, but not a perfect match to Earth’s continental shelves, meaning the picture remains incomplete.

The idea of an ancient Martian ocean dates back to the 1970s, when the Viking program missions detected possible shoreline-like features and a northern basin that may have been an ancient sea floor. However, these findings were never conclusive.

One challenge is that proposed shoreline elevations on Mars do not remain consistent, instead fluctuating in ways that are difficult to explain. Scientists suggest this could be due to volcanic activity or crustal deformation, but confirming this remains difficult.

More recent missions have added new evidence. China’s Zhurong rover detected possible ancient beach deposits buried beneath northern plains, in a region already suspected to contain remnants of an ancient shoreline system.

Mars today still contains water, mainly in polar ice caps, with additional subsurface water possibly detected by NASA’s InSight lander. However, most of its water was lost over time as the planet’s atmosphere thinned, allowing water molecules to escape into space.

Future missions may help resolve the debate. The European Space Agency’s Rosalind Franklin rover, scheduled for launch in 2028 and landing in 2030, is expected to study Martian surface and subsurface geology in greater detail.

Confirming the existence of an ancient Martian ocean would significantly reshape understanding of the planet’s history and its potential to have once supported life.