Martian Ocean Evidence Found in Northern Hemisphere Deltas

New satellite images of Mars reveal what may be the fossilized remains of an ancient ocean, reshaping our understanding of the planet’s watery past.

Researchers from the University of Bern identified river delta-like structures in Martian imagery, suggesting an ancient ocean covering the northern hemisphere.

The study used high-resolution images from the ExoMars Trace Gas Orbiter, Mars Express, and Mars Reconnaissance Orbiter to map deposits at elevations of 3,650–3,750 meters (11,975–12,300 feet), dating to 3.37 billion years ago. Co-author Fritz Schlunegger stated, 'Our reconstruction of the sea level is based on clear evidence for such a coastline,' according to the University of Bern statement.

The proposed ocean would have been at least as large as Earth's Arctic Ocean. The team emphasized that this research distinguishes itself from earlier, less precise claims by relying on high-resolution imaging and precise elevation data.

The study, published in NPJ Space Exploration, provides a detailed reconstruction of Martian coastal features but does not address habitability or life, as the source material makes no such claims.

By contrast, earlier interpretations of Martian topography lacked the resolution to confirm such large-scale oceanic structures. The authors note that further analysis of sediment composition and stratigraphy will be required to validate the timeline and extent of the proposed ocean.