English researchers from Imperial College London claim that up to 90% of Venus was once covered by liquid oceans holding a volume equivalent to 40% of Earth’s modern seas. Published in Earth and Planetary Science Letters under the title “The lost oceans of Venus,” the study shifts planetary debate from climate models to physical geological markers captured by NASA’s Magellan radar mission.
Rewriting Planetary History Through Radar Data
For decades, standard planetary science dictated that Venus either lost its primordial water before its modern surface even formed or never possessed open bodies of liquid water to begin with. However, a team led by Richard Ghail, alongside co-authors Eloise Crouch and Philippa Mason, has taken a fundamentally different approach. Instead of relying solely on theoretical climate simulations—such as those published in 2016 by Michael Way’s team at the National Aeronautics and Space Administration (NASA)—the Imperial College London researchers hunted for physical, structural footprints etched directly into the venusian terrain.
The research calculates that these ancient marine bodies featured an average depth of 1,400 meters and a salinity level hovering around 35 grams per liter—a concentration that mirrors Earth’s own modern seawater. More critically, the team’s geological modeling dates the catastrophic runaway greenhouse effect that evaporated these vast waters to less than one billion years ago. This timeline places the loss of venusian oceans far more recently than previous scientific literature assumed.
Three Geological Indicators of a Submerged Past
To build a compelling case for marine activity, Ghail’s team analyzed structural anomalies across the lowlands of Venus using radar imaging originally captured by NASA’s Magellan spacecraft. None of these three clues are entirely conclusive on their own, but when layered together, they outline a cohesive narrative of a water-rich world.
- Polygonal Terrain: Researchers examined six distinct types of polygonal fracture networks spanning one to several kilometers across in the planet’s lowlands. These shapes closely match the polygonal fault systems that form on Earth within clay-rich marine sediments, such as those found in the Caribbean’s Grenada Basin, where deeply buried mud compacts, expels water, and fractures upon shrinking.
- Canali Formations: The vast, winding channels crisscrossing the planet—dominated by Baltis Vallis, the longest canyon system in the solar system—were traditionally classified as ancient lava flows. The study argues that their geometry aligns far more precisely with submarine sediment currents carving deep-sea trenches.
- Salt-Backed Ridges: The widespread crinkled ridges cutting across venusian plains sit atop evaporite deposits. Calculations indicate a salt layer at least 64 meters thick, mirroring the subterranean remnants left behind during Earth’s Messinian salinity crisis, which dried out the Mediterranean Sea roughly six million years ago.
Implications for Future Space Missions and Earth’s Climate
While the geological interpretation remains debated by scientists who point toward traditional volcanic and tectonic explanations, upcoming interplanetary exploration aims to settle the dispute. Both the European Space Agency’s EnVision mission and NASA’s VERITAS mission are scheduled for the 2030s. These spacecraft will carry advanced radar instrumentation capable of piercing the dense venusian surface layers to definitively confirm or deny the existence of these suspected salt deposits.
The stakes extend far beyond planetary history. As Ghail and his team note, if a terrestrial planet like Venus can lose its oceans and collapse into an unlivable, 465-degree Celsius greenhouse state in a relatively short geological window, the study plants a warning about the potential for runaway greenhouse effects to alter the future of our own planet.
