Venus radar study reveals vast underground lava cave

by Robert Schreiber
Berlin, Germany (SPX) Feb 10, 2026

Volcanic activity is a key force shaping the surfaces of rocky planets, and new work from Italy indicates that Venus hosts a giant empty lava tube beneath its surface. Using radar images from NASA's Magellan mission, a team at the University of Trento has identified a skylight feature in the Nyx Mons region that reveals a large underground cavity interpreted as a lava conduit.

The study, published in Nature Communications, relies on Synthetic Aperture Radar data collected between 1990 and 1992 by the Magellan spacecraft. Because Venus is shrouded in thick clouds that block optical views, radar imaging is essential for investigating its geology and any processes occurring below the surface. The research focuses on localized surface collapses that may indicate the presence of subsurface voids.

Lava tubes generally form when flowing lava develops a solid insulating crust while molten rock continues to move inside the channel. Once the lava drains away, an empty tunnel can remain, with occasional roof collapses opening skylights that are visible at the surface. Similar features have already been found or proposed on the Moon and Mars, but demonstrating their existence on Venus has been more difficult.

Lead author Lorenzo Bruzzone, a full professor of Telecommunications and head of the Remote Sensing Laboratory at the University of Trento, coordinated the analysis. The team developed and applied an imaging technique designed to detect and characterize underground conduits near skylights in radar data. By examining Magellan images of Nyx Mons, they found clear signatures of a large subsurface cavity associated with a surface pit.

According to the study, the inferred conduit has an estimated diameter of roughly one kilometer, a roof at least 150 meters thick and an empty void extending to depths of no less than 375 meters. These dimensions place the Venus lava tube at the upper end of what scientists have suggested or observed for similar structures on the Moon and above typical sizes expected on Earth or Mars. The researchers note that this is consistent with Venus also having lava channels that are larger and longer than those on other planets.

Bruzzone points out that the identification of a volcanic cavity on Venus is important because it validates long-standing theories that such features should exist under the planet's surface. He explains that our understanding of Venus remains limited and that until now there has been no direct observational evidence of subsurface lava tubes on Earth's so-called twin. The discovery, he argues, deepens knowledge of how volcanic and internal processes have influenced Venusian evolution.

The physical and atmospheric conditions on Venus appear to favor the formation of extensive lava tubes. Compared with Earth, Venus has lower surface gravity and a much denser atmosphere, factors that can enable rapid development of a thick insulating crust as lava flows away from a vent. This environment may promote the creation of large and stable underground channels capable of spanning great distances.

The available Magellan data allow the team to confirm and measure only the section of the cavity near the identified skylight. However, by analyzing the morphology and elevation of the surrounding terrain, and by noting the presence of other pits similar to the main feature, the researchers suggest that the subsurface conduits in the Nyx Mons region could extend for at least 45 kilometers. If true, the system would rank among the most extensive known lava tube networks in the Solar System.

To verify this hypothesis and search for additional lava tubes on Venus, scientists will need new observations at higher spatial resolution and with improved subsurface sensing capabilities. The study highlights how upcoming missions such as the European Space Agency's Envision and NASA's Veritas will be crucial. Both spacecraft are planned to carry advanced radar instruments that can capture sharper images of the surface and detect small pits that might mark further skylights.

Envision will also host an orbital ground-penetrating radar, the Subsurface Radar Sounder, designed to probe several hundred meters below the Venusian surface. This instrument could reveal underground conduits even where no skylight or collapse pit is visible from above. The University of Trento team argues that their newly reported lava tube is likely only the beginning of a broader effort to map and understand Venus's hidden volcanic architecture.

Research Report:Radar-Based Observation of a Lava Tube on Venus