Scientists Detect Subsurface Lava Tube on Venus

Researchers from the University of Trento have identified a substantial underground lava tube beneath Venus's surface, marking the first such discovery on the planet. The finding, published in Nature Communications, is based on radar data from NASA's Magellan mission conducted between 1990 and 1992.

Venus's surface is predominantly shaped by volcanic activity, featuring extensive lava plains and long lava channels. However, direct evidence of subsurface volcanic structures like lava tubes has been elusive due to the planet's dense atmosphere, which obscures optical imaging. Lava tubes form when the surface of a lava flow cools and hardens, creating an insulating crust while molten lava continues to flow beneath. Once the eruption ceases, it can leave behind long, hollow conduits. Similar structures have been identified on the Moon and Mars, but confirming their existence on Venus has been challenging.

The research team focused on the Nyx Mons region, a volcanic area named after the Greek goddess of the night. By analyzing radar reflections around surface features known as skylights—pits that form when the roof of a lava tube partially collapses—they detected a large subsurface cavity. This structure is interpreted as a lava tube approximately 1 kilometer in diameter, with a roof thickness of at least 150 meters and an empty void extending to a depth of at least 375 meters. These dimensions place the Venusian lava tube among the largest known in the Solar System.

Venus's physical conditions may favor the formation of large lava tubes. The planet's lower gravity allows underground cavities to remain stable at greater sizes, while its dense atmosphere helps lava flows cool rapidly at the surface, creating thick insulating crusts. This combination may explain why lava channels and tubes on Venus appear larger and longer than those found elsewhere.

The discovery has significant implications for upcoming missions to Venus. The European Space Agency's EnVision and NASA's VERITAS spacecraft will carry advanced radar systems capable of producing higher-resolution images. EnVision will also include a subsurface radar sounder designed to probe hundreds of meters below the surface, potentially detecting lava tubes even when no skylights are visible. This advancement could enhance our understanding of Venus's geological history and its potential for past or present volcanic activity.