A scientific research team from the University of Trento in Italy recently announced that they discovered a giant hollow lava tunnel under the surface of Venus, providing humans with direct evidence of the underground volcanic structure of this "Twin Earth" for the first time. This finding suggests that Venus' volcanic activity likely played a long-term and critical role in its geological evolution.
The research was funded by the Italian Space Agency. By re-analyzing synthetic aperture radar data obtained by NASA's Magellan probe between 1990 and 1992, scientists identified a representative collapse pit and a huge underground cavity structure below it in the Nyx Mons area of Venus. The paper was published in Nature Communications on February 9.
Lorenzo Bruzzone, head of the Remote Sensing Laboratory and professor at the Department of Information Engineering and Computer Science at the University of Trento, said that humankind's understanding of Venus is still very limited, and it has never been able to directly observe the processes taking place beneath its surface before. "The volcanic cavity identified this time is particularly important because it provides the first observational evidence for Venus' underground lava tubes that have only remained at the theoretical level for a long time," he said. He pointed out that this discovery not only helps to deepen the understanding of the evolution of Venus, but also opens a new perspective for future planetary research.
On Earth and the Moon, lava tunnels are usually formed during volcanic eruptions when flowing lava forms a crust on the surface, continues to flow inside, and eventually leaves a hollow channel. Because such structures lie underground, they are often only identified when the top collapses to form a "skylight," and its surface pits are seen as potential entrance clues into the lava tube. However, Venus is shrouded in thick clouds all year round, and optical cameras cannot directly observe the surface and subsurface. Scientists can only rely on radar imaging to "see through" the planet.
The scientific research team used self-developed imaging technology to focus on processing the radar images taken by the "Magellan" in the local surface collapse area, trying to find signals of underground conduits near the "skylight". The analysis results show that there is an underground passage of staggering scale under the Nickus Mountain area, with an estimated diameter of about 1 km, a top "rock cap" thickness of at least 150 meters, and a cavity depth of no less than 375 meters. The research team interpreted it as a giant lava tube (pyroduct).
Research points out that the environmental conditions on Venus may be more conducive to the formation of unusually large lava tunnels. Compared with Earth, Venus's lower gravity and dense atmosphere may allow lava overflowing from volcanic vents to form a thick insulating shell faster during the flow process, thereby maintaining large-scale underground lava channels for a long time. The width and height of the lava tube identified this time significantly exceed the known lava tubes on Earth and the theoretical expectations for lava tubes on Mars. Its size is close to or even larger than the largest similar structures detected by humans on the moon. This size characteristic is also consistent with observations of other volcanic landforms on Venus, such as lava channels on its surface that tend to be longer and wider than those on other terrestrial planets.
The current data can only confirm and measure the section of the cavity close to the "skylight". However, through analysis of the surrounding terrain relief and morphology, and combined with many similar collapse pits nearby, the research team inferred that this underground lava channel system is likely to extend outward for at least 45 kilometers. To test this hypothesis and find more lava tubes on Venus, Bruzzone emphasized, higher-resolution radar images and new data from radar systems with greater penetrating capabilities will be needed.
The results are regarded as important precursor information for multiple upcoming Venus exploration missions. Among them, the European Space Agency's "EnVision" mission and NASA's "VERITAS" mission both plan to carry advanced radar payloads to obtain higher-resolution surface images to conduct detailed analysis of small-scale collapse pits and their surrounding structures. "EnVision" will also be equipped with an orbit-mounted Subsurface Radar Sounder, which can detect subsurface structures at a depth of hundreds of meters. Even if there are no surface openings, it is expected to directly "see" underground lava channels.
Bruzzonet said that this is only a "first glimpse" of the underground volcanic world of Venus. In the future, with the launch of a new generation of detectors and data return, humans are expected to systematically draw a "map" of Venus' underground lava network. He believes that this will not only reshape mankind's understanding of Venus' internal activities and surface renewal mechanisms, but may also provide a natural shielded space and scientific exploration target for future robots and even manned exploration.