Scientists discover first evidence of lava tubes on Venus

Venus is often called Earth’s “sister planet” because of their similarities in size, mass, and composition. Both are rocky worlds that formed about the same time in the inner solar system; however, despite these similarities, Venus evolved into a world vastly different from Earth, with surface temperatures around 465°C, crushing atmospheric pressure 90 times greater than Earth’s and thick clouds containing sulfuric acid circling the planet. These dramatic differences between two such similar planets make Venus a fascinating subject for planetary scientists to study.

Beyond their similar dimensions, Venus and Earth share another similarity: both planets are geologically active and have been shaped by volcanism. Venus’s surface is dominated by vast volcanic plains, enormous shield volcanoes and vast lava flows. Like Earth, Venus has been resurfaced by molten rock erupting from its interior, creating landscapes that bear striking resemblances to volcanic regions on our own planet.

Understanding these volcanic features, including the underground structures they create, offers a window into the geological processes that have shaped both worlds and provides clues about why they took such different evolutionary paths.

An international team led by Barbara De Toffoli from the University of Padova have been studying radar images and topographic data from earlier Venus missions. They focused their attention on the planet’s large shield volcanoes, those exceeding 100 kilometers in diameter to search for signs of collapsed lava tubes.

These features are natural tunnels that form when the surface of a lava flow cools and solidifies while hot lava continues to flow underneath. Once the lava drains away, it leaves behind a hollow tube. They identified four clear curving chains of pits that appear to mark where sections of underground tubes have collapsed.

These tubes have been found on the moon and Earth, but until now, their existence on Venus remained purely theoretical. Their existence on Venus, or any planet for that matter, provides valuable insights into the volcanic history and perhaps excitingly, may even serve as a shelter for future human exploration missions. This may sound somewhat fanciful but their subsurface nature would offer protection from the hostile environment of the surface.

Unlike straight pit chains caused by tectonic forces pulling the crust apart, these formations curve and wind across the surface, following the natural downhill flow of ancient lava. The team were convinced the pit discovery is not related to tectonic activity due largely to their sinuous nature but also their dimensions, since tectonic pits present as different sizes.

The team identified four instances of these pits and interestingly they all exist on the flanks of volcanoes covered with extensive lava flows. This is exactly where you would expect to find lava tubes. The pits are also aligned in a downhill orientation, making this consistent with lava flowing downhill.

This discovery significantly advances our understanding of how Venus has evolved geologically. The planet’s extreme surface conditions make it notoriously difficult to study. Lava tubes offer a window into Venus’s volcanic past and could help us to refine models of the planet’s thermal and tectonic evolution.

I have to confess though, as a not-so-closet geek, I’m quite taken by the concept of these extensive subterranean tunnels being used by future human explorers. With upcoming missions like the ESA EnVision mission to Venus which has a Subsurface Radar Sounder we will get to reveal the true extent of these tubes and perhaps take us a tiny step closer to human exploration.