Radar-based observation of a lava tube on Venus

Intense volcanism has played a significant role in shaping Venus's surface and geology. The existence of lava tubes (i.e., pyroducts) on Venus has been largely hypothesized but never confirmed. Being a subsurface structure, the presence of a lava tube can be revealed by a localized collapse of the roof denoted as skylight. Between 1990 and 1992, the Synthetic Aperture Radar (SAR) instrument on board the Magellan spacecraft mapped the Venusian surface. By leveraging a SAR imaging technique developed for detecting and characterizing accessible subsurface conduits in the proximity of skylights, we analysed the Magellan radar images in locations where there is evidence of localized surface collapses. Our analyses reveal the existence of a large and open subsurface conduit in the Nyx Mons region. This feature is hypothesized to be a pyroduct, characterized by a diameter of about 1 km, a roof thickness of at least 150 m and an empty void height of no less than 375 m. The conduit extends in the subsurface for at least 300 meters from the skylight.