Astronomers say they\u2019ve spotted a vast cave lurking beneath the surface of Venus \u2014 providing the strongest evidence yet that the planet is tunneled with lava tubes.<\/p>\n
The discovery of the cave, described in a new study<\/a> published in Nature Communications, adds to our understanding of how Venus was shaped by its hellish preponderance of volcanos.<\/p>\n \u201cOur knowledge of Venus is still limited, and until now we have never had the opportunity to directly observe processes occurring beneath the surface of Earth\u2019s twin planet,\u201d said coauthor Lorenzo Bruzzone at the University of Trento in a statement<\/a> about the work. \u201cThe identification of a volcanic cavity is therefore of particular importance, as it allows us to validate theories that for many years have only hypothesized their existence.\u201d<\/p>\n Scientists have long suspected that Venus harbored lava tubes<\/a>, which are also known as pyroducts. Its surface is scattered with perhaps tens of thousands of volcanoes, and is scarred with volcanic plains and lava channels. Several studies have indicated signs of recent volcanic activity on the planet<\/a>. Clues like these indicated that Venus\u2019s history was dominated by volcanism, but direct evidence of the lava tubes has, until now, eluded detection, while it remained unclear how Venus\u2019 weaker gravity and far denser atmosphere than Earth would affect their formation.<\/p>\n On top of the obvious challenge of spotting something underground, optical observations of Venus\u2019 surface are virtually impossible. The planet is permanently shrouded in a thick cloud layer of sulfur and carbon dioxide, trapping the Sun\u2019s heat and contributing to its incredible surface temperature of over 870 degrees Fahrenheit.<\/p>\n Radar, however, can penetrate this sulfuric shroud. Instead of relying on fresh observations, the researchers combed through data collected by NASA\u2019s Magellan spacecraft between 1990 and 1992 using its Synthetic Aperture Radar.\u00a0\u201cSAR works by transmitting radio waves towards the surface and measuring the time it takes for the waves to bounce back after interacting with the terrain,\u201d the authors explained in the paper. \u201cBy processing the returned radar signals, a detailed backscattering map of the Venusian surface has been produced.\u201d<\/p>\n The team analyzed the radar images \u201cwhere there are signs of localized surface collapses using an imaging technique that we have developed to detect and characterize underground conduits near skylights,\u201d said Bruzzone. (In geology, a skylight refers to a hole formed on a planet\u2019s surface where the roof of a lava tube collapsed.)<\/p>\n Their analysis revealed a \u201clarge subsurface conduit in the region of Nyx Mons,\u201d Bruzzone said, referring to a shield volcano that\u2019s a mighty 225 miles wide. This conduit, or essentially a large cave formed by volcanism, they argue, is a lava tube, and a remarkably large one at that. The team estimates a diameter of around one kilometer, which is bigger than pyroducts found on Earth and Mars, lining up with scientists\u2019 predictions.<\/p>\n \u201cThe available data allow us to confirm and measure only the portion of the cavity close to the skylight. However, analysis of the morphology and elevation of the surrounding terrain, together with the presence of other pits similar to the one studied, supports the hypothesis that the subsurface conduits may extend for at least 45 kilometers,\u201d\u00a0Bruzzone said. But \u201cto test this hypothesis and identify additional lava tubes, new higher-resolution images and data acquired by radar systems capable of penetrating the surface will be required.\u201d<\/p>\n