Venus is called Earth’s twin because these two planets have comparable masses and diameters. However, our understanding of Venus is limited due to the thick atmosphere shrouding its surface. We know even less about its subsurface. Volcanism, which transfers internal material to the surface, is key to understanding the interior. Venus has a volcanic past, evinced by its global lava plains and numerous volcanic edifices. Volcanoes like Idunn Mons exhibit lava flows that may be only hundreds of years old or less. However, until recently, there had been no direct detections of volcanic activity.
Robert Herrick of the University of Alaska Fairbanks and Scott Hensley of NASA’s Jet Propulsion Laboratory detected volcanic activity with 30-year-old data from NASA’s Magellan mission. Magellan used radar, which can peer through the atmosphere, to image Venus in three cycles, with ~42% of the surface being imaged twice or more. Focusing on areas proposed to be volcanically active, the authors searched for changed surface features by manually comparing radar images from different cycles (the different viewing conditions of each cycle meant that the process could not be automated). Eventually, they found a volcanic vent on the flank of Maat Mons that had expanded (2.2 to 4.0 km2) and had become irregular in shape between cycle 1 and cycle 2, a difference of about eight months. The authors simulated how the pre-changed vent of cycle 1 would look under the viewing geometry of cycle 2 and concluded that the substantial difference observed could only be accounted for by a physical change, plausibly caused by an expanding lava lake or collapse due to magma drainage.
This detection demonstrates that Venus is not just recently but is currently volcanically active. Future missions to Venus, especially those carrying radar instruments like NASA’s Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy (VERITAS) and ESA’s EnVision, will search for surface changes relative to those detected by Magellan and clarify how volcanically active Venus is. READ MORE