IMPLICATIONS FOR THE RESURFACING HISTORY AND FUTURE EXPLORATION FROM DETECTION OF ACTIVE VOLCANISM ON VENUS (Invited Presentation)

Recently we (Herrick and Hensley, Science, v379, p. 1205-1208, 2023) identified a volcanic vent on Venus that changed over an eight-month period between imaging Cycles 1 and 2 of the Magellan mission. The vent is located near the summit of Maat Mons, the tallest volcano on Venus and the location of the planet’s largest geoid anomaly. Although Maat Mons has long been considered the most likely place on Venus to have recent volcanism, observing change over only an eight-month period almost certainly makes Venus at least in the range of Earth’s intraplate basaltic volcanism in terms of overall activity. That no obvious changes over multi-decade time spans of Arecibo imaging were observed loosely constrains current Venus volcanic resurfacing to not be orders of magnitude greater than Earth. For images with opposite look geometry, as between Magellan Cycles 1 and 2, it is all but impossible to separate real surface changes from imaging geometry differences if the change does not alter the topographic shape of the surface (as occurred for the vent we studied). We would like to use future missions to globally assess current levels of volcanic and tectonic activity. Both InSAR and repeat imaging with similar viewing geometry within a single mission, if planned to provide an adequate global sampling of locales, could provide good global constraints on which parts of the planet are active and their level of activity. Inter-mission comparisons provide a much longer timeline, but assessing changes is both location and data set specific, so these analyses can be used to assess a given study area with time but are more challenging to use for a systematic global assessment of activity. The VERITAS mission will be collecting SAR data at a much shorter wavelength than Magellan, Arecibo, and the upcoming EnVision mission; the team is developing software and protocols for comparing its SAR data with these other data sets.