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What is the eruptive flux on Venus? Comparison with Earth and Suggestions for Targeted Observations by VenSAR

Matthew E. Pritchard1 , Elizabeth Eiden1, Frederico Galetto1, Philippa Mason2, Catherine L. Johnson3,4, Scott D. King5, and the VenSAR Science Team

  • Affiliations: 1Cornell University, Earth and Atmospheric Sciences, Ithaca, United States, 2Imperial College London, Department of Earth Science and Engineering, London, United Kingdom, 3Planetary Science Institute Tucson, Tucson, United States, 4University of British Columbia, Vancouver, BC, Canada 5Virginia Tech, Department of Geosciences, Blacksburg, United States

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 245

  • Programme No: 1.4.8

  • Theme 1 > Session 4

Abstract

Estimates of the global volcanic output on Venus vary widely (0.01-10 km3/year).  The VenSAR (Venus Synthetic Aperture Radar) instrument launches on the EnVision spacecraft in 2031. We ask: how well will it quantify volcanic flux?  We use the size-frequency distribution and deposit dimensions from large eruptions on Earth, augmenting the size by 75% for the higher temperature and pressure on Venus (Flynn et al., 2023).  We find that ~100% of these eruptions would be detectable with VenSAR-VenSAR imaging and ~90% with VenSAR-Magellan.  However, even if volcanic activity is spatially resolved, the radar images must show observable change.  We examine SAR amplitude changes at 25 basaltic terrestrial lava flows using different polarizations from European Space Agency's Sentinel-1a/b satellites. Only 56% of deposits were detected for any polarization, suggesting that detecting and mapping new deposits on Venus will be challenging.  The difference in wavelength and incidence angle also impact the detectability of surface change.  We will employ scattering theory to extrapolate their impacts on flow detectability.  Targeting VenSAR at the right volcanoes is critical.  If all eruptions were the same size, a sampling of a small number could be sufficient.  Eruption size on Earth and Io vary by orders of magnitude, so we need to measure a range of eruption sizes on Venus. Assuming a size-frequency distribution similar to Earth and Io, if VenSAR images the 20-40% most active volcanic features, we could detect 79-92% of the mass flux. If we target the least active, we would detect zero.