Abstract DGP2026-96

Constraining surface composition and searching for volcanic activity on Venus: The Venus Emissivity Mapper instrument on VERITAS and EnVision missions

Ana-Catalina Plesa (1), Giulia Alemanno (1), Nils Mueller (1,2), M. Darby Dyar (3,4), Suzanne E. Smrekar (5), Thomas Widemann (6), Severine Robert (7), Emmanuel Marcq (8), Martin Pertenais (1), Till Hagelschuer (1), Gisbert Peter (1) and the Venus Emissivity Mapper Team

(1) Institute for Space Research, DLR, Rutherfordstrasse 2, 12489 Berlin, Germany (ana.plesa@dlr.de), (2) Freie Universität Berlin, Institute of Geological Sciences, Department of Earth Sciences, Berlin, Germany, (3) Dept. of Astronomy, Mount Holyoke College, South Hadley, MA 01075, (4) Planetary Science Institute, Tucson, AZ, 85719, (5) Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena CA, 91109 (USA), (6) LESIA, Paris, France, (7) Royal Belgian Institute for Space Aeronomy, Brussels, Belgium, (8) LATMOS, IPSL, U. Versailles Saint-Quentin, Guyancourt, France.

Venus, often called Earth’s twin, is one of the Solar System’s most extreme environments—hosting a dense, hostile atmosphere and a geologically young surface dominated by volcanoes. Volcanic activity and the surface composition are directly linked to the amount of differentiation that our neighbor experienced through time, providing key information about Venus’ thermochemical history. While several observations indicate that Venus was volcanically active in the recent past and that magmatic activity may still be ongoing [e.g., 1 – 5], information about the surface composition and the current level of magmatic activity is still needed.

Three Venus missions (ESA’s EnVision and NASA’s VERITAS and DAVINCI missions) have been selected to explore our sister planet in the next decade with unprecedented detail. All three missions include instruments targeting the 1 µm spectral region [6] where Fe transitions occur that may distinguish differences in surface composition [7]. The Venus Emissivity Mapper instrument, called VEM on VERITAS and VenSpec-M on EnVision, will be used as a multi-spectral imaging systems [8, 9] and have successfully passed the Preliminary Design Review (PDR) in 2025. On EnVision, VenSpec-M is part of the VenSpec Suite [10], and together with high-resolution IR (VenSpec-H) and UV (VenSpec-U) spectrometers, it will provide critical information for understanding the surface-atmosphere interactions on Venus.

Both VEM and VenSpec-M instruments have six surface bands that cover five atmospheric windows around 1 µm. These will be used to distinguish between different rock types using relative (via slope and ratios between bands) and absolute (by comparison with laboratory experiments) emissivity. The instruments will also search for active volcanic eruptions on Venus using surface bands to search for thermal signatures associated with active volcanism, and three additional water vapor bands that are sensitive to the abundance of water vapor potentially associated with volcanic outgassing.

Currently, measurements are performed at PSL with the goal of building a comprehensive dataset for the interpretation of VEM data. These include measurements on basalts vs. granites samples, investigations of end-member mineral mixing effects in emissivity, and studies of the emissivity response of weathered vs. unweathered Venus analogs [11]. Measurements on samples collected during field campaigns can be compared to field measurements performed using a VEM instrument emulator to improve data interpretation and calibration techniques [12]. The surface mapping performed by VEM and VenSpec-M will characterize emissivity changes and provide nearly full coverage of Venus surface.

Acknowledgements: A portion of this research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract 80NM0020F0035 with NASA.

References:

[1] Helbert et al., GRL, 2008. [2] Smrekar et al., Science, 2010. [3] Smrekar et al., Nat. Geosci., 2023. [4] Herrick & Hensley, Science, 2023. [5] Sulcanese et al., Nat. Astron., 2024. [6] Helbert et al., Bulletin of the AAS, 2021. [7] Mueller et al., JGR, 2008. [8] Helbert et al. Proc. SPIE 107650D, 2018. [9] Pertenais et al. Proc. SPIE 136120G, 2025. [10] Alemanno et al., this meeting. [11] Alemanno et al., Proc. SPIE 1268606, 2023. [12] Garland et al., Proc. SPIE 136120F, 2025.