Abstract DGP2026-20

Coupled Surface–Atmosphere Investigations of Venus with the VenSpec Suite aboard ESA’s EnVision Mission

G. Alemanno (1), S. Robert (2), E. Marcq (3), O. Barraud (1), T. Widemann (8), P. Tackley (4), P. Machado (5), M. Min (6), M. Ferus (7), S. Vinatier (8), J. Lasue (9), L.M. Lara (10), A-C. Plesa (1), J.T. Erwin (2), E. Neefs (2), R. De Cock (2), A.C. Vandaele (2), S. Bertran (3), B. Lustrement (3), T. Hagelschuer (1), M. Pertenais (1), G. Peter (1), F. Wolff (1), S. Del Togno (1), Hafemeister L. (1), J. M. Castro (10), Denk T. (1), A. Nathues (11), Venderlei C. P. (12), Maturilli A. (1), Hueso R. (13), Aoki S. (14), Maia J. (1), Van den Neucker A. (1), Grenfell J.L. (1), Bolsée D. (2), Gilli G. (10) and the VenSpec Science Team

(1) Instute of Space Research, DLR, Germany, (2) BIRA-IASB, Belgium, (3) LATMOS – IPSL, Univ. Versailles – St Quentin, France, (4) ETH, Switzerland, (5) IA, Portugal; 6SRON, Netherlands, (7) Czech Academy of Science, Czech Republic, (8) LIRA, Observatoire de Paris-Meudon, France, (9) IRAP, Obs. Midi-Pyrénées France, (10) IAA-CSIC, Spain, (11) Max Planck Institute for Solar System Research, Göttingen, Germany, (12) Instituto Mauá de Tecnologia, Brazil, (13) Universidad del País Vasco, Bilbao, Spain, (14) The University of Tokyo, Japan.

The ESA EnVision mission aims to achieve a comprehensive understanding of Venus by investigating its geological and atmospheric evolution, addressing why Venus and Earth—despite similar size and bulk composition—followed dramatically different evolutionary pathways. Central to EnVision’s scientific objectives is the VenSpec Suite, a set of complementary spectrometers designed to investigate the coupled Venusian surface–atmosphere system, and to search for signs of ongoing or past volcanic activity.

The VenSpec Suite consists of three synergistic instruments - VenSpec-U, VenSpec-H, and VenSpec-M – with a common interface towards the spacecraft, the Central Control Unit (CCU). Together, they provide coordinated observations from the surface to the upper atmosphere, enabling a holistic view of Venus’ present state and geological history. VenSpec-U is an ultraviolet spectral imager operating between 190 and 380 nm at low and high spectral resolution, optimized to monitor trace gases, cloud properties, and the unknown UV absorber at cloud tops. VenSpec-H is a high-resolution infrared spectrometer covering four near-IR bands between 1.16 and 2.48 μm, targeting key atmospheric species in the troposphere and mesosphere of Venus at high spectral resolution. Polarization filters are also included in the design to characterize the hazes in the mesosphere. VenSpec-M is a multispectral imaging spectrometer operating in 14 near-IR channels (0.79–1.51 μm), designed to retrieve surface thermal emission through atmospheric windows near 1 μm, map surface emissivity and composition, and monitor thermal and compositional anomalies associated with volcanic activity. The CCU provides a harmonized data and power interface between the instruments and the spacecraft. It is designed to provide robust power switching and a unified commanding interface to the instruments, improving operability and coherence of datasets.

VenSpec addresses several core scientific objectives: - a comprehensive search for volcanic activity through the detection of atmospheric gas anomalies, thermal signatures, and surface compositional changes; - characterization of surface–atmosphere coupling by tracking volcanic plumes and gas exchanges from the surface to the cloud tops; - measurement of key tropospheric and mesospheric trace gases, including SO₂, SO, H₂O, HDO, OCS, CO, and HCl; - near-global mapping of surface composition and weathering state to constrain crustal evolution and resurfacing history; and - monitoring of upper-atmospheric chemistry, clouds, and dynamics.

The VenSpec science activities are coordinated by a joint, cross-instrument science team organized into interdisciplinary working groups. These groups foster strong synergies between observations, laboratory experiments, atmospheric modeling, radiative transfer, and ground-based measurements, ensuring coherent scientific exploitation of the VenSpec data and maximizing the mission’s contribution to our understanding of Venus and terrestrial planet evolution.