The EnVision Mission to Venus – mission overview and science preparations

EnVision is ESA’s next mission to Venus in partnership with NASA, where NASA provides the Synthetic Aperture Radar payload and mission support for critical phases [1]. The mission was adopted in January 2024, and ESA awarded Thales Alenia Space (TAS) the contract to build the Envision spacecraft on 28 January 2025. The launch is scheduled for 2031, and the science operations at Venus would start in summer 2034, after the mission cruise and aerobraking phase around Venus to achieve a low Venus polar orbit. EnVision will provide a holistic view of the planet from its inner core to its upper atmosphere, studying the planets history, geological activity and climate. It aims to establish the nature and current state of Venus’ geological evolution and its connection with the atmosphere. The overall science objectives are to: (i) characterize the sequence of events that formed the regional and global surface features of Venus, as well as the geodynamic framework that has controlled the release of internal heat over Venus history; (ii) determine how geologically active the planet is today; (iii) establish the interactions between the planet and its atmosphere at present and through time. Furthermore, EnVision will look for evidence of past liquid water on the planet surface.

The nominal science phase of the mission will last six Venus cycles (~four Earth years), and ~210 Tbits of science data will be downlinked using a Ka-/X-band communication system. The science objectives will be addressed by five instruments and one experiment, provided by ESA member states and NASA. The NASA provided VenSAR S-band radar will perform targeted surface imaging as well as polarimetric and stereo imaging, radiometry, and altimetry. The high-frequency Subsurface Radar Sounder (SRS) will sound the upper crust in search of material boundaries for the first time. Three spectrometers, VenSpec-U, VenSpec-H and VenSpec-M, operating in the UV and Near- and Short Wave-IR, respectively, will map trace gases, search for volcanic gas plumes above and below the clouds, and map surface emissivity and composition. A Radio Science Experiment (RSE) investigation will exploit the spacecraft Telemetry Tracking and Command (TT&C in Ka-/X bands) system to determine the planet’s gravity field and to sound the structure and composition of the middle atmosphere and cloud layer in radio occultation. ASI, DLR, BelSPO, and CNES lead the procurements of the SRS, VenSpec-M, VenSpec-H and VenSpec-U instruments and the Radio Science Experiment (RSE), respectively. All instruments have heritage and robust margins relative to the requirements, with designs suitable for operation in the Venus environment, and were chosen to meet the broad range of measurement requirements needed to support the EnVision scientific objectives. The EnVision science teams will adopt an open data policy, with public release of the scientific data after validation and verification. Public calibrated data availability are provided <6 months after data downlink.

In 2024, the Envision Science Working Team and its appointed Regions of Interest (ROI) Working Group started to work on a refined version of the Venus ROIs to be observed by the instruments and experiment. In particular, the planning of the VenSAR SAR imaging observations requires careful preparation and optimization, due to the high data rates and inter-planetary downlink limitations, balancing the observation needs between the mission instruments and experiment. Further activities include the maturation of the instrument and mission design, science performance simulations and confirmation, definition and preparations of the characterization, calibration, operations and data processing. Finally, the Envision science community is steadily growing with several scientific activities on-going to prepare for mission data exploitation.

The scientific objectives, instrumentation, and status of the EnVision mission will be presented, including an overview of on-going scientific and technical activities and the next steps in the mission preparation.

Acknowledgements: The Envision instrument (science) teams, further project team members, and industry partners.

References:

[1] ESA (2023): EnVision, Understanding why Earth’s closest neighbour is so different, ESA Definition Study Report, https://www.cosmos.esa.int/web/envision/links.