The EnVision Mission to Venus: mission concept and status

EnVision is ESA’s next mission to Venus and was adopted as part of the ESA Science Programme in January 2024. Thales Alenia Space Itay (TAS-I) was awarded the contract to build the spacecraft in December 2024. The launch is scheduled for the early 2030s, and the start of the science operations at Venus is expected in mid 2030s, following the mission cruise and aerobraking phase around Venus to achieve a low Venus polar orbit.

The scientific objective of EnVision is to provide a holistic view of the planet from its inner core to its upper atmosphere, studying the planets history, activity and climate. EnVision aims to establish the nature and current state of Venus’ geological evolution and its relationship with the atmosphere. EnVision’s 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 its surface.

The Envision spacecraft will be a roughly rectangular three-axis stabilised satellite, weighing approximately 4.1 tonnes at launch (1.7 tonnes dry mass), measuring approx. 2 m x 2 m x 3 m in stowed configuration, with two deployable solar arrays. It will have a power budget of around 3 kW and a large volume (210 Tbits) of science data to be downlinked to Earth with a fixed 2.54 m diameter High Gain Antenna. Notable characteristics are the high-thrust main engine, the X/X/Ka band TT&C system, and the relatively long aerobraking phase (11 months). The mission profile requires a high thrust (1kN) main engine for orbital manoeuvres. The mission will launch with an Ariane 64 rocket in direct escape, and the Venus orbit insertion will be highly elliptic. The final science orbit will be reached by means of Aerobraking. The Aerobraking phase will be followed by a 2-months instrument in-orbit commissioning phase prior to the science operation phase.

The nominal science phase of the mission will last six Venus cycles (~four Earth years). The NASA S-band Synthetic Aperture Radar contribution is at the time of writing not likely to be included on the mission, and ESA is currently investigating alternative European S-band SAR technologies for the intended targeted surface imaging as well as polarimetric and stereo imaging, radiometry, and altimetry. The high-frequency Subsurface Radar Sounder (SRS) will perform novel sounding of the upper crust in search of material boundaries. The three spectrometers, VenSpec-U, VenSpec-H and VenSpec-M, operating in the UV and Near-IR, will map trace gases, search for volcanic gas plumes above and below the clouds, and map surface emissivity and composition. The Radio Science Experiment (RSE) 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. All instruments have Venus heritage and have recently passed their Preliminary Design Reviews (PDRs).

The Envision mission concept, design and status will be presented, including an overview of on-going technical maturity activities and the next steps in the mission preparation.