The EnVision mission to Venus: Discovering why our closest neighbour is so different

EnVision was selected as ESA’s 5th Medium-class mission in the Agency’s Cosmic Vision plan, targeting a launch in the early 2030s. The mission is a partnership between ESA and NASA. The primary goal is to provide a holistic view of Venus, from its inner core up to its upper atmosphere by a single mission, and will be the first mission of its kind. More specifically, EnVision will characterise Venus’ core and mantle structure, in order to study past geologic processes. This also allows scientists to look for potential evidence of past liquid water. Observations of Venus’ surface topography and emissivity will be combined with atmospheric sounding to look for present day activity and to better understand its past and current climate. Recent modelling studies strongly suggest that the evolution of the atmosphere and interior of Venus are coupled, emphasizing the need to study the atmosphere, surface, and interior of Venus as a system.

The nominal science phase of the mission will last six Venus sidereal days (four Earth years). The EnVision payload consists of a comprehensive measurement suite spanning ultraviolet, infrared, and microwave wavelengths. The VenSAR S-band radar, provided by NASA, will provide targeted polarimetric imagery as well as radiometry and altimetry observations. The high frequency Subsurface Radar Sounder (SRS), will penetrate the upper 100 m to 1 km of the planets’ surface. Three spectrometers, VenSpec-U, VenSpec-H and VenSpec-M, operated in the UV and near and shortwave Infrared, will map trace gases, including search for volcanic gas plumes above and below the clouds, and map surface emissivity and composition. This suite is complemented by Radio Science investigation exploiting the spacecraft Telemetry Tracking and Command system to observe the planet’s gravity field with a spatial resolution of ~250 km and to sound the structure and composition of the middle atmosphere and the cloud layer in radio occultation.

In this presentation, the motivation for EnVision will be presented together with an overview of the instruments and how they are used to address the science questions. Previous and upcoming Venus missions, and their scientific synergy and complementarity with EnVision, will also be presented an discussed.