EnVision
EnVision is an orbital mission to Venus being developed by the European Space Agency (ESA) that is planned to perform high-resolution radar mapping and atmospheric studies. EnVision is designed to help scientists understand the relationships between its geological activity and the atmosphere, and it would investigate why Venus and Earth took such different evolutionary paths. The probe was selected as the fifth medium mission (M5) of ESA's Cosmic Vision programme in June 2021, with launch planned for 2031. The mission will be conducted in collaboration with NASA, with the potential sharing of responsibilities currently under assessment. Science  goals. EnVision will deliver new insights into geological history through complementary imagery, polarimetry, radiometry and spectroscopy of the surface coupled with subsurface sounding and gravity mapping; it will search for thermal, morphological, and gaseous signs of volcanic and other geological activity; and it will trace the fate of key volatile species from their sources and sinks at the surface through the clouds up to the mesosphere. Core science measurements include: high-resolution mapping of specific targets, surface change, geomorphology, topography, subsurface, thermal emission, , , D/H ratio, gravity, spin rate, and spin axis. The specific mission's goals are: The scientists  who submitted the EnVision proposal in response to the call for proposals for the M5 mission of ESA's Cosmic Vision program are Richard Ghail of Royal Holloway, University of London, Colin Wilson, Department of Physics, University of Oxford, UK and Thomas Widemann, LESIA, Observatoire de Paris and Université de Versailles-Saint-Quentin (France). Science payload. EnVision is an ESA mission in collaboration with NASA, and contributions from individual ESA member states for the provision of payload elements. NASA is contributing the VenSAR instrument and supplies DSN support. The other payload instruments are contributed by ESA member states, with ASI , DLR, BelSPO, and CNES leading the procurement of SRS, VenSpec-M, VenSpec-H and VenSpec-U instruments respectively. Radio Science Experiment. Any orbiting spacecraft is sensitive to the local gravity field, plus the gravity field of the Sun and, to a minor extent, other planets. These gravitational perturbations generate spacecraft orbital velocity perturbations, from which the gravity field of a planet can be determined. "EnVision"'s low-eccentricity, near-polar and relatively low altitude orbit offers the opportunity to obtain a high-resolution gravity field at each longitude and latitude of the Venusian globe. The analysis of the gravity field  together with the topography gives insights on the lithospheric and crustal structure, allowing to better understand Venus's geological evolution. In the absence of seismic data, the measurements of the tidal deformation and proper motion of the planet provide the way to probe its deep internal structure (size and state of the core). The tidal deformation can be measured in the "EnVision" orbital velocity perturbations through the gravitational potential variations it generates (k2 tidal Love number). The co-Principal Investigators of "EnVision" Radio Science and Gravity experiment are Caroline Dumoulin, LPG, Université de Nantes, France, and Pascal Rosenblatt, LPG, Université  de Nantes, France.