Abstract DGP2026-36

The Radio Science Experiment on EnVision will perform extensive studies of the gravitational field but also Radio Occultations to sense the Venus atmosphere and ionosphere at a high vertical resolution of only a few hundred metres. These radio occultations provide electron density profiles in the ionosphere and profiles in the troposphere and mesosphere providing atmospheric density, temperature and pressure profiles in the upper troposphere and mesosphere. Additionally, they allow to study the H2SO4 absorption in the Venus cloud layer. These measurements will allow to study short term changes in the atmosphere and ionosphere. EnVision will use two coherent frequencies (X- and Ka-band) to separate dispersive and nondispersive effects. This allows to distinguish between ionospheric wave structures and other noise induced effects in the ionosphere. The use of Ka-band allows to study the H2SO4 absorption in the Venus cloud layer due to its high sensitivity to sulfuric acid absorption. The monitoring of the H2SO4 content helps to detect signatures of possible volcanic activity. Ka-band is also sensitive to liquid H2SO4 which allows (in combination with X-band) to distinguish between gaseous and liquid H2SO4 absorption features on Venus for the very first time. The short orbital period of EnVision in combination with its near polar orbit allows to cover all latitudes, longitudes, local times and solar zenith angles on Venus. Especially short-term variations caused by atmospheric waves can be identified to study traveling or stationary small-scale atmospheric structures.