The upper atmosphere of Venus: Model predictions for mass spectrometry measurements

Venus is the closest and most similar planet to Earth in the whole solar system, yet, basic measurements aremissing. The atmospheric composition has been studied to some extent with the Pioneer Venus Orbiter missionand the more recent Venus Express, however, the concentration of many species and their isotopic ratios are notyet known with satisfying accuracy. Especially when it comes to the heavy noble gases as Kr and Xe, there is littleto no collected data in thisfield. These elements form a key link to the reconstruction of the atmospheric evolution, which would deliver crucial information on the formation of Earth-like bodies. Knowing the abundances ofthe noble gases may allow us to answer the question why Venus did not evolve to a potentially habitable planet like its neighbour Earth.This paper presents a meta-study of existing observations of Venus' upper atmosphere and exosphere and anexospheric model of the thermal and hot atmosphere of Venus above the homopause. Mass spectra for possiblefuture Venus missions are predicted, as for example the EnVision mission of ESA. The main focus are the heavynoble gases and requirements for the trajectories are proposed. In addition, mass spectra and recommendedintegration times for the Venusflyby of ESA's JUICE mission are derived