VIRTIS (Visible and Infrared Thermal Imaging Spectrometer)
is a complex instrument initially devoted to the remote sensing study of comet Wirtanen on the Rosetta mission, at wavelengths between 0.3 and 5 µm. The focal planes, with state of the art CCD and infrared detectors achieve high sensitivity for low emissivity sources. Due to the high flexibility of operational modes of VIRTIS, these performances are also ideally adapted for the study of Venus atmosphere, both on night and day side. VIRTIS is therefore aimed to provide a 4-dimensional study of Venus atmosphere (2D imaging + spectral dimension + temporal variations), the spectral variations permitting a sounding at different levels of the atmosphere, from the ground up to the thermosphere. The infrared capability of VIRTIS is especially well fitted to the thermal sounding of the night side atmosphere (Taylor et al, 1997), which give a tomography of the atmosphere down to the surface.