The Venus Express mission aims at a global investigation of the Venus atmosphere, plasma environment, and some surface properties from orbit. The instruments PFS and SPICAV inherited from the Mars Express mission and VIRTIS from Rosetta form a powerful spectrometric and spectro-imaging payload suite. Venus Monitoring Camera (VMC) – a miniature wide-angle camera with 17.5º field of view – was specifically designed and built to complement these experiments and provide imaging context for the mission. The figure shows the VMC instrument with one side of the box taken off.
VMC will take images of Venus in four narrow band filters centered at 365, 513, 965, and 1000 nm all sharing one CCD detector. Spatial resolution on the cloud tops will range from 0.2 km/px in pericentre to 45 km/px in apocentre where full Venus disc will be in the field of view. VMC will significantly contribute to the study of cloud structure and morphology, atmospheric dynamics, and surface imaging. The UV channel will be used to investigate distribution and nature of the unknown UV absorber, to determine the wind field at the cloud tops (70 km) by tracking UV features, and to study wave phenomena. The night side observations in the near-infrared filter at 1000 nm, which is centered at the atmospheric transparency “window”, will provide for the first time thermal imaging of the Venus surface from orbit. These observations will determine spatial distribution of surface temperature and will search for active volcanoes. This channel will also yield global wind field in the main cloud deck (50 km) by tracking near-IR features. The other near-IR channel (965 nm) centered at the absorption band of atmospheric water will investigate H2O spatial distribution at the cloud tops on the day side and in the lower 10 km at night. The visible channel at 513 nm was designed to map the O2 airglow and its variability on the night side. The VMC images and movies of the cloud motions Venus atmosphere will be of significant interest for the public outreach programme.
The tests in cruise included the observations of stars, Venus, and Earth-Moon system and stray light tests. They demonstrated good performance of the instrument. The figure shows false colour image of the Earth and Moon taken by VMC from a distance of 3.5 Mkm. Both planets were only few VMC pixels across. The visible and UV channels were strongly overexposed.
The VMC instrument was designed and manufactured in cooperation with the Institute of Computer and Communication Network Engineering (IDA, Technical University, Braunschweig) and the Institute for Planetary Exploration (DLR, Berlin) with the MPS being the PI institute. The optics was manufactured by the FISBA OPTIKS (St. Gallen, Switzerland).