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"Venus Express:
mission results and future plans" D.V. Titov (Max-Planck Institute
for Solar System Research, Space Research
Institute of Abstract: More than 25
spacecraft from the Venus Express
continues and extends the investigations of earlier missions by providing
detailed monitoring of processes and phenomena in the atmosphere and
near-space environment of Venus. Radio, solar and stellar occultation, together
with thermal emission spectroscopy, sound the atmospheric structure in the
altitude range from 150 to Multi-spectral imaging
is performed to investigate the cloud morphology at different levels and its
latitudinal and temporal changes. Venus Monitoring Camera (VMC) shows
evidence of convection in the cloud layer at low latitudes. Streaky cloud
features indicate that the convection ceases in the middle and high
latitudes. Sequences of images are used to track motions of the cloud
features and to derive wind speeds in the 50- The chemistry and
dynamics of the mesopause region (~100 km altitude) is being studied by
observing non-LTE emission from O2 and NO molecules in the UV and
near-IR. This airglow peaks at the equator, close to midnight and
approximately at the mesopause level, indicating a thermospheric
solar-antisolar component in the atmospheric circulation. Composition
measurements over a wide range of altitudes are providing vertical profiles
of CO, H2O, HDO, HCl, HF, and SO2 in the mesosphere
(70- The magnetometer (MAG)
and ASPERA (Analyser of Space Plasmas and Energetic Atoms) measure the
magnetic field and densities of neutral atoms, ions and electrons in-situ. These observations determine
the structure and properties of the circumplanetary plasma and characterize
escape processes at Venus. They cover the time of solar minimum, and thus
complement Pioneer Venus investigations at solar maximum. Interestingly, the
H/O ratio was found to be ~2 thus suggesting that these ions are escaping in
the stoichiometric ratio of water. The magnetometer is detecting whistler
signals in ~10% of the pericentre passes. This is interpreted as evidence of
lightning and the rate is estimated to be at least as frequent as on
Earth. |