The space-based observatory in this case is Venus Express (VEx). Venus Express is a European Space Agency Satellite. It was launched in November 2005, and has been orbiting Venus since April 2006. Its scientific payload is focussed mainly on study of the atmosphere, but also has some ability to map the surface of Venus, as well as study the interaction of Venus with the solar wind. Venus Express has nearly exhausted its reserves of propellant, and the spacecraft is expected to plunge into the atmosphere of Venus before the end of 2014; however, it has returned several terabytes of scientific data which will be analysed during this project.
The present EuroVenus grant finances the scientific exploitation of three VEx datasets in particular. The Solar Occultation in the InfraRed (SOIR) instrument measures the extinction of sunlight as it sets (or rises) behind the atmosphere; this permits very sensitive measurement of temperatures, aerosols and trace species abundances in the upper atmosphere of Venus, at altitudes of roughly 80 – 150 km. The VEnus RAdio Science (VeRa) experiment studies the way the radio signals pass through the atmosphere of Venus on their way from the VEx spacecraft to receiving stations on Earth; this reveals vertical profiles of atmospheric temperature and sulphuric acid vapour abundances at 40 – 90 km altitude, as well as electron densities in the lower ionosphere (90 – 150 km altitude). Finally, the Venus Monitoring Camera (VMC) and Visible / InfraRed Thermal Imaging Spectrometer (VIRTIS) instruments are used to measure winds by tracking moving cloud features in image sequences. In addition to these VEx science investigations, a number of other space-based observatories witnessed Venus pass in front of the Sun on 6 June 2012, including the SDO, STEREO and HiNode Solar telescopes; their observations of how light passed through the atmosphere of Venus on its way to the Earth is being studied for clues as to the properties of the Venus upper atmosphere.