Venus also has much to teach us about how Earthlike planets work. Venus has an enormous greenhouse warming, caused mainly by carbon dioxide – its atmosphere has over 100,000 times more CO2 than does is found on the Earth – but as on Earth, a very important role is played by the cloud layer. The upper atmospheres of Venus and Earth are remarkably similar not only in basic meteorological variables of pressure temperature, but also in their chemical cycles, involving sulphate aerosols, water, and halogen species. Finally, Venus winds are also intriguing ; although the planet spins around only once every 243 days, the atmosphere spins over 50 times faster, taking only around 4-5 days to complete a full circumnavigation of the planet. This is called atmospheric super-rotation, and is thought to be inevitable for all Earthlike planets with slow rotation rates – but its underlying mechanisms remain unclear.
Mars may be the planet dominating the headlines these days, with NASA’s rovers and orbiters and the European Space Agency’s capable “Mars Express” satellite - but Venus gets far less attention. There is only one spacecraft currently at Venus, and that is the European Space Agency’s Venus Express satellite. Venus Express has been orbiting Venus since 2006, using a range of cameras and other scientific instruments to look at the atmosphere at all levels from the ground up to the edge of space. Venus Express has far outlived its original mission duration of 500 days, so it has done exceptionally well, but it cannot keep going forever, because it uses fuel on a daily basis to help control its height above the planet and the direction in which it is pointing ; at some point within the next couple of years its fuel reserves will be exhausted and it will eventually burn up in Venus’s atmosphere. The scientific examination of the datasets will continue for many years later, though, as new generations of scientists can examine and re-examine the data safely stored on Earth.
European researchers are currently leading the world when it comes to Venus research, not only using Venus Express but also using telescopes. Venus is the closest planet to Earth, so is a spatially extended target for telescope observation. Telescopes may be far from Venus, but they are very sensitive because of their enormous mirrors and sophisticated instrumentation. European researchers have developed techniques which allow them to directly measure wind speeds on Venus, using the phenomenon of Doppler shift as used in speed cameras on Earth, using telescope observations from Earth. Faint traces gases such as sulphur dioxide SO2 can be measured from earth, giving clues about other processes such as volcanic eruptions, lightning and cloud processes. These telescopic observations from Earth ensure that our knowledge of Venus will continue to grow even when there is no spacecraft at the planet.
The EuroVenus project is funded by the European Commission’s Seventh Framework Program (FP7/2007-2013) under Grant 606798 for a duration of three years (oct. 2013-sep. 2016) to study various aspects of Venus in a co-ordinated way using both space-based observations (in particular from Venus Express) and ground-based observations (from telescopes). The project brings together researchers from France (Observatoire de Paris-Meudon/LESIA), Belgium (Belgium Institute for Space Aeronomy), Germany (Rhenish Institute for Environmental Research at the University of Cologne), Portugal (Faculty of Sciences and Center for Astronomy and Astrophysics of the University of Lisbon, and the UK (University of Oxford).
