Atmospheres of Venus and Mars


The terrestrial planets possess several common characteristics (e.g. their mass, diameter, density or their distance to the sun), but they also differ in many respects. For example, Venus and Mars have a neutral atmosphere dominated by CO2, while the atmosphere of the Earth has been influenced by the life, which has enriched atmosphere with oxygen. The atmosphere of Mars, now arid and dry, has lost almost all of its water and its oxygen. Venus no longer shows any sign of tectonic activity, unlike the Earth. But an intense greenhouse effect bring its surface to a temperature of 480° C and Venus is now an uninhabitable planet.

These similarities and differences currently are subject to a significant research activity aimed at a better quantification and understanding of the processes by which lead these three planets, which probably were very similar at the begining, along such a different evolutionary path. Ground based observations have been gradually supplemented by a series of space missions studying the composition, the dynamics and the structure of Mars and Venus. The LPAP is actively involved in the ESA-lead missions Mars Express and the previous Venus Express. These missions provide us with crucial information concerning the temperature distribution, the transportation of atmospheric constituents by the winds and physico-chemical processes driving them. We mainly analyze the airglow associated with these chemical reactions and the precipitation of energetic electrons from the solar wind.
Our work allows us to specify the importance of the day-night transport, to characterize the distribution of oxygen and nitrogen on the night side of the two planets and to clarify the relationship between the flow of electrons and the residual magnetic field.
We also participate to the ESA mission named TGO/EXOMARS, which  started orbiting Mars in 2016. The infrared spectrometers from the NOMAD instrument suite is mapping the latitudinal and seasonal variation of the distribution of several atmospheric constituents, such as ozone. Finally, our team is analyzing the spectral images from the IUVS spectrometer aboard NASA spacecraft MAVEN. This instrument, designed to assess the flow of particles leaving the atmosphere of Mars,  also provides a wealth of new observations concerning the atmospheric temperature, composition and the aurorae.

Mars Express

Maven

ExoMars

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