HR: 17:05h
AN: SM34A-04 INVITED     [Abstracts]
TI: What new Plasma and Aeronomy Measurements are Required to Constrain the Climate Evolution of Mars and Venus?
AU: * Lundin, R
EM: rickard.lundin@irf.se
AF: Swedish Institute of Space Physics, Teknikhuset, Umea, SE-90187, Sweden
AB: Solar forcing is the main driver for the climate and atmospheric evolution of Mars and Venus. Climate evolution is a complex issue that strongly couples to the evolution of the atmosphere and ionosphere. On basis of new data from Mars Express (MEX) and Venus Express (VEX) we have reached a somewhat better understanding of the consequences of solar wind forcing for the upper atmosphere and ionosphere of Venus and Mars. For instance, we observe a strong dependence of the ionospheric mass escape on solar wind forcing for Mars. Some new results from MEX and VEX relevant for solar forcing will be presented. Besides solar wind forcing we have the solar X-ray, EUV and UV radiation interacting with the planetary ionosphere and upper atmosphere. The combined solar forcing may vary substantially with time, on short-terms ranging from hours (e.g. CMEs) to decades (solar cycle). The long-term variability/trend is even more pronounced and important for the evolution of a planetary atmosphere, considering that the forcing terms may have been up to a factor of 1000 times higher in the early period of the solar system. However, knowing the impact of the short- term variability (up to a factor of 10) better, we should be able to improve our understanding of the long-term evolution as well. To understand the short-term solar forcing effects on planets such as Mars and Venus will require special tailored missions and adequate instrumentation. The cause - solar forcing (solar wind, X-ray, EUV and UV), and the effect - (e.g. atmospheric expansion, ionospheric ion- and sputtering outflow) should be measured simultaneously. However, with missions carried out properly the prospects are intriguing. We may be able to scale, on basis of the present solar forcing variability, back to the decisive time periods that made the Earth-like planets evolve so differently.
DE: 2700 MAGNETOSPHERIC PHYSICS (6939)
DE: 2756 Planetary magnetospheres (5443, 5737, 6033)
DE: 5421 Interactions with particles and fields
DE: 5443 Magnetospheres (2756)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly