Kinetic properties of the interface between the solar wind and the
magnetosphere of Venus and Earth: modeling and 
observations by Venus Express and Cluster

Marius M. Echim (1,2), R. Maggiolo (1), J. De Keyser (1), H. Gunell (1), T. Zhang (3),
G. Voitcu (2), R. Lundin (4), and S. Barabash (4)

(1) Belgian Institute for Space Aeronomy, Brussels, Belgium (2) Institute for Space Sciences, Bucharest,
 Romania, (3) Space Research Institute, Austrian Academy of Sciences, Graz, Austria, (4)Swedish Institute for Space
 Physics, Kiruna, Sweden

In June 2006 Venus Express crossed several times the outer boundary of the Venus induced magnetosphere, its
magnetosheath and the bow shock. During the same interval Cluster spacecraft surveyed the dawn flank of the
terrestrial magnetosphere, intersected the Earth's magnetopause and spent long time intervals in the
 magnetosheath. This configuration offers the opportunity to investigate simultaneously the interface between
 Venus and Earth's outer plasma layers and the shocked solar wind. We discuss the kinetic structure of the
 magnetopause of both planets, its global characteristics and the effects on the interaction between the planetary
 plasma and the solar wind. A quasi-stationary Vlasov equilibrium model is constructed for both planetary
 magnetopauses when the MP can be described by a tangential discontinuity as is the case for Venus Express
 and Cluster  MP observations from June 27, 2006. The kinetic model provides good estimates of the magnetic
 field profile  across the interface.  The model is also in agreement with plasma data and evidence the role of
 planetary and  solar wind ions on the  spatial scale and equilibrium of the magnetopause of the two planets: the
 (Chapman- Ferrraro) current in the MP layer is mainly carried by electrons and protons with properties similar to
 the solar  wind particles in the  case of Venus; the terrestrial MP current is carried mainly by particles having
 kinetic  properties consistent with  the planetary species. This difference, suggested by model results,  results
 most  probably from the  particularities of the interaction between the solar wind and an induced magnetosphere
 in  one case and a "proper"/terrestrial magnetosphere in the other case.