The solar wind interaction with Mars: results of three-dimensional three-species MHD studies

Abstract

The interaction of the solar wind with planets with no or only very weak intrinsic magnetic fields, such as Mars and Venus, involves their ionosphere/atmosphere system. Single-species MHD models, which incorporate some of the important mass-loading processes, have been useful in reproducing numerous observed features at these planets, such as the location of the bow shock, but they do have obvious limitations. Our present 3D MHD model uses three continuity equations in order to consider protons in the solar wind and the two dominant heavy ion species (O + 2 and O +) in the ionosphere, separately. We have used this model to study the interaction processes at Mars. The model results are in general agreement with the average observed bow shock shape and position and predict reasonable locations for the ionopause. The calculated oxygen escape flux down the tail was estimated to be about 3 × 10 25 s −1, which is consistent with Phobos-2 estimates. We also studied the possible effect of the surface crustal magnetic field on the bow shock and the ionosphere of Mars.