Induced magnetic fields and plasma motions in the inner part of the Martian magnetosphere

International audienceAnalysis of MAVEN/STATIC observations in the Martian upper atmosphere, bounded at higher altitudes by the shocked solar wind, shows that the draping of interplanetary magnetic field penetrates down to low altitudes ( ∼ 200 − 250 km) and governs dynamics of the ionosphere. The upper ionospheric plasma is driven into motion flowing around Mars similar to the shocked solar wind in the adjacent magnetosheath. Such a fluid-like motion is accompanied by ion acceleration caused by the bending of the magnetic field, leading to ion extraction and finally to ion pickup. Extraction of ions and their acceleration produces a recoil effect of the bulk ionosphere in the opposite direction. This provides a strong asymmetry in ion dynamics in two different hemispheres, accompanied by wrapping of the magnetic field lines around Mars and respective reconnection