Mass‐loading asymmetry in upstream region near Mars

Abstract
The measurements carried out by the electric field probe onboard the PHOBOS‐2 spacecraft reveal that the mass‐loading taking place in the solar wind far upstream of the Martian bow shock is dependent upon the orientation of the interplanetary magnetic field. The asymmetry of mass‐loading is caused by H+ pickup ions originating from the extended cold hydrogen Martian exosphere and reflected from the bow shock. The distribution of pickup protons in the upstream region is analysed in a test particle approach, which seems to be confirmed by the Phobos data.