The Venus plasma environment

Abstract

The thesis deals with the investigation of the plasma environment of Venus using data of the ASPERA-4 (Analyzer of Space Plasmas and Energetic Atoms) experiment onboard the Venus Express (VEX) spacecraft as well as a 3D hybrid code in order to study the solar wind - atmosphere interaction of an unmagnetized planet. (1) Data Analysis: By using data from the ion and electron spectrometers, the shapes and average locations of the plasma boundaries (bow shock, upper and lower boundary of the mantle region) around the planet are determined. Additionally, the variation of the terminator bow shock position is analyzed as a function of the solar wind dynamic pressure and solar EUV flux. It is demonstrated that the shock location is insensitive to the upstream ram pressure and that the changes in the solar EUV radiation are too small over the period of the VEX observations to analyze solar activity dependence.