Spacecraft charging and its impact on in-situ measurements: application to Rosetta

This study is related to the analysis of the plasma environment surrounding ROSETTA. In order to enhance the study of N. Gilet and G. Wattieaux, the electron density, the electron distribution function and the thickness of the plasma sheath are investigated. This investigation is based on the use of Spacecraft Plasma Interaction Software (SPIS), a simulation program developed by ONERA and ARTENUM, initially funded by ESA (now recognized as a standard for Spacecraft-Plasma interaction simulations). The electron density and the electron distribution function are investigated starting from data gathered from SPIS simulations. The thickness of the plasma sheath is investigated by comparing the electron density profile with an artificial equivalent electron density function. First, the analysis is applied to simple-shaped spacecrafts (spherical and cylindrical). Second, the analysis is applied to ROSETTA’s geometry (composed by the main body of the spacecraft, the solar panels, the booms, the LAP instruments and MIP). The plasma parameters are close to the values measured/expected in the environment surrounding ROSETTA. In the last part of the document it is shown that with full-PIC simulations the plasma surrounding ROSETTA behaves like the plasma surrounding a cylindrical- shaped spacecraft, due to the presence of the solar panels