Anticipated impact plasma problems for the COPERNIC-RPA experiment in the cometary environment

Spacecraft-plasma interactions during the flight through the cometary environment at a very high relative velocity that may influence the charged particle measurements by the Copernic-RPA experiment onboard Giotto in the last 2 min of the mission are considered. The most sensitive areas are the electrostatic environment of Giotto and the secondary particle population. It is necessary to simulate the trajectories of the particles coming into the detectors in order to know their distortion by the electrostatic environment of Giotto. The secondary electrons and ions should not mask the spectrum of the cometary plasma, even though they may contaminate the low energy part. Direct impact of dust onto the exposed portion of the detectors has very little chance of occurring. Indirect effects of heavy dust impact on the bumper shield may produce anomalies in the performances of the instruments but will not destroy them.