The Mip Experiment of the Rosetta Orbiter: a Mutual Impedance Probe for Waves and Plasmas Diagnosis

Abstract

The ROSETTA orbiter and lander will rendez-vous with the comet 67P/ Churyumov-Gerasimenko round 2014 and study it for a period of nearly 2 years. A plasma and wave package, the ROSETTA Plasma Consortium, RPC, is part of the orbiter payload. Five sensors will determine the development and activity of the comet during its approach to the Sun. One of these instruments, the Mutual Impedance Probe, MIP, has to measure the electron density and temperature in the cometary coma, and in particular, inside the contact surface. Furthermore, the MIP will determine the bulk velocity of the ionized outflowing atmosphere, define the spectral distribution of natural waves from 7 kHz to 3.5 MHz, and monitor dust and gas activities around the nucleus. The MIP instrumentation has been developed by the LPC2E of CNRS (Orléans, France) and the ESTEC/RSSD of ESA (Noordwijk, The Netherlands). To reach the comet, the spacecraft must undergo four planet gravity assistances. The first one, an Earth flyby, occurred in early March 2005. At the closest approach, on 4 March at 22:09 UT, ROSETTA passed at about 1950 km over the Pacific Ocean just west of Mexico. During this event, valuable observations have actually been made by the MIP in the Earth's plasmasphere, a high electron-density region dominated by the Earth's magnetic field. The MIP principle of measurements, the instrument design, and the scientific results obtained in the Earth's plasmasphere are presented.