GIADA: The Grain Impact Analyser and Dust Accumulator for the Rosetta space mission

Abstract The ESA ROSETTA mission will perform a rendezvous with comet 67P/Churyumov-Gerasimenko and will follow and study it from about 3.25 AU to perihelion at 1.34 AU and, during the foreseen extended mission, up to 2 AU post-perihelion, in order to observe for the first time the onset of activity of a comet and to follow its evolution. The GIADA (Grain Impact Analyser and Dust Accumulator) instrument, on board the ROSETTA orbiter, is aimed to analyse physical and dynamical properties of individual particles ejected by the nucleus and to monitor the dust flux and spatial distribution as a function of time. To achieve these scientific goals, GIADA is composed of different modules: an optical detection system, to monitor the light scattered by single particles entering the instrument, an impact sensor, to detect the momentum carried by the particles, and five micro-balances, to measure the dust flux from different directions. In this work we will describe the technical characteristics and the scientific performances of the flight model of the instrument. The preliminary results of GIADA calibration demonstrate that the instrument is perfectly compatible with design specifications and is suitable to achieve unprecedented scientific results about cometary dust physics.