DISC - the Dust Impact Sensor and Counter : dust in situ instrument for Comet Interceptor ESA mission

Comet Interceptor (CI) space mission, selected by ESA in June 2019 as the first F-Class mission, will study a dynamically new comet or an interstellar object passing through our Solar System for the first time by a unique multi-point 'snapshot' measurement, complementing single spacecraft observations made at other comets. CI is composed of a primary spacecraft, S/C A, which also acts as a communication hub, and two sub-spacecraft, S/C B1 (provided by JAXA) and S/C B2 (provided by ESA), that will allow multi-point observations of the DNC and the surrounding environment. The instrument suite Dust-Fields-Plasma (DFP) will be in charge of understanding: dust in the coma, magnetic field, plasma and energetic neutral atoms. We relate here on the Dust Impact Sensor and Counter (DISC) unit, part of the DFP suite, devoted to the coma dust characterization. DISC, part of the scientific payload on S/C A and S/C B2 of the mission, will detect and measure the momentum of individual dust impacting its sensitive surface during the DNC encounter.DISC architecture originates from the Impact Sensor Subsystem of the GIADA (Grain Impact Analyzer and Dust Accumulator) instrument that successfully flew on board the Rosetta/ESA spacecraft. DISC consists of a square aluminum plate whose sensitive area is 84 mm x 84 mm. Four lead zirconate titanate ceramic Piezoelectric, with resonant frequency 200kHz, are placed at the corners of the plate, one of which will act as an internal calibrator. DISC will characterize the coma dust environment at the spacecraft close encounter, in particular it will: 1) define the dust mass distribution for particles in the mass range 10‑15 - 10‑8 kg ejected from the nucleus; 2) count dust particles with mass >10‑15 kg; 3) constrain dust particles density/structure. We describe the DISC design, aims, methods, performances evaluation by real and simulated High Velocity Impacts and expected results. Acknowledgments:We thank the Italian Space Agency (ASI) within the ASI-INAF agreements I/024/12/0 and 2020-4-HH.0