DISC-the Dust Impact Sensor and Counter onboard the comet interceptor/ESA space mission: performance evaluation through simulations and laboratory tests.

Comet Interceptor is an ESA Fast-class space mission, which will be launched in 2029 towards an as-yet-undiscovered dynamically new comet, i.e., never having approached the Sun before. Such objects are difficult to target, they can only be discovered when entering the inner Solar System and becoming active. This implies that Comet Interceptor will probably be launched before the target is even discovered. The Comet Interceptor probe, composed of three spacecraft, i.e. S/C-A, S/C-B2 (provided by ESA) and S/C-B1 (provided by JAXA), will be parked in L2 and directed towards the selected target for a close flyby to be performed by S/C B1 and B2 and a far flyby by S/C A.The Dust Impact Sensor and Counter (DISC) (Fig. 1), devoted to the dust coma characterization, is part of the payload selected for C I. It will be mounted on-board two of the three spacecraft, as part of the Dust-Fields-Plasma (DFP) suite, dedicated to study: 1) dust in the coma; 2) magnetic field; 3) plasma and energetic neutral atoms. The DISC architecture originates from the Impact Sensor subsystems, part of the Grain Impact Analyzer and Dust Accumulator (GIADA) that successfully flew on-board the ESA/Rosetta spacecraft.DISCs main scientific objectives are: 1) to define the dust mass distribution for particles in the mass range 10-15-10-8 kg ejected from the cometary nucleus; 2) to count dust particles with mass > 10-15 kg; 3) to constrain dust particle density/structure.DISCs sensing plate will be exposed to the cometary dust environment and subjected to Hyper-Velocity Impacts (HVI), due to the high fly-by speed (10 70 km/s). In this context, we conducted a study on DISCs capabilities under HVIs and the energies associated with the expected cometary dust impact, in order to verify the instrument performances in the dust coma environment during the flyby. We have devised an approach implying different techniques/methods: 1) Numerical simulation of HVI on a simulated DISC sensing plate, 2) HVI of real projectiles on the DISC breadboard at the Light Gas Gun(LGG) facility, 3) HVI simulated by means of a high-power laser on the DISC breadboard.We are going to present the results from the application of the first and second methods, which allowed us to compute the DISC response function and sensitivity, and the maximum rate of detectable impacting particles.ACKNOWLEDGEMENTS This research was also supported by the Italian Space Agency (ASI) within the ASI-INAF agreements I/024/12/0, 2020-4-HH.0 and 2023-14-HH.0, and the Europlanet project 20-EPN2-116 "HIDISCC (Hypervelocity Impacts for DISC Calibration)".