Finite Element Analysis of the Filter Strip Assembly Qualification test for the EnVisS camera

The Entire Visible Sky (EnVisS) camera is an instrument specifically designed to fly on the first European Space Agency (ESA) Fast class mission, Comet Interceptor, whose launch is foreseen for the end of 2029. The mission goal is to deepen our knowledge on comets and on the Solar System formation by encountering and exploring a Dynamically New Comet (DNC) or an Interstellar Object (ISO) originating outside the solar system. EnVisS is a fish-eye camera that aims to image, in push-frame mode, the whole comet coma in the visible spectrum. The scientific task is to investigate the radiance and the polarization properties of the comet coma diffused light, and one of the key elements of the camera that will make this study possible is the instrument Filter Strip Assembly (FSA). This filter package (which has been designed by the CNR-IFN of Padova and Leonardo SpA of Campi Bisenzio, Florence) is conceived to be composed of three filter strips glued side by side, having the same thickness but different optical properties. The central strip is a high transmission broadband filter in the range 550-800 nm with no polarization properties, while the side ones are linear polarization filters with the same transmission bandpass as the broadband and with polarization axis at 45◦ from one another. This filter package will be attached to an ad-hoc aluminum supporting structure by means of four adhesive joints. One of the evaluations required to space-qualify the gluing procedure is a shear test aiming to verify the shear strength of the adhesive joints connecting the FSA to the supporting aluminum structure. This assessment has been carried out experimentally in the Leonardo SpA facilities, while a Finite Element Analysis (FEA) simulation has been performed by the CNR-IFN team using the Patran-Nastran software. In this paper both experimental test and simulation are illustrated and the results reported and compared.