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G. Mondello, E. Suetta, N. Tonetti (Alenia Difesa-Officine Galileo)
In the frame of the Rosetta mission the VIRTIS instrument (Visible and Infrared Thermal Imaging Spectrometer), built by Officine Galileo as Prime Contractor for the Italian Space Agency (ASI) and with contributions from the French Observatoire de Paris-Meudon and the German DLR (Deutsches Zentrum fur Luft und Raumfahrt), is an imaging spectrometer that combines three unique data channels in one compact instrument committed to the multispectral mapping and high resolution spectral analysis of the comet 46P/Wirtanen. This is accomplished by means of two separate optical heads, Virtis-M (VM) and Virtis-H (VH) integrated in the Optics Module (OM). The Virtis OM is composed of an optical bench which provides mechanical support and thermal insulation to the VM and VH optical heads, the passive radiators system for cooling the optical heads at an operating temperature of about 130K and an active cooling to maintain the infrared detectors at 70K, based on Stirling cycle cryocoolers. The OM includes also a pair of very compact cover mechanisms. Two optical heads with three focal planes in a very compact design, high thermal gradients, multi-stage passive cooling and a mass limited to about 20 Kg result in a thermo-mechanical sophisticated design. This paper presents an overview of the OM configuration and the results of the environmental qualification testing performed on a representative model.
Keywords: Optics Module, passive cooling, active cooling, environmental testing.