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The TET-1 HSRS camera structure: the second flight heritage of Cesic

One of the core payload elements of the Technologie-Erprobungs-Träger-1 (TET-1, Technology Experiment Carrier) satellite, a mission of the German Aerospace Center (DLR), is the Hot Spot Recognition System (HSRS). Based on the flight experience with the HSRS instrument, which was launched in 2001 on board of the Bi-Spectral Infrared Detection microsatellite (BIRD), the instrument will be re-used on TET-1 after a comprehensive design update. The objectives of the update are a significant reduction of the overall mass budget and an integrated design approach for the co-registration of two cooled infrared and one visible camera systems. To reach a co-aligned assembly with high accuracy, a minimized camera structure for all lenses and detectors has been designed. In close collaboration with the DLR, ECM manufactured the new camera structure of the HSRS using its ceramic composite material, Cesic®, in order to achieve the required low coefficient of thermal expansion, high stiffness, and low mass. In this paper, we describe the ESA-space-qualified process of manufacturing such high-precision space structures and Cesic®'s advantages compared to competing materials, especially with respect to material properties and versatility of manufacturing. We also present the results of testing the HSRS Cesic® camera structure under launch and space environmental conditions, including vibration, shock, and thermal vacuum exposures. The HSRS camera structure described here is the second flight heritage of Cesic®. The first was two all-Cesic® telescopes ECM manufactured for the SPIRALE mission (Système Préparatoire Infra-Rouge pour l'Alerte), a French space-based early warning demonstration system consisting of two satellites. The SPIRALE satellites were launched in February 2009 and are performing successfully. The prime contractor was THALES ALENIA SPACE. The results presented here and the flight experience with the SPIRALE telescopes demonstrate that ECM's Cesic® composite is a superior material for the manufacture of light-weighted, stiff, and low-CTE space structures, with improved performance compared to aluminum and other traditional metal materials.