SPACE OPTICAL PAYLOADS, NEW APPLICATION AREA FOR HIGH-TEMPERATURE COMPOSITES

High temperature composites have been extensively developed in order t o produce thermal protection systems of reusable re-entry vehicles and launchers. This development effort covers all aspects including sizin g, design, manufacturing processes characterization, non destructive i nspection, and all industrial facilities which have also been installe d. Strong interest recently appeared for these materials to meet requi rements for different space applications. In particularly, for more st ringent optical payloads, new materials with high performance requirem ents have appeared. In the field of high dimensionally stable structur es for telescopes, materials have to meet severe requirements, such as low coefficients of thermal expansion, good specific modulus, long-te rm stability (moisture and chemical insensitivity), etc. Carbon/carbon (C/C) composites can meet these specifications. To demonstrate this c apability a structure has been designed, manufactured and will be subm itted for complete testing (work supported by ESA/ESTEC). The main ava ilable results (part feasibility, characterizations, analysis and stab ility performance budgets) are presented. For future telescope mirrors , silicon carbide is already known as a good candidate. However, an in novative concept based on silicon carbide sandwich honeycomb technolog y, which allows optimized design, has been developed. The first charac terization results and manufacturing capabilities are presented. (C) 1 998 Published by Elsevier Science Ltd. All rights reserved.