All-SiC telescope technology: recent progress and achievements

Abstract

Last decade EADS-ASTRIUM and its partner Boostec, has become world leader in the field of Silicon Carbide (SiC) optical payloads. In the framework of earth and scientific observation, high and very high-resolution optical payloads have been developed. This leadership allowed EADS-ASTRIUM to propose a large and complete range of space-based system for optical observation. Ceramic mirrors and structures are becoming attractive for high precision light weighted opto-mechanical applications. Developments over the past 15 years by EADS-ASTRIUM and by Boostec have demonstrated the feasibility and versatility of the SiC material for numerous applications. The most favorable characteristics of this material are high stiffness, high thermal conductivity and low thermal expansion (CTE). Furthermore, SiC allows relatively quick and cheap manufacturing of components because the components can be shaped with conventional tools in a milling process of the green body material. Through different joining processes, SiC allows for large size applications and systems. Only the scale of the available production facilities, the largest of which currently is 4 m in diameter, limits size of the structures and mirrors that can be manufactured . After a short recall of the SiC material properties, this paper describes recent impressive developments namely the ∅ 3,5m primary mirror for Herschel telescope, the ∅ 1,5m primary mirror for Aladin telescope and the 1,5m x 0,6 m mirror demonstrator for the GAIA mission. Main conclusion from the feasibility study of the ∅ 3,5m SPICA telescope are also presented.