Herschel, the world's largest silicon carbide space telescope
Astrium has been awarded by the European Space Agency a 25 Meuros contract for the realisation of the Herschel Space telescope, on silicon carbide technology. The 3.5 metre telescope to be flown on Herschel will be the largest silicon carbide space imagery telescope ever launched.
The Herschel telescope is to be delivered in 2005 for a launch planned in 2007. Herschel main goal is to study how the first stars and galaxies were formed and evolved.
Silicon carbide is an exceptional material, with outstanding mecathermal properties enabling manufacture of very large ultra light weight mirrors. The Herschel telescope will weigh 300 kg rather than the 1.5 tons required with standard technology.
In June 2001, Astrium had already delivered the largest monolithic sintered Silicon Carbide (SiC) piece ever realised, a full size segment for the Herschel telescope. The complete mirror will comprise 12 of them assembled by brazing at 1500°C.
Astrium had previously manufactured for ESA a mirror measuring 1.35 meter in diameter. Fabricated, polished and tested entirely in Europe, these mirrors are made of silicon-carbide material developed by the SiCSpace consortium, grouping Astrium and Boostec. Tests have demonstrated the optical performance of the mirrors at –160°C, necessary for the infrared application of Herschel.
CNES, for its part, has contracted Astrium for an R&D project to develop very large mirrors for Earth observation instruments using a green body bonding assembly technology. The aim is to manufacture mirrors with a surface density of 20 kg/m2 .
Silicon carbide has already been used for other scientific and application programs, including Rosetta (ESA), Sofia (NASA/DLR) and Earth observation spacecraft both in France and abroad.
The SiCSpace consortium was created in 1997 by Astrium and Boostec to develop the use of silicon-carbide in instruments, and to handle marketing of this material.
Astrium and Boostec have carried out joint research and development since 1992 on the production of space instruments, namely mirrors and structures made of silicon-carbide. The delivery of the Herschel prototype mirror results from the strong collaboration between an innovative small company and an international prime contractor for the benefit of their customers.
