One of the key technologies for next generation space telescopes requiring large-scale reflectors are light-weight
materials having high specific strength, high specific stiffness, low coefficient of thermal expansion and high coefficient
of thermal conductivity. Several candidates, such as fused silica, beryllium, silicon carbide and carbon fiber reinforced
composites, have been evaluated.
An example of the latter material is a Hybrid Carbon-Fiber Reinforced SiC composite or HB-Cesic - a trademark of
ECM - which has been developed by ECM and MELCO to meet the stringent space telescope requirements. Mechanical
performance, such as stiffness, bending strength and fracture toughness, were significantly improved using HB-Cesic
compared to our classic Cesic material. Thermal expansion and thermal conductivity of HB-Cesic at cryogenic
temperatures are now partly established and excellent performance for large future space mirrors and structures are
expected. In this paper we will report on the current status of development of HB-Cesic and describe the first successful
applications made with this new improved material.