Low Cost Producible Composite Mirror and Sensor Support Structures for Exoatmospheric Interceptors

The missile defense midcourse Exoatmospheric Interceptor Kill Vehicle (EKV) uses beryllium as the baseline material in the optical sensor mirrors and support structures to provide a lightweight, dimensionally-stable optical subsystem. Beryllium has health and safety issues related to its toxicity, which results in higher costs and producibility issues related to its fabrication long-lead time. Future advanced optical mirror systems, such as the four-mirror on-axis sensor concept for the EKV Upgrade Program, need alternative materials and designs with equivalent performance, reduced costs, and improved producibility compared to beryllium. Optical sensor performance is a function of the dimensional-stability of the optical elements, their attachment, and the structure connecting the optical elements in addition to the optical design. In the Phase I study, a Vanguard Composites Group and Schafer Corporation Team demonstrated analytically that an integrated composite mirror and structure design approach can provide an alternative to beryllium. A lightweight, high stiffness on-axis interceptor optical sensor mirror system was designed using Silicon Lightweight Foam Mirror System (called "SLMS", a trademark of Schafer Corporation) composite mirror materials and graphite fiber-reinforced polymer matrix composite optical component support structures (called "OptiGraf", a trademark of Vanguard Composites Group) in an integrated composite design. A Phase II proposed program will develop and demonstrate a SLMS-OptiGraf lightweight, high stiffness on-axis interceptor optical sensor composite mirror and support structure concept for both the mirror and support structure to provide competitive performance to alternative beryllium designs. The program scope will include developing the SLMS-OptiGraf designs, conducting component optical and structural tests, and fabricating full-scale components of an interceptor optical sensor mirror system for qualification testing.