The Advanced Structures/Controls Integrated Experiment (ASCIE): A Control Technology Test Bed For Large Segmented Reflectors

Abstract

Improvements in state-of-the-art focal plane sensors mean that the next level of performance improvement for astronomical instruments must come from an increase in the aperture. While both monolithic and segmented mirrors are being considered for ground-based systems, weight and volume constraints make segmented reflectors the only practical approach for space systems. Segmented reflectors require an active segment-alignment control system in order to make the reflecting surface have the optical performance of a monolith. This paper describes an experimental apparatus developed at the Lockheed Palo Alto Research Laboratory called the Advanced Structures/Controls Integrated Experiment (ASCIE). The ASCIE consists of a Cassegrain optical configuration with a 2-m seven-segment actively controlled primary mirror supported by a light, flexible truss structure. The ASCIE is a response to the need for experiments that can simulate the complex dynamic behavior of a large structure and which address the myriad problems associated with precision control of optical surfaces. This paper describes the ASCIE test bed, presents details of the control and optical measurement systems, and reports on preliminary performance results.