Design of Very High-Resolution Satellite Telescopes Part III: Telescope Size Reduction

The design of a very high-resolution Korsch-based optical satellite telescope with a ground sampling distance of 25 cm through employing a primary mirror with a diameter of 1.4 m is investigated previously in Part I, and the system performance is evaluated in Part II. In this Part III, the telescope size reduction using the deployable synthetic primary mirror approach is presented. Since the largest telescope element, the primary mirror size reduction is useful for decreasing the telescope volume and mass. Consequently, the reduction in satellite development cost and relaxing the selection of the launch vehicle are attained. Three configurations of segmented sparse apertures are conceptually examined, including rectangular, trapezoidal, and hexagonal patterns. The performance of each configuration with a different number of segments is evaluated. Through the tradeoff criterion, the optimal number of segments is investigated. The assessment parameters adopted in the study involve the number of segments, modulation transfer function, stowed volume, and segment width. The results show that without a significant loss in optical performance, a volume reduction of about 70% is accomplished.