Cryogenic performance of a passive lightweight mirror

Advanced spaceborne optical system currently under consideration, such as the Next Generation Space Telescope, will require the use of large UV segmented mirrors that can perform at cryogenic temperatures. The mirrors must be rugged, low risk, reliable, and capable of surviving launch. A design approach that utilizes passive segments in order to meet the optical system design requirements at cryogenic temperatures offers significant advantages in weight, performance, and reliability. A comparison of passive mirror designs using alternate mirror materials and the results of prototype testing at cryogenic temperature will be presented.