The space environment presents some unique problems for optics. Components must be designed to survive variations in temperature, exposure to ultraviolet radiation, particle radiation, atomic oxygen and contamination from the immediate environment. To determine the importance of these phenomena, a series of passive exposure experiments have been conducted which included, among others, the Long Duration Exposure Facility (LDEF, 1984-1990), the Passive Optical Sample Assembly (POSA, 1996-1997) and most recently, the Materials on the International Space Station Experiment (MISSE, 2001-2005). The MISSE program benefited greatly from past experience so that at the conclusion of this 4 year mission, samples which remained intact were in remarkable condition. This study will review data from different aspects of this experiment with emphasis on optical properties and performance.