In recent years there has been considerable interest in the variation of optical element properties in the environment of earth orbital space. This has primarily occurred due to the requirements of astronomical researchers, since orbiting optical observatories could potentially contribute so much to this science. One of the presently active efforts to generate an investigation capability in this area is associated with the National Aeronautics and Space Administration's Apollo Telescope Mount (ATM) Program. Since about mid 1966, one particular area of optical property variation has been actively investigated. This is the potential problem of optical degradation of sophisticated optical systems due to spacecraft effluences. This degradation would occur through one of two mechanisms: (a) particulates in a suspended (vapor) state of various size distributions producing spurious scattering of light, and/or (b) direct degradation by deposition (or condensation) of particulate contaminants onto critical optics by physical adsorption. This latter process could be followed by polymerization reactions and chemical adsorption due to solar uv irradiation.
W. Walding Moore, Philip W. Tashbar, and George L. Burns, "An Investigational Technique for the Behavior of a Contaminated Optical Surface in the Near Ultraviolet–Visible–Near Infrared," Appl. Spectrosc. 24, 457-459 (1970)