Following thermal vacuum/thermal balance testing, a gray haze was discovered on the corners of the Wide Field/Planetary Camera (WF/PC) aperture window. The phenomenon was suggested to be a result of molecular transport from a low outgassing structural adhesive. Detailed analyses, both chemical and analytical, were conducted to assess the formation of the haze. Each material was considered individually, as it was not known if the actual contamination was a result of one, many, or possibly none of the materials considered. Results of the analytical assessment and the comparison with the aforementioned chemical analyses provided incontrovertible evidence as to the cause of the window haze. The resultant cleanup and subsequent elimination of the problem are also addressed. [Editor's Note: This 1990 paper is republished as part of the Journal of the IEST 50th anniversary celebration. It is accompanied by remarks from Patti Hansen, author of "Overview of the HST Contamination Engineering Program at 15 Years: A Cleanliness Metric for Success with Optical Satellites" paper in this issue.]

Millard, J. M., Jet Propulsion Laboratory Contamination Analysis Program-Programmer and User Manual, JPL Report No. 715-55, prepared by the Jet Propulsion Laboratory for the Goddard Space Flight Center, August (1980).
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