Contamination Threats to Critical Surfaces from Handling and Storage Practices

Abstract

It is well known that in a thermal-vacuum or space environment, critical optical, electrical, or mechanical surfaces can be contaminated by the outgassed products of materials or by poor procedures in handling or vacuum testing. From contamination monitoring of recent spacecraft instrument thermal-vacuum tests it now appears that some of the materials and practices commonly used to protect critical surfaces from molecular or particulate contaminants can themselves represent significant threats. Included are clean room and clean tent materials, gloves, tissues, and covering or packaging materials. Mass and infrared spectral analyses of these materials and the environments and instruments exposed to them indicate the contaminants are largely plasticizers, slip or antistatic agents, and binders used in the manufacture of these products. Products of particular threat include vinyl gloves, booties, and clean tent walls and some polyethylene sheets and bags. Of the techniques investigated for reducing these threats, the use of alternate protective materials or the solvent cleaning of such materials and parts exposed to them appear more effective than does the vacuum baking of the contaminated parts.