Surface accommodation of molecular contaminantsTheoretical consideration and supporting data are presented regarding the nature of the transport mechanisms which cause the adsorption of gases on spacecraft surfaces. Particular attention is given to the concept of a sticking coefficient which is the ratio of the thermally accommodated mass to the total incident mass. Existing molecular accommodation data are examined in terms of spacecraft applications and recent contamination-control data are introduced. Two distinct yet linked concepts emerge which are the accommodation and sticking coefficients, and surface roughness contributes significantly to both coefficients. A general equation regarding the coefficients is developed, and the data are found to fit the equation basically. It is concluded that a more precise characterization of the coefficients can be obtained through experimentation under simulated spacecraft conditions.
Document ID
19910070380
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Chen, Philip T. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hedgeland, Randy J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Thomson, Shaun R. (EER Systems Corp. Seabrook, MD, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1990
Subject Category
Inorganic And Physical Chemistry
Meeting Information
Meeting: Optical System Contamination: Effects, Measurement, Control II