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Modeling of Transmittance Degradation Caused by Optical Surface Contamination by Atomic Oxygen Reaction with Adsorbed SiliconesA numerical procedure is presented to calculate transmittance degradation caused by contaminant films on spacecraft surfaces produced through the interaction of orbital atomic oxygen (AO) with volatile silicones and hydrocarbons from spacecraft components. In the model, contaminant accretion is dependent on the adsorption of species, depletion reactions due to gas-surface collisions, desorption, and surface reactions between AO and silicone producing SiO(x), (where x is near 2). A detailed description of the procedure used to calculate the constituents of the contaminant layer is presented, including the equations that govern the evolution of fractional coverage by specie type. As an illustrative example of film growth, calculation results using a prototype code that calculates the evolution of surface coverage by specie type is presented and discussed. An example of the transmittance degradation caused by surface interaction of AO with deposited contaminant is presented for the case of exponentially decaying contaminant flux. These examples are performed using hypothetical values for the process parameters.
Document ID
Document Type
Preprint (Draft being sent to journal)
Snyder, Aaron
(NASA Glenn Research Center Cleveland, OH United States)
Banks, Bruce
(NASA Glenn Research Center Cleveland, OH United States)
Miller, Sharon
(NASA Glenn Research Center Cleveland, OH United States)
Stueber, Thomas
(DYNACS Engineering Co., Inc. Brook Park, OH United States)
Sechkar, Edward
(DYNACS Engineering Co., Inc. Brook Park, OH United States)
Date Acquired
September 7, 2013
Publication Date
June 1, 2001
Subject Category
Spacecraft Design, Testing And Performance
Report/Patent Number
NAS 1.15:210597
Meeting Information
International Symposium on Optical Science and Technology(San Diego, CA)
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.

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