Monte Carlo Modeling of Atomic Oxygen Interaction with Protected Polymers for Projection of Materials Durability in Low Earth Orbit

1992 ◽  
Vol 278 ◽  
Author(s):  
Bruce A. Banks ◽  
Bruce M. Auer ◽  
Sharon K. Rutledge ◽  
Linda Gebauer ◽  
Edward A. Sechkar
Keyword(s):  
Monte Carlo ◽  
Atomic Oxygen ◽  
Protective Coatings ◽  
Polymeric Materials ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Textured Surfaces ◽  
Photovoltaic Array ◽  
Defect Sites ◽  
Oxygen Interaction

AbstractAtomic oxygen in low Earth orbit (LEO) readily attacks and oxidizes exposed spacecraft polymeric materials such as polyimide Kapton photovoltaic array blankets. The application of thin film silicon dioxide protective coatings can greatly extend the useful life of such materials in LEO. A Monte Carlo computational model has been developed which simulates atomic oxygen interaction with polymeric and protective coating materials for both ground laboratory and in-space experiments, allowing the determination of the geometrical shape of atomic oxygen attack of protected polymeric materials at defect sites in protective coatings. Modeling of attack of unprotected carbon-carbon composite materials predicts textured surfaces suitable for high emittance radiators. Results for fiberglass composites indicate loss of the matrix polymer leading to friable fibers. The computational modeling to project in-space performance based on ground laboratory testing predicts mass loss per fluence in space to be approximately one third that observed in plasma ashers.

Leveling Coatings for Reducing Atomic Oxygen Defect Density in Graphite Fiber-Epoxy Composites

1994 ◽  
Vol 37 (3) ◽  
pp. 26-31
Author(s):  
D. Jaworske ◽  
K. de Groh ◽  
G. Podojil ◽  
T. McCollum ◽  
J. Anzic
Keyword(s):  
Atomic Oxygen ◽  
Defect Density ◽  
Protective Coatings ◽  
Protective Layer ◽  
Oxide Coating ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Protective Oxide ◽  
Low Viscosity ◽  
Defect Sites

Pinholes or other defect sites in a protective oxide coating provide pathways for atomic oxygen in low-Earth orbit to reach underlying material. Onc concept for enhancing the lifetime of materials in low-Earth orbit is to apply a leveling coating to the material prior to applying any reflective and protective coatings. Using a surface-tension-leveling coating concept, a low-viscosity epoxy was applied to the surface of several composite coupons. A protective layer of 1000 Å of SiO2 was deposited on top of the leveling coating, and the coupons were exposed to an atomic oxygen environment in a plasma asher. Pinhole populations per unit area were estimated by counting the number of undercut sites observed by scanning electron microscopy. Defect density values of 180,000 defects/cm2 were reduced to about 1000 defects/cm2 as a result of the applied leveling coating. These improvements occur at a mass penalty of about 2.5 mg/cm2.

scholarly journals Property changes in materials due to atomic oxygen in the low Earth orbit

2021 ◽  
Author(s):  
Aki Goto ◽  
Kaori Umeda ◽  
Kazuki Yukumatsu ◽  
Yugo Kimoto
Keyword(s):  
Photoelectron Spectroscopy ◽  
Atomic Oxygen ◽  
Surface Reactions ◽  
Ccd Camera ◽  
Polymeric Materials ◽  
Thermal Control ◽  
Polyimide Film ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Exposure Experiment

AbstractWe expect satellites at altitude below 300 km, very low Earth orbit (VLEO), making observations of the Earth at optical wavelength with increasingly higher resolution. The density of atomic oxygen (AO) at VLEO is significantly higher than that at LEO; severe degradation of spacecraft materials (polymers) due to the high-flux AO is a serious concern. To clarify VLEO environmental effects on spacecraft materials, we designed the Material Degradation Monitor (MDM) and MDM2 missions. The MDM is a material exposure experiment onboard the Super Low-Altitude Test Satellite (SLATS). It aims to understand reactions and degradation of polymeric materials depending on AO fluence in VLEO. In the MDM, samples of spacecraft material were exposed at altitude of 160–560 km; their degradation behaviors were observed optically by a CCD camera for 1.8 years. The MDM2 is a material exposure experiment onboard the International Space Station (ISS) and aims to correctly understand surface reactions and degradation of the same samples used in the MDM at a given AO fluence. In the MDM2, the samples were exposed at altitude of 400 km for 1 year and then returned to Earth for analysis. Based on the results from both missions, we will help in the molecular design of more-durable materials, and establish design standards for future VLEO satellites. This study aims to quantitatively understand the surface reactions and degradation of the 11 types of thermal control materials exposed on the ISS in the MDM2. Five types of multilayer insulation (MLI) films (three types of Si-containing AO protective materials (a silsesquioxane-(SQ-) containing coated polyimide film, two types of polysiloxane-block polyimide (BSF-30) films), an ITO-coated polyimide film, and a Beta Cloth), and flexible optical solar reflectors (flexible OSRs) were found to have a high durability against erosion by AO. This was determined by measuring their loss of mass and thermo-optical properties. The Ag/Inconel layer’s discoloration and peeling were observed for three types of FEP/Ag films as determined by the Ag layer’s oxidation by AO. Also, X-ray photoelectron spectroscopy (XPS) showed that reactions of the Si-containing materials, the SQ-coated polyimide film and the BSF-30 film, form a layer of silica that protects against AO. Even though the concentration of Si in the SQ-coating is the same or greater than in the BSF-30 film, the amount of the SQ-coating that reacted was larger than that of the BSF-30 film under the same AO fluence. Moreover, the effective ability of the UV-shielding coating, composed of ITO and CeO2 coated onto one of the BSF-30 films, was demonstrated by UV–Vis spectrometry. Its sufficient AO protection was confirmed by mass measurements, XPS analyses, and FE-SEM observations.

scholarly journals Low Earth Orbital Atomic Oxygen Interactions with Spacecraft Materials

2004 ◽  
Vol 851 ◽  
Author(s):  
Bruce A. Banks ◽  
Kim K. de Groh ◽  
Sharon K. Miller
Keyword(s):  
Atomic Oxygen ◽  
Protective Coatings ◽  
Low Earth Orbit ◽  
Oxidation Products ◽  
Textured Surfaces ◽  
Aluminum Coatings ◽  
Volatile Oxidation Products ◽  
Residual Atmosphere ◽  
The Impact ◽  
Atomic Oxygen Erosion

ABSTRACTAtomic oxygen, formed in Earth's thermosphere, interacts readily with many materials on spacecraft flying in low Earth orbit (LEO). All hydrocarbon based polymers and graphite are easily oxidized upon the impact of ∼4.5 eV atomic oxygen as the spacecraft ram into the residual atmosphere. The resulting interactions can change the morphology and reduce the thickness of these materials. Directed atomic oxygen erosion will result in the development of textured surfaces on all materials with volatile oxidation products. Examples from space flight samples are provided. As a result of the erosive properties of atomic oxygen on polymers and composites, protective coatings have been developed and are used to increase the functional life of polymer films and composites that are exposed to the LEO environment. The atomic oxygen erosion yields for actual and predicted LEO exposure of numerous materials are presented. Results of in-space exposure of vacuum deposited aluminum protective coatings on polyimide Kapton indicate high rates of degradation are associated with aluminum coatings on both surfaces of the Kapton. Computational modeling predictions indicate that less trapping of the atomic oxygen occurs, with less resulting damage, if only the space-exposed surface is coated with vapor deposited aluminum rather than having both surfaces coated.

scholarly journals Lessons Learned from Atomic Oxygen Interaction with Spacecraft Materials in Low Earth Orbit

2009 ◽  
Author(s):  
Bruce A. Banks ◽  
Kim K. de Groh ◽  
Sharon K. Miller ◽  
Deborah L. Waters ◽  
Jacob I. Kleiman
Keyword(s):  
Atomic Oxygen ◽  
Low Earth Orbit ◽  
Lessons Learned ◽  
Earth Orbit ◽  
Oxygen Interaction

scholarly journals The Effect of Low Earth Orbit Atomic Oxygen Exposure on Phenylphosphine Oxide-Containing Polymers

2000 ◽  
Vol 12 (1) ◽  
pp. 43-52 ◽  
Author(s):  
John W Connell
Keyword(s):  
Thin Film ◽  
Atomic Oxygen ◽  
Low Earth Orbit ◽  
Space Environment ◽  
Earth Orbit ◽  
Cooperative Effort ◽  
Flight Experiment ◽  
Oxygen Exposure ◽  
Atomic Oxygen Exposure ◽  
Phenylphosphine Oxide

Thin films of phenylphosphine oxide-containing polymers were exposed to low Earth orbit aboard a space shuttle flight (STS-85) as part of flight experiment designated Evaluation of Space Environment and Effects on Materials (ESEM). This flight experiment was a cooperative effort between the NASA Langley Research Center (LaRC) and the National Space Development Agency of Japan (NASDA). The thin-film samples described herein were part of an atomic oxygen exposure (AOE) experiment and were exposed to primarily atomic oxygen (∼1×1019 atoms cm−2). The thin-film samples consisted of three phosphine oxide-containing polymers (arylene ether, benzimidazole and imide). Based on post-flight analyses using atomic force microscopy, x-ray photo-electron spectroscopy and weight loss data, it was found that the exposure of these materials to atomic oxygen (AO) produces a phosphorus oxide layer on the surface of the samples. Earlier work has shown that this layer provides a barrier towards further attack by AO. Consequently, these materials do not exhibit linear erosion rates which is in contrast with most organic polymers. Qualitatively, the results obtained from these analyses compare favourably with those obtained from samples exposed to AO and/or an oxygen plasma in ground-based exposure experiments. The results of the low Earth orbit AO exposure on these materials will be compared with those of ground-based exposure to AO.

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