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Research Containing: Atomic oxygen

Development of a thin film solar cell interconnect for the PowerSphere concept

by on 9 June 2015in Technology Development & Demonstration No comment

Progressive development of microsatellite technologies has resulted in increased demand for lightweight electrical power subsystems including solar arrays. The use of thin film photovoltaics has been recognized as a key solution to meet the power needs. The lightweight cells can generate sufficient power and still meet critical mass requirements. Commercially available solar cells produced on lightweight substrates are being studied as an option to fulfill the power needs. The commercially available solar cells are relatively inexpensive and have a high payoff potential. Commercially available thin film solar cells are primarily being produced for terrestrial applications. The need to convert the solar cell from a terrestrial to a space compatible application is the primary challenge. Solar cell contacts, grids and interconnects need to be designed to be atomic oxygen resistant and withstand rapid thermal cycling environments. A mechanically robust solar cell interconnect is also required in order to withstand handling during fabrication and survive during launch. The need to produce the solar cell interconnects has been identified as a primary goal of the PowerSphere program and is the topic of this paper. Details of the trade study leading to the final design involving the solar cell wrap around contact, flex blanket, welding process, and frame will be presented at the conference.

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http://www.sciencedirect.com/science/article/pii/S0921510704005161

Changes in Optical and Thermal Properties of the MISSE 2 Peace Polymers and Spacecraft Silicones

by on 9 June 2015in Technology Development & Demonstration No comment

This paper documents optical and thermal properties of polymers and silicones from the Materials International Space Station Experiment 2 (MISSE 2) Polymer Erosion and Contamination Experiment (PEACE) Polymers experiment and from the MISSE 4 Spacecraft Silicones experiment. PEACE included forty-one polymer samples that were exposed to the low Earth orbit (LEO) environment on the exterior of the International Space Station (ISS) for almost four years. The Spacecraft Silicones experiment is comprised of eight DC 93-500 silicone samples manufactured by Dow Corning, four of which were flown as part of MISSE 2, and four of which were flown as part of MISSE 4. MISSE 4 was exposed to the space environment on the exterior of ISS for 1 year. Both the PEACE Polymers and the Spacecraft Silicone experiments were exposed to atomic oxygen (AO) along with solar and charged particle radiation while in LEO. The majority of the PEACE samples are comprised of numerous thin film layers stacked together. Because many of the PEACE polymers are commonly used for spacecraft applications, their optical and thermal properties are very important. DC 93-500 silicone is a popular spacecraft optical adhesive, often used for photovoltaic applications, hence changes in optical properties, particularly transmittance, due to LEO exposure is very important. Changes in optical and thermal properties due to LEO environmental exposure have been analyzed for all of the materials that could be measured. Due to the long duration space exposure, several of the MISSE 2 samples were too degraded for their properties to be measured. Total and diffuse reflectance, and total and diffuse transmittance, were measured as a function of wavelength and compared with non-exposed control samples. Specular reflectance and specular transmittance were then computed. Thermal emittance data was also generated for numerous samples. For most samples, specular and diffuse reflectance characteristics changed greatly upon directed LEO atomic oxygen exposure. Typically, there is a decrease in specular reflectance with an increase in diffuse reflectance. These optical property changes are relevant to glare issues, Fresnel lens photovoltaic concentrator power loss issues and issues with spatial variations in the thermal load on a spacecraft. The wavelength dependant data also allows computation of the change in solar absorptance (αs) and thermal emittance, which is critical for predicting thermal control characteristics of a spacecraft. A summary of the MISSE 2 PEACE Polymers and Spacecraft Silicones experiments, the specific materials flown, optical and thermal property measurement procedures, and the optical and thermal property data are presented.

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The Effect of Ash and Inorganic Pigment Fill on the Atomic Oxygen Erosion of Polymers and Paints

by on 9 June 2015in Technology Development & Demonstration No comment

Low atomic oxygen fluence (below 1×10(exp 20) atoms/sq cm) exposure of polymers and paints that have a small ash content and/or inorganic pigment fill does not cause a significant difference in erosion yield compared to unfilled (neat) polymers or paints. However, if the ash and/or inorganic pigment content is increased, the surface population of the inorganic content will begin to occupy a significant fraction of the surface area as the atomic oxygen exposure increases because the ash is not volatile and remains as a loosely attached surface layer. This results in a reduction of the flux of atomic oxygen reacting with the polymer and a reduction in the rate of erosion of the polymer remaining. This paper presents the results of ground laboratory and low Earth orbital (LEO) investigations to evaluate the fluence dependence of atomic oxygen erosion yields of polymers and paints having inorganic fill content.

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Japanese Space Materials Exposure Experiment Utilizing International Space Station

by on 9 June 2015in Physical Sciences No comment

Space environment effects on materials are very severe and complex. It depends on the orbit in which the spacecraft is placed. Especially, in the orbit in which International Space Station (ISS) is operated, the interaction with not only space high energy particle but also the neutral gas, which is the atomic oxygen is dominant, become a problem in its performance. In addition, the surface degradation which is associated with contamination is one of the concerns for optics performance. So, space environment and its effect data is very important for spacecraft design. Space materials exposure experiment is that space materials is exposed in space, retrieved on the ground and analyzed. We can understand the real space environment effects on materials from this experimentsamples. NASA's Long Duration Exposure Facility (LDEF) during its 5 years and 9 months in LEO revealed the micrometeoroid or orbital debris environment from the impacts on its samples. NASDA, the forerunner of JAXA, has implemented the space materials exposure experiment on the space shuttle and ISS. Micro-Particles Capturer (MPAC) and Space Environment Exposure Device (SEED) are the Japanese space materials exposure experiment on ISS. The MPAC is a micrometeoroid capture experiment. The SEED is a passive experiment designed to exposure materials. The SM/MPAC&SEED experiment is one of the first Japanese experiments on the Russian Service Module (SM) of ISS. This experiment had been implemented with cooperation between Russia and Japan. In October 2005, all this samples were retrieved on the ground from ISS by Soyuz-10S and transferred to Japan. I will report the status of the experiment and the preliminary report the retrieved samples. And future experimental plan will be reported.

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Ground‐Laboratory to In‐Space Atomic Oxygen Correlation for the PEACE Polymers

by on 9 June 2015in Physical Sciences No comment

The Materials International Space Station Experiment 2 (MISSE 2) Polymer Erosion and Contamination Experiment (PEACE) polymers were exposed to the environment of low Earth orbit (LEO) for 3.95 years from 2001 to 2005. There were forty‐one different PEACE polymers, which were flown on the exterior of the International Space Station (ISS) in order to determine their atomic oxygen erosion yields. In LEO, atomic oxygen is an environmental durability threat, particularly for long duration mission exposures. Although space flight experiments, such as the MISSE 2 PEACE experiment, are ideal for determining LEO environmental durability of spacecraft materials, ground‐laboratory testing is often relied upon for durability evaluation and prediction. Unfortunately, significant differences exist between LEO atomic oxygen exposure and atomic oxygen exposure in ground‐laboratory facilities. These differences include variations in species, energies, thermal exposures and radiation exposures, all of which may result in different reactions and erosion rates. In an effort to improve the accuracy of ground‐based durability testing, ground‐laboratory to in‐space atomic oxygen correlation experiments have been conducted. In these tests, the atomic oxygen erosion yields of the PEACE polymers were determined relative to Kapton H using a radio‐frequency (RF) plasma asher (operated on air). The asher erosion yields were compared to the MISSE 2 PEACE erosion yields to determine the correlation between erosion rates in the two environments. This paper provides a summary of the MISSE 2 PEACE experiment; it reviews the specific polymers tested as well as the techniques used to determine erosion yield in the asher, and it provides a correlation between the space and ground‐laboratory erosion yield values. Using the PEACE polymers’ asher to in‐space erosion yield ratios will allow more accurate in‐space materials performance predictions to be made based on plasma asher durability evaluation.

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http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.3076865

The Materials on International Space Station Experiment (MISSE): First Results from MSFC Investigations

by on 9 June 2015in Physical Sciences No comment

Hundreds of material samples were passively exposed to the space environment for nearly four years as part of the Materials on International Space Station Experiment (MISSE). The experiment was planned for one year of exposure, but its return was delayed by the Columbia accident and subsequent grounding of the Space Shuttle fleet. The experiment was attached externally to the Quest Airlock. Atomic oxygen fluence and ultraviolet radiation dose varied across the experiment because of shadowing and space station orientation. Over a hundred meteoroid/space debris impacts were found. Many polymer film samples were completely eroded by atomic oxygen. Some particulate contamination was noted, but black light inspection and the transmission measurements of magnesium fluoride windows indicated that molecular contaminant deposition was limited. Optical property changes in thermal control materials are discussed.

Related URLs:
http://dx.doi.org/10.2514/6.2006-472

Passive Space Environment Effect Measurement on JEM/MPAC&SEED

by on 9 June 2015in Physical Sciences No comment

A space materials exposure experiment was conducted on the exterior of the International Space Station (ISS) using the Micro-Particles Capturer and Space Environment Exposure Device (MPAC&SEED) of the Japan Aerospace Exploration Agency (JAXA). The MPAC&SEED experiments were aboard both the Russian Service Module (SM/MPAC&SEED) and the exposed Facility of the Japanese Experiment Module, KIBO Exposed Facility (JEM/MPAC&SEED). The JEM/MPAC&SEED was attached to the Space Environment Data Acquisition Equipment-Attached Payload (SEDA-AP). The MPAC&SEED experiment included samples to monitor the fluence of AO, UV, the total dose of space radiation and the maximum temperature. In this paper, the results of the analyses of the space environment effects on the JEM/MPAC&SEED monitoring samples are described.

Related URLs:
http://dx.doi.org/10.1007/978-3-642-30229-9_6

MISSE 2 PEACE Polymers Erosion Morphology Studies

by on 9 June 2015in Physical Sciences No comment

Forty-one different polymer samples, collectively called the Polymer Erosion and Contamination Experiment (PEACE) Polymers, were exposed to the low Earth orbit (LEO) environment on the exterior of the International Space Station (ISS) for nearly four years as part of the Materials International Space Station Experiment 2 (MISSE 2). The objective of the PEACE Polymers experiment was to determine the atomic oxygen erosion yield of a wide variety of polymeric materials after long term exposure to the space environment. The polymers range from those commonly used for spacecraft applications to more recently developed polymers. Additional polymers, not considered for spacecraft applications, were included to explore erosion yield dependence upon chemical composition. The polymers were typically in thin-film form (25 to 500 μm thick) and depending on the polymer thickness and estimated erosion yield, stacking of numerous thin film sample layers was often necessary. Several thick single layer materials, such as epoxy and pyrolytic graphite, were also included. The PEACE Polymers experiment was flown in MISSE Passive Experiment Container 2 (PEC 2) on the exterior of the ISS Quest Airlock and was exposed to ram atomic oxygen, along with solar and charged particle radiation, for the majority of the mission; hence the polymers typically developed very diffuse textures. The average atomic oxygen fluence was 8.43 x 1021 atoms/cm2. This paper documents the erosion morphology of numerous MISSE 2 PEACE polymer samples. Erosion cone structures were examined for high and low erosion yield samples. Also examined were the erosion characteristics for thin film polymers eroded through several layers. Of particular interest was documentation of the erosion of a thin film polymer outer layer at cone valleys, and the corresponding erosion morphology of the underlying layer. This information is relevant to the durability of materials and components on spacecraft that are protected by thin film polymers. The MISSE 2 PEACE Polymers experiment is unique because it has the widest variety of polymers flown collectively in LEO for a long duration and was exposed to an unusually clean LEO spacecraft environment. This paper provides high fluence ram atomic oxygen erosion morphology data applicable to spacecraft durability.

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MISSE PEACE Polymers Atomic Oxygen Erosion Results

by on 9 June 2015in Physical Sciences No comment

Forty-one different polymer samples, collectively called the Polymer Erosion and Contamination Experiment (PEACE) Polymers, have been exposed to the low Earth orbit (LEO) environment on the exterior of the International Space Station (ISS) for nearly 4 years as part of Materials International Space Station Experiment 2 (MISSE 2). The objective of the PEACE Polymers experiment was to determine the atomic oxygen erosion yield of a wide variety of polymeric materials after long term exposure to the space environment. The polymers range from those commonly used for spacecraft applications, such as Teflon (DuPont) FEP, to more recently developed polymers, such as high temperature polyimide PMR (polymerization of monomer reactants). Additional polymers were included to explore erosion yield dependence upon chemical composition. The MISSE PEACE Polymers experiment was flown in MISSE Passive Experiment Carrier 2 (PEC 2), tray 1, on the exterior of the ISS Quest Airlock and was exposed to atomic oxygen along with solar and charged particle radiation. MISSE 2 was successfully retrieved during a space walk on July 30, 2005, during Discovery s STS-114 Return to Flight mission. Details on the specific polymers flown, flight sample fabrication, pre-flight and post-flight characterization techniques, and atomic oxygen fluence calculations are discussed along with a summary of the atomic oxygen erosion yield results. The MISSE 2 PEACE Polymers experiment is unique because it has the widest variety of polymers flown in LEO for a long duration and provides extremely valuable erosion yield data for spacecraft design purposes.

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NASA Glenn Research Center's Materials International Space Station Experiments (MISSE 1-7)

by on 9 June 2015in Physical Sciences No comment

NASA Glenn Research Center (Glenn) has 39 individual materials flight experiments (>540 samples) flown as part of the Materials International Space Station Experiment (MISSE) to address long duration environmental durability of spacecraft materials in low Earth orbit (LEO). MISSE is a series of materials flight experiments consisting of trays, called Passive Experiment Carriers (PECs) that are exposed to the space environment on the exterior of the International Space Station (ISS). MISSE 1-5 have been successfully flown and retrieved and were exposed to the space environment from one to four years. MISSE 6A & 6B were deployed during the STS-123 shuttle mission in March 2008, and MISSE 7A & 7B are being prepared for launch in 2009. The Glenn MISSE experiments address atomic oxygen (AO) effects such as erosion and undercutting of polymers, AO scattering, stress effects on AO erosion, and in-situ AO fluence monitoring. Experiments also address solar radiation effects such as radiation induced polymer shrinkage, stress effects on radiation degradation of polymers, and radiation degradation of indium tin oxide (ITO) coatings and spacesuit fabrics. Additional experiments address combined AO and solar radiation effects on thermal control films, paints and cermet coatings. Experiments with Orion Crew Exploration Vehicle (CEV) seals and UltraFlex solar array materials are also being flown. Several experiments were designed to provide ground-facility to in-space calibration data thus enabling more accurate in-space performance predictions based on ground-laboratory testing. This paper provides an overview of Glenn s MISSE 1-7 flight experiments along with a summary of results from Glenn s MISSE 1 & 2 experiments.

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