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Research Containing: Material science

MISSE 6 Polymer Film Tensile Experiment

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

The Polymer Film Tensile Experiment (PFTE) was flown as part of Materials International Space Station Experiment 6 (MISSE 6). The purpose of the experiment was to expose a variety of polymer films to the low Earth orbital environment under both relaxed and tension conditions. The polymers selected are those commonly used for spacecraft thermal control and those under consideration for use in spacecraft applications such as sunshields, solar sails, and inflatable and deployable structures. The dog-bone shaped samples of polymers that were flown were exposed on both the side of the MISSE 6 Passive Experiment Container (PEC) that was facing into the ram direction (receiving atomic oxygen, ultraviolet (UV) radiation, ionizing radiation, and thermal cycling) and the wake facing side (which was supposed to have experienced predominantly the same environmental effects except for atomic oxygen which was present due to reorientation of the International Space Station). A few of the tensile samples were coated with vapor deposited aluminum on the back and wired to determine the point in the flight when the tensile sample broke as recorded by a change in voltage that was stored on battery powered data loggers for post flight retrieval and analysis. The data returned on the data loggers was not usable. However, post retrieval observation and analysis of the samples was performed. This paper describes the preliminary analysis and observations of the polymers exposed on the MISSE 6 PFTE.

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A miniature microcontroller curve tracing circuit for space flight testing transistors

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

This paper describes a novel miniature microcontroller based curve tracing circuit, which was designed to monitor the environmental effects on Silicon Carbide Junction Field Effect Transistor (SiC JFET) device performance, while exposed to the low earth orbit environment onboard the International Space Station (ISS) as a resident experiment on the 7th Materials on the International Space Station Experiment (MISSE7). Specifically, the microcontroller circuit was designed to operate autonomously and was flown on the external structure of the ISS for over a year. This curve tracing circuit is capable of measuring current vs. voltage (I-V) characteristics of transistors and diodes. The circuit is current limited for low current devices and is specifically designed to test high temperature, high drain-to-source resistance SiC JFETs. The results of each I-V data set are transmitted serially to an external telemetered communication interface. This paper discusses the circuit architecture, its design, and presents example results.

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http://scitation.aip.org/content/aip/journal/rsi/86/2/10.1063/1.4908163

Materials Interactions with Space Environment: International Space Station – May 2000 to May 2002

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

The set of materials interactions with the space flight environment that have produced the largest impacts on the verification and acceptance of flight hardware and on flight operations of the International Space Station (ISS) Program during the May 2000 to May 2002 time frame are described in this paper. In-flight data, flight crew observations, and the results of ground-based test and analysis directly supporting programmatic and operational decision-making are reported.

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http://dx.doi.org/10.1007/1-4020-2595-5_3

Embrittlement of MISSE 5 Polymers After 13 Months of Space Exposure

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

Understanding space environment induced degradation of spacecraft materials is essential when designing durable and stable spacecraft components. As a result of space radiation, debris impacts, atomic oxygen interaction, and thermal cycling, the outer surfaces of space materials degrade when exposed to low Earth orbit (LEO). The objective of this study was to measure the embrittlement of 37 thin film polymers after LEO space exposure. The polymers were flown aboard the International Space Station and exposed to the LEO space environment as part of the Materials International Space Station Experiment 5 (MISSE 5). The samples were flown in a nadir-facing position for 13 months and were exposed to thermal cycling along with low doses of atomic oxygen, direct solar radiation and omni-directional charged particle radiation. The samples were analyzed for space-induced embrittlement using a bend-test procedure in which the strain necessary to induce surface cracking was determined. Bend-testing was conducted using successively smaller mandrels to apply a surface strain to samples placed on a semi-suspended pliable platform. A pristine sample was also tested for each flight sample. Eighteen of the 37 flight samples experienced some degree of surface cracking during bend-testing, while none of the pristine samples experienced any degree of cracking. The results indicate that 49% of the MISSE 5 thin film polymers became embrittled in the space environment even though they were exposed to low doses (~2.75 krad (Si) dose through 127 μm Kapton) of ionizing radiation.

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http://dx.doi.org/10.1007/978-3-642-30229-9_35

Post-Flight Characterization of Samples for the MISSE-7 Spacesuit Fabric Exposure Experiment

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

Six samples of pristine and dust-abraded outer layer spacesuit fabrics were included in the Materials International Space Station Experiment-7, in which they were exposed to the wake side low Earth orbit environment (LEO) on the International Space Station (ISS) for 18 months in order to determine whether abrasion by lunar dust increases radiation degradation. The fabric samples were characterized using optical microscopy, field emission scanning electron microscopy, and tensile testing before and after exposure on the ISS. Comparison of pre- and post-flight characterizations showed that wake side LEO environment darkened and reddened all six fabrics, increasing their integrated solar absorptance by 7 to 38 percent. There was a decrease in the ultimate tensile strength and elongation to failure of lunar dust abraded Apollo spacesuit fibers by a factor of four and increased the elastic modulus by a factor of two. The severity of the degradation of the fabric samples over this short exposure time demonstrates the necessity to find ways to prevent or mitigate radiation damage to spacesuits when planning extended missions to the Moon.

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Degradation of Spacesuit Fabrics on Low Earth Orbit

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

Six samples of pristine and dust-abraded outer layer spacesuit fabrics were included in the Materials International Space Station Experiment-7, in which they were exposed to the wake-side low Earth orbit environment on the International Space Station (ISS) for 18 months in order to determine whether abrasion by lunar dust increases radiation degradation. The fabric samples were characterized using optical microscopy, optical spectroscopy, field emission scanning electron microscopy, atomic force microscopy, and tensile testing before and after exposure on the ISS. Comparison of pre- and post-flight characterizations showed that the environment darkened and reddened all six fabrics, increasing their integrated solar absorptance by 7 to 38 percent. There was a decrease in the ultimate tensile strength and elongation to failure of lunar dust abraded Apollo spacesuit fibers by a factor of four and an increase in the elastic modulus by a factor of two.

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Pre-Flight Characterization of Samples for the MISSE-7 Spacesuit Fabric Exposure Experiment

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

A series of six sample spacesuit pressure garment assembly (PGA) fabric samples were prepared for the Materials International Space Station Experiment 7 (MISSE-7) flight experiment to test the effects of damage by lunar dust on the susceptibility of the fabrics to radiation damage. These included pristine Apollo-era fluorinated ethylene-propylene (FEP) fabric, Apollo-era FEP fabric that had been abraded with JSC-1A lunar simulant, and a piece of Alan Bean s Apollo 12 PGA sectioned from near the left knee. Also included was a sample of pristine orthofabric, and orthofabric that had been abraded to two different levels with JSC-1A. The samples were characterized using optical microscopy, field emission scanning electron microscopy, and atomic force microscopy. Two sets of six samples were then loaded in space environment exposure hardware, one of which was stored as control samples. The other set was affixed to the MISSE-7 experiment package, and will be mounted on the International Space Station, and exposed to the wake-side low Earth orbit environment. It will be retrieved after an exposure of approximately 12 months, and returned for post flight analysis.

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MISSE 1 and 2 Tray Temperature measurements

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

The Materials International Space Station Experiment (MISSE 1 & 2) was deployed August 10, 2001 and retrieved July 30, 2005. This experiment is a co-operative endeavor by NASA-LaRC, NASA-GRC, NASA MSFC, NASA-JSC, the Materials Laboratory at the Air Force Research Laboratory, and the Boeing Phantom Works. The objective of the experiment is to evaluate performance, stability, and long term survivability of materials and components planned for use by NASA and DOD on future LEO, synchronous orbit, and interplanetary space missions. Temperature is an important parameter in the evaluation of space environmental effects on materials. The MISSE 1 & 2 had autonomous temperature data loggers to measure the temperature of each of the four experiment trays. The MISSE tray-temperature data loggers have one external thermistor data channel, and a 12 bit digital converter. The MISSE experiment trays were exposed to the ISS space environment for nearly four times the nominal design lifetime for this experiment. Nevertheless, all of the data loggers provided useful temperature measurements of MISSE. The temperature measurement system has been discussed in a previous paper. This paper presents temperature measurements of MISSE payload experiment carriers (PECs) 1 and 2 experiment trays.

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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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