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Jun 13, 2011
06/11
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deGroh, Kim K.; Banks, Bruce A.; Ma, Davi
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Surfaces on the leading edge of spacecraft in low Earth orbit (e.g., surface facing the velocity direction), such as on the International Space Station, are subject to atomic oxygen attack, and certain materials are susceptible to erosion. Therefore, ground-based laboratory testing of the atomic oxygen durability of spacecraft materials is necessary for durability assessment when flight data are not available. For accurate space simulation, the facility is commonly calibrated on the basis of...
Topics: ROBUSTNESS (MATHEMATICS), RUNWAYS, PRECISION, PROTOTYPES, SPACING, AIRPORTS, ROUTES
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May 22, 2011
05/11
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Rutledge, Sharon K.; Banks, Bruce A.; Cales, Michae
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A comparison of the relative erosion yields (volume of material removed per oxygen atom arriving) for FEP Teflon, polyethylene, and pyrolytic graphite with respect to Kapton HN was performed in an atomic oxygen directed beam system, in a plasma asher, and in space on the EOIM-III (Evaluation of Oxygen Interaction with Materials-III) flight experiment. This comparison was performed to determine the sensitivity of material reaction to atomic oxygen flux, atomic oxygen fluence, and vacuum...
Topics: LEADERSHIP, LECTURES, NASA PROGRAMS, POLICIES, SPACE LAW, AEROSPACE INDUSTRY, DECISION MAKING,...
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Jun 9, 2011
06/11
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Banks, Bruce A.; Miller, Sharon K.; deGroh, Kim K
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Atomic oxygen is formed in the low Earth orbital environment (LEO) by photo dissociation of diatomic oxygen by short wavelength () 243 nm) solar radiation which has sufficient energy to break the 5.12 eV O2 diatomic bond in an environment where the mean free path is sufficiently long ( 108 meters) that the probability of reassociation or the formation of ozone (O3) is small. As a consequence, between the altitudes of 180 and 650 km, atomic oxygen is the most abundant species. Spacecraft impact...
Topics: DESIGN ANALYSIS, REVIEWING, NASA PROGRAMS, PROJECT MANAGEMENT
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May 28, 2011
05/11
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Rutledge, Sharon K.; Banks, Bruce A.; Chichernea, Virgil A
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A noncontact method is described which uses atomic oxygen to remove soot and char from the surface of a painting. The atomic oxygen was generated by the dissociation of oxygen in low pressure air using radio frequency energy. The treatment, which is an oxidation process, allows control of the amount of material to be removed. The effectiveness of char removal from half of a fire-damaged oil painting was studied using reflected light measurements from selected areas of the painting and by visual...
Topics: EXTRATERRESTRIAL RADIATION, SPACE OBSERVATIONS (FROM EARTH), MAGNETIC DISTURBANCES, INTERPLANETARY...
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May 27, 2011
05/11
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Banks, Bruce A.; Rutledge, Sharon K.; Norris, Mary J
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Soot and other carbonaceous combustion products deposited on the surfaces of porous ceramic, stone, ivory and paper can be difficult to remove and can have potentially unsatisfactory results using wet chemical and/or abrasive cleaning techniques. An atomic oxygen source which operates in air at atmospheric pressure, using a mixture of oxygen and helium, has been developed to produce an atomic oxygen beam which is highly effective in oxidizing soot deposited on surfaces by burning candles made...
Topics: SUBSONIC FLOW, NOZZLE FLOW, SOUND FIELDS, JET AIRCRAFT NOISE, AIR JETS, ENGINE NOISE, NEAR FIELDS,...
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Jun 2, 2011
06/11
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Banks, Bruce A.; Karniotis, Christina A.; Dworak, David; Soucek, Mar
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The exposure of most silicones to atomic oxygen in low Earth orbit (LEO) results in the oxidative loss of methyl groups with a gradual conversion to oxides of silicon. Typically there is surface shrinkage of oxidized silicone protective coatings which leads to cracking of the partially oxidized brittle surface. Such cracks widen and branch crack with continued atomic oxygen exposure ultimately allowing atomic oxygen to reach any hydrocarbon polymers under the silicone coating. A need exists for...
Topics: DIGITAL SYSTEMS, DESIGN ANALYSIS, SYNCHRONISM, TIME FUNCTIONS, SYSTEMS ENGINEERING, CLOCKS,...
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May 28, 2011
05/11
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Banks, Bruce A.; deGroh, Kim K.; Rutledge, Sharon K.; Haytas, Christy A
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The exposure of silicones to atomic oxygen in low Earth orbit causes oxidation of the surface, resulting in conversion of silicone to silica. This chemical conversion increases the elastic modulus of the surface and initiates the development of a tensile strain. Ultimately, with sufficient exposure, tensile strain leads to cracking of the surface enabling the underlying unexposed silicone to be converted to silica resulting in additional depth and extent of cracking. The use of silicone...
Topics: CONFERENCES, AIR TRAFFIC CONTROL, RUNWAYS, AIR TRANSPORTATION, AIRLINE OPERATIONS, AIR TRAFFIC,...
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May 26, 2011
05/11
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Banks, Bruce A.; deGroh, Kim K.; Stueber, Thomas J.; Sechkar, Edward A.; Hall, Rachelle L
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Metallized Teflon fluorinated ethylene propylene (FEP) thermal control insulation is mechanically degraded if exposed to a sufficient fluence of soft x-ray radiation. Soft x-ray photons (4-8 A in wavelength or 1.55 - 3.2 keV) emitted during solar flares have been proposed as a cause of mechanical properties degradation of aluminized Teflon FEP thermal control insulation on the Hubble Space Telescope (HST). Such degradation can be characterized by a reduction in elongation-to-failure of the...
Topics: SUPERSONIC INLETS, COMPUTATIONAL FLUID DYNAMICS, COMPUTERIZED SIMULATION, PROPULSION SYSTEM...
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Jun 9, 2011
06/11
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Banks, Bruce A.; Gaier, James R.; Hung, Ching-Cheh; Walters, Patty A.; Sechkar, Ed; Panko, Scott; Kamiotis, Christina A
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Within NASA's Project Prometheus, high specific impulse ion thrusters for electric propulsion of spacecraft for the proposed Jupiter Icy Moon Orbiter (JIMO) mission to three of Jupiter's moons: Callisto, Ganymede and Europa will require high voltage operation to meet mission propulsion. The anticipated approx.6,500 volt net ion energy will require electrical insulation and propellant isolation which must exceed that used successfully by the NASA Solar Electric Propulsion Technology Readiness...
Topics: REUSABLE LAUNCH VEHICLES, AIRCRAFT DESIGN, NUMERICAL ANALYSIS, SUPPORT SYSTEMS, LOGISTICS
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Jun 26, 2011
06/11
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Daniels, Christopher C.; Miller, Sharon K.; Waters, Deborah L; deGroh, Henry, III; Dunlap, Patrick H., Jr.; Finkbeiner, Joshua R.; Steinetz, Bruce M.; Bastrzyk, Marta B.; Oswald, Jay J.; Banks, Bruce A.; Dever, Joyce A.
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A universal docking and berthing system is being developed by the National Aeronautics and Space Administration (NASA) to support all future space exploration missions to low-Earth orbit (LEO), to the Moon, and to Mars. The Low Impact Docking System (LIDS) is being designed to operate using a seal-on-seal configuration in numerous space environments, each having unique exposures to temperature, solar radiation, reactive elements, debris, and mission duration. As the LIDS seal is likely to be...
Topics: ALGORITHMS, REAL TIME OPERATION, MOMENTUM, GYROSCOPES, TARGETS, REACTION WHEELS, AUTONOMY, SYSTEMS...
