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At least 1,009 records · Page 56

Effects of Nuclear Interactions in Space Radiation Transport

Space radiation transport codes have been developed to calculate radiation effects behind materials in human mission to the Moon, Mars or beyond. We study how nuclear fragmentation processes affect predictions from such radiation transport codes. In particular, we investigate the effects of fragmentation cross sections at different energies on fluxes, dose and dose-equivalent from galactic cosmic rays behind typical shielding materials.

Lin, Zi-Wei↗

Capturing, Analyzing, Maintaining, and Disseminating Shape Memory Material Data Between Information Management Systems

With an increased demand on reducing the time, cost, and effort to develop new materials, Integrated Computational Materials Engineering (ICME) has received widespread attention in various engineering disciplines as a catalyst for significantly reducing experimental testing during the material design process. An ICME approach to design can enable ‘fit-for-purpose’ materials to be realized in engineering applications by incorporating well-understood process-property-performance relationships between the various length and time scales in a material’s structure, enabling material optimization. However, such an approach requires validated multiscale models at the various length scales for a material, which in turn requires a large amount of data, a robust means of storing the data, and the ability to link data to developed material models. The NASA Vision 2040 [1] has identified nine key elements to enabling ICME approaches in system level design, with one being “Data, Information, and Visualization”, thus outlining the importance of a robust information management system for ICME. As the relationship between microstructure, properties, and material performance become better understood and incorporated into multiscale models that can be leveraged in application design, the emergence of new materials with application-driven properties can be realized. One such new material class that has seen growing attention are shape memory materials (SMM), in which a material can transition between a deformed and undeformed state via a reversible phase transformation when subject to a thermal, mechanical, or magnetic load [2]. SMMs have been used widely in aerospace and biomedical industries, including applications such as actuators, low-shock mechanisms, medical staples, braces, and stents [3, 4]. These materials exhibit unique behavior due to their ability to transition between phases, and thus the mechanisms that enable this transition must be captured in a data information management system and incorporated into SMM material models. At NASA Glenn Research Center, the Shape Memory Materials Database (SMMD) Tool has been developed to capture the necessary information that governs SMM material behavior and provide users the ability to select and visualize various SMMs for a specific application [5]. The database contains point-wise data for published SMM materials, along with the pedigree metadata for traceability necessary for a robust information management system. The database is also capable of storing in-house test data performed at NASA GRC by interacting with the developed Shape Memory Alloy (SMA) Analytics tool to extract the necessary point-wise values and populate the database. Although the SMMD Tool offers its users a single, authoritative source for SMM material data that is critical for model development and material design, the full material pedigree of the in-house test data for SMMs is not currently captured and is out of the scope for the SMMD tool. In this work, the schema for capturing SMM test data within the larger NASA GRC ICME Schema [6, 7, 8, 9] will be developed and implemented for thermomechanical tests conducted at NASA GRC. The developed schema will not only store the relevant data needed for the SMMD tool, but also the material pedigree (i.e., production of the bulk material, bulk material analysis, sample cut-out diagrams, sample fabrication procedure, etc.), test pedigree (i.e., test equipment used, measurement systems used, raw test data), and analysis pedigree (i.e., how the data in the SMMD tool is calculated). Furthermore, a Python-based framework will be developed to seamlessly interact between the SMA Analytics and SMMD tools, which will write the full dataset and associated metadata to the GRC Information Management System before passing the required point-wise data to the SMMD tool. Data informatics is a key element of the NASA Vision 2040, which requires not only that data is stored and maintained throughout the material lifecycle, but that the data is also accessible and reusable such that material development efforts can be minimized. Therefore, for an ICME design approach to be realized, a centralized information management system that drives the ICME process must be able to communicate with other databases. The work that will be presented in this presentation will therefore not only demonstrate the ability of NASA GRC’s information management system to capture SMM data, but also its ability to interact with pre-existing tools specialized for such materials.

Data management↗

New approaches to hypersonic aircraft

Hypersonic airbreathers aerodynamic, structural and propulsive system interactions, discussing hydrogen fuel heat sink, airframe and engine cooling and airframe materials

Becker, J. V.↗

Space and energy conservation housing prototype unit development

Construction plans are discussed for a house which will demonstrate the application of advanced technology to minimize energy requirements and to help direct further development in home construction by defining the interaction of integrated energy and water systems with building configuration and construction materials. Housing unit designs are provided and procedures for the analysis of a variety of housing strategies are developed.

Sunshine, D. R.↗

Absolute plate motions by boundary velocity minimizations

The main interaction of the earth's interior with the lithosphere is as a material source and sink. An absolute reference frame defined by minimizing the translational motion of tectonic plate boundaries differs by 0.6 cm/year from a frame defined by hot spot traces and by 0.4 cm/year from the frame defined by the most plausible model of drag forces on the plates. The rms absolute translational velocities are about 2 cm/year for ocean-ocean plate boundaries and 1.5 cm/year for ocean-continent plate boundaries. The close agreement between the source and sink and the drag-dependent definitions suggests that the lithosphere, as a stress guide, to some extent controls the locations of its sources and sinks.

Kaula, W. M.↗

Eight-color photometry of Hyperion, Iapetus, and Phoebe

The Phoebe, Hyperion and Iapetus Saturn satellites are discussed in light of eight-color spectrophotometry, which together with observed V magnitudes and Voyager spacecraft-derived diameters yields geometric albedos of 0.07 for Iapetus, 0.06 for Phoebe, and maximum- and minimum-dimension based limits of 0.19 and 0.25 respectively for Hyperion. While both Hyperion and Iapetus have similar, very reddish spectra, it is noted that Hyperion has a much higher albedo than the dark side of Iapetus. The mean spectrum of Phoebe is much flatter, with a broad absorption feature near 1 micron. The determination of these optical differences between the surface materials of Phoebe and the dark side of Iapetus constrains the possible interaction modes between Phoebe and the other two satellites.

Tholen, D. J.↗

Ringed planets - Still mysterious. I

The ring systems of Jupiter, Saturn and Uranus have been studied particularly since the Voyager flights, in order to obtain more information on the rings' origin and structure. These ring systems all have satellites but the structure and number of satellites are different. Jupiter, with its two satellites, has a ring that is roughly 6000 km wide while Uranus has nine ringlets, most of which are no wider than tens of kilometers and which are separated by empty space. The three planetary ring systems also show distinctions in composition; for example, the rings of Saturn are thought to be icy while Jupiter's consist mostly of rocky material. The effect that countless particles, which make up each ring and interact with each other through collisions and gravitational attractions, have on the system's energy and angular momentum has been discussed. Spiral density waves and spiral bending waves, are explained by the resonance theory. Further study is needed in this area since the resonance theory does not account for all observed ring structures.

Cuzzi, J. N.↗

Corrosion Prevention in Copper Combustion Chamber Liners of Liquid Oxygen/Methane Booster Engines

Prior research conducted by United Technologies Research Center and Rockwell International Rocketdyne Division encountered severe copper corrosion while flowing hydrocarbon fuels through copper cooling tubes. These experimental results have very important implications for the development of low-cost, regeneratively cooled, oxygen/hydrocarbon bipropellant booster engines. Aerojet TechSystems undertook a program sponsored by NASA/Lewis Research Center in 1986 with two objectives: (1) to define the corrosive interaction process that occurs between hydrocarbon fuels and copper combustion chamber liner materials, using both static and dynamic test methods, and (2) to identify and demonstrate protective measures against this corrosive process. The results of the first program task demonstrated that the most damaging corrosive process was caused by trace amounts of sulfur-containing impurities in the hydrocarbon fuel which react with the copper chamber liner material to form cuprous sulfide (Cu2S), as reported in Paper No. AlAA 88-3215. Experiments were conducted which demonstrated this corrosive process with Mil-Spec RP-1, propane, and methane fuels in contact with OFHC, NASA-Z, and ZrCu coppers. The preliminary results of the second program task demonstrated that electrodeposited gold and platinum coatings held promise of preventing corrosion of copper chamber liners by methane contaminated with sulfur-containing impurities, as reported in Paper No. AIAA 89-2738. Experiments were conducted which demonstrated greatly reduced corrosion of copper by hydrogen sulfide (H2S) and methyl mercaptan (CH3SH) as measured impurities in methane. This paper presents the concluding, confirmatory results from the second program task. The efficacy of a protective gold coating on NASA-Z copper cooling channel walls was conclusively demonstrated. Tests were conducted in the Aerojet Carbothermal Test Facility which provide realistic simulations of booster engine cooling channel conditions such as temperature, pressure, flow velocity, and heat flux. Dynamic test series were performed with methane containing 5 and 10 ppm (by volume) hydrogen sulfide. Gold-plated and unplated copper alloy specimens were evaluated. The tests demonstrated that gold coatings were effective in preventing corrosion of the copper. Posttest metallographic examinations of the unplated specimens showed severe corrosion as a result of reaction with the sulfur containing contaminant in the fuel. In contrast, posttest metallographic examination of the gold-coated specimens showed no corrosion under similar operating conditions. The findings from metallurgical and chemical analyses of the copper specimens, chemical analysis of the methane, and description of all test conditions are provided. Conclusions are reached as to the efficacy of the plating methods and the effectiveness of the metal coatings in the prevention of corrosion in hydrocarbon-fueled booster engine combustion chamber liners.

S D Rosenberg↗

Microgravity strategic planning exercise

The Center for Space and Advanced Technology supported a planning exercise for the Microgravity Program management at the Marshall Space Flight Center. The effort focused on the status of microgravity work at MSFC and elsewhere with the objective of preparing a goal-oriented strategic planning document which could be used for informational/brochure purposes. The effort entailed numerous interactions and presentations with Field Center programmatic components and Headquarters personnel. Appropriate material was consolidated in a draft format for a MSFC Strategic Plan.

Halpern, Richard↗

A summary of existing and planned experiment hardware for low-gravity fluids research

NASA's ground-based and space-based low-gravity facilities are summarized, and an overview of selected experiments that have been developed for use in these facilities is presented. A variety of ground-based facilities (drop towers and aircraft) used to conduct low-gravity experiments for in-space experimentation are described. Capabilities that are available to the researcher and future on-orbit fluids facilities are addressed. The payload bay facilities range from the completely self-contained, relatively small get-away-special canisters to the Materials Science Laboratory and to the larger Spacelab facilities that require crew interaction.

Hill, Myron E.↗

Total Dose Effects (TDE) of heavy ionizing radiation in fungus spores and plant seeds: Preliminary investigations

The opportunity to compare cosmic radiation effects caused during long and short duration exposure flights in biological objects are limited until now, and data obtained so far are very rare and insufficient. Because of the very long exposure of the experiment during the Long Duration Exposure Facility (LDEF) mission (approximately 2000 days) structural changes of the hardware material can be expected which will influence its biocompatibility and, thus, will interact with the radiobiological effects. The aim of the experiment flown on LDEF was a detailed investigation of biological effects caused by cosmic radiation especially of particles of high atomic number Z and high energy. The flight hardware consisted of standard BIOSTACK containers; in these containers a special sandwich construction consisted of visual plastic detectors with seed rsp. spore layers interlocked.

Kranz, A. R.↗

Commercial investigation results for the generic bioprocessing apparatus flown on United States Microgravity Laboratory-1

The Generic Bioprocessing Apparatus (BPA) payload was developed by BioServe to support the commercial flight development needs of our specialized consortia comprised of business, academic, and government entities. The consortia have commitments to explore commercial opportunities in bioprocessing, biomedical models, and closed agricultural systems. In addition, some members of BioServe have interests in the development and/or qualification of enabling flight hardware used in life sciences space flight testing. Some business and academic entities have interests in more than one of these consortia. To aid in payload development, flight, and analysis, each consortium member contributes resources ranging from proprietary expertise and materials, to hardware and cash. Professionals from business, academia, and government often interact with each other via graduate research assistants who do much of the 'hands-on' payload preparation and subsequent data analyses. The GBA supported research, testing, and development activities for each different BioServe consortium. It produced an environment in which professionals from diverse backgrounds came together with a single focus. And, it provided a truly novel learning environment for a youthful new cadre of space professionals committed to the exploration of commercial opportunities presented by space. Since the GBA supported a large number of different experiments, this paper briefly describes the payload characteristics and the essential operations of the payload. A summary of the experiments is presented. Finally, a few of the experiments are described in detail highlighting some novel effects of space flight on life science systems. Portions of the reported work have or will appear in appropriate archival journals as cited in the bibliography. In several instances, data collected from USML-1 have been supplemented with related data collected on more recent STS missions.

Stodieck, Louis S.↗

GHRS observations of mass-loaded flows in Abell 78

Spectroscopic observations of the central star of the planetary nebula Abell 78 were obtained with the Goddard High Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope (HST) in the vicinity of the C IV lambda 1548.2, 1550.8 doublet. We find a series of narrow absorption features superposed on the broad, P Cygni stellar wind profile. These features are seen in both components of the doublet at heliocentric radial velocities of -18, -71, -131, and -192 km/s. At higher velocities, individual components are no longer distinct but, rather, merge into a continuous absorption extending to approximately -385 km/s. This is among the highest velocities ever detected for gas in a planetary nebula. The -18 km/s feature originates in an outer envelope of normal composition, while the -71 km/s feature is produced in the wind-swept shell encircling an irregular wind-blown bubble in the planetary nebula center. The hydrogen-poor ejecta of Abell 78, consisting of dense knots with wind-blown tails, are located in the bubble's interior, in the vicinity of the stellar wind termination shock. The high-velocity C IV lambda 154 absorption features can be explained as due to parcels of ejecta being accelerated to high velocities as they are swept up by the stellar wind during its interaction with dense condensations of H-poor ejecta. As the ablated material is accelerated, it will partially mix with the stellar wind, creating a mass-loaded flow. The abundance anomalies seen at the rim of the bubble attest to the transport of H-poor knot material by such a flow.

Harrington, J. Patrick↗

STS-87 Day 13 Highlights

On this thirteenth day of the STS-87 mission, the flight crew, Cmdr. Kevin R. Kregel, Pilot Steven W. Lindsey, Mission Specialists Winston E. Scott, Kalpana Chawla, and Takao Doi, and Payload Specialist Leonid K. Kadenyuk continue work in the mini laboratory called the microgravity glovebox facility. This facility allows crew members to interactively work with two different experiments today studying the formation of composite materials in an attempt to accurately map the roles of gravity-induced convection and sedimentation on the samples.

Source record↗

Air oxidation of hydrazine. 1. Reaction kinetics on natural kaolinites, halloysites, and model substituent layers with varying iron and titanium oxide and O- center contents

Air oxidation of hydrazine was studied by using a group of kaolinites, halloysites, and substituent oxides as models for the tetrahedral and octahedral sheets. The rate was found to be linear with oxygen. The stoichiometry showed that oxygen was the primary oxidant and that dinitrogen was the only important nitrogen-containing product. The rates on kaolinites were strongly inhibited by water. Those on three-dimensional silica and gibbsite appeared not to be. That on a supposedly layered silica formed from a natural kaolinite by acid leaching showed transitional behavior--slowed relative to that expected from a second-order reaction relative to that on the gibbsite and silica but faster than those on the kaolinites. The most striking result of the reaction was the marked increase in the rate of reaction of a constant amount of hydrazine as the amount of clay was increased. The increase was apparent (in spite of the water inhibition at high conversions) over a 2 order of magnitude variation of the clay weight. The weight dependence was taken to indicate that the role of the clay is very important, that the number of reactive centers is very small, or that they may be deactivated over the course of the reaction. In contrast to the strong dependence on overall amount of clay, the variation of amounts of putative oxidizing centers, such as structural Fe(III), admixed TiO2 or Fe2O3, or O- centers, did not result in alteration of the rate commensurate with the degree of variation of the entity in question. Surface iron does play some role, however, as samples that were pretreated with a reducing agent were less active as catalysts than the parent material. These results were taken to indicate either that the various centers interact to such a degree that they cannot be considered independently or that the reaction might proceed by way of surface complexation, rather than single electron transfers.

NASA Discipline Number 52-20↗

8th Spacecraft Charging Technology Conference

The 8th Spacecraft Charging Technology Conference was held in Huntsville, Alabama, October 20-24, 2003. Hosted by NASA s Space Environments and Effects (SEE) Program and co-sponsored by the Air Force Research Laboratory (AFRL) and the European Space Agency (ESA), the 2003 conference saw attendance from eleven countries with over 65 oral papers and 18 poster papers. Presentation topics highlighted the latest in spacecraft charging mitigation techniques and on-orbit investigations, including: Plasma Propulsion and Tethers; Ground Testing Techniques; Interactions of Spacecraft and Systems With the Natural and Induced Plasma Environment; Materials Characterizations; Models and Computer Simulations; Environment Specifications; Current Collection and Plasma Probes in Space Plasmas; On-Orbit Investigations. A round-table discussion of international standards regarding electrostatic discharge (ESD) testing was also held with the promise of continued discussions in the off years and an official continuation at the next conference.

Minor, J. L.↗

Long term organ culture of human prostate tissue in a NASA-designed rotating wall bioreactor

PURPOSE: To maintain ex vivo integral prostatic tissue including intact stromal and ductal elements using the NASA-designed Rotating Wall Vessel (RWV) which maintains colocalized cells in an environment that promotes both three-dimensional cellular interactions together with the uniform mass transfer of nutrients and metabolic wastes. MATERIALS AND METHODS: Samples of normal prostate were obtained as a byproduct of transurethral prostatectomy or needle biopsy. Prostatic tissue dissected into small 1 x 1 mm. blocks was cultured in the Rotating Wall Vessel (RWV) Bioreactor for various time periods and analyzed using histological, immunochemical, and total cell RNA assays. RESULTS: We report the long term maintenance of benign explanted human prostate tissue grown in simple culture medium, under the simulated microgravity conditions afforded by the RWV bioreactor. Mesenchymal stromal elements including blood vessels and architecturally preserved tubuloglandular acini were maintained for a minimum of 28 days. Cytokeratins, vimentin and TGF-beta2 receptor and ligand were preserved through the entire culture period as revealed by immunocytochemistry. Prostatic acid phosphatase (PAP) was continuously expressed during the culture period, although somewhat decreased. Prostatic specific antigen (PSA) and its transcript were down regulated over time of culture. Prostatic carcinoma cells from the TSU cell line were able to invade RWV-cultured benign prostate tissue explants. CONCLUSIONS: The RWV bioreactor represents an additional new technology for culturing prostate tissue for further investigations concerning the basic physiology and pathobiology of this clinically important tissue.

Prostate/chemistry/cytology↗

Holistic Design for Total Product Well Being

Recent hardware development work at NASA's Marshall Space Flight Center creates and argument for the use of a holistic design approach as opposed to a piece part design approach. A piece part design approach being one where individual pieces are developed to their finished state having to meet certain interface and human engineering requirements without much consideration to the final product as a whole. A holistic design approach being one where the final product is evaluated early and frequently during the design process, and individual parts are developed with consideration to how they interact a whole,and how they interact with the user and environment. Examples from the development of the Materials Science Research Rack - 1 will illustrate: a design failure due to piece part design; a design save, due to a failure of piece part design, but saved by evaluating the design holistically; and a design success due to a holistic design approach.

Adams, Chris W.↗