1,004 research outputs found

    Ground simulation of a Mars-entry-capsule aeroshell environmental history

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    Design of facility for simulating Mars space capsule entr

    The Thermal Conduction Process in Carbonaceous Chars

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    Conductive heat transfer in porous carbonaceous chars of degraded phenolic nylon sampl

    Fabrication development of lightweight honeycomb-sandwich structures for extraterrestrial planetary probe missions

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    Lightweight resin fiber glass honeycomb sandwich structure fabrication and comparison with aluminum structures for planetary probe

    Polar Environmental Monitoring

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    The present and projected benefits of the polar regions were reviewed and then translated into information needs in order to support the array of polar activities anticipated. These needs included measurement sensitivities for polar environmental data (ice/snow, atmosphere, and ocean data for integrated support) and the processing and delivery requirements which determine the effectiveness of environmental services. An assessment was made of how well electromagnetic signals can be converted into polar environmental information. The array of sensor developments in process or proposed were also evaluated as to the spectral diversity, aperture sizes, and swathing capabilities available to provide these measurements from spacecraft, aircraft, or in situ platforms. Global coverage and local coverage densification options were studied in terms of alternative spacecraft trajectories and aircraft flight paths

    Shipboard fisheries management terminals

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    The needs of the National Marine Fisheries Service (NMGS), National Weather Service, and the U.S. Coast Guard for locational, biological, and environmental data were assessed. The fisheries conservation zones and the yellowfin tuna jurisdiction of the NMFS operates observer programs on foreign and domestic fishing vessels. Data input terminal and data transfer and processing technology are reviewed to establish available capability. A matrix of implementation options is generated to identify the benefits of each option, and preliminary cost estimates are made. Recommendations are made for incremental application of available off the shelf hardware to obtain improved performance and benefits within a well bounded cost. Terminal recommendations are made for three interdependent shipboard units emphasizing: (1) the determination of location and fishing activity; (2) hand held data inputting and formatting in the fishing work areas; and (3) data manipulation, merging, and editing

    Data Requirements for Oceanic Processes in the Open Ocean, Coastal Zone, and Cryosphere

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    The type of information system that is needed to meet the requirements of ocean, coastal, and polar region users was examined. The requisite qualities of the system are: (1) availability, (2) accessibility, (3) responsiveness, (4) utility, (5) continuity, and (6) NASA participation. The system would not displace existing capabilities, but would have to integrate and expand the capabilities of existing systems and resolve the deficiencies that currently exist in producer-to-user information delivery options

    A systematic review of heat-shield technology for extraterrestrial atmospheric entry

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    Heat shield technology for extraterrestrial atmospheric entr

    XUV Opacity of Aluminum between the Cold-Solid to Warm-Plasma Transition

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    We present calculations of the free-free XUV opacity of warm, solid-density aluminum at photon energies between the plasma frequency at 15 eV and the L-edge at 73 eV, using both density functional theory combined with molecular dynamics and a semi-analytical model in the RPA framework with the inclusion of local field corrections. As the temperature is increased from room temperature to 10 eV, with the ion and electron temperatures equal, we calculate an increase in the opacity in the range over which the degree of ionization is constant. The effect is less pronounced if only the electron temperature is allowed to increase. The physical significance of these increases is discussed in terms of intense XUV-laser matter interactions on both femtosecond and picosecond time-scales.Comment: 4 pages, 3 figure

    A Lightweight 6 1/2-ft Aeroshell for an Early Mars Probe Mission

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    Lightweight 6 1/2 ft sphere-cone honeycomb sandwich structure with elastomeric ablator for Mars probe missio

    Static and Dynamic Magnetism in Underdoped Superconductor BaFe1.92_{1.92}Co0.08_{0.08}As2_2

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    We report neutron scattering measurements on single crystals of BaFe1.92_{1.92}Co0.08_{0.08}As2_2. The magnetic Bragg peak intensity is reduced by 6 % upon cooling through TC_C. The spin dynamics exhibit a gap of 8 meV with anisotropic three-dimensional (3d) interactions. Below TC_C additional intensity appears at an energy of ∼\sim4.5(0.5) meV similar to previous observations of a spin resonance in other Fe-based superconductors. No further gapping of the spin excitations is observed below TC_C for energies down to 2 meV. These observations suggest the redistribution of spectral weight from the magnetic Bragg position to a spin resonance demonstrating the direct competition between static magnetic order and superconductivity.Comment: 4 pages, 4 figure
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