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  • 1
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    Stratigraphy of the North Polar Layered Deposits of Mars from High-Resolution Topography (2016)
    Wiley
    Details
    Publication Date: 2016-08-02
    Description: The stratigraphy of the layered deposits of the polar regions of Mars is theorized to contain a record of recent climate change linked to insolation changes driven by variations in the planet's orbital and rotational parameters. In order to confidently link stratigraphic signals to insolation periodicities, a description of the stratigraphy is required based on quantities that directly relate to intrinsic properties of the layers. We use stereo Digital Terrain Models (DTMs) from the High Resolution Imaging Science Experiment (HiRISE) to derive a characteristic of North Polar Layered Deposits (NPLD) strata that can be correlated over large distances: the topographic protrusion of layers exposed in troughs, which is a proxy for the layers’ resistance to erosion. Using a combination of image analysis and a signal-matching algorithm to correlate continuous depth-protrusion signals taken from DTMs at different locations, we construct a stratigraphic column that describes the upper ~500 m of at least 7% of the area of the NPLD, and find accumulation rates that vary by factors of up to two. We find that, when coupled with observations of exposed layers in orbital images, the topographic expression of the strata is consistently continuous through large distances in the top 300 – 500 m of the NPLD, suggesting it is better related to intrinsic layer properties than brightness alone.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    Approximate line shapes for hydrogen (1978)
    Elsevier
    Details
    Publication Date: 1978-10-01
    Print ISSN: 0022-4073
    Electronic ISSN: 1879-1352
    Topics: Physics
    Published by Elsevier
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  • 3
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    Mass loss shape change and real-gas aerodynamic effects on a jovian atmospheric probe (1977)
    Elsevier
    Details
    Publication Date: 1977-05-01
    Print ISSN: 0094-5765
    Electronic ISSN: 1879-2030
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Elsevier
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  • 4
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    Viscous shock-layer solutions with coupled radiation and ablation for earth entry (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 29; 173-181
    Format: text
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  • 5
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    Non-Boltzmann Modeling for Air Shock-Layer Radiation at Lunar-Return Conditions (2008)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: This paper investigates the non-Boltzmann modeling of the radiating atomic and molecular electronic states present in lunar-return shock-layers. The Master Equation is derived for a general atom or molecule while accounting for a variety of excitation and de-excitation mechanisms. A new set of electronic-impact excitation rates is compiled for N, O, and N2+, which are the main radiating species for most lunar-return shock-layers. Based on these new rates, a novel approach of curve-fitting the non-Boltzmann populations of the radiating atomic and molecular states is developed. This new approach provides a simple and accurate method for calculating the atomic and molecular non-Boltzmann populations while avoiding the matrix inversion procedure required for the detailed solution of the Master Equation. The radiative flux values predicted by the present detailed non-Boltzmann model and the approximate curve-fitting approach are shown to agree within 5% for the Fire 1634 s case.
    Keywords: Lunar and Planetary Science and Exploration
    Format: application/pdf
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  • 6
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    Viscous-shock-layer solutions with coupled radiation and ablation injection for earth entry (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Results are obtained for the forebody of a planetary exploration vehicle entering the earth's atmosphere. A viscous-shock-layer analysis is used assuming the flow to be laminar and in chemical equilibrium. Presented results include coupled radiation and ablation injection. This study further includes the effect of different transport and thermodynamic properties and radiation models. A Lewis number of 1.4 appears adequate for the radiation-dominated flows. Five velocities corresponding to different possible trajectory points at an altitude of 70 km have been further analyzed in detail. Sublimation and radiative equilibrium wall temperatures are employed for cases with and without coupled injection, respectively. For the cases analyzed here, the mass injection rates are small. However, the rates could become large if a lower altitude is used for aerobraking and/or the body size is increased. A comparison of the equilibrium results with finite-rate chemistry calculation shows the flowfield to be in chemical equilibrium.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 90-1697
    Format: text
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  • 7
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    Computational analysis and preliminary redesign of the nozzle contour of the Langley hypersonic CF4 tunnel (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A computational analysis, modification, and preliminary redesign study was performed on the nozzle contour of the Langley Hypersonic CF4 Tunnel. This study showed that the existing nozzle was contoured incorrectly for the design operating condition, and this error was shown to produce the measured disturbances in the exit flow field. A modified contour was designed for the current nozzle downstream of the maximum turning point that would provide a uniform exit flow. New nozzle contours were also designed for an exit Mach number and Reynolds number combination which matches that attainable in the Langley 20-Inch Mach 6 Tunnel. Two nozzle contours were designed: one having the same exit radius but a larger mass flow rate than that of the existing CF4 Tunnel, and the other having the same mass flow rate but a smaller exit radius than that of the existing CF4 Tunnel.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: NASA-TM-89042 , L-16170 , NAS 1.15:89042
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  • 8
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    Equilibrium radiative heating tables for aerobraking in the Martian atmosphere (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Studies currently underway for Mars missions often envision the use of aerobraking for orbital capture at Mars. These missions generally involve blunt-nosed vehicles to dissipate the excess energy of the interplanetary transfer. Radiative heating may be of importance in these blunt-body flows because of the highly energetic shock layer around the blunt nose. In addition, the Martian atmosphere contains CO2, whose dissociation products are known to include strong radiators. An inviscid, equilibrium, stagnation point, radiation-coupled flow-field code has been developed for investigating blunt-body atmospheric entry. The method has been compared with ground-based and flight data for air, and reasonable agreement has been found. In the present work, the method was applied to a matrix of conditions in the Martian atmosphere. These conditions encompass most trajectories of interest for Mars exploration spacecraft. The predicted equilibrium radiative heating to the stagnation point of the vehicle is presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-102659 , NAS 1.15:102659
    Format: application/pdf
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  • 9
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    Equilibrium radiative heating tables for Earth entry (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The recent resurgence of interest in blunt-body atmospheric entry for applications such as aeroassisted orbital transfer and planetary return has engendered a corresponding revival of interest in radiative heating. Radiative heating may be of importance in these blunt-body flows because of the highly energetic shock layer around the blunt nose. Sutton developed an inviscid, stagnation point, radiation coupled flow field code for investigating blunt-body atmospheric entry. The method has been compared with ground-based and flight data, and reasonable agreement has been found. To provide information for entry body studies in support of lunar and Mars return scenarios of interest in the 1970's, the code was exercised over a matrix of Earth entry conditions. Recently, this matrix was extended slightly to reflect entry vehicle designs of current interest. Complete results are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-102652 , NAS 1.15:102652
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  • 10
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    Overview of CFD methods and comparison with flight aerothermal data (1988)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: An overview of previously published aerothermal investigations which demonstrate the capabilities of detailed computational fluid dynamics and engineering codes to predict the aerothermal environment about an entry vehicle is presented. The overview consists of a brief discussion of the computational methods and experimental data and includes comparisons between the computed results and data. The overview focuses primarily on analyses of flight data since these data provide the unique capability to assess the real-gas chemistry options in the codes. The computed results are based on a series of codes which are employed by the Aerothermodynamics Branch of the Space System Division at the Langley Research Center. The flight data, which were measured on the Reentry F, the Space Shuttle, and the Fire II vehicles, represent a wide range of vehicle configurations and freestream conditions. Also, results of one recent set of ground tests are included since the tests provide data on a model of a pending flight project. The comparisons of the predicted results and data demonstrate the adequacy of the present computational fluid dynamics capabilities and indicate the potential to predict the aerothermal environment about future flight vehicles.
    Keywords: AERODYNAMICS
    Type: AGARD, Validation of Computational Fluid Dynamics. Volume 2: Poster Papers; 17 p
    Format: text
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