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NASA Technical Reports Server (NTRS) (686.496 recursos)

The NTRS is a valuable resource for students, educators, researchers, and the public for access to NASA's current and historical technical literature since it was first released in 1994. NTRS provides access to approximately 500K aerospace related citations, 90K full-text online documents, and 111K images and videos. NTRS numbers continues to grow over time as new scientific and technical information (STI) is created or funded by NASA. The type of information found in NTRS include: conference papers, images, journal articles, photos, meeting papers, movies, patents, research reports, and technical videos.

Mostrando recursos 61 - 80 de 321.855

  1. Continental-Scale Mapping of Adelie Penguin Colonies from Landsat Imagery

    Schwaller, Mathew R.; Southwell, Colin; Emmerson, Louise
    Breeding distribution of the Adlie penguin, Pygoscelis adeliae, was surveyed with Landsat-7 Enhanced Thematic Mapper Plus (ETM+) data in an area covering approximately 330 of longitude along the coastline of Antarctica.An algorithm was designed to minimize radiometric noise and to retrieve Adlie penguin colony location and spatial extent from the ETM+data. In all, 9143 individual pixels were classified as belonging to an Adlie penguin colony class out of the entire dataset of 195 ETM+ scenes, where the dimension of each pixel is 30 m by 30 m,and each scene is approximately 180 km by 180 km. Pixel clustering identified a...

  2. Directional and Spectral Irradiance in Ocean Models: Effects on Simulated Global Phytoplankton, Nutrients, and Primary Production

    Gregg, Watson W.; Rousseaux, Cecile S.
    The importance of including directional and spectral light in simulations of ocean radiative transfer was investigated using a coupled biogeochemical-circulation-radiative model of the global oceans. The effort focused on phytoplankton abundances, nutrient concentrations and vertically-integrated net primary production. The importance was approached by sequentially removing directional (i.e., direct vs. diffuse) and spectral irradiance and comparing results of the above variables to a fully directionally and spectrally-resolved model. In each case the total irradiance was kept constant; it was only the pathways and spectral nature that were changed. Assuming all irradiance was diffuse had negligible effect on global ocean primary production....

  3. Simulating PACE Global Ocean Radiances

    Gregg, Watson W.; Rousseaux, Cecile S.
    The NASA PACE mission is a hyper-spectral radiometer planned for launch in the next decade. It is intended to provide new information on ocean biogeochemical constituents by parsing the details of high resolution spectral absorption and scattering. It is the first of its kind for global applications and as such, poses challenges for design and operation. To support pre-launch mission development and assess on-orbit capabilities, the NASA Global Modeling and Assimilation Office has developed a dynamic simulation of global water-leaving radiances, using an ocean model containing multiple ocean phytoplankton groups, particulate detritus, particulate inorganic carbon (PIC), and chromophoric dissolved organic...

  4. NExSS/NAI Joint ExoPAG SAG 16 Report on Remote Biosignatures for Exoplanets

    Domagal-Goldman, Shawn; Parenteau, Mary Nicole; Kiang, Nancy Y.
    Future exoplanet observations will soon focus on the search for life beyond the Solar System. Exoplanet biosignatures to be sought are those with global, potentially detectable, impacts on a planet. Biosignatures occur in an environmental context in which geological, atmospheric, and stellar processes and interactions may work to enhance, suppress or mimic these biosignatures. Thus biosignature scienceis inherently interdisciplinary. Its advance is necessary to inform the design of the next flagship missions that will obtain spectra of habitable extrasolar planets. The NExSS NAI Joint Exoplanet Biosignatures Workshop Without Walls brought together the astrobiology, exoplanet, and mission concept communities to review,...

  5. The Impact of ENSO on Trace Gas Composition in the Upper Troposphere to Lower Stratosphere

    Waugh, Darryn Warwick; Ziemke, Jerry; Oman, Luke; Douglass, Anne
    The El Nino-Southern Oscillation (ENSO) is the dominant mode of interannual variability in the tropical troposphere and its effects extend well into the stratosphere. Its impact on atmospheric dynamics and chemistry cause important changes to trace gas constituent distributions. A comprehensive suite of satellite observations, reanalyses, and chemistry climate model simulations are illuminating our understanding of processes like ENSO. Analyses of more than a decade of observations from NASAs Aura and Aqua satellites, combined with simulations from the Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM) and other Chemistry Climate Modeling Initiative (CCMI) models, and the Modern-Era Retrospective Analysis for Research...

  6. Quantifying Chemical Ozone Loss in the Arctic Stratosphere with GEOS-STRATCHEM Data Assimilation System

    Wargan, K.; Nielsen, J. E.
    A faithful representation of polar stratospheric chemistry in models and its connection with dynamical variability is essential for our understanding of the evolution of the ozone layer in a changing climate and during the projected continuing decline of ozone depleting substances in the atmosphere. We use a new configuration of the Goddard Earth Observing System Data Assimilation System with a stratospheric chemistry model to study ozone depletion in the Arctic polar stratosphere during the exceptionally cold (in the stratosphere) winters 2015/2016 and 2010/2011.

  7. Introduction to GPS and other Global Navigation Satellite Systems

    Winternitz, Luke
    GPS tutorial presentation given by GSFC at NIST time and frequency seminar for more than the past 10 years. Minor updates from last year to keep current.

  8. Zinnia Germination and Lunar Soil Amendment

    Reese, Laura
    Germination testing was performed to determine the best method for germinating zinnias. This method will be used to attempt to germinate the zinnia seeds produced in space. It was found that seed shape may be critically important in determining whether a seed will germinate or not. The ability of compost and worm castings to remediate lunar regolith simulant for plant growth was tested. It was found that neither treatment effectively improves plant growth in lunar regolith simulant. A potential method of improving lunar regolith simulant by mixing it with arcillite was discovered.

  9. HAWC Results and Future Development

    Hui, C. Michelle
    No abstract available

  10. Overview of TTE/CFS Integration

    Loveless, Andrew
    No abstract available

  11. Battery Design Implications on Thermal Runaway Severity: NASA ISS SAFER Battery Safety Assessment

    Reid, Concha; Barrera, Thomas; Dalton, Penni; Stuart, Samuel; Doughty, Dan; Graika, Jason
    No abstract available

  12. Multi-Wavelength Laser Transmitter for the Two-Step Laser Time-of-Flight Mass Spectrometer

    Fahey, Molly E.; Grubisic, Andrej; Yu, Anthony W.; Uckert, Kyle; Getty, Stephanie; Li, Steven X.; Farcy, Benjamin J.; Li, Xiang
    No abstract available

  13. Multi-Wavelength Laser Transmitter for the Two-Step Laser Time-of-Flight Mass Spectrometer

    Farcy, Benjamin J.; Grubisic, Andrej; Uckert, Kyle; Li, Steven X.; Li, Xiang; Getty, Stephanie; Yu, Anthony W.; Fahey, Molly E.
    Missions to diverse Outer Solar System bodies will require investigations that can detect a wide range of organics in complex mixtures, determine the structure of selected molecules, and provide powerful insights into their origin and evolution. Previous studies from remote spectroscopy of the Outer Solar System showed a diverse population of macromolecular species that are likely to include aromatic and conjugated hydrocarbons with varying degrees of methylation and nitrile incorporation. In situ exploration of Titan's upper atmosphere via mass and plasma spectrometry has revealed a complex mixture of organics. Similar material is expected on the Ice Giants, their moons, and...

  14. Potential Synergies Between TROPICS and GOES-R

    Kuligowski, Bob; Zavodsky, Bradley T.
    No abstract available

  15. Navier-Stokes Simulation of UH-60A RotorWake Interaction Using Adaptive Mesh Refinement

    Chaderjian, Neal M.
    High-resolution simulations of rotor/vortex-wake interaction for a UH60-A rotor under BVI and dynamic stallconditions were carried out with the OVERFLOW Navier-Stokes code.a. The normal force and pitching moment variation with azimuth angle were in good overall agreementwith flight-test data, similar to other CFD results reported in the literature.b. The wake-grid resolution did not have a significant effect on the rotor-blade airloads. This surprisingresult indicates that a wake grid spacing of (Delta)S=10% ctip is sufficient for engineering airloads predictionfor hover and forward flight. This assumes high-resolution body grids, high-order spatial accuracy, anda hybrid RANS/DDES turbulence model.c. Three-dimensional dynamic stall was found...

  16. The NASA Ames Research Center Institutional Scientific Collection: History, Best Practices and Scientific Opportunities

    French, Alison; Choi, Sungshin; Rask, Jon C.; Stewart, Helen; Chakravarty, Kaushik
    The NASA Ames Life Sciences Institutional Scientific Collection (ISC), which is composed of the Ames Life Sciences Data Archive (ALSDA) and the Biospecimen Storage Facility (BSF), is managed by the Space Biosciences Division and has been operational since 1993. The ALSDA is responsible for archiving information and animal biospecimens collected from life science spaceflight experiments and matching ground control experiments. Both fixed and frozen spaceflight and ground tissues are stored in the BSF within the ISC. The ALSDA also manages a Biospecimen Sharing Program, performs curation and long-term storage operations, and makes biospecimens available to the scientific community for research...

  17. Incorporating Planetary-Scale Waves Into the VTGCM: Understanding the Waves Impact on the Upper Atmosphere of Venus.

    Shields, D.; Liu, H.; Bougher, S. W.; Brecht, A. S.
    Venus has proven to have a very dynamic upper atmosphere. The upper atmosphere of Venus has been observed for many decades by multiple means of observation (e.g. ground-based, orbiters, probes, fly-by missions going to other planets). As of late, the European Space Agency Venus Express (VEX) orbiter has been a main observer of the Venusian atmosphere. Specifically, observations of Venus' O2 IR nightglow emission have been presented to show its variability. Nightglow emission is directly connected to Venus' circulation and is utilized as a tracer for the atmospheric global wind system. More recent observations are adding and augmenting temperature and...

  18. Parametric Investigation on the Use of Lateral and Logitudinal Rotor Trim Flapping for Tiltrotor Noise Reduction

    Malpica, Carlos
    This paper presents an acoustics parametric study of the effect of varying lateral and longitudinal rotor trim flapping angles (tip-path-plane tilt) on noise radiated by an isolated 26-ft diameter proprotor, similar to that of the AW609 tiltrotor, in edgewise flight. Three tip-path-plane angle of attack operating conditions of -9, 0 and 6 deg, at 80 knots, were investigated. Results showed that: 1) minimum noise was attained for the tip-path-plane angle of attack value of -9 deg, and 2) changing the cyclic trim state (i.e., controls) altered the airloads and produced noticeable changes to the low-frequency (LF) and blade-vortex interaction (BVI)...

  19. Association Between Vascular Density and Loss of Protective RAS During Early NPDR by Fractal Dimension

    Grant, Maria B.; Parsons-Wingerter, Patricia; Radhakrishnan, Krisnan; Lim, Shiyin; Chalam, K. V.; Vyas, Ruchi J.; Yaqian, Duan; Predovic, Marina; Murray, Matthew; Bryant, Douglas
    Purpose: Our hypothesis predicts that blood vessels within the retina increase in density during early-stage nonproliferative diabetic retinopathy (NPDR), based on previous results of a small retrospective study. For the current prospective study, the remodeling of arteries and veins during progression of early NPDR is assessed by a repertoire of parameters that includes the fractal dimension (D(sub f) ). In complex structures such as branching vascular trees, D(sub f) is a sensitive measure of space-filing capacity. The renin-angiotensin system (RAS) is implicated in DR pathogenesis and the function of circulating angiogenic cells (CACs), a critical bone marrow-derived population instrumental in...

  20. Solar Power Generation in Extreme Space Environments

    Elliott, Frederick W.; Piszczor, Michael F.
    The exploration of space requires power for guidance, navigation, and control; instrumentation; thermal control; communications and data handling; and many subsystems and activities. Generating sufficient and reliable power in deep space through the use of solar arrays becomes even more challenging as solar intensity decreases and high radiation levels begin to degrade the performance of photovoltaic devices. The Extreme Environments Solar Power (EESP) project goal is to develop advanced photovoltaic technology to address these challenges.

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