Recursos de colección

NASA Technical Reports Server (NTRS) (685.753 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 101 - 120 de 321.212

  1. OGLE-2012-bLG-0950Lb: the First Planet Mass Measurement From Only Microlens Parallax and Lens Flux

    Fukui, A.; Rattenbury, N.; Suzuki, D.; Sumi, T.; Bhattacharya, A.; Beaulieu, J. P.; Bond, I. A.; Koshimoto, N.; Bennett, D. P.; Udalski, A.
    We report the discovery of a microlensing planet OGLE-2012-BLG-0950Lb with a planet/host mass ratio Periapsis Approx. = 2 x10(exp. -4). A long term distortion detected in both MOA and OGLE light curve can be explained by themicrolens parallax due to the Earths orbital motion around the Sun. Although the finite source effect is not detected, we obtain the lens flux by the high resolution Keck AO observation. Combining the microlens parallax and the lens flux reveal the nature of the lens: a planet with mass of M(sub p) = 35(+17/-)M compared to Earth is orbiting around an M-dwarf with mass...

  2. Combining Livestock Production Information in a Process-Based Vegetation Model to Reconstruct the History of Grassland Management

    Wang, Xuhui; Havlik, Petr; Campioli, Matteo; Joiner, Joanna; Hauglustaine, Didier A.; Piao, Shilong; Zhang, Xianzhou; Wang, Tao; Ciais, Philippe; Chang, Jinfeng; Herrero, Mario; Bai, Yongfei; Soussana, Jean-Francois; Viovy, Nicolas; Yue, Chao; Peng, Shushi S.
    Grassland management type (grazed or mown) and intensity (intensive or extensive) play a crucial role in the greenhouse gas balance and surface energy budget of this biome, both at field scale and at large spatial scale. However, global gridded historical information on grassland management intensity is not available. Combining modelled grass-biomass productivity with statistics of the grass-biomass demand by livestock, we reconstruct gridded maps of grassland management intensity from 1901 to 2012. These maps include the minimum area of managed vs. maximum area of unmanaged grasslands and the fraction of mown vs. grazed area at a resolution of 0.5deg by...

  3. Providing Comprehensive and Consistent Access to Astronomical Observatory Archive Data: The NASA Archive Model

    Desai, Vandana R.; Landry, Walter; Dower, Theresa; Teplitz, Harry I.; Imel, David; Ebert, Rick; McGlynn, Thomas; Smale, Alan; White, Richard L.; Groom Steve L.; Donaldson, Thomas; Guiseppina, Fabbiano A; Accomazzi, Alberto; Pevunova, Olga; Aloisi, Alessandra; Mazzerella, Joseph M.; Berriman, Graham B.
    Since the turn of the millennium a constant concern of astronomical archives have begun providing data to the public through standardized protocols unifying data from disparate physical sources and wavebands across the electromagnetic spectrum into an astronomical virtual observatory (VO). In October 2014, NASA began support for the NASA Astronomical Virtual Observatories (NAVO) program to coordinate the efforts of NASA astronomy archives in providing data to users through implementation of protocols agreed within the International Virtual Observatory Alliance (IVOA). A major goal of the NAVO collaboration has been to step back from a piecemeal implementation of IVOA standards and define...

  4. Estimates of Lightning NOx Production Based on OMI NO2 Observations Over the Gulf of Mexico

    Allen, Dale; Ring, Allison; Holzworth, Robert; Bucsela, Eric; Krotkov, Nickolay; Pickering, Kenneth E.
    We evaluate nitrogen oxide (NO(sub x) NO + NO2) production from lightning over the Gulf of Mexico region using data from the Ozone Monitoring Instrument (OMI) aboard NASAs Aura satellite along with detection efficiency-adjusted lightning data from the World Wide Lightning Location Network (WWLLN). A special algorithm was developed to retrieve the lightning NOx [(LNO(sub x)] signal from OMI. The algorithm in its general form takes the total slant column NO2 from OMI and removes the stratospheric contribution and tropospheric background and includes an air mass factor appropriate for the profile of lightning NO(sub x) to convert the slant column...

  5. Disk Detective: Discovery of New Circumstellar Disk Candidates Through Citizen Science

    Bhattacharjee, Shambo; Kuchner, Marc J.; Wisniewski, John P.; Schawinski, Kevin; Silverberg, Steven M.; Padgett, Deborah L.; Jung, Dawoon; Mcelwain, Michael; Bans, Alissa S.; Currie, Thayne; Lintott, Chris; Thaller, Michelle L.; Debes, John H.; Rebull, Luisa M.; Nesvold, Erika; Grady, Carol A.; Kenyon, Scott J.; Garcia, Luciano
    The Disk Detective citizen science project aims to find new stars with 22 micron excess emission from circumstellar dust using data from NASAs Wide-field Infrared Survey Explorer (WISE) mission. Initial cuts on the AllWISE catalog provide an input catalog of 277,686 sources. Volunteers then view images of each source online in 10different bands to identify false positives (galaxies, interstellar matter, image artifacts, etc.). Sources that survive this online vetting are followed up with spectroscopy on the FLWO Tillinghast telescope. This approach should allow us to unleash the full potential of WISE for finding new debris disks and proto planetary disks....

  6. Comparison of Sun-Induced Chlorophyll Fluorescence Estimates Obtained from Four Portable Field Spectroradiometers

    Burkart, Andreas; Julitta, Tommaso; Davies, Neville; Colombo, Roberto; Mac Arthur, Alasdair; Middleton, Elizabeth M.; Corp, Lawrence A.; Hom, Milton; Rascher, Uwe; Cogliati, Sergio; Rossini, Micol; Schickling, Anke
    Remote Sensing of Sun-Induced Chlorophyll Fluorescence (SIF) is a research field of growing interest because it offers the potential to quantify actual photosynthesis and to monitor plant status. New satellite missions from the European Space Agency, such as the Earth Explorer 8 FLuorescence EXplorer (FLEX) mission-scheduled to launch in 2022 and aiming at SIF mapping-and from the National Aeronautics and Space Administration (NASA) such as the Orbiting Carbon Observatory-2 (OCO-2) sampling mission launched in July 2014, provide the capability to estimate SIF from space. The detection of the SIF signal from airborne and satellite platform is difficult and reliable ground...

  7. Initial Results from Radiometer and Polarized Radar-Based Icing Algorithms Compared to In-Situ Data

    Reehorst, Andrew L.; Serke, David; King, Michael
    In early 2015, a field campaign was conducted at the NASA Glenn Research Center in Cleveland, Ohio, USA. The purpose of the campaign is to test several prototype algorithms meant to detect the location and severity of in-flight icing (or icing aloft, as opposed to ground icing) within the terminal airspace. Terminal airspace for this project is currently defined as within 25 kilometers horizontal distance of the terminal, which in this instance is Hopkins International Airport in Cleveland. Two new and improved algorithms that utilize ground-based remote sensing instrumentation have been developed and were operated during the field campaign. The...

  8. A Comparison of Mangrove Canopy Height Using Multiple Independent Measurements from Land, Air, and Space

    Trettin, Carl; Fatoyinbo, Temilola; Simard, Marc; Lagomasino, David; Feliciano, Emanuelle; Lee, SeungKuk
    Canopy height is one of the strongest predictors of biomass and carbon in forested ecosystems. Additionally, mangrove ecosystems represent one of the most concentrated carbon reservoirs that are rapidly degrading as a result of deforestation, development, and hydrologic manipulation. Therefore, the accuracy of Canopy Height Models (CHM) over mangrove forest can provide crucial information for monitoring and verification protocols. We compared four CHMs derived from independent remotely sensed imagery and identified potential errors and bias between measurement types. CHMs were derived from three spaceborne datasets; Very-High Resolution (VHR) stereophotogrammetry, TerraSAR-X add-on for Digital Elevation Measurement (DEM), and Shuttle Radar Topography...

  9. International Space Exploration Coordination Group Assessment of Technology Gaps for Dust Mitigation for the Global Exploration Roadmap

    Mary, Natalie; Agui, Juan; Mugnuolo, Raffaele; Wong, Henry; Straka, Sharon; Wander, Michel; Pirrotta, Simone; Vangen, Scott; Lefebvre, Daniel; Tomlinson, Taryn; Calle, Carlos; Picard, Martin; Abel, Phil; Smith, Jonathan Drew; Bedirian, Mireille; Gaier, James R.; Buffington, Jesse
    The International Space Exploration Coordination Group (ISECG) formed two Gap Assessment teams to evaluate topic discipline areas that had not been worked at an international level to date. Accordingly, the ISECG Technology Working Group (TWG) recommended two discipline areas based on Global Exploration Roadmap (GER) Critical Technology Needs reflected within the GER Technology Development Map (GTDM): Dust Mitigation and LOX/Methane Propulsion, with this paper addressing the former. The ISECG approved the recommended Gap Assessment teams, and tasked the TWG to formulate the new teams with subject matter experts (SMEs) from the participating agencies. The participating agencies for the Dust Mitigation...

  10. Combustion Products Monitor: Trade Study Testing

    Wallace, William T.; Trowbridge, John B.
    Current combustion products monitoring on the International Space Station (ISS) uses a handheld device (Compound Specific Analyzer-Combustion Products, CSA-CP) containing electrochemical sensors used to measure the concentration of carbon monoxide (CO), hydrogen chloride (HCl), hydrogen cyanide (HCN), and oxygen (O2). The CO sensor in this device accounts for a well-known cross-sensitivity with hydrogen (H2), which is important, as ISS air can contain up to 100 ppm H2. Unfortunately, this current device is being discontinued, and due to space constraints, the new model cannot accommodate the size of the current CO sensor. Therefore, a trade study was conducted in order to...

  11. Observation of Gravitational Waves from a Binary Black Hole Merger

    Addesso, P.; Abernathy, M. R.; Acernese, F.; Abbott, R.; Abbott, T. D.; Adams, C.; Abbott, B. P.; Singer, L. P.; Camp, Jordan B.; Ackley, K.; Adams, T.
    On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0 x 10(exp -21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ring down of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent...

  12. Hydrometeorological Hazards: Monitoring, Forecasting, Risk Assessment, and Socioeconomic Responses

    Wu, Huan; Ward, Philip; Tang, Qiuhong; Huang, Maoyi; Kirschbaum, Dalia B.
    Hydrometeorological hazards are caused by extreme meteorological and climate events, such as floods, droughts, hurricanes,tornadoes, or landslides. They account for a dominant fraction of natural hazards and occur in all regions of the world, although the frequency and intensity of certain hazards and societies vulnerability to them differ between regions. Severe storms, strong winds, floods, and droughts develop at different spatial and temporal scales, but all can become disasters that cause significant infrastructure damage and claim hundreds of thousands of lives annually worldwide. Oftentimes, multiple hazards can occur simultaneously or trigger cascading impacts from one extreme weather event. For example,...

  13. Geomorphic and Geologic Controls of Geohazards induced by Nepal's 2015 Gorkha Earthquake

    Bajracharya, S.; Heijenk, R.; Kargel, J. S.; Leonard, G. J.; Fujita, K.; Gurung, D. R.; Kirschbaum, D.; Fielding, E. J.; Geai, M. L.; Green, D.; Steiner, J.; Anderson, E.; Miles, E. S.; Breashears, D. F.; Glasscoe, M. T.; Dhital, M. R.; Byers, A.; Evans, L.; Shugar, D. H.; Bevington, A.; Bawden, G. W.; Haritashya, U.K.; Donnellan, A.; Geertsema, M.; Collins, B.
    The Gorkha earthquake (Magnitude 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing approx.9,000 and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes induced geohazards in Nepal and China and an assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision makers. We mapped 4,312 co-seismic and post-seismic landslides. We also surveyed 491 glacier lakes for earthquake damage, but found only 9 landslide-impacted lakes...

  14. Radiation-Induced Backgrounds in Astronomical Instruments: Considerations for Geosynchronous Orbit and Implications for the Design of the WFIRST Wide-Field Instrument

    Stauffer, Craig; Armani, Nerses; Xapsos, Michael A.; Hirata, Christopher M.; Kruk, Jeffrey W.
    Geosynchronous orbits are appealing for solar or astrophysical observatories because they permit continuous data downlink at high rates. The radiation environment in these orbits presents unique challenges, however. This paper describes both the characteristics of the radiation environment in geosynchronous orbit and the mechanisms by which this radiation generates backgrounds in photon detectors. Shielding considerations are described, and a preliminary shielding design for the proposed Wide-Field InfraRed Survey Telescope observatory is presented as a reference for future space telescope concept studies that consider a geosynchronous orbit.

  15. Using Landsat, MODIS, and a Biophysical Model to Evaluate LST in Urban Centers

    Bounoua, Lahouari; Al-Hamdan, Mohammad Z.; Lachir, Asia; Quattrochi, Dale A.; Zhang, Ping
    In this paper, we assessed and compared land surface temperature (LST) in urban centers using data from Landsat, MODIS, and the Simple Biosphere model (SiB2). We also evaluated the sensitivity of the models LST to different land cover types, fractions (percentages), and emissivities compared to reference points derived from Landsat thermal data. This was demonstrated in three climatologically- and morphologically-different cities of Atlanta, GA, New York, NY, and Washington, DC. Our results showed that in these cities SiB2 was sensitive to both the emissivity and the land cover type and fraction, but much more sensitive to the latter. The practical...

  16. Regional and Local Variations in Atmospheric Aerosols Using Ground-Based Sun Photometry During Distributed Regional Aerosol Gridded Observation Networks (DRAGON) in 2012

    Holben, Brent N.; Nakata, Makiko; Sano, Itaru; Mukai, Sonoyo
    Aerosol mass concentrations are affected by local emissions as well as long-range transboundary (LRT) aerosols. This work investigates regional and local variations of aerosols based on Distributed Regional Aerosol Gridded Observation Networks (DRAGON).We constructed DRAGON-Japan and DRAGON-Osaka in spring of 2012. The former network covers almost all of Japan in order to obtain aerosol information in regional scale over Japanese islands. It was determined from the DRAGON-Japan campaign that the values of aerosol optical thickness (AOT) decrease from west to east during an aerosol episode. In fact, the highest AOT was recorded at Fukue Island at the western end of...

  17. Applications for ICESat-2 Data

    Markus, Thorsten; Birkett, Charon M.; Neumann, Thomas; Escobar, Vanessa M.; Babonis, Greg; Brown, Molly E.; Delgado Arias, Sabrina; Glenn, Nancy F.; Jasinski, Michael F.; Posey, Pamela
    NASA;s Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) mission, scheduled to launch no later than April 2018 (and currently slated for October 2017), is being developed to continue the multiyear observations of the earths surface elevation, ice, and clouds started by ICESat. To increase the use of the satellite data after launch, the ICESat-2 mission invested in an applications program aimed at innovatively applying the data in a variety of fields. The program provides a framework for building a broad and well-defined user community during the prelaunch period to maximize the use of data products after launch and to provide...

  18. Evaluation of VIIRS, GOCI, and MODIS Collection 6 AOD Retrievals Against Ground Sunphotometer Observations Over East Asia

    Levy, R. C.; Xiao, Q.; Liu, Y.; Holben, B.; Kim, J.; Zhang, H.; Choi, M.; Li, S.; Kondragunta, S.
    Persistent high aerosol loadings together with extremely high population densities have raised serious air quality and public health concerns in many urban centers in East Asia. However, ground-based air quality monitoring is relatively limited in this area. Recently, satellite-retrieved Aerosol Optical Depth (AOD) at high resolution has become a powerful tool to characterize aerosol patterns in space and time. Using ground AOD observations from the Aerosol Robotic Network (AERONET) and the Distributed Regional Aerosol Gridded Observation Networks (DRAGON)-Asia Campaign, as well as from handheld sunphotometers, we evaluated emerging aerosol products from the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the...

  19. Empirical Modeling of the Storm Time Innermost Magnetosphere Using Van Allen Probes and THEMIS Data: Eastward and Banana Currents

    Roelof, E. C.; Sitnov, M. I.; Ukhorskiy, A. Y.; Le, G.; Tsyganenko, N. A.; Stephens, G. K.
    The structure of storm time currents in the inner magnetosphere, including its innermost region inside 4R(sub E), is studied for the first time using a modification of the empirical geomagnetic field model TS07D and new data from Van Allen Probes and Time History of Events and Macroscale Interactions during Substorms missions. It is shown that the model, which uses basis-function expansions instead of ad hoc current modules to approximate the magnetic field, consistently improves its resolution and magnetic field reconstruction with the increase of the number of basis functions and resolves the spatial structure and evolution of the innermost eastward...

  20. Modeling the Swift Bat Trigger Algorithm with Machine Learning

    Lien, Amy Y.; Graff, Philip B.; Sakamoto, Takanori; Baker, John G.
    To draw inferences about gamma-ray burst (GRB) source populations based on Swift observations, it is essential to understand the detection efficiency of the Swift burst alert telescope (BAT). This study considers the problem of modeling the Swift / BAT triggering algorithm for long GRBs, a computationally expensive procedure, and models it using machine learning algorithms. A large sample of simulated GRBs from Lien et al. is used to train various models: random forests, boosted decision trees (with AdaBoost), support vector machines, and artificial neural networks. The best models have accuracies of greater than or equal to 97 percent (less than...

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