Recursos de colección

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 121 - 140 de 321.855

  1. Engine Icing Data - An Analytics Approach

    Flegel, Ashlie B.; Fitzgerald, Brooke A.
    Engine icing researchers at the NASA Glenn Research Center use the Escort data acquisition system in the Propulsion Systems Laboratory (PSL) to generate and collect a tremendous amount of data every day. Currently these researchers spend countless hours processing and formatting their data, selecting important variables, and plotting relationships between variables, all by hand, generally analyzing data in a spreadsheet-style program (such as Microsoft Excel). Though spreadsheet-style analysis is familiar and intuitive to many, processing data in spreadsheets is often unreproducible and small mistakes are easily overlooked. Spreadsheet-style analysis is also time inefficient. The same formatting, processing, and plotting procedure...

  2. Communications and Intelligent Systems Division - Division Overview

    Miranda, Felix A.
    This presentation provides an overview of the research and engineering work being performed in the competency fields of advanced communications and intelligent systems with emphasis on advanced technologies, architecture definition, and systems development for application in current and future aeronautics and space communications systems.

  3. International Space Station Lithium-Ion Battery Start-Up

    Bowens, Ebony; North, Tim; Dalton, Penni J.; Balcer, Sonia
    International Space Station Lithium-Ion Battery Start-Up.The International Space Station (ISS) primary Electric Power System (EPS) was originally designed to use Nickel-Hydrogen (Ni-H2) batteries to store electrical energy. The electricity for the space station is generated by its solar arrays, which charge batteries during insolation for subsequent discharge during eclipse. The Ni-H2 batteries are designed to operate at a 35 depth of discharge (DOD) maximum during normal operation in a Low Earth Orbit. As the oldest of the 48 Ni-H2 battery Orbital Replacement Units (ORUs) has been cycling since September 2006, these batteries are now approaching their end of useful life....

  4. NASA GSFC Report on CCSDS Recommendations 2.1.8A B Minimum Earth Station Transmitter Frequency Resolution for Spacecraft Receiver Acquisition

    Fong, Wai; Lee, Wing
    In Fall 2016, ESA presented paper SLS-RFM 16-10 documenting a possible issue with the frequency lock-in range specification in Recommendation 2.1.8A of typically 267 to 1067 Hz in considerings (b) from considerings (a) for loop bandwidths [2B(sub LO)] in the range of 200 to 800 Hz with a recommendation of 100 Hz step size for frequency sweeping. The paper calculated the lock-in range to be (+/-)266 to (+/-)1064 rad/s or (+/-)42 to (+/-)168 Hz. Also, Recommendation 2.1.8B has the same issue for considering (a) and (b), i.e. for 2B(sub LO) =10 Hz, a lock-in range of 13 Hz was specified...

  5. Snow Process Estimation Over the Extratropical Andes Using a Data Assimilation Framework Integrating MERRA Data and Landsat Imagery

    Girotto, Manuela; Cortes, Gonzalo; Margulis, Steven
    A data assimilation framework was implemented with the objective of obtaining high resolution retrospective snow water equivalent (SWE) estimates over several Andean study basins. The framework integrates Landsat fractional snow covered area (fSCA) images, a land surface and snow depletion model, and the Modern Era Retrospective Analysis for Research and Applications (MERRA) reanalysis as a forcing data set. The outputs are SWE and fSCA fields (1985-2015) at a resolution of 90 m that are consistent with the observed depletion record. Verification using in-situ snow surveys showed significant improvements in the accuracy of the SWE estimates relative to forward model estimates,...

  6. CDDIS: NASA's Archive of Space Geodesy Data and Products Supporting GGOS

    Noll, Carey; Michael, Patrick
    The Crustal Dynamics Data Information System (CDDIS) supports data archiving and distribution activities for the space geodesy and geodynamics community. The main objectives of the system are to store space geodesy and geodynamics related data and products in a central archive, to maintain information about the archival of these data,to disseminate these data and information in a timely manner to a global scientific research community, and provide user based tools for the exploration and use of the archive. The CDDIS data system and its archive is a key component in several of the geometric services within the International Association of...

  7. The Candidate Progenitor of the Type IIn SN 2010jl Is Not an Optically Luminous Star

    Arendt, Richard G.; Smith, Nathan; Foley, Ryan J.; Filippenko, Alexei V.; Dwek, Eli; Miller, Adam; Kelly, Patrick L.; Andrews, Jennifer; Shivvers, Isaac; Van Dyk, Schuyler D.; Fox, Ori D.
    A blue source in pre-explosion Hubble Space Telescope (HST)/Wide-Field Planetary Camera 2 (WFPC2) images falls within the 5 Sigma astrometric error circle (approx. 0." 24) derived from post-explosion ground-based imaging of SN 2010jl. At the time the ground-based astrometry was published, however, the SN had not faded sufficiently forpost-explosion HST follow-up observations to determine a more precise astrometric solution and/or confirm if the pre-explosion source had disappeared, both of which are necessary to ultimately disentangle the possible progenitor scenarios. Here we present HST/WFC3 imaging of the SN 2010jl field obtained in 2014, 2015, and 2016 when the SN had faded...

  8. TRMM Data Improvement as Part of the GPM Data Processing

    Stocker, Erich F.; Stout, J.; Woltz, L.; Ji, Y.; Kelley, O.; Kwiatkowski, J.
    NASA has a long standing commitment to the improvement of its mission datasets. Indeed, data reprocessing is always built into the plans, schedule and budget for the mission data processing system. However, in addition to these ongoing mission reprocessing, NASA also supports a final reprocessing of all the data for a mission upon its completion (known as Phase F). TRMM Phase F started with the end of the TRMM mission in June of 2015. This last reprocessing has two overall goals: improvement of the TRMM mission data products; incorporation of the 17+ years of TRMM data into the ongoing NASA/JAXA...

  9. The First Simultaneous Microlensing Observations by Two Space Telescopes: Spitzer and Swift Reveal a Brown Dwarf in Event OGLE-2015-BLG-1319

    Street, R. A.; Sumi, T.; Bozza, V.; Shvartzvald, Y.; Gould, A.; Udalski, A.; Calchi Novati, S.; Hundertmark, M.; Barry, R. K.; Beichman, C.; Bennett, D. P.; Gehrels, N.; Li, Z.
    Simultaneous observations of microlensing events from multiple locations allow for the breaking of degeneracies between the physical properties of the lensing system, specifically by exploring different regions of the lens plane and by directly measuring the "microlens parallax". We report the discovery of a 30-65M J brown dwarf orbiting a K dwarf in the microlensing event OGLE-2015-BLG-1319. The system is located at a distance of approximately 5 kpc toward the Galactic Bulge. The event was observed by several ground-based groups as well as by Spitzer and Swift, allowing a measurement of the physical properties. However, the event is still subject...

  10. Update of S-NPP VIIRS Thermal Emissive Bands Radiometric Calibration Stability Monitoring Using the Moon

    Xiong, Xiaoxiong; Li, Yonghong; Wang, Zhipeng
    The Suomi-NPP VIIRS thermal emissive bands (TEB) are radiometrically calibrated on-orbit with reference to an onboard blackbody (BB) regularly operated at approximately 292.5 K. The calibration stability at other temperature ranges can be evaluated based on the observations of remote targets with stable thermal properties, such as the Moon. VIIRS has scheduled viewings of the Moon on a nearly monthly basis at a phase angle of nearly -51 degrees. In this study, the brightness temperatures (BT) of the lunar surface retrieved using the detector gain coefficients calibrated with the BB are trended to monitor the calibration stability of VIIRS TEB....

  11. Camx Ozone Source Attribution in the Eastern United States Using Guidance from Observations During DISCOVER-AQ Maryland

    Dickerson, Russell R.; Anderson, Daniel C.; Stauffer, Ryan M.; Goldberg, Daniel L.; Canty, Timothy P.; Salawitch, Ross J.; Martins, Douglas K.; Ehrman, Sheryl H.; Vinciguerra, Timothy P.; Hembeck, Linda; Thompson, Anne M.
    A Comprehensive Air-Quality Model with Extensions (CAMx) version 6.10 simulation was assessed through comparison with data acquired during NASA's 2011 Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) Maryland field campaign. Comparisons for the baseline simulation (Carbon Bond 2005 (CB05) chemistry, Environmental Protection Agency 2011 National Emissions Inventory) show a model overestimate of NOy by +86.2% and an underestimate of HCHO by -28.3%. We present a new model framework (Carbon Bond 6 Revision 2 chemistry (CB6r2), Model of Emissions of Gases and Aerosols from Nature (MEGAN) version 2.1 biogenic emissions, 50% reduction...

  12. A Massive Shell of Supernova-Formed Dust in SNR G54.1+0.3

    Dwek, Eli; Slane, Patrick; Raymond, John C.; Arendt, Richard G.; Borkowski, Kazimiera J.; Gelfand, Joseph D.; Reynolds, Stephen P.; Temim, Tea
    While theoretical models of dust condensation predict that most refractory elements produced in core-collapsesupernovae (SNe) efficiently condense into dust, a large quantity of dust has so far only been observed inSN1987A. We present an analysis of observations from the Spitzer Space Telescope, Herschel SpaceObservatory, Stratospheric Observatory for Infrared Astronomy, and AKARI of the infrared shell surrounding thepulsar wind nebula in the supernova remnant G54.1+0.3. We attribute a distinctive spectral feature at 21 m to amagnesium silicate grain species that has been invoked in modeling the ejecta-condensed dust in Cas A, whichexhibits the same spectral signature. If this species is responsible...

  13. The Future of Planetary Climate Modeling and Weather Prediction

    Kiang, N. Y.; Schmidt, G. A.; Kopparapu, R. K.; Del Genio, A. D.; Sohl, L. E.; Domagal-Goldman, S. D.
    Modeling of planetary climate and weather has followed the development of tools for studying Earth, with lags of a few years. Early Earth climate studies were performed with 1-dimensionalradiative-convective models, which were soon fol-lowed by similar models for the climates of Mars and Venus and eventually by similar models for exoplan-ets. 3-dimensional general circulation models (GCMs) became common in Earth science soon after and within several years were applied to the meteorology of Mars, but it was several decades before a GCM was used to simulate extrasolar planets. Recent trends in Earth weather and and climate modeling serve as a...

  14. Biosignatures of Exoplanets

    Kiang, Nancy Y.
    Are we alone? Ancient astronomers across the continents knew the existence of five Solar System planets visible to the naked eye. They could tell that these celestial wanderers were unlike stars in that they only reflected light from the Sun. In the early 1600s, Galileo developed the first telescopes able to observe spots moving across the Sun and the passage of moons across the face of Jupiter. He verified the theory of Aristarchus (3rd c. BC), and refined by Nicolaus Copernicus (mid 16th c.) and Johannes Kepler (late 16th c.), that the Earth and the other planets, in fact, orbit...

  15. VHF SoOp (Signal of Opportunity) Technology Demonstration for Soil Moisture Measurement Using Microwave Hydraulic Boom Truck Platform

    Deshpande, M.; O'Neill, P. E.; Joseph, A. T.; Miles, L.
    A goal of this research is to test deployable VHF antennas for 6U Cubesat platforms to enable validation of root zone soil moisture (RZSM) estimation algorithms for signal of opportunity (SoOp) remote sensing over the 240-270 MHz frequency band. The proposed work provides a strong foundation for establishing a technology development path for maturing a global direct surface soil moisture (SM) and RZSM measurement system over a variety of land covers. Knowledge of RZSM up to a depth of 1 meter and surface SM up to a depth of 0.05 meter on a global scale, at a spatial resolution of...

  16. Biomechanical Modeling of the Deadlift Exercise to Improve the Efficacy of Resistive Exercise Microgravity Countermeasures

    Sheehan, C. C.; Thompson, W. K.; Funk, J. H.; Lewandowski, B. E.; Gallo, C. A.; Perusek, G. P.; Funk, N. W.; DeWitt, J. K.; Jagodnik, K. M.
    During long-duration spaceflight missions, astronauts exposure to microgravity without adequate countermeasures can result in losses of muscular strength and endurance, as well as loss of bone mass. As a countermeasure to this challenge, astronauts engage in resistive exercise during spaceflight to maintain their musculoskeletal function. The Hybrid Ultimate Lifting Kit (HULK) has been designed as a prototype exercise device for an exploration-class vehicle; the HULK features a much smaller footprint than previous devices such as the Advanced Resistive Exercise Device (ARED) on the International Space Station (ISS), which makes the HULK suitable for extended spaceflight missions in vehicles with limited...

  17. Spacecraft Mission Design for the Mitigation of the 2017 PDC Hypothetical Asteroid Threat

    Englander, Jacob A.; Lyzhoft, Joshua; Barbee, Brent W.; Chodas, Paul W.; Sarli, Bruno V.
    This paper presents a detailed mission design analysis results for the 2017 Planetary Defense Conference (PDC) Hypothetical Asteroid Impact Scenario, documented at https://cneos.jpl.nasa.gov/ pd/cs/pdc17/. The mission design includes campaigns for both reconnaissance (flyby or rendezvous) of the asteroid (to characterize it and the nature of the threat it poses to Earth) and mitigation of the asteroid, via kinetic impactor deflection, nuclear explosive device (NED) deflection, or NED disruption. Relevant scenario parameters are varied to assess the sensitivity of the design outcome, such as asteroid bulk density, asteroid diameter, momentum enhancement factor, spacecraft launch vehicle, and mitigation system type. Different trajectory...

  18. Spacecraft Mission Design for the Mitigation of the 2017 PDC Hypothetical Asteroid Threat

    Barbee, Brent W.; Sarli, Bruno V.; Englander, Jacob A.; Lyzhoft, Josh; Chodas, Paul W.
    This paper presents a detailed mission design analysis results for the 2017 Planetary Defense Conference (PDC) Hypothetical Asteroid Impact Scenario, documented at https:cneos.jpl.nasa.govpdcspdc17. The mission design includes campaigns for both reconnaissance (flyby or rendezvous) of the asteroid (to characterize it and the nature of the threat it poses to Earth) and mitigation of the asteroid, via kinetic impactor deflection, nuclear explosive device (NED) deflection, or NED disruption. Relevant scenario parameters are varied to assess the sensitivity of the design outcome, such as asteroid bulk density, asteroid diameter, momentum enhancement factor, spacecraft launch vehicle, and mitigation system type. Different trajectory types...

  19. Increased Jet Noise Due to a "Nominally Laminar" State of Nozzle Exit Boundary Layer

    Zaman, K. B. M. Q.
    A set of 2-in. diameter nozzles is used to investigate the effect of varying exit boundary layer state on the radiated noise from high-subsonic jets. It is confirmed that nozzles involving turbulent boundary layers are the quietest while nozzles involving a "nominally laminar" boundary layer are loud especially on the high-frequency side of the sound pressure level spectrum. The latter boundary layer state involves a "Blasius-like" mean velocity profile but higher turbulence intensities compared to those in the turbulent state. The higher turbulence in the initial region of the jet shear layer leads to increased high-frequency noise. The results strongly...

  20. Increased Jet Noise Due to a "Nominally Laminar" State of Nozzle Exit Boundary Layer

    Zaman, K. B. M. Q.
    A set of 2-inch diameter nozzles is used to investigate the effect of varying exit boundary layer state on the radiated noise from high-subsonic jets. It is confirmed that nozzles involving turbulent boundary layers are the quietest while nozzles involving a nominally-laminar boundary layer are loud especially on the high-frequency side of the sound pressure level spectrum. The latter boundary layer state involves a Blasius-like mean velocity profile but higher turbulence intensities compared to those in the turbulent state. The higher turbulence in the initial region of the jet shear layer leads to increased high-frequency noise. The results strongly suggest...

Aviso de cookies: Usamos cookies propias y de terceros para mejorar nuestros servicios, para análisis estadístico y para mostrarle publicidad. Si continua navegando consideramos que acepta su uso en los términos establecidos en la Política de cookies.