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NASA Technical Reports Server (NTRS) (656,664 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.

NASA Center for AeroSpace Information (CASI) (513,494) NIX Images (81,938)


Mostrando recursos 1 - 20 de 3,215

1. A Comparison of the Red Green Blue (RGB) Air Mass Imagery and Hyperspectral Infrared Retrieved Profiles and NOAA G-IV Dropsondes - Folmer, Michael; Berndt, Emily; Dunion, Jason
RGB air mass imagery is derived from multiple channels or paired channel differences. The combination of channels and channel differences means the resulting imagery does not represent a quantity or physical parameter such as brightness temperature in conventional single channel imagery. Without a specific quantity to reference, forecasters are often confused as to what RGB products represent. Hyperspectral infrared retrieved profiles and NOAA G-IV dropsondes provide insight about the vertical structure of the air mass represented on the RGB air mass imagery and are a first step to validating the imagery.

2. The Road to Realizing In-Space Manufacturing - Clinton, Raymond G.
Additive Manufacturing in space offers tremendous potential for dramatic paradigm shift in the development and manufacturing of space architectures. Additive Manufacturing in space offers the potential for mission safety risk reduction for low Earth orbit and deep space exploration; new paradigms for maintenance, repair, and logistics. Leverage ground-based technology developments, process characterization, and material properties databases. Investments are required primarily in the microgravity environment. We must do the foundational work. It's not sexy, but it is required.

3. Porous Plate Water Boiler Design Study Final Report - Sangiovanni, J. J.; Hepner, P. H.
This study program was conducted to obtain a sound theoretical understanding of and a valid analytical method for predicting the performance of porous plate water boilers.

4. Flight Avionics Hardware Roadmap - Some, Raphael; McCabe, Mary; Redifer, Matt; Powell, Wes; West, John; Goforth, Monte; Paulick, Paul; Buscher, Deborah; Chen, Yuan; Partridge, Harry; Wade, Ray; Vitalpur, Sharada; Sherman, Aaron
The Avionics Technology Roadmap takes an 80% approach to technology investment in spacecraft avionics. It delineates a suite of technologies covering foundational, component, and subsystem-levels, which directly support 80% of future NASA space mission needs. The roadmap eschews high cost, limited utility technologies in favor of lower cost, and broadly applicable technologies with high return on investment. The roadmap is also phased to support future NASA mission needs and desires, with a view towards creating an optimized investment portfolio that matures specific, high impact technologies on a schedule that matches optimum insertion points of these technologies into NASA missions. The...

5. Detection of Reduced Nitrogen Compounds at Rocknest Using the Sample Analysis At Mars (SAM) Instrument on the Mars Science Laboratory (MSL) - Navarro-Gonzalez, R.; Eigenbrode, J.; McAdam, A. C.; Wray, J.; Coll, P.; Franz, H. B.; Stern, J. C.; Steele, A.; Freissinet, C.; Mahaffy, P. R.; Glavin, D.; McKay, C.; Jones, J. H.; Brunner, A.
The Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) Curiosity Rover detected nitrogen-bearing compounds during the pyrolysis of Rocknest material at Gale Crater. Hydrogen cyanide and acetonitrile were identified by the quadrupole mass spectrometer (QMS) both in direct evolved gas analysis (EGA). SAM carried out four separate analyses from Rocknest Scoop 5. A significant low temperature release was present in Rocknest runs 1-4, while a smaller high temperature release was also seen in Rocknest runs 1-3. Here we evaluate whether these compounds are indigenous to Mars or a pyrolysis product resulting from known terrestrial materials...

6. Detection of the Compressed Primary Stellar Wind in eta Carinae* - Corcoran, M. F.; Hamaguchi, K.; Madura, T. I.; Gull, T. R.; Teodoro, M.
A series of three Hubble Space Telescope Space Telescope Imaging Spectrograph (HST/STIS) spectroscopic mappings, spaced approximately one year apart, reveal three partial arcs in [Fe II] and [Ni II] emissions moving outward from ? Carinae. We identify these arcs with the shell-like structures, seen in the 3D hydrodynamical simulations, formed by compression of the primary wind by the secondary wind during periastron passages.

7. Can the 62 Day X-ray Period of ULX M82 X-1 Be Due to a Precessing Accretion Disk? - Strohmayer, Tod E.; Pasham, Dheeraj R.
We have analyzed all the archival RXTE/PCA monitoring observations of the ultraluminous X-ray source (ULX) M82 X-1 in order to study the properties of its previously discovered 62 day X-ray period (Kaaret & Feng 2007). Based on the high coherence of the modulation it has been argued that the observed period is the orbital period of the binary. Utilizing a much longer data set than in previous studies we find: (1) The phase-resolved X-ray (3-15 keV) energy spectra - modeled with a thermal accretion disk and a power-law corona - suggest that the accretion disk's contribution to the total flux...

8. Discovery of a 7 mHz X-Ray Quasi-Periodic Oscillation from the Most Massive Stellar-Mass Black Hole IC 10 X-1 - Pasham, Dheeraj R.; Strohmayer, Tod E.; Mushotzky, Richard F.
We report the discovery with XMM-Newton of an approx.. = 7 mHz X-ray (0.3-10.0 keV) quasi-periodic oscillation (QPO) from the eclipsing, high-inclination black hole binary IC 10 X-1. The QPO is significant at >4.33 sigma confidence level and has a fractional amplitude (% rms) and a quality factor, Q is identical with nu/delta nu, of approx. = 11 and 4, respectively. The overall X-ray (0.3-10.0 keV) power spectrum in the frequency range 0.0001-0.1 Hz can be described by a power-law with an index of approx. = -2, and a QPO at 7 mHz. At frequencies approx. > 0.02 Hz there...

9. Generating Global Leaf Area Index from Landsat: Algorithm Formulation and Demonstration - Votava, Petr; Zhang, Gong; Michaelis, Andrew; Hashimoto, Hirofumi; Samanta, Arindam; Melton, Forrest; Wang, Weile; Milesi, Cristina; Nemani, Ramakrishna R.; Ganguly, Sangram; Gao, Feng; Vermote, Eric; Myneni, Ranga B.; Dungan, Jennifer L.; Knyazaikhin, Yuri
This paper summarizes the implementation of a physically based algorithm for the retrieval of vegetation green Leaf Area Index (LAI) from Landsat surface reflectance data. The algorithm is based on the canopy spectral invariants theory and provides a computationally efficient way of parameterizing the Bidirectional Reflectance Factor (BRF) as a function of spatial resolution and wavelength. LAI retrievals from the application of this algorithm to aggregated Landsat surface reflectances are consistent with those of MODIS for homogeneous sites represented by different herbaceous and forest cover types. Example results illustrating the physics and performance of the algorithm suggest three key factors that influence the LAI retrieval process: 1)...

10. Sea Ice Thickness, Freeboard, and Snow Depth products from Operation IceBridge Airborne Data - Sonntag, J. G.; Farrell, S. L.; Panzer, B.; Galin, N.; Kurtz, N. T.; Onana, V. D.; Studinger, M.; Lindsay, R.; Harbeck, J. P.
The study of sea ice using airborne remote sensing platforms provides unique capabilities to measure a wide variety of sea ice properties. These measurements are useful for a variety of topics including model evaluation and improvement, assessment of satellite retrievals, and incorporation into climate data records for analysis of interannual variability and long-term trends in sea ice properties. In this paper we describe methods for the retrieval of sea ice thickness, freeboard, and snow depth using data from a multisensor suite of instruments on NASA's Operation IceBridge airborne campaign. We assess the consistency of the results through comparison with independent...

11. Elemental GCR Observations during the 2009-2010 Solar Minimum Period - vonRosenvinge, T. T.; Davis, A. J.; Mewaldt, R. A.; Cummings, A. C.; deNolfo, G. A.; Leske, R. A.; Binns, W. R.; Christian, E. R.; Israel, M. H.; Lave, K. A.; Stone, E. C.; Wiedenbeck, M. E.
Using observations from the Cosmic Ray Isotope Spectrometer (CRIS) onboard the Advanced Composition Explorer (ACE), we present new measurements of the galactic cosmic ray (GCR) elemental composition and energy spectra for the species B through Ni in the energy range approx. 50-550 MeV/nucleon during the record setting 2009-2010 solar minimum period. These data are compared with our observations from the 1997-1998 solar minimum period, when solar modulation in the heliosphere was somewhat higher. For these species, we find that the intensities during the 2009-2010 solar minimum were approx. 20% higher than those in the previous solar minimum, and in fact...

12. Galactic Cosmic-Ray Energy Spectra and Composition during the 2009-2010 Solar Minimum Period - deNolfo, G. A.; VonRosenvinge, T. T.; Mewaldt, R. A.; Wiedenbeck, Mark E.; Israel, M. H..; Binns, W. R.; Cummings, A. C.; Davis, A. J.; Leske, R. A.; Stone, E. C.; Christian, E. R.; Lave, K. A.
We report new measurements of the elemental energy spectra and composition of galactic cosmic rays during the 2009-2010 solar minimum period using observations from the Cosmic Ray Isotope Spectrometer (CRIS) onboard the Advanced Composition Explorer. This period of time exhibited record-setting cosmic-ray intensities and very low levels of solar activity. Results are given for particles with nuclear charge 5 <= Z <= 28 in the energy range approx. 50-550 MeV / nucleon. Several recent improvements have been made to the earlier CRIS data analysis, and therefore updates of our previous observations for the 1997-1998 solar minimum and 2001-2003 solar maximum...

13. Unification of X-ray Winds in Seyfert Galaxies: From Ultra-fast Outflows to Warm Absorbers - Braito, V.; Cappi, M.; Nemmen, R. S.; Gaspari, M.; Tombesi, F.; Reynolds, C. S.; Reeves, J. N.
The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60 per cent, consistent...

14. Nuclear Thermal Propulsion Ground Test History - Gerrish, Harold P.
Nuclear Thermal Propulsion (NTP) was started in ~1955 under the Atomic Energy Commission as project Rover and was assigned to Los Alamos National Laboratory. The Nevada Test Site was selected in 1956 and facility construction began in 1957. The KIWI-A was tested on July 1, 1959 for 5 minutes at 70MW. KIWI-A1 was tested on July 8, 1960 for 6 minutes at 85MW. KIWI-A3 was tested on October 10, 1960 for 5 minutes at 100MW. The National Aeronautics and Space Administration (NASA) was formed in 1958. On August 31, 1960 the AEC and NASA established the Space Nuclear Propulsion Office...

15. A Research Reactor Concept to Support NTP Development - Gerrish, Harold P.; Blue, T. E.; Eades, Michael J.; Hardin, Leroy A.
In support of efforts for research into the design and development of man rated Nuclear Thermal Propulsion (NTP), the National Aeronautics and Space Administration (NASA), Marshall Space Flight Center (MSFC), is evaluating the potential for building a Nuclear Regulatory Commission (NRC) licensed NTP based research reactor (NTPRR). The proposed NTPRR would be licensed by NASA and operated jointly by NASA and university partners. The purpose of the NTPRR would be used to perform further research into the technologies and systems needed for a successful NTP project and promote nuclear training and education.

16. Mars Ascent Vehicle Test Requirements and Terrestrial Validation - Cathey, Henry M.; Smith, David A.; Dankanich, John W.
The Mars robotic sample return mission has been a potential flagship mission for NASA s science mission directorate for decades. The Mars Exploration Program and the planetary science decadal survey have highlighted both the science return of the Mars Sample Return mission, but also the need for risk reduction through technology development. One of the critical elements of the MSR mission is the Mars Ascent Vehicle, which must launch the sample from the surface of Mars and place it into low Mars orbit. The MAV has significant challenges to overcome due to the Martian environments and the Entry Descent and...

17. International VLBI Service for Geodesy and Astrometry 2012 Annual Report - Behrend, Dirk; Baver, Karen D.; Armstrong, Kyla L.
This volume of reports is the 2012 Annual Report of the International VLBI Service for Geodesy and Astrometry (IVS). The individual reports were contributed by VLBI groups in the international geodetic and astrometric community who constitute the permanent components of IVS. The IVS 2012 Annual Report documents the work of the IVS components for the calendar year 2012, our fourteenth year of existence. The reports describe changes, activities, and progress ofthe IVS. Many thanks to all IVS components who contributed to this Annual Report. With the exception of the first section and parts of the last section (described below), the...

18. Chemical Enrichment and Physical Conditions in IZw18* - Hubeny, I.; Heap, S.; Lebouteiller, V.; Kunth, D.
Low-metallicity star-forming dwarf galaxies are prime targets to understand the chemical enrichment of the interstellar medium. The H I region contains the bulk of the mass in blue compact dwarfs, and it provides important constraints on the dispersal and mixing of heavy elements released by successive star-formation episodes. The metallicity of the H I region is also a critical parameter to investigate the future star-formation history, as metals provide most of the gas cooling that will facilitate and sustain star formation. Aims. Our primary objective is to study the enrichment of the H I region and the interplay between star-formation...

19. Analysis of Supergranule Sizes and Velocities Using Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) and Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) Dopplergrams - Williams, Peter E.; Beck, J. G.; Pesnell, William D.; Lee, S.
Co-temporal Doppler images from Solar and Heliospheric Observatory (SOHO)/ Michelson Doppler Imager (MDI) and Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) have been analyzed to extract quantitative information about global properties of the spatial and temporal characteristics of solar supergranulation. Preliminary comparisons show that supergranules appear to be smaller and have stronger horizontal velocity flows within HMI data than was measured with MDI. There appears to be no difference in their evolutionary timescales. Supergranule sizes and velocities were analyzed over a ten-day time period at a 15-minute cadence. While the averages of the time-series retain the aforementioned differences, fluctuations of...

20. Structural Benchmark Creep Testing for Microcast MarM-247 Advanced Stirling Convertor E2 Heater Head Test Article SN18 - Krause, David L.; Brewer, Ethan J.; Pawlik, Ralph
This report provides test methodology details and qualitative results for the first structural benchmark creep test of an Advanced Stirling Convertor (ASC) heater head of ASC-E2 design heritage. The test article was recovered from a flight-like Microcast MarM-247 heater head specimen previously used in helium permeability testing. The test article was utilized for benchmark creep test rig preparation, wall thickness and diametral laser scan hardware metrological developments, and induction heater custom coil experiments. In addition, a benchmark creep test was performed, terminated after one week when through-thickness cracks propagated at thermocouple weld locations. Following this, it was used to develop...

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