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NASA Technical Reports Server (NTRS) (685.125 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 320.544

  1. Fe(II) Oxidation and Sources of Acidity on Mars

    Niles, P. B.; Sutter, B.; Peretyazkho, T. S.
    There is an apparent paradox be-tween the evidence that aqueous environments on Mars were predominantly acidic, and the fact that Mars is predominantly a basaltic (and olivine-rich) planet. The problem being that basalt and olivine will act to neutralize acidic solutions they come into contact with, and that there is a lot more basaltic crust on Mars than water or acid. This is especially true if there is an appreciable amount of water available to bring the acid in contact with the basaltic crust. Several hypotheses for ancient mar-tian environments call on long lived groundwater and aqueous systems.

  2. Heterogeneity of Water Concentrations in the Mantle Lithosphere Beneath Hawaii

    Clague, D.; Peslier, A. H.; Bizimis, M.
    The amount and distribution of water in the oceanic mantle lithosphere has implications on its strength and of the role of volatiles during plume/lithosphere interaction. The latter plays a role in the Earth's deep water cycle as water-rich plume lavas could re-enrich an oceanic lithosphere depleted in water at the ridge, and when this heterogeneous lithosphere gets recycled back into the deep mantle. The main host of water in mantle lithologies are nominally anhydrous minerals like olivine, pyroxene and garnet, where hydrogen (H) is incorporated in mineral defects by bonding to structural oxygen. Here, we report water concentrations by Fourier...

  3. Training Early Career Scientists in Flight Instrument Design Through Experiential Learning: NASA Goddard's Planetary Science Winter School.

    Brown, T.; Lakew, B.; Bleacher, L. V.; Bracken, J.; Rivera, R.
    The NASA Goddard Planetary Science Winter School (PSWS) is a Goddard Space Flight Center-sponsored training program, managed by Goddard's Solar System Exploration Division (SSED), for Goddard-based postdoctoral fellows and early career planetary scientists. Currently in its third year, the PSWS is an experiential training program for scientists interested in participating on future planetary science instrument teams. Inspired by the NASA Planetary Science Summer School, Goddard's PSWS is unique in that participants learn the flight instrument lifecycle by designing a planetary flight instrument under actual consideration by Goddard for proposal and development. They work alongside the instrument Principal Investigator (PI) and...

  4. A Strong Merger Shock in Abell 665

    Sarazin, C.; Wik, D.; Sun, M.; Morandi, A.; Dasadia, S.; Govoni, F.; Giovannini, G.; Markevitch, M.; Feretti, L.
    Deep (103 ks) Chandra observations of Abell 665 have revealed rich structures in this merging galaxy cluster, including a strong shock and two cold fronts. The newly discovered shock has a Mach number of M =3.0 +/- 0.6, propagating in front of a cold disrupted cloud. This makes Abell 665 the second cluster, after the Bullet cluster, where a strong merger shock of M is approximately 3 has been detected. The shock velocity from jump conditions is consistent with (2.7 +/- 0.7) 10(exp 3) km s(exp 1). The new data also reveal a prominent southern cold front with potentially heated...

  5. Stochastic Template Bank for Gravitational Wave Searches for Precessing Neutron Star-Black Hole Coalescence Events

    Lundgren, Andrew; Haris, K.; Fehrmann, Henning; Indik, Nathaniel; Nielsen, Alex B.; Krishnan, Badri; Pai, Archana; Dal Canton, Tito
    Gravitational wave searches to date have largely focused on non-precessing systems. Including precession effects greatly increases the number of templates to be searched over. This leads to a corresponding increase in the computational cost and can increase the false alarm rate of a realistic search. On the other hand, there might be astrophysical systems that are entirely missed by non-precessing searches. In this paper we consider the problem of constructing a template bank using stochastic methods for neutron star-black hole binaries allowing for precession, but with the restrictions that the total angular momentum of the binary is pointing toward the...

  6. Evolution of Intrinsic Scatter in the SFR-Stellar Mass Correlation at 0.5 less than z Less Than 3

    Dekel, Avishai; Acquaviva, Viviana; Gawiser, Eric; Grogin, Norman A.; Ferguson, Henry C.; De Mello, Duilia F.; Kurczynski, Peter; Bell, Eric F.; Gardner, Jonathan P.
    We present estimates of intrinsic scatter in the star formation rate (SFR)--stellar mass (M*) correlation in the redshift range 0.5 less than z less than 3.0 and in the mass range 10(exp 7) less than M* less than 10(exp 11) solar mass. We utilize photometry in the Hubble Ultradeep Field (HUDF12) and Ultraviolet Ultra Deep Field (UVUDF) campaigns and CANDELS/GOODS-S and estimate SFR, M* from broadband spectral energy distributions and the best-available redshifts. The maximum depth of the UDF photometry (F160W 29.9 AB, 5 sigma depth) probes the SFR--M* correlation down to M* approximately 10(exp 7) solar mass, a factor...

  7. The Potassium - Argon Laser Experiment ( KArLE): Design Concepts

    Cho, Yuichiro; Cohen, B. A.
    No abstract available

  8. Basaltic Lithic Clasts in Type 1A and 2A Mesosiderites: Trend Towards a Eucritic Compotision

    Frasl, Barbara; Corrigan, Catherine M.; Rubin, Alan E.; Baecker, Bastian; Cohen, Barbara A.
    No abstract available

  9. Unique Spectroscopy and Imaging of Mars with the James Webb Space Telescope

    Hartogh, Paul; Milam, Stefanie N.; Mumma, Michael J.; Lopez-Valverde, Miguel A.; Villanueva, Geronimo L.; Clancy, R. Todd; Smith, Michael D.; Altieri, Francesca; Fouchet, Thierry; Novak, Robert E.; Encrenaz, Therese; Lellouch, Emmanuel
    In this paper, we summarize the main capabilities of the James Webb Space Telescope (JWST) for performing observations of Mars. The distinctive vantage point of JWST at the Sun-Earth Lagrange point (L2) will allow sampling the full observable disk, permitting the study of short-term phenomena, diurnal processes (across the east-west axis), and latitudinal processes between the hemispheres (including seasonal effects) with excellent spatial resolutions (0.''07 at 2 micron). Spectroscopic observations will be achievable in the 0.7-5 micron spectral region with NIRSpec at a maximum resolving power of 2700 and with 8000 in the 1-1.25 micron range. Imaging will be attainable...

  10. Dual-Telescope Multi-Channel Thermal-Infrared Radiometer for Outer Planet Fly-By Missions

    Loeffler, Mark; Nixon, Conor A.; Hurley, Jane; Jennings, Donald E.; Hewagama, Tilak; Nicoletti, Anthony; Amato, Michael; Calcutt, Simon; Lakew, Brook; Howard, Joseph; Hsieh, Wen-Ting; Quilligan, Gerard; Aslam, Shahid; West, Garrett; Bowles, Neil; Hurford, Terry; Howett, Carly
    The design of a versatile dual-telescope thermal-infrared radiometer spanning the spectral wavelength range 8-200 microns, in five spectral pass bands, for outer planet fly-by missions is described. The dual- telescope design switches between a narrow-field-of-view and a wide-field-of-view to provide optimal spatial resolution images within a range of spacecraft encounters to the target. The switchable dual-field- of-view system uses an optical configuration based on the axial rotation of a source-select mirror along the optical axis. The optical design, spectral performance, radiometric accuracy, and retrieval estimates of the instrument are discussed. This is followed by an assessment of the surface coverage...

  11. The Spectrum of Jupiters Great Red Spot: the Case for Ammonium Hydrosulfide (NH4SH)

    Chanover, Nancy J.; Loeffler, Mark J.; Hudson, Reggie L.; Simon, Amy A.
    Here we present new ultraviolet-visible spectra of irradiated ammonium hydrosulde (NH4SH), a reported Jovian atmospheric cloud component, for a range of temperatures and radiation doses and make assignments to the spectral features. We show that the combination of radiolysis and thermal annealing of NH4SH causes the originally featureless ultraviolet-visible reectance spectrum to evolve into one that absorbs in the ultraviolet-visible region. Furthermore, we nd that our laboratory spectra resemble HST (Hubble Space Telescope) spectra below 500 nanometers, suggesting that the more stable reaction products of NH4SH radiolysis are likely an important component of the Great Red Spot.

  12. Stellar Laboratories

    Rauch, T.; Quinet, T.; Werner, K.; Kruk, J. W.; Hoyer, D.; Demleitner, M.
    For the spectral analysis of high-resolution and high signal-to-noise (SN) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: To identify molybdenum lines in the ultraviolet (UV) spectra of the DA-type white dwarf G191B2B and the DO-type white dwarf RE 0503289 and, to determine their photospheric Mo abundances, reliable Mo iv-vii oscillator strengths are used. Methods: We newly calculated Mo iv-vii oscillator strengths to consider their radiative and collisional bound-bound transitions indetail in our NLTE stellar-atmosphere models for...

  13. Hard X-Ray Emission of the Luminous Infrared Galaxy NGC 6240 as Observed by Nustar

    Fiore, F.; Comastri, A.; Stern, D.; Harrison, F. A.; Hailey, C. J.; Brandt, W. N.; Boggs, S. E.; Arévalo, P.; Gandhi, P.; Zappacosta, L.; Craig, W. W.; Zhang, W.; Puccetti, S.; Brightman, M.; Balokovic, M.; Annuar, A.; Alexander, D. M.; Bauer, F. E.; Walton, D. J.; Marinucci, A.; Urry, C. M.; La Massa, S.; Christensen, F. E.; Koss, M. J.; Luo, B.; Ricci, C.
    We present a broadband (approx.0.370 keV) spectral and temporal analysis of NuSTAR observations of the luminous infrared galaxy NGC 6240 combined with archival Chandra, XMM-Newton, and BeppoSAX data. NGC 6240 is a galaxy in a relatively early merger state with two distinct nuclei separated by approx.1.5. Previous Chandra observations resolved the two nuclei and showed that they are both active and obscured by Compton-thick material. Although they cannot be resolved by NuSTAR, we were able to clearly detect, for the first time, both the primary and the reflection continuum components thanks to the unprecedented quality of the NuSTAR data at...

  14. Measuring a Truncated Disk in Aquila X-1

    Chakrabarty, Deepto; Zhang, William W.; Feurst, Felix; King, Ashley L.; Chenevez, Jerome; Christensen, Finn E.; Craig, William W.; Harrison, Fiona A.; Tomsick, John A.; Walton, Dominic J.; Boggs, Steven E.; V, Charles J.; Romano, Patrizia; Stern, Daniel; Miller, Jon M.; Barret, Didier; Parker, Michael L.
    We present NuSTAR and Swift observations of the neutron star Aquila X-1 during the peak of its 2014 July outburst. The spectrum is soft with strong evidence for a broad Fe K(alpha) line. Modeled with a relativistically broadened reflection model, we find that the inner disk is truncated with an inner radius of 15 +/- 3RG. The disk is likely truncated by either the boundary layer and/or a magnetic field. Associating the truncated inner disk with pressure from a magnetic field gives an upper limit of B < 5+/- 2x10(exp 8) G. Although the radius is truncated far from the...

  15. Direct Radiative Effect of Aerosols Based on PARASOL and OMI Satellite Observations

    Hasekamp, Otto P.; Torres, Omar; Lacagnina, Carlo
    Accurate portrayal of the aerosol characteristics is crucial to determine aerosol contribution to the Earth's radiation budget. We employ novel satellite retrievals to make a new measurement-based estimate of the shortwave direct radiative effect of aerosols (DREA), both over land and ocean. Global satellite measurements of aerosol optical depth, single-scattering albedo (SSA), and phase function from PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) are used in synergy with OMI (Ozone Monitoring Instrument) SSA. Aerosol information is combined with land-surface bidirectional reflectance distribution function and cloud characteristics from MODIS (Moderate Resolution Imaging Spectroradiometer)...

  16. Marginalizing Instrument Systematics in HST WFC3 Transit Light Curves

    Sing, D.K.; Wakeford, H. R.; Mandell, A.; Deming, D.
    Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) infrared observations at 1.1-1.7 microns probe primarily the H2O absorption band at 1.4 microns, and have provided low-resolution transmission spectra for a wide range of exoplanets. We present the application of marginalization based on Gibson to analyze exoplanet transit light curves obtained from HST WFC3 to better determine important transit parameters such as "ramp" probability (R (sub p)) divided by "ramp" total (R (sub asterisk)), which are important for accurate detections of H2O. We approximate the evidence, often referred to as the marginal likelihood, for a grid of systematic models using...

  17. Lava Eruption and Emplacement: Using Clues from Hawaii and Iceland to Probe the Lunar Past

    Whelley, P. L.; Hamilton, C. W.; Needham, D. H.; Bleacher, J. E.; Young, K. E.; Richardson, J. A.; Sutton, S. S.; Scheidt, S. P.
    Investigating recent eruptions on Earth is crucial to improving understanding of relationships between eruption dynamics and final lava flow morphologies. In this study, we investigated eruptions in Holuhraun, Iceland, and Kilauea, Hawaii to gain insight into the lava dynamics near the source vent, the initiation of lava channels, and the origin of down-channel features. Insights are applied to Rima Bode on the lunar nearside to deduce the sequence of events that formed this lunar sinuous rille system.These insights are crucial to correctly interpreting whether the volcanic features associated with Rima Bode directly relate to eruption conditions at the vent and,...

  18. The Geographic Distribution of Boulder Halo Craters at Mid-to-High Latitudes on Mars

    Dyar, M. D.; Holt, J. W.; Chaffey, P. M.; Fassett, C. I.; Kreslavsky, M. A.; Wagoner, C. M.; Watters, J. L.; Hanlon, A. E.; Levy, J. S.; King, I. R.; Rader, L. X.
    Extensive evidence exists for ground ice at mid-to-high latitudes on Mars, including results from neutron spectroscopy [1-3], thermal properties [4-5], geomorphology [e.g., 6-9], and the in situ observations of Mars Phoenix [10]. This ground ice has been hypothesized to be emplaced diffusively and fill pores [11], or to have accumulated by ice and dust deposition that draped or mantled the terrain [7, 12]. These two processes are not mutually exclusive; both potentially have occurred on Mars [5]. One of the landforms found in areas where ground ice is common on Mars are boulder halo craters [e.g., 13-15] (Figure 1), which...

  19. Standards for Analysis of Ce, La, Pb, Rb, Se, Sr, Y, AND Zr in Rock Samples Using Laser-induced Breakdown Spectroscopy and X-ray Fluorescence

    Lepore, Kate; Ytsma, Caroline; Dyar, M. Darby; Wagoner, Carlie; Treiman, Allan; Fassett, Caleb I.; Hanlon, Avery; Mackie, Jason
    Analytical geochemistry has long depended on the availability of robust suites of rock standards with well-characterized compositions. Standard rock powders for wet chemistry and x-ray fluorescence were initially characterized and supplied to the community by the U.S. Geological Survey, which continues to distribute a few dozen standards. Many other rock standards have subsequently been developed by organizations such as the Centre de Recherches Ptrographiques et Gochimiques (CRPG) and Brammer Standard Company, Inc.

  20. Unreported Emission Lines of Rb, Ce, La, Sr, Y, Zr, Pb and Se Detected Using Laser-Induced Breakdown Spectroscopy

    Dyar, M. D.; Mackie, J.; Lepore, K. H.; Fassett, C. I.
    Information on emission lines for major and minor elements is readily available from the National Institute of Standards and Technology (NIST) as part of the Atomic Spectra Database. However, tabulated emission lines are scarce for some minor elements and the wavelength ranges presented on the NIST database are limited to those included in existing studies. Previous work concerning minor element calibration curves measured using laser-induced break-down spectroscopy found evidence of Zn emission lines that were not documented on the NIST database. In this study, rock powders were doped with Rb, Ce, La, Sr, Y, Zr, Pb and Se in concentrations...

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