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  • Other Sources  (40)
  • 2005-2009  (20)
  • 1990-1994  (20)
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  • 1930-1934
  • 2009  (20)
  • 1990  (20)
  • 1
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    Wide-angle astrometry with the Mark III stellar interferometer (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Astrometric measurements made with the Mark III stellar interferometer on five nights in August-September 1988 yielded average formal 1-sigma errors for 12 FK5 stars of 6 mas in declination and 10 mas in right ascension. This improvement in precision over previously reported measurements with this instrument made in 1986 is attributable to several factors: a second 12 m baseline; oriented E-S, was added to the instrument to improve the determination of right ascension; two-color analysis was included in the data-reduction process, along with a new central-fringe identification algorithm using three spectral channels, in order to reduce atmospheric errors; thermal control was greatly improved; and changes were made to observational procedures and hardware to monitor variations in the delay offset due to residual thermal drifts. Approximately half of the new positions are within 50 mas of their FK5 positions. However, an extended series of measurements are needed to ascertain the accuracy that can be achieved by interferometry.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 100; 1701-171
    Format: text
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  • 2
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    World-wide interactive access to scientific databases via satellite and terrestrial data network (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: In order to demonstrate the possibilities for scientific networking and data transfer, a first temporary satellite network link was installed between Czecholovakia and the European space operations center in Darmstadt, during the meeting of the inter-agency consultative group for space science in Prague. Several experiments to show interactive nature of the facility and the capability of the system were carried out, and it was proven that, despite the temporary nature of the installation, the planned demonstrations could be conducted in real time. Demonstrations included electronic mail message, orbit prediction and solar X-ray data. The results of the experiment provided insight into possibilities of data exchange.
    Keywords: DOCUMENTATION AND INFORMATION SCIENCE
    Type: ESA Bulletin (ISSN 0376-4265); 61, Fe; 63-69
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  • 3
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    CLEAR: Automating control centers with expert system technology (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Communications Link Expert Assistance Resource (CLEAR) is a fault-isolation expert system to be utilized in the operational environment of the Cosmic Background Explorer (COBE) Mission Operations Room (MOR). CLEAR will assist the COBE Flight Operations Team (FOT) during periods of real-time data acquisition by isolating faults in the spacecraft communication link with the Tracking and Data Relay Satellite (TDRS), providing advice on how to correct them, and logging the events for post-pass evaluation. After a brief introduction to the problem domain, the system requirements, tool selection, development approach, system operation and lessons learned during the transformation of the system from the prototype to the delivered, operation system are described.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA, Lyndon B. Johnson Space Center, Third Annual Workshop on Space Operations Automation and Robotics (SOAR 1989); p 289-293
    Format: application/pdf
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  • 4
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    Space Shuttle Flight Support Motor no. 1 (FSM-1) (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Space Shuttle Flight Support Motor No. 1 (FSM-1) was static test fired on 15 Aug. 1990 at the Thiokol Corporation Static Test Bay T-24. FSM-1 was a full-scale, full-duration static test fire of a redesigned solid rocket motor. FSM-1 was the first of seven flight support motors which will be static test fired. The Flight Support Motor program validates components, materials, and manufacturing processes. In addition, FSM-1 was the full-scale motor for qualification of Western Electrochemical Corporation ammonium perchlorate. This motor was subjected to all controls and documentation requirements CTP-0171, Revision A. Inspection and instrumentation data indicate that the FSM-1 static test firing was successful. The ambient temperature during the test was 87 F and the propellant mean bulk temperature was 82 F. Ballistics performance values were within the specified requirements. The overall performance of the FSM-1 components and test equipment was nominal.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-184078 , NAS 1.26:184078 , TWR-50068 , PUBL-910801
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  • 5
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    A parametric shell analysis of the shuttle 51-L SRB AFT field joint (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Following the Shuttle 51-L accident, an investigation was conducted to determine the cause of the failure. Investigators at the Langley Research Center focused attention on the structural behavior of the field joints with O-ring seals in the steel solid rocket booster (SRB) cases. The shell-of-revolution computer program BOSOR4 was used to model the aft field joint of the solid rocket booster case. The shell model consisted of the SRB wall and joint geometry present during the Shuttle 51-L flight. A parametric study of the joint was performed on the geometry, including joint clearances, contact between the joint components, and on the loads, induced and applied. In addition combinations of geometry and loads were evaluated. The analytical results from the parametric study showed that contact between the joint components was a primary contributor to allowing hot gases to blow by the O-rings. Based upon understanding the original joint behavior, various proposed joint modifications are shown and analyzed in order to provide additional insight and information. Finally, experimental results from a hydro-static pressurization of a test rocket booster case to study joint motion are presented and verified analytically.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TM-102748 , NAS 1.15:102748
    Format: application/pdf
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  • 6
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    Spectral determinations for discrete sources with EGRET (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The ability of the EGRET (Energetic Gamma-Ray Experimental Telescope) to determine the spectral parameters of point sources in 14-day exposures, as planned for the initial survey phase of the GRO (Gamma Ray Observatory) mission, is explored by numerical simulation. Results are given for both galactic and extragalactic objects as a function of source strength and for representative levels of diffuse background emission.
    Keywords: ASTRONOMY
    Type: NASA, Goddard Space Flight Center, The Energetic Gamma-Ray Experiment Telescope (EGRET) Science Symposium; p 201-213
    Format: application/pdf
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  • 7
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    Aeroacoustic effects of reduced aft tip speed at constant thrust for a model counterrotation turboprop at takeoff conditions (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A model high-speed, advanced counterrotation propeller, F7/A7, was tested in the NASA Lewis Research Center's 9- by 15-foot anechoic wind tunnel at simulated takeoff and approach conditions of Mach 0.2. The propeller was operated in a baseline configuration with the forward and aft rotor blade setting angles (36.2deg and 35.4 deg) and forward and aft rotational speeds essentially equal. Two additional configurations were tested with the aft rotor at increased blade setting angles and the rotational speed reduced to achieve overall performance similar to that of the baseline configuration. The aft rotor blade angles were adjusted such that the thrust and power absorption for each rotor remained the same as for the baseline configuration. Acoustic data were taken with an axially translating microphone probe that was attached to the tunnel floor. Concurrent aerodynamic data were taken to define propeller operating conditions. The aft rotor fundamental tone was about 6 dB lower with the 36.2 deg and 38.4 deg blade setting angles, and about 9 dB lower with the 36.2 and 41.4 deg blade setting angles. Predicted noise reductions based on tip speed considerations were 5 and 9.5 dB, respectively, for the two altered blade setting angles.
    Keywords: ACOUSTICS
    Type: AIAA PAPER 90-3933
    Format: text
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  • 8
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    An Overview of the NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project and Ultra High Bypass Partnership Research Goals (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An overview of the NASA Fundamental Aeronautics Program (FAP) mission and goals is presented. One of the subprograms under the FAP, the Subsonic Fixed Wing Project (SFW), is the focus of the presentation. The SFW system environmental metrics are discussed, along with highlights of planned, systematic approach to research to reduce the environmental impact of commercial aircraft in the areas of acoustics, fuel burn and emissions. The presentation then focuses on collaborative research being conducted with U.S. Industry on the Ultra High Bypass (UHB) engine cycle, the propulsion cycle selected by the SFW to meet the system goals. The partnerships with General Electric Aviation to investigate Open Rotor propulsion concepts and with Pratt & Whitney to investigate the Geared Turbofan UHB engine are highlighted, including current and planned future collaborative research activities with NASA and each organization.
    Keywords: Aeronautics (General)
    Type: E-17352 , 15th AIAA Conference; May 11, 2009 - May 13, 2009; Miami, FL; United States
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  • 9
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    Measuring Massive Black Hole Binaries with LISA (2009)
    In:  Other Sources
    Details
    Publication Date: 2019-07-19
    Description: The coalescence of two massive black holes produces gravitational waves (GWs) which can be detected by the space-based detector LISA. By measuring these waves, LISA can determine the various parameters which characterize the source. Measurements of the black hole masses and spins will provide information about the growth of black holes and their host galaxies over time. Measurements of a source's sky position and distance may help astronomers identify an electromagnetic counterpart to the GW event. The counterpart's redshift, combined with the GW-measured luminosity distance, can then be used to measure the Hubble constant and the dark energy parameter $w$. Because the potential science output is so high, it is useful to know in advance how well LISA can measure source parameters for a wide range of binaries. We calculate expected parameter estimation errors using the well-known Fisher matrix method. Our waveform model includes the physics of spin precession, as well as subleading harmonics. When these higher-order effects are not included, strong degeneracies between some parameters cause them to be poorly determined by a GW measurement. When precession and subleading harmonics are properly included, the degeneracies are broken, reducing parameter errors by one to several orders of magnitude.
    Keywords: Astrophysics
    Format: text
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  • 10
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    Thin nearly wireless adaptive optical device (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A thin nearly wireless adaptive optical device capable of dynamically modulating the shape of a mirror in real time to compensate for atmospheric distortions and/or variations along an optical material is provided. The device includes an optical layer, a substrate, at least one electronic circuit layer with nearly wireless architecture, an array of actuators, power electronic switches, a reactive force element, and a digital controller. Actuators are aligned so that each axis of expansion and contraction intersects both substrate and reactive force element. Electronics layer with nearly wireless architecture, power electronic switches, and digital controller are provided within a thin-film substrate. The size and weight of the adaptive optical device is solely dominated by the size of the actuator elements rather than by the power distribution system.
    Keywords: Mechanical Engineering
    Format: application/pdf
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