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  • 1
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    Giotto Extended Mission (GEM) (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The primary objectives of the Giotto Extended Mission (GEM), are to determine the composition and physical state of the Grigg Skjellerup Comet's nucleus; to determine the processes that govern the composition and distribution of neutral and ionized species in the cometary atmosphere. Giotto consists of a single European Space Agency (ESA) spacecraft that was launched in 1985 from Center Spatial Guyanis in French Guiana on an Ariane launch vehicle. After a successful launch into geostationary orbit and a heliocentric transfer trajectory, the spacecraft successfully encountered Halley's Comet in 1986. One month after encountering Halley's Comet, Mar. 1986, the spacecraft was placed in hibernation in a heliocentric orbit slightly less than 1 AU. Between Feb. and Jul. 1990 the spacecraft was successfully reactivated, checked out, and placed on a trajectory course to intercept comet Grigg Skjellerup. The spacecraft has been in hibernation since Jul. 1990. Information is presented in tabular form in the following areas: coverage goals, Deep Space Network Support, frequency assignments, telemetry, command, and tracking support responsibility.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: JPL, California Inst. of Tech., Deep Space Network: Mission Support Requirements; 4 p
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  • 2
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    A preliminary damage tolerance methodology for composite structures (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The certification experience for the primary, safety-of-flight composite structure applications on the F-16 is discussed. The rationale for the selection of delamination as the major issue for damage tolerance is discussed, as well as the modeling approach selected. The development of the necessary coupon-level data base is briefly summarized. The major emphasis is on the description of a full-scale fatigue test where delamination growth was obtained to demonstrate the validity of the selected approach. A summary is used to review the generic features of the methodology.
    Keywords: COMPOSITE MATERIALS
    Type: NASA. Langley Research Center Failure Anal. and Mech. of Failure of Fibrous Composite Struct.; p 67-94
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  • 3
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    Recovering from execution errors in SIPE (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: In real-world domains (e.g., a mobile robot environment), things do not always proceed as planned, so it is important to develop better execution-monitoring techniques and replanning capabilities. These capabilities in the SIPE planning system are described. The motivation behind SIPE is to place enough limitations on the representation so that planning can be done efficiently, while retaining sufficient power to still be useful. This work assumes that new information given to the execution monitor is in the form of predicates, thus avoiding the difficult problem of how to generate these predicates from information provided by sensors. The replanning module presented here takes advantage of the rich structure of SIPE plans and is intimately connected with the planner, which can be called as a subroutine. This allows the use of SIPE's capabilities to determine efficiently how unexpected events affect the plan being executed and, in many cases, to retain most of the original plan by making changes in it to avoid problems caused by these unexpected events. SIPE is also capable of shortening the original plan when serendipitous events occur. A general set of replanning actions is presented along with a general replanning capability that has been implemented by using these actions.
    Keywords: CYBERNETICS
    Type: Jet Propulsion Lab., California Inst. of Tech., Proceedings of the Workshop on Space Telerobotics, Volume 3; p 79-90
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  • 4
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    General equation for the precession of a gyroscope (1970)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Precession equations of gyroscope onboard near earth satellite, comparing Schiff and Brans- Dicke theories
    Keywords: PHYSICS, GENERAL
    Type: ; BROTECHNIKA, NO. 2(
    Format: text
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  • 5
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    The Nustar Spectrum of Mrk 335: Extreme Relativistic Effects Within Two Gravitational Radii of the Event Horizon? (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: We present 3-50 keV NuSTAR observations of the active galactic nuclei Mrk 335 in a very low flux state. The spectrum is dominated by very strong features at the energies of the iron line at 5-7 keV and Compton hump from 10-30 keV. The source is variable during the observation, with the variability concentrated at low energies, which suggesting either a relativistic reflection or a variable absorption scenario. In this work, we focus on the reflection interpretation, making use of new relativistic reflection models that self consistently calculate the reflection fraction, relativistic blurring and angle-dependent reflection spectrum for different coronal heights to model the spectra. We find that the spectra can be well fitted with relativistic reflection, and that the lowest flux state spectrum is described by reflection alone, suggesting the effects of extreme light-bending occurring within approx. 2 gravitational radii (RG) of the event horizon. The reflection fraction decreases sharply with increasing flux, consistent with a point source moving up to above 10 RG as the source brightens. We constrain the spin parameter to greater than 0.9 at the 3(sigma) confidence level. By adding a spin-dependent upper limit on the reflection fraction to our models, we demonstrate that this can be a powerful way of constraining the spin parameter, particularly in reflection dominated states. We also calculate a detailed emissivity profile for the iron line, and find that it closely matches theoretical predictions for a compact source within a few RG of the black hole.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN24160 , Monthly Notices of Royal Astronomical Society (ISSN 1365-8711); 443; 2; 1723-1732
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  • 6
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    On the Determination of the Spin of the Black Hole in Cyg X-1 from X-Ray Reflection Spectra (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The spin of Cygnus X-I is measured by fitting reflection models to Suzaku data covering the energy band 0.9-400 keY. The inner radius of the accretion disc is found to lie within 2 gravitational radii (rg = GM/c(exp 2)) and a value for the dimensionless black hole spin is obtained of 0.97(sup .0.14) (sup -0.02). This agrees with recent measurements using the continuum fitting method by Gou et al. and of the broad iron line by Duro et al. The disc inclination is measured at 23.7(sup +6.7) (sup -5.4) deg. which is consistent with the recent optical measurement of the binary system inclination by Orosz et al of 27+/- 0.8 deg. We pay special attention to the emissivity profile caused by irradiation of the inner disc by the hard power-law source. 1be X-ray observations and simulations show that the index q of that profile deviates from the commonly used, Newtonian, value of 3 within 3r(sub g), steepening considerably within 2r(sub g). as expected in the strong gravity regime.
    Keywords: Astronomy
    Type: GSFC.JA.00374.2012
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  • 7
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    Flight simulation testing equipment for composite material systems (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A test program is discussed which aims at establishing the time-temperature-stress characteristics of several classes of high-temperature composite materials in order to determine their suitability for applications in supersonic cruise aircraft. Five advanced composite materials (a boron epoxy, a boron polyimide, a graphite epoxy, a graphite polyimide, and diffusion-bonded boron aluminum) are being evaluated using a flight-test simulator capable of long-term automatic testing based on random loading and realistic flight temperature profiles. The design, construction, and checkout of this simulator are described along with the digital load programmer, load magnitude controllers, the hydraulic pumping system, the heating and cooling systems, the control console, and the data recording system. Typical results for short-term tests performed at constant temperatures and accelerated load rates are presented in terms of a random-load spectrum and a wearout model.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: Environmental effects on advanced composite materials; Jun 22, 1975 - Jun 27, 1975; Montreal; Canada
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  • 8
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    Multimegawatt thermionic reactor systems for space applications (1968)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Design features and performance characteristics of thermionic reactor systems for space applications
    Keywords: NUCLEAR ENGINEERING
    Type: NASA-CR-96782 , CONF-680508-2 , INTERN. CONF. ON THERMIONIC ELEC. POWER GENERATION; STRESA; ITALY
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  • 9
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    Multimegawatt thermionic reactor systems for space applications. (1969)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Thermionic reactor systems, discussing hybrid nuclear rocket/nuclear electric Mars mission, design features, performance and electric power characteristics
    Keywords: NUCLEAR ENGINEERING
    Type: INTERNATIONAL CONFERENCE ON THERMIONIC ELECTRICAL POWER GENERATION; May 27, 1968 - May 31, 1968; STRESA; ITALY
    Format: text
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