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  • Aircraft Design, Testing and Performance  (11)
  • SPACECRAFT PROPULSION AND POWER  (9)
  • Astronomy  (8)
  • Space Sciences (General)  (7)
  • 1
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    Effect of Thermospheric Neutral Density upon Inner Trapped-belt Proton Flux (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-11
    Description: We wish to point out that a secular change in the Earth's atmospheric neutral density alters charged-particle lifetime in the inner trapped radiation belts, in addition to the changes recently reported as produced by greenhouse gases. Heretofore, changes in neutral density have been of interest primarily because of their effect on the orbital drag of satellites. We extend this to include the orbital lifetime of charged particles in the lower radiation belts. It is known that the charged-belt population is coupled to the neutral density of the atmosphere through changes induced by solar activity, an effect produced by multiple scattering off neutral and ionized atoms along with ionization loss in the thermosphere where charged and neutral populations interact. It will be shown here that trapped-belt flux J is bivariant in energy E and thermospheric neutral density , as J(E,rho). One can conclude that proton lifetimes in these belts are also directly affected by secular changes in the neutral species populating the Earth s thermosphere. This result is a consequence of an intrinsic property of charged-particle flux, that flux is not merely a function of E but is dependent upon density rho when a background of neutrals is present.
    Keywords: Space Sciences (General)
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Space station electrical power system (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The purpose of this paper is to describe the design of the Space Station Electrical Power System. This includes the Photovoltaic and Solar Dynamic Power Modules as well as the Power Management and Distribution System (PMAD). In addition, two programmatic options for developing the Electrical Power System will be presented. One approach is defined as the Enhanced Configuration and represents the results of the Phase B studies conducted by the NASA Lewis Research Center over the last two years. Another option, the Phased Program, represents a more measured approach to reaching about the same capability as the Enhanced Configuration.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TM-100140 , E-3692 , NAS 1.15:100140 , IAF-87-234
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  • 3
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    Quantifying Low Energy Proton Damage in Multijunction Solar Cells (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: An analysis of the effects of low energy proton irradiation on the electrical performance of triple junction (3J) InGaP2/GaAs/Ge solar cells is presented. The Monte Carlo ion transport code (SRIM) is used to simulate the damage profile induced in a 3J solar cell under the conditions of typical ground testing and that of the space environment. The results are used to present a quantitative analysis of the defect, and hence damage, distribution induced in the cell active region by the different radiation conditions. The modelling results show that, in the space environment, the solar cell will experience a uniform damage distribution through the active region of the cell. Through an application of the displacement damage dose analysis methodology, the implications of this result on mission performance predictions are investigated.
    Keywords: Space Sciences (General)
    Type: Proceedings of the 19th Space Photovoltaic Research and Technology Conference; 8-17; NASA/CP-2007-214494
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  • 4
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    Brayton Power Conversion System Parametric Design Modelling for Nuclear Electric Propulsion (1993)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The parametrically based closed Brayton cycle (CBC) computer design model was developed for inclusion into the NASA LeRC overall Nuclear Electric Propulsion (NEP) end-to-end systems model. The code is intended to provide greater depth to the NEP system modeling which is required to more accurately predict the impact of specific technology on system performance. The CBC model is parametrically based to allow for conducting detailed optimization studies and to provide for easy integration into an overall optimizer driver routine. The power conversion model includes the modeling of the turbines, alternators, compressors, ducting, and heat exchangers (hot-side heat exchanger and recuperator). The code predicts performance to significant detail. The system characteristics determined include estimates of mass, efficiency, and the characteristic dimensions of the major power conversion system components. These characteristics are parametrically modeled as a function of input parameters such as the aerodynamic configuration (axial or radial), turbine inlet temperature, cycle temperature ratio, power level, lifetime, materials, and redundancy.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-191135 , NAS 1.26:191135 , REPT-93RC-010143 , E-8345
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  • 5
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    Space Station Electrical Power System (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The purpose of this paper is to describe the design of the Space Station Electrical Power System. This includes the Photovoltaic and Solar Dynamic Power Modules as well as the Power Management and Distribution System (PMAD). In addition, two programmatic options for developing the Electrical Power System will be presented. One approach is defined as the Enhanced Configuration and represents the results of the Phase B studies conducted by the NASA Lewis Research Center over the last two years. Another option, the Phased Program, represents a more measured approach to reaching about the same capability as the Enhanced Configuration.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: IAF PAPER 87-234
    Format: text
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  • 6
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    Change Detection Experiments Using Low Cost UAVs (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-27
    Description: This paper presents the progress in the development of a low-cost change-detection system. This system is being developed to provide users with the ability to use a low-cost unmanned aerial vehicle (UAV) and image processing system that can detect changes in specific fixed ground locations using video provided by an autonomous UAV. The results of field experiments conducted with the US Army at Ft. A.P.Hill are presented.
    Keywords: Aircraft Design, Testing and Performance
    Type: Infotech@Aerospace; 26-29 Sept. 2005; Arlington, VA; United States
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  • 7
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    Design, Development, and Testing of a Compound Wing V/TOL small UAS (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: This paper discusses the development and testing of an innovative small UAS (Unmanned Aircraft System). The design of the vehicle was driven by the need to both have long endurance yet still have the convenience of V/TOL (Vertical Take-Off and Landing) operation. The paper discusses some of the design considerations and configurations evaluated in searching for a configuration that met the demanding mission requirements. The paper also discusses some aspects of the compound wing and experimental testing conducted to discern the optimum parameters for the wing's design. The paper discusses the results of the preliminary flight testing and outlines further research to be conducted.
    Keywords: Aircraft Design, Testing and Performance
    Type: NF1676L-19089 , SciTech 2015; Jan 05, 2015 - Jan 09, 2015; Kissimmee, FL; United States
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  • 8
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    Status of the SOFIA Observatory (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: The SOFIA observatory has been in routine science operations since returning in January from a 6 month-long heavy maintenance period for the aircraft and the telescope assembly. These operations include a successful 6 week deployment to the Southern hemisphere. This presentation will provide an update to the current operational status of the SOFIA observatory, concentrating on the improvements and upgrades that have been implemented since the heavy maintenance period.
    Keywords: Astronomy
    Type: ARC-E-DAA-TN23899 , International Astronomical Union General Assembly; Aug 03, 2015 - Aug 14, 2015; Honolulu, HI; United States
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  • 9
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    Spitzer Spectroscopy of Low-Mass Dwarfs - Clouds and Chemistry at the Bottom of the IMF (2006)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Brown dwarfs and low-mass stars show evidence of complicated atmospheres, including a variety of molecular species and clouds. Infrared observations are one of the best probes of the physics of these objects, but up until recently these observations have been limited in studies from ground-based telescopes by atmospheric absorption and insufficient sensitivity. With the launch of the Spitzer Space Telescope with its Infrared Spectrograph (IRS) instrument we now have the capability to undertake a systematic study of the atmospheric structure and chemistry in these cool objects. The IRS Dim Suns team has compiled spectra from objects ranging from M1 dwarfs with effective temperatures 3,800K of down to T8 dwarfs with effective temperatures of 700. This talk will present these results and discuss their implications for our understanding of cool dwarf atmospheric physics and structure.
    Keywords: Space Sciences (General)
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  • 10
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    Spitzer Infrared Spectrograph Observations of L, M, and T Dwarfs (2004)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: We present here the first mid-infriared spectra of brown dwarfs, together with observations of a low-mass star. Our targets are the M3.5 dwarf GJ 1001 A, the L8 dwarf DENIS-P JO255-4700, and the T1/T6 binary system epsilon Indi Ba/Bb. As expected, the mid- infrared spectral morphology of these objects changes rapidly with spectral class due to the changes in atmospheric chemistry resulting from their differing effective temperatures and atmospheric structures. By taking advantage of the unprecedented sensitivity of the Infrared Spectrograph instrument of the Spitzer Space Telescope we have detected for the first time the 7.6 micron methane band and confirmed the presence of ammonia in a T dwarf atmosphere.
    Keywords: Astronomy
    Type: SSA-137
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