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  • Other Sources  (3,642)
  • FLUID MECHANICS AND HEAT TRANSFER  (1,357)
  • INSTRUMENTATION AND PHOTOGRAPHY  (1,279)
  • SPACECRAFT DESIGN, TESTING AND PERFORMANCE  (1,006)
  • 1995-1999  (422)
  • 1975-1979  (3,220)
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  • Other Sources  (3,642)
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  • 1
    Publication Date: 2004-12-03
    Description: This paper reports a new balance for the measurement of three components of force - lift, drag and pitching moment - in impulsively starting flows which have a duration of about one millisecond. The basics of the design of the balance are presented and results of tests on a 15 deg semi-angle cone set at incidence in the T4 shock tunnel are compared with predictions. These results indicate that the prototype balance performs well for a 1.9 kg, 220 mm long model. Also presented are results from initial bench tests of another application of the deconvolution force balance to the measurement of thrust produced by a 2D scramjet nozzle.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Shock Tunnel Studies of Scramjet Phenomena 1993; p 107-112
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  • 2
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    Publication Date: 2011-08-24
    Description: We study the onset of a pure Marangoni convection in a liquid layer with two deformable interfaces in the no-gravity environment. Both oscillatory and stationary instabilities are considered for a wide range of parameters. It is shown that only stationary instability is possible when surface tension at the colder interface is lower than that at the hotter one. Oscillatory instability tends to disappear and to be replaced by the stationary instability with increase of the Prandtl number and decrease of surface tension at the colder interface.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Advances in Space Research (ISSN 0273-1177); 16; 7; p. (7)83-(7)86
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  • 3
    Publication Date: 2011-08-24
    Description: A consistent solution of the radiative transfer equation characterizing photon transport in a semi-infinite medium of refractive index greater than or equal to one is obtained following the method of Sobolev. Fresnel specular reflection, Snell's law and isotropic scattering are assumed. An algorithm is developed and its accuracy is demonstrated. A numerical Laplace transform inversion leads to an efficient evaluation for the interior flux and source function distributions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Quantitative Spectroscopy & Radiative Transfer (ISSN 0022-4073); 53; 3; p. 257-267
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  • 4
    Publication Date: 2011-08-24
    Description: Results are reported of the Surface Tension Driven Convection Experiment (STDCE) aboard USML-1 Spacelab. Steady and transient thermocapillary flows were investigated in a 10 cm dia. circular container filled with 10 Cs silicone oil. The velocity and temperature fields were studied in detail under various conditions. It is shown in this paper how the Marangoni number affects the velocity field. A numerical analysis of the flows was also conducted and its results were compared to the experimental data. Good agreement is shown.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Advances in Space Research (ISSN 0273-1177); 16; 7; p. (7)79-(7)82
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  • 5
    Publication Date: 2011-08-24
    Description: The concept of the well-known Langley plot technique, used for the calibration of ground-based instruments, has been generalized for application to satellite instruments. In polar regions, near summer solstice, the solar backscattered ultraviolet (SBUV) instrument on the Nimbus 7 satellite samples the same ozone field at widely different solar zenith angles. These measurements are compared to assess the long-term drift in the instrument calibration. Although the technique provides only a relative wavelength-to-wavelength calibration, it can be combined with existing techniques to determine the drift of the instrument at any wavelength. Using this technique, we have generated a 12-year data set of ozone vertical profiles from SBUV with an estimated accuracy of +/- 5% at 1 mbar and +/- 2% at 10 mbar (95% confidence) over 12 years. Since the method is insensitive to true changes in the atmospheric ozone profile, it can also be used to compare the calibrations of similar SBUV instruments launched without temporal overlap.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 100; D2; p. 2997-3004
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  • 6
    Publication Date: 2010-11-08
    Description: Potential flows may be utilized to represent motions produced in pulsating bulbs. While the initial bulb shape may be arbitrary, sequential shapes are related by affine transformations. Two components appear in the distribution of pressure, one dependent on the instantaneous velocity and the other on the acceleration. For flows with stationary streamlines the inertial impedance is that of a simple mass, and is proportional to the first moment of the actual mass of fluid contained within the bulb. Examples treated are: (1) Expanding and collapsing circular cylinders, and (2) elliptical cylinders in which the perimeter is held constant. The thickness of the pulsatile laminar boundary layer is found to be approximately on millimeter for conditions in the vicinity of the heart. Conditions for separation and turbulence differ from those in steady flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Collected Works of Robert T. Jones; p 957-965
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  • 7
    Publication Date: 2009-11-16
    Description: The results of a parametric study on the entrance flow region in a gas core nuclear reactor are presented. The physical system is modeled as laminar confined, coaxial flow with heat generation in the inner fluid. The governing equations include the boundary layer approximations and the assumptions of only radial radiative transport of energy represented as an energy diffusion term. The Von Mises transformation and a zeta transformation are used to transform the equations into nonlinear nonhomogeneous convective-diffusion equations. A unique combination of forward and backward difference equations which yields accurate results at moderate computational times, is used in the numerical method. Results show that the rapidly accelerating, heat generating inner stream actually shrinks in radius as it expands axially.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Turbulence Coefficients and Stability Studies for the Coaxial Flow or Dissimiliar Fluids; 76 p
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  • 8
    Publication Date: 2006-07-02
    Description: The transient response of an elastic cylindrical shell immersed in an acoustic media that is engulfed by a plane wave is determined numerically. The method applies to the USA-STAGS code which utilizes the finite element method for the structural analysis and the doubly asymptotic approximation for the fluid-structure interaction. The calculations are compared to an exact analysis for two separate loading cases: a plane step wave and an exponentially decaying plane wave.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 3; p 23-28
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  • 9
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    In:  CASI
    Publication Date: 2006-04-10
    Description: The transportation cost associated with space materials processing were studied to determine the feasibility of space manufacturing. The assumptions use to determining the cost estimates for a 12 year planning period are listed, and the orbitor is described in terms of payloads. Shuttle operational costs, ground operational costs, and nonrecurring investment and development costs were analyzed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Econ. Analysis of Materials Processing in Space; p 8-39
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  • 10
    Publication Date: 2006-03-02
    Description: Development of the Apollo thrust vector control digital autopilot (TVC DAP) was summarized. This is the control system that provided pitch and yaw attitude control during velocity change maneuvers using the main rocket engine on the Apollo service module. A list of ten primary functional requirements for this control system are presented, each being subordinate to a more general requirement appearing earlier on the list. Development process functions were then identified and the essential information flow paths were explored. This provided some visibility into the particular NASA/contractor interface, as well as relationships between the many individual activities.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA, Washington Fourth Inter-Center Control Systems Conf.; p 63-82
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  • 11
    Publication Date: 2006-03-02
    Description: The inherent tolerance for nuclear radiation makes fluidic devices candidates for nuclear rocket control systems. Also, they are being considered for supersonic jet engine inlet control because of their high temperature and vibration tolerance. Three new control components being considered for these applications are described. A fluidic circuit to control a pneumatic stepping motor for nuclear rocket control drum actuation is discussed. An all-fluidic sensor being developed for determining the position of the normal shock in the inlet of a supersonic jet engine is outlined. A new vortex valve configuration is developed to prevent supersonic jet engine inlet unstarts by regulating bypass flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA, Washington Fourth Inter-Center Control Systems Conf.; p 365-386
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  • 12
    Publication Date: 2006-02-22
    Description: The measurement capabilities of laser velocimetry and holographic interferometry in transonic airfoil testing were demonstrated. Presented are representative results obtained with these two nonintrusive techniques on a 15.24 cm chord airfoil section. These results include the density field about the airfoil, flow angles in the inviscid flow and viscous flow properties including the turbulent Reynolds stresses. The accuracies of the density fields obtained by interferometry were verified from comparisons with surface pressure and laser velocimeter measurements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 589-599
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  • 13
    Publication Date: 2006-02-22
    Description: Two dimensional airfoil testing was conducted at the Wichita State University Beech Wind Tunnel for a number of years. The instrumentation developed and adapted during this period of testing for determination of flow fields along with traversing mechanisms for these probes are discussed. In addition, some of the techniques used to account for interference effects associated with the apparatus used for this two dimensional testing are presented. The application of a minicomputer to the data reduction and presentation is discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 539-558
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  • 14
    Publication Date: 2006-01-16
    Description: Calculation procedures for compressible turbulent boundary layers were based upon techniques, modeling constants, etc., developed originally for the low speed case. Significant differences and new or altered physics which occur in the compressible case were considered, as compared with the low speed situation. Possible pitfalls and sources of inaccuracy in the calculations were indicated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Calculation Methods for Compressible Turbulent Boundary Layers, 1976; p 9-46
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  • 15
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The selection of measurement systems for experiments conducted in the context of a space flight must be guided by the criteria applicable to any scientific study requiring objective measurements of physiological variables. Steps fundamental to the process of choosing the best instrumentation system are identified and the key factors in matching the operational characteristics of the instrumentation to its intended use are discussed. Special problems in obtaining data from nonhuman primates, whether restrained or unrestrained, are explored. Choices for data processing are evaluated as well as the use of prototype flight tests and simulations to assess future life science experiments for spacelab or payloads for the space shuttle biomedical scientific satellite.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Use of Nonhuman Primates in Space; p 225-243
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  • 16
    Publication Date: 2006-01-12
    Description: Two cryogenic systems are described which will provide cooling for experiments to be flown on Spacelab 2 in the early 1980's. The first system cools a scanning infrared telescope by the transfer of cold helium gas from a separate superfluid helium storage dewar. The flexible design permits the helium storage dewar and transfer assembly to be designed independent of the infrared experiment. Where possible, modified commerical apparatus is used. The second cryogenic system utilizes a specially designed superfluid dewar in which a superfluid helium experiment chamber is immersed. Each dewar system employs a porous plug as a phase separator to hold the liquid helium within the dewar and provide cold gas to a vent line. To maintain the low vapor pressure of the superfluid, each system requires nearly continuous prelaunch vacuum pump service, and each will vent to space during the Spacelab 2 flight.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: ESA Spacecraft Thermal and Environ. Control Systems; p 507-515
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  • 17
    Publication Date: 2006-01-12
    Description: The Life Sciences dedicated Spacelab will enable scientists to test hypotheses in various disciplines. Building upon experience gained in mission simulations, orbital flight test experiments, and the first three Spacelab missions, NASA will be able to progressively develop the engineering and management capabilities necessary for the first Life Sciences Spacelab. Development of experiments for these missions will require implementation of life-support systems not previously flown in space. Plant growth chambers, animal holding facilities, aquatic specimen life-support systems, and centrifuge-mounted specimen holding units are examples of systems currently being designed and fabricated for flight.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: ESA Spacecraft Thermal and Environ. Control Systems; p 467-472
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  • 18
    Publication Date: 2006-01-12
    Description: The method of thermally integrating the experiments for Spacelab is discussed. The scientific payload consists of a combination of European and United States sponsored experiments located in the module as well as on a single Spacelab pallet. The thermal integration must result in accomodating the individual experiment requirements as well as ensuring that the total payload is within the Spacelab Environmental Control System (ECS) resource capability. An integrated thermal/ECS analysis of the module and pallet is performed in concert with the mission timeline to ensure that the agreed upon experiment requirements are accommodated and to ensure the total payload is within the Spacelab ECS resources.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: ESA Spacecraft Thermal and Environ. Control Systems; p 545-559
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  • 19
    Publication Date: 2006-01-12
    Description: A review of the thermal design options for unmanned Shuttle payloads is presented. Because many future Shuttle payloads will have budgets and less time available for the definition of their thermal subsystems, simplified design procedures will be the most cost-effective. The thermal interface between an individual payload and the Orbiter is discussed. A simplified, modular thermal control system that will reduce the cost of providing thermal protection by minimizing both the initial procurement cost of any specialized hardware and the need for a detailed thermal interface analysis is described.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: ESA Spacecraft Thermal and Environ. Control Systems; p 481-486
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  • 20
    Publication Date: 2006-01-12
    Description: A modification to the multipactor electron source used in the study of the behavior of spacecraft insulating materials is described. The electron accelerating system was included within the source, freeing the region between the source and the target of fields produced by the source electrodes.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 881-886
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  • 21
    Publication Date: 2006-01-12
    Description: The definition and procurement program is presented for the set up of a test simulating an electron environment on a model of a communication satellite to study the degradation of the thermal insulation materials during electron bombardment.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 819-833
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  • 22
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    In:  CASI
    Publication Date: 2006-01-12
    Description: Calculations were conducted to determine the effects of electron-produced secondary electrons on the net charging current and the equilibrium voltage of spacecraft surfaces immersed in hot (keV) plasmas. The effects of secondary electrons produced by the primary plasma electrons were examined for aluminum, Teflon, Mylar, and Kapton. The results indicate that it is the primary electron energy region over which the secondary electrons are emitted (rather than the ratio of secondary to primary electrons) which determines the effectiveness of the secondary electrons in limiting the net charging current. While the electron-produced secondary electrons decreased the charging current, they had little effect upon the equilibrium voltages attained.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 756-768
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  • 23
    Publication Date: 2006-01-12
    Description: Equilibrium surface potentials for slab configurations (representative e.g. of a large solar power satellite) are determined under extensive parametric variations of materials, solar exposure and substorm characteristics. The dependence of the charging process for dielectric surfaces on the various material response characteristics is described. The results are used as a guide to the material selection and design of large space systems to minimize dielectric breakdowns and reduce parasitic leakage currents on SPS.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA Lewis Res. Center Spacecraft Charging Technol., 1978; p 711-733
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  • 24
    Publication Date: 2006-01-12
    Description: Available data on the geosynchronous orbit energetic plasma environment were examined, and a crude model was generated to permit an estimation to be made of the number of arc discharges per year to which a thermal blanket groundstrap would be subjected. Laboratory experiments and a survey of the literature on arc discharge characteristics were performed to define typical and worst case arc discharge current waveforms. In-air tests of different groundstrap configurations to a standardized test pulse were performed and a wide variability of durability values were found. A groundstrap technique, not used thus far, was found to be far superior than the others.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 657-681
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  • 25
    Publication Date: 2006-01-12
    Description: The conditions under which multiple valued solutions occur by computing the floating potential of an isolated eclipses surface on a geosynchronous orbit spacecraft were examined. Different approximations for the electron spectra during a geomagnetic substorm were used. The result indicates that if the incident electron flux has a Maxwellian energy distribution, the ratio of the secondary emitted current to the incident electron current is independent of the spacecraft potential. In this case a single value solution to the current equation occurs.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 747-755
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  • 26
    Publication Date: 2006-01-12
    Description: A heuristic model to explain the blowoff of charge during an electron-induced dielectric discharge is presented. It is proposed that blowoff of charge is initiated by a punchthrough or a flashover. The discharge time is assumed to be governed by an LC time constant where L is the inductance of the electrons flowing in the branches of the Lichtenberg figures at an electron range below the irradiated surface and C is the capacitance between the trapped electrons and the substrate for the discharged area. Experiments to verify that blowoff is a consequence of punchthrough or flashover and to measure the punchthrough current and the variation of discharge time with the sample area and thickness were conducted.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 704-710
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  • 27
    Publication Date: 2006-01-12
    Description: The charging and discharging behavior of square, planar samples of silvered, fluorinated ethylene-propylene (FEP) Teflon thermal control tape was measured. The equilibrium voltage profiles scaled with the width of the sample. A wide range of discharge pulse characteristics was observed, and the area dependences of the peak current, charge, and pulse widths are described. The observed scaling of the peak currents with area was weaker than that previously reported. The discharge parameters were observed to depend strongly on the grounding impedance and the beam voltage. Preliminary results suggest that measuring only the return-current-pulse characteristics is not adequate to describe the spacecraft discharging behavior of this material. The seams between strips of tape appear to play a fundamental role in determining the discharging behavior. An approximate propagation velocity for the charge cleanoff was extracted from the data. The samples - 232, 1265, and 5058 square centimeters in area - were exposed at ambient temperature to a 1- to 2-nA/sq cm electron beam at energies of 10, 15, and 20 kilovolts in a 19-meter-long by 4.6-meter-diameter simulation facility at the Lewis Research Center.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Spacecraft Charging Technol., 1978; p 485-506
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  • 28
    Publication Date: 2006-01-12
    Description: The thruster plasma is assumed to be described by a collimated energetic beam and a cloud of ionized thermal propellant produced by charge-exchange. A simple adiabatic model is used to describe the expansion of these neutral plasmas away from the source. As the pressure falls, shielding currents dissipate, and the geomagnetic field takes control of the particles. In low earth orbit, it is concluded that the vehicle easily outruns its thruster plasma. At geosynchronous altitude, the local electric fields around high voltage surfaces collect return current from the thermal plasma that appears to be limited only by the available space charge. Results appropriate to proposed electric propulsion missions and the solar power satellite are presented and operational considerations are discussed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 419-436
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  • 29
    Publication Date: 2006-01-12
    Description: Solar-array voltage-current curves are calculated by assuming the existence of parasitic loads that consist of local currents of charged particles collected by the array. Three cases of interest are calculated to demonstrate how the distribution and magnitude of parasitic currents affect output. Solar array performance degradation became significant when the total parasitic current plus the load current exceeded the short-circuit current. Approximate graphical methods were useful for many applications. Power loss, which was calculated by summing the product of parasitic current and the local potential, underestimated the loss in maximum power.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Spacecraft Charging Technol., 1978; p 358-375
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  • 30
    Publication Date: 2006-01-12
    Description: Present concepts for solar power satellites involve dimensions up to tens of kilometers and operating internal currents up to hundreds of kiloamperes. A question addressed is whether the local magnetic fields generated by these strong currents during normal operation can shield the array against impacts by plasma ions and electrons (and from thruster plasmas) which can cause possible losses such as power leakage and surface erosion. One of several prototype concepts was modeled by a long narrow rectangular panel 2 km wide and 20 km long. The currents flow in a parallel across the narrow dimension (sheet current) and along the edge (wire currents). The wire currents accumulate from zero to 100 kiloamp and are the dominant sources. The magnetic field is approximated analytically. The equations of motion for charged particles in this magnetic field are analyzed. The ion and electron fluxes at points on the surface are represented analytically for monoenergetic distributions and are evaluated.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 376-387
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  • 31
    Publication Date: 2006-01-12
    Description: Active control of the potential of the ISEE-1 satellite by the use of electron guns is reviewed. The electron guns contain a special cathode capable of emitting an electron current selectable between 10 to the -8th power and 10 to the -3rd power at energies from approximately .6 to 41 eV. Results obtained during flight show that the satellite potential can be stabilized at a value more positive than the normally positive floating potential. The electron guns also reduce the spin modulation of the spacecraft potential which is due to the aspect dependent photoemission of the long booms. Plasma parameters like electron temperature and density can be deduced from the variation of the spacecraft potential as a function of the gun current. The effects of electron beam emission on other experiments are briefly mentioned.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 256-267
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  • 32
    Publication Date: 2006-01-12
    Description: A computer code (SCCPOEM) was assembled to describe the charging of dielectrics due to irradiation by electrons. The primary purpose for developing the code was to make available a convenient tool for studying the internal fields and charge densities in electron-irradiated dielectrics. The code, which is based on the primary electron transport code POEM, is applicable to arbitrary dielectrics, source spectra, and current time histories. The code calculations are illustrated by a series of semianalytical solutions. Calculations to date suggest that the front face electric field is insufficient to cause breakdown, but that bulk breakdown fields can easily be exceeded.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 209-238
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  • 33
    Publication Date: 2006-01-12
    Description: Results of the flight of the spacecraft charging sounding rocket payload are given. The payload was designed to create charging by the emission of both positive ions and electrons. The relationship between environmental parameters and changes in vehicle potential during periods of emission was also studied.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 80-90
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  • 34
    Publication Date: 2006-01-12
    Description: The infrared radiation from the earth in two spectral bands during both day and night portions of the orbit is measured. Pictures of cloud cover, three dimensional mappings of cloud cover, temperature mappings of clouds, land, and ocean surface, cirrus cloud content, atmospheric contamination, and relative humidity are provided.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Nimbus 7 User's Guide 247-262 (SEE N79-20148 11-12)
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  • 35
    Publication Date: 2006-01-12
    Description: Ocean momentum and energy transfer parameters on a nearly all weather operational basis are obtained and used. The winds, water vapor, liquid water content, temperature, and mean cloud droplet size are derived from low altitude parameters.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Nimbus 7 User's Guide; p 213-246
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  • 36
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    In:  CASI
    Publication Date: 2006-01-12
    Description: In the absence of gravity, stirring in a liquid is suppressed because of density differences caused by thermal or compositional gradients. However, other mechanisms resulting in natural convection in a microgravity environment exist. One of the most important mechanisms for liquid metals is surface tension driven convection, which becomes predominant in the low gravity environment. In this case, surface tension differences caused by compositional or temperature gradients have been demonstrated to cause stirring in liquids during experiments performed onboard Skylab. Compositional gradients were created by adding a soap solution to a large water globule, which caused vigorous fluid motion for some moments after the addition.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lyndon B. Johnson Space Center Apollo-Soyuz Test Project; 11 p
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  • 37
    Publication Date: 2006-01-16
    Description: This numerical prediction summary indicates the wide variety of such procedures which are available. Most procedures have detailed user manuals, and in many cases the codes are available. Many of the special effects treated by various methods (such as nonequilibrium or equilibrium chemistry, transition, roughness etc.) are indicated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Calculation Methods for Compressible Turbulent Boundary Layers, 1976; p 69-78
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  • 38
    Publication Date: 2006-01-16
    Description: From comparisons of high speed data with low speed closure procedures using variable mean density, there does not appear to be any appreciable influence of compressibility upon turbulent shear stress modeling in compressible turbulent boundary layers, even for extreme cases such as Mach 14 to 20 with a change in density across the layer of up to a factor of 100. Other evidence of apparent lack of compressibility caused new physics which may alter the shear stress for the compressible boundary layer cases including: (1) fluctuation Mach number was generally less than 1; (2) the shear stress distribution through the boundary layer was not a function of Mach number for zero pressure gradient flows; (3) the Morkovin hypothesis was valid up to Mach 5 (based on fluctuation data); (4) profile N power was not a function of Mach number, at least up to Mach 10; and (5) the nondimensional burst period was approximately the same as that for low speed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Calculation Methods for Compressible Turbulent Boundary Layers, 1976; p 47-68
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  • 39
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2006-01-16
    Description: Basic differential equations governing compressible turbulent boundary layer flow are reviewed, including conservation of mass and energy, momentum equations derived from Navier-Stokes equations, and equations of state. Closure procedures were broken down into: (1) simple or zeroth-order methods, (2) first-order or mean field closure methods, and (3) second-order or mean turbulence field methods.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Calculation Methods for Compressible Turbulent Boundary Layers, 1976; p 6-8
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  • 40
    Publication Date: 2006-01-16
    Description: The control of rotational motion of a spacecraft during its free flight regime is traced from pioneer space flight to the year 1952. Essentials of attitude control systems are reviewed and spin stabilization is examined. Other topics include passive stabilization and active closed loop control.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA, Washington Essays on the History of Rocketry and Astronautics, Vol. 1; p 156-169
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  • 41
    facet.materialart.
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    In:  CASI
    Publication Date: 2006-01-16
    Description: Research done by Spanish pioneer rocket scientists in the 19th century was investigated with major emphasis placed on F. Gomez Arias' rocket vehicle project. Arias, considered the world's first designer of rocket propelled, manned aircraft, was interested in solving the problem of space navigation. Major concerns included ascent and direction of heavier-than-airmachines, as well as ascent and direction of balloons.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA, Washington Essays on the History of Rocketry and Astronautics, Vol. 1; p 176-185
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  • 42
    Publication Date: 2006-01-12
    Description: Thermal/environmental control systems concepts being considered for the power module and manned orbital facilities are described. To assure an economically viable program, the approach being pursued is utilization of existing hardware, where possible, and construction of orbital facilities in modular fashion to meet anticipated growth of space processing, astronomy, life science, solar/terrestrial observation, construction, etc. Configurations include Orbiter tended missions (Orbiter remains attached to orbiting facility) and freeflying manned or unmanned earth-orbiting facilities. Utilization of shuttle hardware, e. g., external tank, or the currently orbiting Skylab vehicle is being considered for orbital facilities. Studies include use of Spacelab hardware with a power module to permit extending on-orbit mission time beyond the capability of the current space transportation system. Power levels of 25 kW are being considered for the power module. Mission duration is not limited due to the modular approach and the concept of utilizing a logistics module to provide consumables' resupply capability to the orbital facility.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: ESA Spacecraft Thermal and Environ. Control Systems; p 575-582
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  • 43
    Publication Date: 2006-01-12
    Description: An instrumentation system developed for the detection of electrical transients on space vehicles is presented. The pulse monitor measures the electron pulse environment on a spacecraft at synchronous altitude, and characterizes signals produced by arcing between differentially charged elements on the spacecraft.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 876-880
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  • 44
    Publication Date: 2006-01-12
    Description: A spacecraft charging simulation facility constructed to investigate the response of satellite materials in a typical geomagnetic substorm environment is described. The conditions simulated include vacuum, solar radiation, and substorm electrons. A nuclear threat environment simulation using a flash X ray generator is combined with the spacecraft charging facility. Results obtained on a solar cell array segment used for a preliminary facility demonstration are presented with a description of the facility.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 854-867
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  • 45
    Publication Date: 2006-01-12
    Description: A sample composed of non conductive optical solar reflectors (OSR) was irradiated with low energy electrons at the DERTS facility to study the effects of charge build up on thermal control coating materials. The degration effects on this panel due to electrostatic discharges were investigated to find possible alternatives to limit the amount of damage. The following systems are evaluated: (1) non conductive OSR (non conductive adhesive) (2) non conductive OSR (conductive adhesive); and conductive OSR (conductive adhesive).
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol.; p 682-703
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  • 46
    Publication Date: 2006-01-12
    Description: Samples of aluminized Kapton used for passive thermal control on the VHF shield and the antenna dish of ESA's OTS satellite and its derivatives were subjected to an incident electron beam of 25 keV and irradiated for 8 hours at room temperature and at -173 C under a vacuum of the 10 to the minus 6 th power torr. Visual observations during electron irradiation, measurements of leakage current and discharge characteristics, and material degradation following completion of irradiation are discussed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 570-586
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  • 47
    facet.materialart.
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    In:  CASI
    Publication Date: 2006-01-12
    Description: An existing model for quantitatively predicting electric field build-up in dielectrics is used to demonstrate the importance of material parameters. Results indicate that electron irradiation will produce 10 to the 6th power V/cm in important materials. Parameters which can alter this build-up are discussed. Comparison to known irradiation induced dielectric charging experiments is discussed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 554-569
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  • 48
    Publication Date: 2006-01-12
    Description: Spacecraft-environment interactions are defined as the responses of a spacecraft surface to a charged-particle environment. This response can influence spacecraft system performance. Interactions can be divided into two broad categories: spacecraft passive, in which the environment acts on the spacecraft; and spacecraft active, in which the spacecraft causes the interaction. Passive interactions include the spacecraft-charging phenomenon. Active interactions include the relatively new interactions arising from the use of very large spacecraft and space power systems in future missions. To illustrate active interactions, a large power system operating at elevated voltages is considered. Possible interactions are described, available experimental data are reviewed, and the effect on power system performance is estimated.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Spacecraft Charging Technol., 1978; p 268-294
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  • 49
    Publication Date: 2006-01-12
    Description: A simple charge balance model based on the work of DeForest was adapted for the calculation of spacecraft potentials. The model was calibrated with ATS 5 plasma data. Once calibrated, the model was used to calculate the time-varying potential that was observed as a spacecraft passes in and out of eclipse. Errors on the order of + or - 800 volts were observed over a range of 0 to -10,000 volts. Possible applications of the model to large space structures are discussed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 239-255
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  • 50
    Publication Date: 2006-01-12
    Description: Spacecraft charging results are presented for the DSCS-3 satellite for a severe geomagnetic substorm. Spacecraft charging results were obtained by the use of the electrostatic charging analysis program (ESCAP). The ESCAP computer code which can determine both the transient or steady state differential charging potentials was an engineering design tool that utilized a circuit theory approach to spacecraft charging. Using the ESCAP code, the steady state (static) differential potentials of the outer spacecraft surfaces and metallic structure were obtained for the DSCS-3 satellite when under the influence of a severe geomagnetic substorm during the local midnight-to-dawn quadrant of its geosynchronous orbital path. The results indicated that, in the steady state, most of the DSCS-3 outer surface materials will not achieve differential potentials large enough to produce an electrostatic discharge.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 158-178
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  • 51
    Publication Date: 2006-01-12
    Description: The NASA charging analyzer program (NASCAP) is a three dimensional, finite element computer code capable of simulating the electrostatic charging of an arbitrary body either in a ground test tank or in the space environment. The code incorporated surface property parameters needed to simulate insulating and conducting materials. These parameters are being updated as required to bring the NASCAP predictions into correspondence with data from ground tests. NASCAP predictions are also being compared with data from the ATS 5 spacecraft. The significance of these results is discussed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Spacecraft Charging Technol., 1978; p 144-157
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  • 52
    Publication Date: 2006-01-12
    Description: The P78-2 spacecraft and its payloads are designed to measure the environment at near synchronous altitude and the interactions of the environment on the spacecraft. A brief description of each payload is provided.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 4-10
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  • 53
    Publication Date: 2006-01-12
    Description: The average plasma environment at geosynchronous orbit (GSO) is derived from a whole year's worth of plasma data obtained by the UCSD electrostatic electrometer on board ATS 5. The result is primarily intended for use as a general reference for engineers designing a large spacecraft to be flown at GSO. A simple mathematical formula using a 3rd order polynomial is found to be adequate for representing the yearly averaged particle energy spectrum from 70 to 41,000 eV under different geomagnetic conditions. Furthermore, correlation analyses with the geomagnetic planetary index Kp and with the auroral electrojet index AE were carried out in the hope that the ground observations of the geomagnetic field variations can be used to predict the plasma variations in space. Unfortunately, the results indicate that such forecasting is not feasible by use of these two popular geomagnetic parameters alone.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 23-37
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  • 54
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    In:  CASI
    Publication Date: 2006-01-12
    Description: The CZCS is used to map chlorophyll concentration, sediment distribution, gelbstroffe concentration, and temperature of coastal waters and the open ocean. The data processing techniques used to enhance contrasts over the ocean and to remove the effect of the backscattered atmosphere are presented. The multi-channel scanning radiometer of CZCS is described. The content of water is determined primarily by the CZCS measurement.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center The Nimbus 7 User's Guide; p 19-32
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  • 55
    Publication Date: 2006-01-12
    Description: Three demonstrations of scientific concepts concerning liquids were performed during the Apollo-Soyuz Test Project mission. Chemical foaming, spreading of liquids, and capillary wicking were the subjects of each demonstration photographed in space. The results clearly illustrated the basic principles, and films suitable for educational uses are now available from the first author.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Apollo-Soyuz Test Project; 9 p
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  • 56
    Publication Date: 2006-01-16
    Description: Two relatively straightforward techniques are outlined for determining spacecraft potentials in the limit of a 'thick sheath' surrounding the spacecraft. A statistical model of the various features of the geosynchronous environment based on ATS-5 and ATS-6 data and an analytic model capable of detailed simulation of the low energy geosynchronous environment are also discussed. The results from these two environmental models are then combined with the charging models in order to provide estimates of the relationships between the geomagnetic index and spacecraft potential. The results are compared with actual potential measurements from ATS-5 and ATS-6.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 104-118
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  • 57
    Publication Date: 2006-01-12
    Description: A water vapor radiometer (WVR) was developed that measures the atmospheric noise temperature at two different frequencies near 22 GHz. These noise temperature are used in empirical-theoretical equations that yield tropospheric range delay, in centimeters, through the atmosphere along the beam of the WVR. This range correction is then applied, as needed, to measurements concerning spacecraft range and to VLBI baseline determinations. The WVR design and calibration techniques are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Deep Space Network; p 129-135
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  • 58
    Publication Date: 2006-01-16
    Description: The calibration coefficients of existing water vapor radiometers are dependent upon meteorology profiles. This is shown to be due mainly to incorrect frequency pairs. By properly selecting an optimum frequency pair, the dependency can be reduced to a relatively small amount which can be handily adjusted by surface measurement alone. Hence, a universal calibration equation is applicable to all environmental conditions - site, seasonal and diurnal variations. Optimum frequency pairs are systematically searched. Error analysis indicates that calibration for the water vapor phase delay accurate to less than 2 cm is possible at all elevation angles greater than 15 degrees.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Deep Space Network; p 67-81
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  • 59
    Publication Date: 2006-01-16
    Description: The Deep Space Network is in the process of fielding high-density digital instrumentation recorders for support of the Pioneer Venus 1978 entry experiment and other related tasks. It has long been obvious that these recorders would also serve well as the recording medium for very long base interferometry (VLBI) experiments with relatively weak radio sources, provided that a suitable correlation processor for these tape recordings could be established. The overall design and current status of a VLBI correlator designed to mate with these tape recorders are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Deep Space Network; p 90-98
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  • 60
    Publication Date: 2006-01-12
    Description: Solar array design guidelines for immunity to the geomagnetic substorm environment at geosynchronous altitudes are summarized. The preliminary design guidelines and recommended practices based on these test results are given. It is concluded that specific design and immunity verification problems on each spacecraft program have to be solved on an individual basis until the technology matures to an adequate level.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 834-852
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  • 61
    Publication Date: 2006-01-12
    Description: Metal plates partially covered by 0.01-centimeter-thick fluorinated ethylene-propylene (FEP) Teflon were charged in the Lewis Research Center's geomagnetic substorm simulation facility using 5-, 8-, 10-, and 12-kilovolt electron beams. Surface voltage as a function of time was measured for various initial conditions (Teflon discharged or precharged) with the metal plate grounded or floating. Results indicate that both the charging rates and the levels to which the samples become charged are influenced by the geometry and initial charge state of the insulating surfaces. The experiments are described and the results are presented and discussed. NASA charging analyzer program (NASCAP) models of the experiments have been generated, and the predictions obtained are described. Implications of the study results for spacecraft are discussed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Spacecraft Charging Technol., 1978; p 507-523
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  • 62
    Publication Date: 2006-01-12
    Description: Flexible solar-array substrates, graphite-fiber/epoxy - aluminum honeycomb panels, and thin dielectric films were exposed to monoenergetic electron beams ranging in energy from 2 to 20 keV in the Lewis Research Center's geomagnetic-substorm-environment simulation facility to determine surface potentials, dc currents, and surface discharges. The four solar-array substrate samples consisted of Kapton sheet reinforced with fabrics of woven glass or carbon fibers. They represented different construction techniques that might be used to reduce the charge accumulation on the array back surface. Five honeycomb-panel samples were tested, two of which were representative of Voyager antenna materials and had either conductive or nonconductive painted surfaces. A third sample was of Navstar solar-array substrate material. The other two samples were of materials proposed for use on Intelsat V. All the honeycomb-panel samples had graphite-fiber/epoxy composite face sheets. The thin dielectric films were 2.54-micrometer-thick Mylar and 7.62-micrometer-thick Kapton.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Spacecraft Charging Technol., 1978; p 457-484
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  • 63
    Publication Date: 2006-01-12
    Description: Large Space Systems (LSS) comprise a new class of spacecraft, the design and performance of which may be seriously affected by a variety of environmental interactions. The special concerns associated with spacecraft charging and plasma interactions from the LSS designer's viewpoint are addressed. Survivability of these systems under combined solar U.V., particle radiation and repeated electrical discharges is of primary importance. Additional questions regard the character of electrical discharges over very large areas, the effects of high current/voltage systems and magnitude of induced structural disturbances. A concept is described for a large scale experiment platform.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 388-407
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  • 64
    Publication Date: 2006-01-12
    Description: Knowledge of the floating voltage configuration of a large array in orbit is needed in order to estimate various plasma-interaction effects. The equilibrium configuration of array voltages relative to space depends on the sheath structure. The latter dependence for an exposed array is examined in the light of two finite-sheath effects. One effect is that electron currents may be seriously underestimated. The other is that a potential barrier for electrons can occur, restricting electron currents. A conducting surface is assumed on the basis of a conductivity argument. Finite-sheath effects are investigated. The results of assuming thin-sheath and thick-sheath limits on the floating configuration of a linearly connected array are studied. Sheath thickness and parasitic power leakage are estimated. Numerically computed fields using a 3-D code are displayed in the thick-sheath limit.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 341-357
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  • 65
    facet.materialart.
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    In:  CASI
    Publication Date: 2006-01-12
    Description: In the context of the spacecraft charging technology investigation, studies were made to characterize the response of typical spacecraft surface materials to the charging environment. The objective is to obtain an understanding of the charging and discharging behavior of such materials for the reliable prediction of spacecraft response to charging environments and as a guide for the design of future spacecraft. Materials were characterized in terms of such basic properties as resistivity and secondary emission and in terms of charging and discharging behavior in simulated charging environments.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Spacecraft Charging Technol., 1978; p 437-456
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  • 66
    Publication Date: 2006-01-12
    Description: Some preliminary findings regarding the interactions between the space plasma at GEO and the Marshall Space Flight Center January 1978 baseline Satellite Power Systems (SPS) design are summarized. These include the following: (1) the parasitic load will be dominated by photoelectrons and will amount to about 34 MW; (2) material of higher conductivity than kapton should be used for the solar reflector substrate and the solar cell blanket support material; (3) the satellite structure and solar reflector should be tied electrically to midpoint voltage of each solar cell array; and (4) tests should be run on the proposed solar cell cover glass material (synthetic sapphire) to determine if breakdown is expected.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 408-418
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  • 67
    Publication Date: 2006-01-12
    Description: A large (1m x 10m) flat surface of conductive material was biased to high voltage (+ or - 3000 V) to simulate the behavior of a large solar array in low earth orbit. The model array was operated in a plasma environment of 1,000 to 1,000,000/cu cm, with sufficient free space around it for the resulting plasma sheaths to develop unimpeded for 5-10 meters into the surrounding plasma. Measurements of the resulting sheath thickness were obtained. The observed thickness varied approximately as V to the 3/4 power and N to the 1/2 power. This effect appears to limit total current leakage from the test array until sheath dimensions exceed about 1 meter. Total leakage current was also measured with the array.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 315-340
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  • 68
    Publication Date: 2006-01-12
    Description: An auxiliary payload package called PIX (plasma interaction experiment) was launched on March 5, 1978, on the LANDSAT 3 launch vehicle to study interactions between the space charged-particle environment and surfaces at high applied positive and negative voltages. Three experimental surfaces were used in this package: a plain disk to act as a control, a disk on a Kapton sheet to determine the effect of surrounding insulation on current collection, and a small solar-array segment to evaluate the effect of distributing biased surfaces among an array of insulators. Only half of the results from the 4 hours of PIX operations were recovered. The results did verify effects found in ground simulation testing. The results of this experiment are discussed in detail.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Spacecraft Charging Technol., 1978; p 295-314
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  • 69
    Publication Date: 2006-01-12
    Description: The ATS 5 and ATS 6 data for spacecraft charging during eclipse conditions is analyzed. The ATS 5 and ATS 6 charged to voltages greater than 100 volts for about 55 percent of the eclipse periods examined. The mean spacecraft potential during eclipse was 2 keV for ATS 5, and the highest potential measured was 10 kilovolts. For ATS 6, the mean potential during eclipse was 4 keV, the highest potential measured 20 keV. The average measured spacecraft potentials for both ATS 5 and 6 depend approximately linearly upon Kp. This relationship is due mainly to the dependence of electron current density on Kp near midnight. Spacecraft potentials at geosynchronous orbit may, to a rough approximation, thus be inferred from ground-based measurements of Kp, the planetary 3-hour index.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 38-43
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  • 70
    facet.materialart.
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    In:  CASI
    Publication Date: 2006-01-12
    Description: An analytic simulation of the geosynchronous environment in terms of local time and the daily A sub P index is presented. The simulation is compared with actual statistical data from approximately 50 days of ATS 5 plasma data and 50 days of ATS 6 plasma data. At low levels of activity the model adequately simulates the local time variations of the plasma parameters. At high values of geomagnetic activity, the predicted magnitudes of the plasma parameters agree with the statistical results but the effects of multiple injections are evident in both the data and the simulation, biasing the local time variations.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 11-22
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  • 71
    Publication Date: 2006-01-12
    Description: Experiments conducted on the ATS 5 and ATS 6 which have demonstrated the feasibility of modifying or clamping the environmentally induced potential of these spacecraft are described. The results of these experiments indicate that a thermionic electron source is capable of replacing photo-emitted electrons during eclipse. However, the utility of this type of device is limited if its emission is suppressed by local electric fields. On the other hand, it is shown that a plasma source will not only serve as a substitute for photo-emitted electrons but will also suppress differential charging of isolated elements of the spacecraft which would tend to suppress electron emission. This later device is therefore capable of clamping the potential of a spacecraft without special considerations of its coupling to the ambient plasma.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Spacecraft Charging Technol., 1978; p 44-58
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  • 72
    Publication Date: 2006-01-12
    Description: Results are presented to illustrate the application of established procedures of linear, quadratic, Gaussian optimal estimation and control to a spacecraft with dynamically significant elastic appendages. Interpretations are provided in both time domain and frequency domain, and conclusions are drawn for a wide class of problems of flexible spacecraft attitude control.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: ESA Dyn. and Control of Non-rigid Space Vehicles; 5 p
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  • 73
    Publication Date: 2006-03-02
    Description: The OAO was successfully operating for approximately 11 months and has made over 2500 stellar observations. The OAO control system was a complex system which takes the 4500-lb vehicle through initial stabilization to star tracker control where a pointing accuracy of less than 1 arc minute was achieved. To obtain this pointing accuracy, the system used six orthogonally mounted gimbaled star trackers. The trackers were two gimbaled devices, having a 1-deg field of view with a + or - 43 deg gimbal excursion. The tracker could recognize and track 2.0 magnitude stars or brighter. The flight results indicated spacecraft pointing accuracies of less than 1 arc minute after tracker calibration with spacecraft jitter less than 3 arc seconds.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA, Washington Fourth Inter-Center Control Systems Conf.; p 83-125
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  • 74
    Publication Date: 2011-08-24
    Description: The Magellan spacecraft has been aerobraked into a 197 x 541 km near-circular orbit around Venus from which it is conducting a high-resolution gravity mapping mission. This was the first interplanetary aerobrake maneuver and involved flying the spacecraft through the upper reaches of the Venusian atmosphere 730 times over a 70 day period. Round-trip light-time varied from 9.57 to 18.83 minutes during this period. Navigation for this dynamic phase of the Magellan mission was planned and executed in the face of budget-driven down-sizing with all spacecraft safe modes disabled and a flight-team one-third the size of comparable interplanetary missions. Successful execution of this manuever using spacecraft hardware not designed to operate in a planetary atmosphere, demonstrated a practical cost-saving technique for both large and small future interplanetary missions.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: British Interplanetary Society, Journal (ISSN 0007-094X); 48; 3; p. 111-122
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  • 75
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: Experiences derived from the development, integration, and flight of NASA spacecraft and sounding rockets are presented. They include the International Heat Pipe Experiment, OAO 3, and ATS-6. Typical flight data are presented to show the performance.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ESA Heat Pipes; p 647-653
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  • 76
    Publication Date: 2011-08-16
    Description: The pressure sensor for the Tropical Wind Energy conversion and Reference Level Experiment (TWERLE) is described. Key design features of the sensor are: capacitive coupling, reference at midrange, up-down counting, passive oven, storage at flight pressure and prelaunch calibration. Sensor specifications are given which are based on the production results of 440 units. Drift, as estimated from simulated life tests, is 1 mb per 6 months. The overall weight of the sensor, including thermal package, is 180 g.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Applied Meteorology; 14; Sept
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  • 77
    Publication Date: 2011-08-16
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 78
    Publication Date: 2011-08-16
    Description: A theory is proposed for analyzing the inviscid interpretation of two streams in the case when the difference in total pressure between the streams is relatively small. A stream is considered which discharges from a nozzle or reservoir into a partially moving and partially stationary environment in such a way that the flows leave the solid boundaries in a tangential direction where the two streams first interact. The problem is solved by expanding in a small parameter related to the difference in total pressure between the streams, the zeroth-order solution is obtained by classical methods, and a technique similar to that employed in thin-airfoil theory is used to transfer the first-order boundary conditions to the zeroth-order boundary. A procedure is developed to transform the problem into one that can be solved by standard techniques of the theory of sectionally analytic functions. Solutions are obtained for flows with and without free streamlines, and the general theory is applied to several specific flow configurations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 70; Aug. 12
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  • 79
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    Publication Date: 2011-08-16
    Description: A new approach to seeing in the dark is described which is based on the principles of nonlinear optics employing a crystal such as lithium iodate. A nonlinear optical device capable of producing photons at higher frequencies from lower-frequency incident light is shown to upconvert infrared light directly into visible light. The major advantages of the infrared upconversion process is that it permits the infrared signal to be detected by photon-counting devices presently available for the visible spectral region, and that it can provide sensitivity to infrared radiation without the need for cryogenic cooling of the detector used. Early works on infrared upconversion are reviewed. The development of applications is discussed as to astronomical spectroscopy and infrared image upconversion involving either angular or positional resolution elements. The demonstration of infrared upconversion in rectangular waveguides of single-crystal GaAs by Anderson et al. (1971) indicates future possibilities in upconversion by the use of integrated optics devices.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Sciences Center Newsletter; 9; May 1975
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  • 80
    Publication Date: 2011-08-16
    Description: A tunable, Dicke-switched, infrared heterodyne radiometer (IHR) has been designed, fabricated, tested, and used to observe solar radiation and determine the atmospheric transmissivity in the 9-11-micron spectral band. The IHR provides a spectral resolution of 0.0067 reciprocal cm, a minimum detectable power level of 2.9 times ten to the minus twenty-third power W/Hz, and a temperature resolution of less than 1 K for a source temperature of 1000 K, an IF predetection bandwidth of 100 MHz, and an integration time of 30 s. Detailed design equations and measured IHR performance are presented. The IHR was used to make solar and atmospheric transmission measurements, and a vertical-path atmospheric attenuation of 2.3 dB has been established under favorable weather conditions. The attenuation of solar radiation due to cloud cover and haze has also been investigated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Journal of Quantum Electronics; QE-11; Aug. 197
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  • 81
    Publication Date: 2011-08-16
    Description: An approach is presented for applying the net radiation method developed by Siegel and Howell (1972) and Sparrow and Cess (1966) to systems involving opaque and partially transmitting walls. The results obtained from the basic equations for various values of plate emissivities and temperatures are presented in graphs. Attention is given to the window temperature relative to the temperature of the hot wall and the heat transferred relative to that transferred without the window.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Letters in Heat and Mass Transfer; 2; Mar
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  • 82
    Publication Date: 2011-08-16
    Description: The 7.3 kg cameras for the 1976 Viking Mars expedition feature an array of 12 silicon photodiodes, including six spectral bands for color and near-infrared imaging with an angular resolution of 0.12 deg and four focus steps for broadband imaging, with an improved angular resolution of 0.04 deg. The field of view in elevation ranges from 40 deg above to 60 deg below the horizon, and in azimuth ranges to 342.5 deg. The cameras are mounted 0.8 m apart to provide a stereo view of the area accessible to a surface sampler for biological and chemical investigations. The scanning rates are synchronized to the lander data transmission rates of 16000 bits per sec to the Viking orbiters as relay stations and 250 bits per sec directly to earth. However, image data can also be stored on a lander tape recorder. About 10 million bits of image data will be transmitted during most days of the 60-day-long mission planned for each lander.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Space Science Instrumentation; 1; May 1975
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  • 83
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    Publication Date: 2011-08-16
    Description: The high field fluxgate magnetometer experiment flown aboard the Pioneer XI spacecraft is described. This extremely simple instrument was used to extend the spacecraft's upper-limit measurement capability by approximately an order of magnitude (from 0.14 mT to 1.00 mT) with minimum power and volume requirements. This magnetometer was designed to complement the low-field measurements provided by a helium vector magnetometer and utilizes magnetic ring core sensors with biaxial orthogonal sense coils. The instrument is a single-range, triaxial-fluxgate magnetometer capable of measuring fields of up to 1 mT along each orthogonal axis, with a maximum resolution of 1 microT.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Space Science Instrumentation; 1; May 1975
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  • 84
    Publication Date: 2011-08-16
    Description: A Green's function formulation is used to derive basic reciprocity relations for planar radiative transfer in a general medium with internal illumination. Reciprocity (or functional symmetry) allows an explicit and generalized development of the equivalence between source and probability functions. Assuming similar symmetry in three-dimensional space, a general relationship is derived between planar-source intensity and point-source total directional energy. These quantities are expressed in terms of standard (universal) functions associated with the planar medium, while all results are derived from the differential equation of radiative transfer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer; 15; Sept
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  • 85
    Publication Date: 2011-08-16
    Description: Radiation from an array of longitudinal fins of triangular profile is analyzed, including fin-to-fin and fin-to-base interactions. The effect of base cylinder radiation and the fin-base radiative interaction is found to be significant for fin width/tube radius ratios less than 8. Results presented may be used to optimize the design of a fin array with respect to weight.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 13; May 1975
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  • 86
    Publication Date: 2011-08-16
    Description: The effects of the grid transparency and finite collector size on the values of thermal ion density and temperature determined by the standard RPA (retarding potential analyzer) analysis method are investigated. The current-voltage curves calculated for varying RPA parameters and a given ion mass, temperature, and density are analyzed by the standard RPA method. It is found that only small errors in temperature and density are introduced for an RPA with typical dimensions, and that even when the density error is substantial for nontypical dimensions, the temperature error remains minimum.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Geophysical Research; 80; June 1
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  • 87
    Publication Date: 2011-08-16
    Description: The phase correction for a Michelson interferometer with misaligned mirrors in converging light is shown to give rise to a quadratic phase shift. In general, the calculation of a spectrum from the measured interferogram needs phase correction. Phase corrections have been well worked out for the cases of a linear phase shift and a phase that is slowly varying. The standard procedures for correcting calculated spectra need to be modified, however, to remove any phase errors resulting from misaligned mirrors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 14; June 197
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  • 88
    Publication Date: 2011-08-16
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 13; Apr. 197
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  • 89
    Publication Date: 2011-08-16
    Description: This paper describes the design and performance of a set of cosmic-ray particle experiments for the Pioneer 10/11 and Helios A/B space missions. These experiments had to be very light-weight, low-power and electronically sophisticated in order to meet the spacecraft and scientific requirements. Both sets of missions use several solid-state detector telescopes to measure protons from 100 KeV to 800 MeV and heavier ions up to Neon at 200 MeV per nucleon. Good performance is required for 7-8 years, and the system must tolerate large vibration loads and ionizing radiation doses up to 500,000 rads.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 90
    Publication Date: 2011-08-17
    Description: An explicit representation for the unsteady motion on a transversely sheared mean flow is obtained which corresponds to the gustline motion on a uniform mean flow. The important features of this motion are discussed. It is shown that its velocity, pressure and vorticity are all induced by a certain disturbance field that is a linear combination of the vorticity and particle-displacement fields and is everywhere frozen in the mean flow. The general ideas are illustrated by considering the scattering of a gust by a half-plane embedded in a shear flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 84; Jan. 30
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  • 91
    Publication Date: 2011-08-17
    Description: Estimates of neutron fluxes in different energy ranges are reported for the Skylab spacecraft. Detectors composed of uranium, thorium, and bismuth foils with mica as a fission track recorder, as well as boron foils with cellulose acetate as an alpha-particle recorder, were deployed at different positions in the Orbital Workshop. It was found that the Skylab neutron flux was dominated by high energy (greater than 1 MeV) contributions and that there was no significant time variation in the fluxes. Firm upper limits of 7-15 neutrons/sq cm-sec, depending on the detector location in the spacecraft, were established for fluxes above 1 MeV. Below 1 MeV, the neutron fluxes were about an order of magnitude lower. The neutrons are interpreted as originating from the interactions of leakage protons from the radiation belt with the spacecraft.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Space Science Instrumentation; 3; Nov. 197
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  • 92
    Publication Date: 2011-08-17
    Description: A computer code, NASCAP (NASA Charging Analyzer Program), has been developed by Systems, Science and Software under contract to NASA-LeRC to simulate the charging of a complex spacecraft in geosynchronous orbit. The capabilities of the NASCAP code include a fully three-dimensional solution of Poisson's equation about an object having considerable geometrical and material complexity, particle tracking, shadowing in sunlight, calculation of secondary emission, backscatter and photoemission, and graphical output. A model calculation shows how the NASCAP code may be used to improve our understanding of the spacecraft-plasma interaction.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
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  • 93
    Publication Date: 2011-08-17
    Description: Final results from the CMOS Radiation Effects Measurement (CREM) experiment flown on Explorer 55 are presented and discussed, based on about 15 months of observations and measurements. Conclusions are given relating to long-range annealing, effects of operating temperature on semiconductor performance in space, biased and unbiased P-MOS device degradation, unbiased n-channel device performance, changes in device transconductance, and the difference in ionization efficiency between Co-60 gamma rays and 1-Mev Van de Graaff electrons. The performance of devices in a heavily shielded electronic subsystem box within the spacecraft is evaluated and compared. Environment models and computational methods and their impact on device-degradation estimates are being reviewed to determine whether they permit cost-effective design of spacecraft.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
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  • 94
    Publication Date: 2011-08-17
    Description: A technique has been developed to automatically correct for drifts in the radiometric sensitivity of the detector channels in a direct-reading emission spectrometer. The method utilizes a 1000 W tungsten-halogen reference lamp to illuminate the detectors through the same optical path as that traversed during the analysis of the sample. Detector channel responses to the light are compared to those for the same light intensity at the time of analytical calibration. This corrects for the drift. It is noted that with the exception of positioning the lamp, the procedure is fully automatic.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Spectroscopy; 32; Jan
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  • 95
    Publication Date: 2011-08-17
    Description: The future role of conventional scintillation detector telescopes for line gamma-ray astronomy is discussed. Although the energy resolution of the germanium detectors now being used by several groups is clearly desirable, the larger effective areas and higher efficiencies available with scintillation detectors is advantageous for many observations. This is particularly true for those observations of astrophysical phenomena where significant line broadening is expected.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Gamma Ray Spectry. in Astrophys.; p 438-449
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  • 96
    Publication Date: 2011-08-17
    Description: The absolute counting efficiency and pulse height distributions of a continuous-channel electron multiplier used in the detection of hydrogen, argon and xenon ions are assessed. The assessment technique, which involves the post-acceleration of 8-eV ion beams to energies from 100 to 4000 eV, provides information on counting efficiency versus post-acceleration voltage characteristics over a wide range of ion mass. The charge pulse height distributions for H2 (+), A (+) and Xe (+) were measured by operating the experimental apparatus in a marginally gain-saturated mode. It was found that gain saturation occurs at lower channel multiplier operating voltages for light ions such as H2 (+) than for the heavier ions A (+) and Xe (+), suggesting that the technique may be used to discriminate between these two classes of ions in electrostatic analyzers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 48; Aug. 197
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  • 97
    Publication Date: 2011-08-17
    Description: A numerical method by which data from a single embedded thermocouple can be used to predict the transient thermal environment for both high- and low-conductivity materials is described. The results of an investigation performed to verify the method clearly demonstrate that accurate transient surface heating conditions can be obtained from a thermocouple 1.016 cm from the surface in a low-conductivity material. Space Shuttle Orbiter thermal protection system materials having temperature- and pressure-dependent properties and typical Orbiter entry heating conditions were used to verify the accuracy of the analytical procedure. Analytically generated, as well as experimental, data were used to compare predicted and measured surface temperatures.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Spacecraft and Rockets; 14; Oct. 197
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  • 98
    Publication Date: 2011-08-17
    Description: The physical conditions in laboratory gases and in the upper atmosphere of the planets, including earth, can be deduced from a measurement of the intensity and line profile of different radiating molecules. Because of the low pressures in the upper atmospheres, many molecular lines with small pressure-broadening coefficients are collisionally narrowed. These lines are resolvable with a Fabry-Perot interferometer. Analytical expressions are given relating the measured line intensity and profile to the true line intensity and profile. A deconvolution of the measured profile gives the parameters A, beta, and K characterizing the collisionally narrowed Galatry profile. General expressions for the nonideal interferometer are discussed, and, specifically, mirror defects and a limited detector aperture are treated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 16; June 197
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  • 99
    Publication Date: 2011-08-17
    Description: The two-dimensional leveling problem (Degani, Gutfinger, 1976) is extended to three dimensions in the case where the flow Re number is very low and attention is paid to the free surface boundary condition with surface tension effects included. The no-slip boundary condition on the wall is observed. The numerical solution falls back on the Marker and Cell (MAC) method (Harlow and Welch, 1965) with the computation region divided into a finite number of stationary rectangular cells (or boxes in the 3-D case) and fluid flow traverses the cells (or boxes).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 24; May 1977
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  • 100
    facet.materialart.
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    Publication Date: 2011-08-17
    Description: There exists a need for a relatively inexpensive system for measuring strain in bolts. The torque wrench is one technique for straining bolts which has been widely applied. Unfortunately, friction in the bolt threads and between the nut and the work tend to make such a simple system inaccurate. In practice, a torque wrench is unacceptable for many situations where strain is critical. In this article, an ultrasonic technique is described which can indicate changes in bolt strain to better than one part in 10,000. The technique is based on the one-dimensional propagating-ultrasonic-wave model and uses a new ultrasonic instrument called a Reflection Oscillator Ultrasonic Spectrometer which is a closed-loop feedback marginal-oscillator system that frequency locks the device to the peak of a mechanical resonance in the bolt. The instrument indicates a shift in the bolt resonance frequency due to elongation and changes in velocity of sound due to strain. Data are presented comparing a standard torque wrench to the ultrasonic monitor for different measured stresses on the bolt as well as for different bolt conditions. The strain instrument can be used to monitor changing stresses, to measure material properties and may be applied as a strain gage or load cell.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Experimental Mechanics; 17; May 1977
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