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  • Other Sources  (3,301)
  • INSTRUMENTATION AND PHOTOGRAPHY  (1,195)
  • ASTRONOMY  (1,188)
  • SPACECRAFT DESIGN, TESTING AND PERFORMANCE  (918)
  • Cell & Developmental Biology
  • 1975-1979  (3,295)
  • 1950-1954  (6)
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  • 1
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    Further development of the multipactor discharge electron source (1979)
    In:  CASI
    Details
    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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  • 2
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    The Qualification of a large electron irradiation facility for telecommunication satellite differential charging simulation (1979)
    In:  CASI
    Details
    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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  • 3
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    Secondary electron effects on spacecraft charging (1979)
    In:  CASI
    Details
    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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  • 4
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    Parameter dependence of equilibrium charging potentials (1979)
    In:  CASI
    Details
    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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  • 5
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    Thermal blanket metallic film groundstrap and second surface mirror vulnerability to arc discharges (1979)
    In:  CASI
    Details
    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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  • 6
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    Secondary emission effects on spacecraft charging: Energy distribution considerations (1979)
    In:  CASI
    Details
    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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  • 7
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    Model for breakdown process in dielectric discharges (1979)
    In:  CASI
    Details
    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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  • 8
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    Area scaling investigations of charging phenomena (1979)
    In:  CASI
    Details
    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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  • 9
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    Plasma particle trajectories around spacecraft propelled by ion thrusters (1979)
    In:  CASI
    Details
    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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  • 10
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    Effect of parasitic plasma currents on solar-array power output (1979)
    In:  CASI
    Details
    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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  • 11
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    Magnetic shielding of large high-power-satellite solar arrays using internal currents (1979)
    In:  CASI
    Details
    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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  • 12
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    Spacecraft potential control on ISEE-1 (1979)
    In:  CASI
    Details
    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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  • 13
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    Electron transport model of dielectric charging (1979)
    In:  CASI
    Details
    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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  • 14
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    Design, development, and flight of a spacecraft charging sounding rocket payload (1979)
    In:  CASI
    Details
    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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  • 15
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    Absorption lines in the spectra of distant objects (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Studies that can be carried out with the Space Telescope of absorption line systems which may be expected to occur in the spectra of distant objects are discussed. The phenomenology of quasar absorption line systems is described and the principal suggested explanations are summarized. It is proposed that the numerous Ly-alpha systems are caused by 'extremely large hydrogenic halos around galaxies or clusters of galaxies. Two tests are also described for the origins of known absorption systems, the results of which will favor either the cosmological or intrinsic hypothesis. Absorption lines that are likely to be strongest are listed and a sample observing program is presented.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Sci. Res. with the Space Telescope; p 215-240
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  • 16
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    Space telescope observations of normal galaxies (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Observations of the stellar content of galaxies are discussed. Specific emphasis is placed on the following two types of observation: (1) those objects near enough to observe individual stars; and (2) those so distant that only their integrated light can be observed.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Sci. Res. with the Space Telescope; p 165-180
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  • 17
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    Population statistics of faint stellar and non-stellar objects (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A disc and halo population model is constructed to fit star counts and color data down to V approximately 23 at absolute value of b = 90 deg. This model is used to predict star counts and colors down to V approximately 30. Deviations from these extrapolated relationships provide constraints on the number of faint quasars and black dwarf stars. It is shown that extra-galactic globular clusters start contributing significantly to star counts at V approximately 25 and are more numerous than stars for V 31. Morphological studies of galaxies with approximately 0.5, were made with the space telescope. Significant constraints on theoretical models that describe the evolution of clusters of galaxies are provided.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Sci. Res. with the Space Telescope; p 151-164
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  • 18
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    The space telescope observatory (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A guide to the expected characteristics of the space telescope (ST) observatory is presented. The general objectives of the ST observatory are summarized. The plans for the development of the observatory are described with a brief history of the scientific activities; an account of the scope of the present program; a summary of the major responsibilities of the contractors; and a list of the project milestones are included. The performance characteristics of the observatory are provided including the imaging and stray light characteristics, pointing capability, and operational access. The expected performance characteristics of all six of the first generation science instruments are summarized. The mode of operations is described which includes a discussion of program options, guide star selection, methods of acquisition, and quick look data capabilities.
    Keywords: ASTRONOMY
    Type: Sci. Res. with the Space Telescope; p 5-46
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  • 19
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    Development of the Transient Pulse Monitor (TPM) for Scatha/P78-2 (1979)
    In:  CASI
    Details
    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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  • 20
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    A combined spacecraft charging and pulsed X-ray simulation facility (1979)
    In:  CASI
    Details
    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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  • 21
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    Investigation of electrostatic discharge phenomena on conductive and non-conductive solar reflectors (1979)
    In:  CASI
    Details
    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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  • 22
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    Effects of electron irradiation on large insulating surfaces used for European Communications Satellites (1979)
    In:  CASI
    Details
    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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  • 23
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    Electric fields in irradiated dielectrics (1979)
    In:  CASI
    Details
    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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  • 24
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    Interactions between spacecraft and the charged-particle environment (1979)
    In:  CASI
    Details
    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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  • 25
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    The calculation of spacecraft potential: Comparison between theory and observation (1979)
    In:  CASI
    Details
    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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  • 26
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    Spacecraft charging results for the DSCS-3 satellite (1979)
    In:  CASI
    Details
    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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  • 27
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    Comparison of NASCAP predictions with experimental data (1979)
    In:  CASI
    Details
    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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  • 28
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    Description of the Space Test Program P78-2 spacecraft and payloads (1979)
    In:  CASI
    Details
    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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  • 29
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    Average plasma environment at geosynchronous orbit (1979)
    In:  CASI
    Details
    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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  • 30
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    Prediction of spacecraft potentials at geosynchronous orbit (1979)
    In:  CASI
    Details
    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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  • 31
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    Radio astronomers, X-ray astronomers and the space telescope (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The use of the Space Telescope and the study of objects in the radio and X-ray wavebands, particularly extragalactic objects, are discussed. The scientific objectives of a number of projects which involve observations with the Space Telescope are described.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Sci. Res. with the Space Telescope; p 241-262
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  • 32
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    Planetary astronomy with the space telescope (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Experimental methods in planetary astronomy are discussed using a comparison of the advantages and disadvantages in the astronomical methods of ground based, Earth-orbit, and deep space missions. Problem areas in planetary astronomy which demonstrate the utility and power of the space telescope (ST) over other methods are delineated. These include utilizing the ST for studying the atmospheric dynamics, stratospheric and upper atmospheric processes, and circumplanetary nebulae of the planets. The capability of the ST for solar system observations is summarized with a discussion of the increases in resolution and sensitivity of the ST over other Earth-orbiting telescopes highlighted.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Sci. Res. with the Space Telescope; p 47-75
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  • 33
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    TDRSS solar array arc discharge tests (1979)
    In:  CASI
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    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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  • 34
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    Charging rates of metal-dielectric structures (1979)
    In:  CASI
    Details
    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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  • 35
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    Test results for electron beam charging of flexible insulators and composites (1979)
    In:  CASI
    Details
    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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  • 36
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    Environmental interaction implications for large space systems (1979)
    In:  CASI
    Details
    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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  • 37
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    Plasma sheath effects and voltage distributions of large high-power satellite solar arrays (1979)
    In:  CASI
    Details
    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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  • 38
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    Status of materials characterization studies (1979)
    In:  CASI
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    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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  • 39
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    Space environmental effects and the solar power satellite (1979)
    In:  CASI
    Details
    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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  • 40
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    Sheath effects observed on a 10 meter high voltage panel in simulated low earth orbit plasma (1979)
    In:  CASI
    Details
    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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  • 41
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    Plasma Interaction Experiment (PIX) flight results (1979)
    In:  CASI
    Details
    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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  • 42
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    ATS-5 and ATS-6 potentials during eclipse (1979)
    In:  CASI
    Details
    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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  • 43
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    Modeling of the geosynchronous plasma environment (1979)
    In:  CASI
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    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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  • 44
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    Summary of the two year NASA program for active control of ATS-5/6 environmental charging (1979)
    In:  CASI
    Details
    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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  • 45
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    Direct determination of asteroid diameters from occultation observations (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Of the available earth-based techniques for determining asteroid diameters, observation of stellar occultations involving asteroids is clearly the most direct. The high degree of accuracy achievable by this method has already been demonstrated in the case of Pallas, whose mean diameter has been measured with a standard error of plus or minus 2%. In this paper the problems, results and prospects of the stellar occultation technique are reviewed. It is shown that, with the use of a network of small, portable telescopes, the method is currently applicable to a large number of asteroids. The best results can be expected for asteroids of large angular diameter and regular shape. The potential of lunar occultation observations for asteroid diameter measurements is also briefly discussed.
    Keywords: ASTRONOMY
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  • 46
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    The Surface Contour Radar, a unique remote sensing instrument (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A 36 GHz computer controlled airborne Surface Contour Radar (SCR) is described, which was developed by the Naval Research Laboratory and NASA. The system uses pulse-compression techniques and dual frequency carriers spaced far enough apart to be decorrelated on the sea surface. The continuous wave transmitter is biphase modulated, the return signal is autocorrelated, and the code length and clock rate are variable, providing selectable range resolutions of 0.15, 0.30, 0.61 and 1.52 m. The SCR generates a false-color coded elevation map of the sea surface below the aircraft in real time, and can routinely produce ocean directional wave spectra with off-line data processing.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 47
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    Proper elements and family memberships of the asteroids (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The proper elements tabulated are calculated according to the secular perturbation theory of Williams (1969); the free oscillations are referred to a zero value for the proper argument of perihelion. The secular theory for the planets is taken from Brouwer and van Woerkom (1950). Families with numbers smaller than 100 are reasonably close matches to families found by previous investigators. Families with numbers greater than 100 are new to this work. Guidelines for use of the table are given.
    Keywords: ASTRONOMY
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  • 48
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    Colorimetry and magnitudes of asteroids (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: In the present paper, 1500 UBV observations are analyzed by a new rather general multiple scattering theory which provided clear insight into previously poorly-recognized optical nature of asteroid surfaces. Thus, phase curves are shown to consist of a surface-texture controlled component, due to singly scattered light, and a component due to multiple scattering. Phase curve shapes can be characterized by a single parameter, the multiple scattering factor, Q. As Q increases, the relative importance of the opposition effect diminishes. Asteroid surfaces are particulate and strikingly similar to texture, being moderately porous and moderately rough on a scale greater than the wavelength of light. In concequence, Q (and also the phase coefficient) correlate well with geometric albedo, and there exists a purely photometric means of determining albedos and diameters.
    Keywords: ASTRONOMY
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  • 49
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    Families of minor planets (1979)
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    Publication Date: 2011-08-17
    Description: Physical studies of individual family members show that at least the Themis, Eos, Koronis, Nysa/Hertha, and Budrosa families of minor planets are the result of the breakup of discrete parent bodies. Only a few families have been studied in detail, and even in those few cases, the full force of observational techniques has not been applied. Crucial for the understanding of families and their parent bodies are detailed physical studies of family members; precise mineralogical interpretation of observational data to identify the geochemistry of the parent bodies; and studies of the collisional evolution of family members.
    Keywords: ASTRONOMY
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  • 50
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    Minor planets and related objects. XXVIII - Asteroid magnitudes and phase relations (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 84; July 197
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  • 51
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    Stability bounds for the control of large space structures (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Balas (1977) has discussed the stability problem of reduced-order regulators and estimators in terms of control and observation 'spillover'. The term 'control spillover' was used to define that part of the feedback control which excites the uncontrolled (or residual) modes, and 'observation spillover' was used to define that part of the measurement which is contaminated by residual modes. In this paper, two sufficient conditions are derived via Lyapunov methods for asymptotic stability of large space structures using a class of reduced-order controllers. These conditions give allowable bounds on the spectral norms of control and observation spillover terms. The sufficient condition given by a specified inequality equation appears to be less conservative, and should be useful as a design tool for the control of large space structures.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Guidance and Control; 2; July-Aug
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  • 52
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    Space Telescope optics (1979)
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    Publication Date: 2011-08-17
    Description: The paper reviews the optical technology that has been developed over the last decade for the Space Telescope. The optical design of the telescope, the optical performance control system, and the anticipated optical performance are all presented. Consideration is also given to the initial complement of focal plane instruments.
    Keywords: ASTRONOMY
    Type: Optical Engineering; 18; May-June
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    Forbidden Fe X and forbidden Fe XIV emission from Puppis A and other supernova remnants (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Measurements of Fe XIV 5303-A and Fe X 6374-A forbidden emission from several supernova remnants are reported, and their relation to X-ray observations is discussed. The brightest Fe XIV forbidden-emission region in Puppis A is interpreted as being the result of the supernova shock wave's interacting with a dense cloud in the interstellar medium.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 228
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  • 54
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    Detection of hairline cracks in textured silicon solar cells (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Using a focused laser scanner, the optical technique described in the present paper can be used to detect hairline cracks of the type occurring in solar cells subjected to surface texturing. The technique is capable of detecting cracks of the order of a few microns, which, otherwise, can be observed only under high magnification using an optical microscope. The technique consists of scanning a solar cell with a finely focused laser beam and recording the photoresponse (short circuit current or open circuit voltage) as a function of beam position. The presence of a crack is manifested by a sharp dip in the photoresponse.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 18; Mar. 1
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  • 55
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    The low-noise 115-GHz receiver on the Columbia-GISS 4-ft radio telescope (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The superheterodyne millimeter-wave radiometer on the Columbia-GISS 4-ft telescope is described. This receiver uses a room-temperature Schottky diode mixer, with a resonant-ring filter as LO diplexer. The diplexer has low signal loss, efficient LO power coupling, and suppresses most of the LO noise at both sidebands. The receiver IF section has a parametric amplifier as its first stage with sufficient gain to overcome the second-stage amplifier noise. A broad-banded quarter-wave impedance transformer minimizes the mismatch between mixer and paramp. At 115 GHz, the SSB receiver noise temperature is 860 K, which is believed to be the lowest figure so far reported for a room-temperature receiver at this frequency.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Microwave Theory and Techniques; MTT-27; Mar. 197
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  • 56
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    Status of the Space Telescope project in the United States (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A general description of the evolution of the Large Space Telescope project is given, including mirror construction, interface requirements, and the review cycle for the scientific instruments. The anticipated participation of ESA scientists through the means of the Science Institute is discussed.
    Keywords: ASTRONOMY
    Type: ESA Astron. Uses of the Space Telescope; p 27-31
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    The Spacelab Wide Angle Telescope (SWAT) (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A fast wide angle telescope that will be capable of imaging to the darker sky limit and in the ultraviolet wavelength region available above the atmosphere is described. The telescope (SWAT) has a resolution comparable to that of the large ground-based Schmidt telescope and a field of at least five degrees. A number of astrophysically important investigations can only be accomplished with such a telescope, e.g., detection of hidden, hot objects like hot white dwarfs and subwarfs in stellar binary systems, and energetic regions in globular clusters and galaxy nuclei. It permits unique studies of the UV-morphology of extended objects and allows discovery of very faint extensions, halos, jets, and filaments in galaxies. It can contribute to the investigation of dust in the Milky Way and in other galaxies and, with an objective prism, spectra of very faint objects can be obtained. The SWAT will localize objects for further study with the narrow-field Space Telescope.
    Keywords: ASTRONOMY
    Type: ESA Astron. Uses of the Space Telescope; p 375-392
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  • 58
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    Contamination enhanced electrostatic discharge mechanisms (1979)
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    Publication Date: 2011-08-17
    Description: The two problems of enhanced electrostatic discharge (ESD) and contamination are discussed. It is shown that there is a synergistic relationship between them such that one enhances the probability of occurance of the other. The action of both provides substantially more deleterious affects than the effects of both separately. Mechanisms for such a relationship are discussed as well as application to large advanced technology systems.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: ESA Spacecraft Mater. in Space Environ.; p 145-158
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  • 59
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    Pointing and control of planetary spacecraft - The next 20 years (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Four basic categories of spacecraft pointing and control systems are discussed: (1) spin stabilized, (2) dual spin, (3) three-axis, and (4) momentum bias. Goals, mission requirements, and payloads should be considered for selection of control systems. A set of representative requirements, including life and environmental, vehicle/payload orientation and accuracy requirements, and control-system operational and functional requirements are discussed. Attention is given to design constraints imposed by the system selection. It is noted that sensitivity of any system design to increasing accuracy and flexibility in science-mission reprogramming will be major cost factors.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Astronautics and Aeronautics; 17; Oct. 197
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  • 60
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    Engineering evaluation of existing space hardware for utilization in small self-contained payloads (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The NASA small self-contained payload program allows research and development experiments of less than 5 cu ft to be flown in the Orbiter payload bay on a space available basis. Materials processing equipment available from Apollo, Skylab, SPAR, and MEA that include such items as furnaces for metallurgical processing and crystal growth, apparatus for measuring crystallization processes, and electrophoretic separators for cell separation are being offered by NASA through this program. Eighteen items for the self-contained payload program were evaluated and many were found to be suitable.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: ESA Mater. Sci. in Space; p 205-210
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    Geodetic interferometry submission for the IUGG Quadrennial Report (1979)
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    Publication Date: 2011-08-17
    Description: The present paper reviews the activities of two major VLBI (Very Long Baseline Interferometry) groups, within the United States, which have been concentrating on geodetic measurements for a number of years. The activities have resulted in the development of transportable VLBI terminals for regional surveying applications; development of VLBI techniques for obtaining station positions; establishment of relative epochs and rates of the hydrogen maser clocks at the stations; the acquisition of polar motion and earth rotation data in support of deep space tracking functions; and the development of VLBI techniques necessary for tectonic measurements on trans- and intercontinental baselines and for astrometry, polar-motion and earth-rotation observations.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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    Qualitative and quantitative flow visualization technique using ozone (1979)
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    Publication Date: 2011-08-17
    Description: The paper describes a new flow-visualization technique based on the absorption of ultraviolet light by ozone. Ozone is an excellent tracer, because as a gas it has the same effective physical properties as air. Ozone strongly absorbs the principal line (253.7 nm) of a mercury lamp, so that when an ozone-traced flow passes between a mercury lamp and a fluorescent screen, a sharp, shadow-like image of the ozone tracer is cast on the screen. Quantitative photometry can be carried out by replacing the screen with ultraviolet detectors that yield the path-integrated column density of ozone in the flow. High-speed quantitative point monitoring (10 Hz at 10 ppb O3) is possible with capillary probes and chemiluminescent analysis.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 50; June 197
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    Infrared photometry and spectrophotometry of G75.84+0.4 (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Photometric mapping of G75.84+0.4 at 12.6 microns is compared with previously published radio maps of the region to deduce the relative dust/gas mass ratio for the dust responsible for the 12.6-micron emission. Spectrophotometry from 2-4 microns and 8-13 microns of the highest-emission-measure region reveals the presence of the fine structure lines of forbidden Ar III at 8.99 microns, forbidden Ne II at 12.78 microns, and forbidden S IV at 10.53 microns. Estimates of the abundance of these ions are made, and the nature of the exciting source is discussed.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 74; 3, Ma; May 1979
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    Stability of inner planetary systems (1979)
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    Publication Date: 2011-08-17
    Description: The stability of inner planetary systems with arbitrary mass ratios is studied on the basis of the model of the plane restricted three-body problem. A quantitative stability criterion is obtained in terms of the difference between the critical value of the Jacobi constants (at which bifurcation can occur) and the critical value corresponding to a planetary orbit. An orbit is stable if it cannot leave a region that contains only the larger central body (Hill). For small values of the mass parameter, the maximum dimensionless radius of a Hill-stable orbit is 1 minus 2.4 times the cube root of the mass parameter.
    Keywords: ASTRONOMY
    Type: Zeitschrift fuer angewandte Mathematik und Physik; 30; Mar. 25
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  • 65
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    Trends in the automation of planetary spacecraft (1979)
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    Publication Date: 2011-08-17
    Description: The automation of planetary spacecraft at the Jet Propulsion Laboratory (JPL) is discussed. Factors affecting the development of spacecraft automation, such as predictable and repetitive functions and narrow time-window, are analyzed. The volume of command data transmitted to the spacecraft is considered, together with an examination of 'autonomy' (executing functions without outside control) in relation to the ground command activity needed during the mission. The role of the spacecraft's growing computational power in increasing vehicle autonomy is noted.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Astronautics and Aeronautics; 17; May 1979
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    A high resolution holographic particle sizing system (1979)
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    Publication Date: 2011-08-17
    Description: This paper will review briefly the requirements of holography with respect to particle sizing techniques. A holographic construction system and the appropriate reconstruction system will be discussed regarding their characteristics and performance (i.e. system resolution, magnification, system aberration and correction of aberrations, and maximum total test volume). The capabilities of a commercial particle sizing system used to obtain particle sizes and distribution information from reconstructed holograms will be described and characterized. It will be shown that by using the methods described, high resolution throughout large test volumes can be achieved.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 18; May-June
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  • 67
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    Transparent electrically conducting thin films for spacecraft temperature control applications (1979)
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    Publication Date: 2011-08-17
    Description: Thin transparent films of In2O3 or In2O3 + SnO2 prepared by evaporation or sputtering have been tested for use as surface layers for spacecraft temperature control coatings. The films are intended to prevent nonuniform electric charge buildup on the spacecraft exterior. Film thicknesses of 300 to 500 A were found to be optimal in terms of durability and minimum impact on the solar absorptance and the thermal emissivity of the underlayers. As a verification of their suitability for long-duration space missions, the films were subjected to simulated solar UV plus proton irradiation in a vacuum.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Applied Optics; 18; May 15
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  • 68
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    Measurement of the polarization effects of an instrument using partially polarized light (1979)
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    Publication Date: 2011-08-17
    Description: Accuracy of a radiometer is adversely affected by scene polarization if the receiving optical system is sensitive to polarization. It is therefore necessary to specify and measure the sensitivity of the system to polarized light. The Mueller-Stokes matrix of an instrument may be determined experimentally and used to predict the effects of the instrument on any beam. The specification of a maximum polarization sensitivity stated in terms of the degree of polarization produced in an unpolarized beam can be experimentally verified even though an unpolarized beam is not available in the laboratory for direct measurement.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 18; Mar. 15
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  • 69
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    Post-development image intensification by autoradiography (1979)
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    Publication Date: 2011-08-17
    Description: A method of post-development intensification of photographic images using a newly developed autoradiographic procedure is described. Radioactive Thiourea-S35 is combined with silver in the developed emulsion, which is then contact printed with a receiver emulsion. The beta decay from S35 produces an enhanced autoradiographic image. The laboratory technique is described and results of astronomical applications are presented.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 91
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  • 70
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    A comparison of luminosity calibrations for MK classifications of OB stars (1979)
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    Publication Date: 2011-08-17
    Keywords: ASTRONOMY
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  • 71
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    A general algorithm for the solution of Kepler's equation for elliptic orbits (1979)
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    Publication Date: 2011-08-17
    Description: An efficient algorithm is presented for the solution of Kepler's equation f(E)=E-M-e sin E=0, where e is the eccentricity, M the mean anomaly and E the eccentric anomaly. This algorithm is based on simple initial approximations that are cubics in M, and an iterative scheme that is a slight generalization of the Newton-Raphson method. Extensive testing of this algorithm has been performed on the UNIVAC 1108 computer. Solutions for 20,000 pairs of values of e and M show that for single precision, 42.0% of the cases require one iteration, 57.8% two and 0.2% three. For double precision one additional iteration is required.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 20; Oct. 197
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  • 72
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    Pointing and control of planetary spacecraft - The next 20 years (1979)
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    Publication Date: 2011-08-17
    Description: The preliminary pointing and control systems for five planetary mission groups are presented, as well as the rationale and key characteristics for each system type. The five groups entail: (1) a preliminary survey, (2) a detailed remote observation, (3) close scrutiny in deep space, (4) close scrutiny near the sun, and (5) a sample return. Attention is given to each group with respect to two- and three-axis control and various instruments for spin control. The future development of component trends and needs, electronic trends, electromechanical development, gyros and other general system trends are discussed in detail.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Astronautics and Aeronautics; 17; Nov. 197
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  • 73
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    Airborne stellar spectrophotometry from 1.2 to 5.5 microns - Absolute calibration and spectra of stars earlier than M3 (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Airborne infrared spectrophotometry (1.2-5.5 microns, 1.5% resolution) is presented for 13 stars which have been extensively used as infrared calibration objects: alpha Lyr, alpha CMA, alpha UMi, beta Dra, and mu Her; the K giants beta Gem, alpha UMa, alpha Boo, gamma-1 And, and alpha Tau; and the M giants beta And, beta Peg, and alpha Cet. These spectra, obtained using NASA's Kuiper Airborne Observatory and Lear Jet Observatory, are virtually free of the interfering effects of terrestrial absorptions. Absolute calibration of the spectrophotometry was based on the theoretical model of alpha Lyr by Schild, Peterson, and Oke (1971), which fits photometric measurements at shorter wavelengths. The resulting flux densities are compared with previous ground-based photometry.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series; 41; Nov. 197
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  • 74
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    Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars (1979)
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    Publication Date: 2011-08-17
    Description: This paper discusses effective temperatures, angular diameters, distances, and linear diameters that have been determined for 160 O and B stars on the basis of published UV spectrophotometry, visible and near-IR intermediate-band photometry, and model-atmosphere fluxes. The results are compared with previous measurements and calculations for main-sequence and giant O and B stars. It is found that: (1) the flux effective temperatures of O and B supergiants are systematically lower than those of main-sequence and giant stars of the same subtype; (2) the effective temperatures and radii of Beta Cep stars are the same as those of nonvariable stars of the same spectral type; (3) Be stars that do not have two Balmer jumps have effective temperatures very similar to those of normal B stars of the same subtype; (4) O and B stars increase in size from the main sequence to supergiants; and (5) late B supergiants are approximately twice as large as O9 supergiants.
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society; vol. 189
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  • 75
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    Twenty southern peculiar emission-line stars (1979)
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    Publication Date: 2011-08-17
    Description: Observational data for 20 southern stars having emission-line spectra that suggest a significant degree of mass ejection are given in order to present an atlas of their spectra and to give a quantitative description of their appearance during the 1961-62 epoch. Most of the stars are P Cygni stars; others include nova-like, peculiar Be, and symbiotic stars, as well as stellar planetary nebulae and emission-line binaries, all of whose spectra were obtained with the Newtonian two-prism Zeiss Spectrograph and the 74-inch reflector at Mount Stromlo Observatory. It is noted that among the P Cygni stars, there is a strong correlation between the a-e expansion velocity and the strength of Balmer emission, while in both the P Cygni and the Bep stars, there is positive dependence of Fe II and negative dependence of (Fe II) emission strengths on Balmer emission strength.
    Keywords: ASTRONOMY
    Type: Vistas in Astronomy; 23; pt. 3
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  • 76
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    Airborne laser induced fluorescence system for measuring OH and other trace gases in the parts-per-quadrillion to parts-per-trillion range (1979)
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    Publication Date: 2011-08-17
    Description: Described in detail is a laser induced fluorescence system which has been successfully interfaced with two aircraft sampling platforms (i.e., Sabreliner jet and an L-188C Electra). This system, which has been under development for four years, presently consists of the following major components: (1) a Nd-Yag laser driven oscillator-amplifier dye laser; (2) a sampling manifold with associated fluorescence detection optics; (3) an OH calibration chamber; (4) a laser beam steering assembly; and (5) sampling electronics and data processing hardware. During the last three years, this system has been flown some 50,000 air miles making tropospheric OH radical measurements over the latitude range of 70 N to 57 S. OH concentrations measured during these flights have ranged from 30 parts-per-quadrillion (3.7 x 10 to the 5th molecules/sq cm) at altitudes of 6 km to 0.8 parts-per-trillion (2.0 x 10 to the 7th molecules/sq cm) at 0.5 km. Computations have been completed which indicate that the existing aircraft system with modest modifications should also be capable of detecting natural tropospheric levels of NO, SO2, CH2O, NO2, HNO2, NO3, H2O2 and CS2 by using both conventional laser-induced fluorescence methodology and multiphoton techniques.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 50; Dec. 197
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  • 77
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    NASCAP modelling of environmental-charging-induced discharges in satellites (1979)
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    Publication Date: 2011-08-17
    Description: A study of the charging and discharging characteristics of a typical geosynchronous satellite experiencing time-varying geomagnetic substorms, in sunlight, is conducted. The NASA Charging Analyzer Program (NASCAP) is used. An electric field criteria of 1.5 x 10 to the 5th volts/cm to initiate discharges and transfer of 67% of the stored charge is used in this study, based on ground test results. The substorm characteristics are arbitrarily chosen to evaluate effects of electron temperature and particle density (which is equivalent to current density). It has been found that while there is a minimum electron temperature for discharges to occur, the rate of discharges is dependent on particle density and duration times of the encounter. Hence, it is important to define the temporal variations in the substorm environments.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
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  • 78
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    Electron, electron-bremsstrahlung and proton depth-dose data for space-shielding applications (1979)
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    Publication Date: 2011-08-17
    Description: A data set has been developed, consisting of depth-dose distributions for omni-directional electron and proton fluxes incident on aluminum shields. The principal new feature of this work is the accurate treatment, based on detailed Monte Carlo calculations, of the electron-produced bremsstrahlung component. Results covering the energy region of interest in space-shielding calculations have been obtained for the absorbed dose (a) as a function of depth in a semi-infinite medium, (b) at the edge of slab shields, and (c) at the center of a solid sphere. The dose to a thin tissue-equivalent detector was obtained as well as that in aluminum. Various results and comparisons with other work are given.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
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  • 79
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    Computer image processing and recognition (1979)
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    Publication Date: 2011-08-18
    Description: A systematic introduction to the concepts and techniques of computer image processing and recognition is presented. Consideration is given to such topics as image formation and perception; computer representation of images; image enhancement and restoration; reconstruction from projections; digital television, encoding, and data compression; scene understanding; scene matching and recognition; and processing techniques for linear systems.
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  • 80
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    The International Ultraviolet Explorer: Case study in spacecraft design (1979)
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    Publication Date: 2011-08-17
    Description: The International Ultraviolet Explorer (IUE) is a geosynchronous scientific satellite that was conceived as an international space observatory capable of measuring UV spectra of faint celestial bodies. Simple operational procedures allow the astronomers to joystick the spaceborne telescope about the sky, using familiar ground-based observatory techniques. The present paper deals with the IUE project objectives, the technical problems, constraints, trade-offs, and the problem solving techniques used in the IUE program.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
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  • 81
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    Osculating orbital elements of the asteroids (1979)
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    Publication Date: 2011-08-17
    Description: In the present paper, osculating orbital elements are listed for 2118 numbered asteroids, of which 17 are considered lost. The columns give asteroid number; name; semimajor axis, in AU; eccentricity; longitude of the ascending mode; argument of perihelion; mean anomaly; and Julian date of epoch minus 2,400,000.
    Keywords: ASTRONOMY
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  • 82
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    Collisional evolution of asteroids - Populations, rotations, and velocities (1979)
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    Publication Date: 2011-08-17
    Description: The collisional evolution of various initial populations of asteroids is simulated numerically and compared with the present asteroid size-frequency distribution to find those populations which collisionally relax to the present belt. Both orbital and size distributions are treated, as well as the simultaneous evolution of two collisionally interacting populations with different physical properties. If the initial belt distribution was a power law, the initial belt population at the time when the present high-collision speed was established was probably only modestly larger than the present population. However, other distributions allow a more massive early belt. The rotational evolution due to collisions of asteroids with power-law distributions is also examined and compared with observations, leading to conclusions generally in agreement with those of size evolution. The high-collision speed in the present belt is likely due to Jupiter. Gravitational stirring by massive Jupiter-scattered planetesimals or secular resonances sweeping through the belt are the most probable mechanisms.
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  • 83
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    Earth-crossing asteroids - Orbital classes, collision rates with earth, and origin (1979)
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    Publication Date: 2011-08-17
    Description: Asteroids that can intersect the orbit of the earth are discussed, which include Aten asteroids (semimajor axis (a) less than 1 AU, aphelion greater than 0.983 AU), Apollo asteroids (a greater than 1 AU, perihelion less than 1.017 AU), and Amor asteroids (perihelion distance between 1.017 and 1.3 AU). The principal sources of earth-crossing asteroids appear to be extinct comet nuclei and collision fragments from regions in the main asteroid belt. The total population of earth-crossers is estimated at 13,000, of which approximately 8% are Atens, 50% are Apollos, and 40% are Amors,and the present collision rate of such asteroids with the earth is estimated at about 3.5 objects, to absolute magnitude 18, per million years.
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  • 84
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    Modification of a Kowa RC-2 fundus camera for self-photography without the use of mydriatics (1979)
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    Publication Date: 2011-08-17
    Description: Research on retinal circulation during space flight required the development of a simple technique to provide self monitoring of blood vessel changes in the fundus without the use of mydriatics. A Kowa RC-2 fundus camera was modified for self-photography by the use of a bite plate for positioning and cross hairs for focusing the subject's retina relative to the film plane. Dilation of the pupils without the use of mydriatics was accomplished by dark-adaption of the subject. Pictures were obtained without pupil constriction by the use of a high speed strobe light. This method also has applications for clinical medicine.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Brain Research Bulletin; 4; 1979
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  • 85
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    On-axis velocity component measurement with laser velocimeters (1979)
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    Publication Date: 2011-08-17
    Description: The application of Doppler shifted laser light to the measurement of the two velocity components normal to the optical axis of the system is relatively simple as compared to the measurement of the on-axis velocity component. The present paper deals with the reference-beam (local oscillator) technique and the dual-beam (fringe mode) technique, which have been developed for measuring the on-axis component. Some results obtained for the on-axis component are examined.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA Journal; 17; Sept
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  • 86
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    Remote measurement of the transverse wind velocity component using a laser Doppler velocimeter (1979)
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    Publication Date: 2011-08-17
    Description: The wind speed transverse to the line-of-sight of a laser Doppler radar has been measured using the intensity fluctuations of the returned signal. These measurements were made at a range of 100 m with a CO2 CW laser Doppler velocimeter, which was simultaneously performing its design function of determining the radial velocity component. The transverse component measurements are compared with those obtained using a u, v, w Gill propeller anemometer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 18; Sept. 1
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  • 87
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    Field-widened pinhole camera (1979)
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    Publication Date: 2011-08-17
    Description: Wood demonstrated a method in 1906 that allowed 180-deg FOV but required that the film be immersed in a tank of water. This paper presents a technique that yields the same 180-deg FOV without the necessity of wetting the film. Rays from a 180-deg FOV cone are reduced to 84-deg cone due to refraction at the glass surface. If the cone were then incident on another glass/air plane surface, it would be expanded back to 180 deg.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 18; Sept. 1
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  • 88
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    M2 ocean tide parameters and the deceleration of the moon's mean longitude from satellite orbit data (1979)
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    Publication Date: 2011-08-17
    Description: An estimation is made of the principal long-period spherical harmonic parameters in the representation of the M2 ocean tide from the orbital histories of the three satellites 1967-92A, Starlette, and GEOS 3. The data used are primarily the evolution of the orbital inclinations of the satellites in conjunction with the longitude of the ascending node from GEOS 3. Analysis procedure and analytic formulation, as well as ocean tidal parameter estimation and deceleration of the lunar mean longitude are outlined. The credibility of the M2 ocean tide solution is further enhanced by the close accord between the computed value for the deceleration of the lunar mean longitude and other recently reported estimates. It is evident from the results presented that studies of close earth satellite orbits are able to provide important information about the tidal forces acting on the earth.
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    Depletion of satellite atoms in a collisionless exosphere by radiation pressure (1979)
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    Publication Date: 2011-08-17
    Description: Perturbations of hydrogen atoms in Keplerian orbits are examined by analyzing the rates of change of the classical orbital elements. There are three main effects: high inclination orbits with eccentricities e at least 0.4 are forced toward the ecliptic plane within a few weeks, the perigees of direct orbits drift rapidly toward stable positions roughly westward of the planet, and satellite orbits in or near such a stable point rapidly lower their perigees and the satellite's life is ended by a collision in the atmosphere. Thus there are effects tending to diminish the number of highly eccentric orbits with distant apogees in six principal directions. The various lifetimes are compared for a sample of initial elements.
    Keywords: ASTRONOMY
    Type: Icarus; 39; Aug. 197
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  • 90
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    Magnetic shielding in a low temperature torsion pendulum experiment (1979)
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    Publication Date: 2011-08-17
    Description: A new type of ether drift experiment searches for anomalous torques on a permanent magnet. A torsion pendulum is used at liquid helium temperature, so that superconducting cylinders can be used to shield magnetic fields. Lead shields attenuate the earth's field, while Nb-Sn shields fastened to the pendulum contain the fields of the magnet. The paper describes the technique by which the earth's field can be reduced below 0.0001 G while simultaneously the moment of the magnet can be reduced by a factor 7 x 10 to the 4th.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 50; Aug. 197
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  • 91
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    Measurement of turbulent fluctuations in high-speed flows using hot wires and hot films (1979)
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    Publication Date: 2011-08-17
    Description: The paper examines the dynamic calibrations of the hot film and modified hot-wire probes with a view to assess their suitability for use in experiments for the measurement of turbulent fluctuations in compressible boundary-layer flows. Results are presented of tests on some sensors in both subsonic and supersonic boundary-layer flows. A simple technique is presented for determining dynamic calibration correction factors for the sensitivities involved.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 50; Aug. 197
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  • 92
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    Polarization and scattering characteristics in the atmospheres of earth, Venus, and Jupiter (1979)
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    Publication Date: 2011-08-17
    Description: Our understanding of atmospheric scattering phenomena has increased through the combined developments of new electro-optical instrumentation, theoretical solutions for complex model atmospheres, and large computers enabling computation of such solutions. Earth satellites permit external, planetwide observations of our atmosphere, while spacecraft permit detailed measurements of the scattering by other planetary atmospheres. Some recent results are: elucidation of the effects of ozone absorption and high-altitude aerosol scattering on twilight colors and polarization; identification of a cloudbow on Venus and consequent deduction of the cloud particle shape, size distribution, and refractive index; and, the interpretation of Rayleigh scattering on Jupiter in terms of cloud-top topography.
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  • 93
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    Absolute calibration in the 1750 A-3350 A region (1979)
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    Publication Date: 2011-08-17
    Description: The absolute flux measurements in the rocket ultraviolet made by Bohlin, Frimout, and Lillie (BFL) are revised using a more correct treatment of the air extinction that enters the air calibration of their instrument. The absorption by molecular oxygen and ozone, Rayleigh scattering, and extinction by aerosols is tabulated for general use in ultraviolet calibrations performed in air. The revised absolute flux of Eta UMa and final fluxes for Alpha Lyr and Zeta Oph are presented in the 1750 A-3350 A region. The absolute flux of the star Eta UMa (B3 V) is compared to four other independent determinations in the 1200 A-3400 A region and a maximum difference of 35% is found near 1500 A between the OAO-2 and Apollo 17 fluxes. Longward of 1700 A the typical scatter in the different determinations is only plus or minus 5%. The rocket measurements of BFL, the ANS and TD-1 satellite data, and the Apollo 17 data are compared to the ultraviolet fluxes from the OAO-2, demonstrating a photometric reproducibility of about plus or minus 3%. Therefore, all four sets of spectrophotometry can be reduced to a common absolute scale.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 91
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  • 94
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    X-ray observations of H1908+050 /=SS 433/ (1979)
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    Publication Date: 2011-08-17
    Description: The X-ray source H1908+050 (=4U 1908+05 = A1909+04) was observed for three 6 day periods in 1977 and 1978 with the HEAO A-2 experiment. Because of the positional error box and variability of the source, the unusual emission-line object and variable radio source SS 433 has been suggested as the optical counterpart. The X-ray luminosity of the source varied by a factor of about 2 on a time scale of 6 months, and the spectrum of the object is consistent with either a power law of photon index of 2.1 or with 14.3 KeV thermal bremsstrahlung emission with an about 575 eV equivalent-width iron line. These X-ray characteristics argue against the source being extragalactic, but do not uniquely identify the type of source. The measurements are consistent with emission from a white dwarf with 100 million gauss magnetic field, but are also similar to the X-ray emission sometimes seen from Cir X-1. A search has been made for X-ray emission from similar radio sources, but no new X-ray sources were detected. A previously known source, A1850+00, is a possible counterpart for one of these radio sources.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 230
    Format: text
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  • 95
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    High-resolution polarization structure of H-beta in Be shell stars measured with a new Digicon spectropolarimeter (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 228
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  • 96
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    Photographic observations of Theta-1 Orionis (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Photographic observations of the eclipsing binary Theta-1 Ori A suggest a secondary minimum near phase 0.64 of its 65.43233-day period. This minimum may be wavelength dependent. The star Theta-1 Ori E is suspected of being variable.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 90
    Format: text
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  • 97
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    Polarization-sensitive spectroradiometer - Two methods for overcoming the problems of measuring reflectance spectra (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The spectra obtained using a spectroradiometer are incorrect if the incident light from the sample is polarized, and if, at the same time, polarization is introduced into the transmitted beam by components of the spectroradiometer. Two methods are proposed for obtaining correct power reflectance spectra. One way is to average two incorrect reflectance spectra, which are taken at mutually orthogonal angles of rotation of the radiometer about its optical axis. Another way is by averaging reflectance spectra of mutually orthogonal polarized light components. When the orientation of one component is chosen such that it is in the plane of polarization of the incoming light, the latter method also gives the correct degree of polarization.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 18; Feb. 15
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  • 98
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    Remote sensing using solid-state array technology (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper describes the design features and capabilities of a remote sensor that uses solid-state linear arrays and operates in a 'pushbroom' scan mode to provide the required performance. Pushbroom scanning is a term describing the technique of using the forward motion of a satellite platform to sweep a linear array of detectors oriented perpendicular to the ground track across a scene being imaged. One array is typically used for each spectral channel. Satellite motion provides one direction of scan and electronic sampling of the detectors in the crosstrack dimension provides the orthogonal scan component to form an image. The detector array is sampled at the appropriate rate so that contiguous lines are produced. The performance of a pushbroom system is discussed relative to radiometric sensitivity, detector array geometric fidelity, and radiometric correction. System advantages are precision geometric positioning of the detectors, very high sensitivity and favorable SNR, low power consumption, and no moving optics.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 99
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    Ray-tracing the convex curved crystal X-ray spectrograph (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The convex curved crystal X-ray spectrograph has recently seen increasing use for the spectral analysis of transient plasmas. The present paper describes the calculation of ray paths through the spectrograph for both localized and extended sources. The method traces a ray from any given source point to its point of diffraction by the curved crystal and then to the imaging circle, where the image point is obtained. Application of the ray tracing method is made to some actual experimental configurations to obtain resolution values and source sizes. Wavelength calibrations are obtainable with the ray tracing method in advance of instrument construction.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 18; Feb. 1
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  • 100
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    Graphic design of pinhole cameras (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper describes a graphic technique for the analysis and optimization of pinhole size and focal length. The technique is based on the use of the transfer function of optical elements described by Scott (1959) to construct the transfer function of a circular pinhole camera. This transfer function is the response of a component or system to a pattern of lines having a sinusoidally varying radiance at varying spatial frequencies. Some specific examples of graphic design are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 18; Feb. 1
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