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  • Other Sources  (2,265)
  • LUNAR AND PLANETARY EXPLORATION  (1,424)
  • AERODYNAMICS  (841)
  • Inorganic Chemistry
  • 1975-1979  (2,265)
  • 1978  (1,079)
  • 1976  (1,186)
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  • 1975-1979  (2,265)
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  • 1
    Publication Date: 2006-02-22
    Description: An experimental study of slotted upper and lower walls in a two dimensional transonic wind tunnel with solid sidewalls is reported. Results are presented for several slot spacings and slot openness ratios. The experimental data were pressure measurements which were made on an airfoil model and on a sidewall near one of the slotted walls. The slotted-wall boundary condition coefficient, which related the pressure and streamline curvature near the wall, was determined from the wall pressure measurements. The measured wall-induced interference was correlated with the experimental values for the boundary condition coefficient. This correlation was compared with theory.
    Keywords: AERODYNAMICS
    Type: Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 459-471
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  • 2
    Publication Date: 2006-02-22
    Description: Finite difference procedures were successfully used to solve the steady transonic flow about airfoils and appear to provide a practical means for calculating the corresponding unsteady flow. The purpose of the paper is to describe a finite difference procedure derived from the equations for the potential flow by assuming small perturbations and harmonic motion. The velocity potential is divided into steady and unsteady parts, and the resulting unsteady equation is linearized on the basis of small amplitudes of oscillation. The steady velocity potential, which must be calculated first, is described by the classical nonlinear transonic differential equation.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 657-670
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  • 3
    Publication Date: 2006-02-22
    Description: An in-flight wing wake section drag investigation was conducted using traversing pitot and static probes. The primary objective was to develop measurement techniques and improve the accuracy of in-flight wing profile drag measurements for low values of dynamic pressure and Reynolds number. Data were obtained on a sailplane for speeds from about 40 knots to 125 knots at chord Reynolds numbers between 1,000,000 and 3,000,000. Tests were conducted with zero flap deflection, deflected flaps, and various degrees of surface roughness, and for smooth and rough atmospheric conditions. Several techniques were used to increase data reliability and to minimize certain bias errors. A discussion of the effects of a total pressure probe in a pressure gradient, and the effects of discrete turbulence levels, on the data presented and other experimental results is also included.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 601-621
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  • 4
    Publication Date: 2006-02-22
    Description: A method for calculating the transonic flow over steady and oscillating airfoils was developed by Isogai. It solves the full potential equation with a semi-implicit, time-marching, finite difference technique. Steady flow solutions are obtained from time asymptotic solutions for a steady airfoil. Corresponding oscillatory solutions are obtained by initiating an oscillation and marching in time for several cycles until a converged periodic solution is achieved. In this paper the method is described in general terms, and results are compared with experimental data for both steady flow and for oscillations at several values of reduced frequency. Good agreement for static pressures is shown for subcritical speeds, with increasing deviation as Mach number is increased into the supercritical speed range. Fair agreement with experiment was obtained at high reduced frequencies with larger deviations at low reduced frequencies.
    Keywords: AERODYNAMICS
    Type: Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 689-700
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  • 5
    Publication Date: 2006-02-22
    Description: The uses of laser Doppler velocimeter, hot wire, and surface hot film techniques in the study of turbulent flows are described, and data obtained in compressible flows are discussed. Applications are illustrated with measurements of wind tunnel freestream turbulence characteristics and with data obtained in transitional, turbulent, and separated shear flows. A new method which was developed for the study of time dependent and unsteady turbulent flows is also presented.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 571-588
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  • 6
    Publication Date: 2006-01-16
    Description: Winograd's algorithm for computing the discrete Fourier transform is extended considerably for certain large transform lengths. This is accomplished by performing the cyclic convolution, required by Winograd's method, by a fast transform over certain complex integer fields. This algorithm requires fewer multiplications than either the standard fast Fourier transform or Winograd's more conventional algorithms.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: The Deep Space Network; p 134-140
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  • 7
    Publication Date: 2011-08-17
    Description: In 6 of the 7 instances where posteclipse brightening of Io has been reported by observers using blue filters, a major solar flare occurred within 10 degrees of the sub-Jovian longitude in the 100-day interval prior to observation. In none of the 18 instances where no posteclipse brightening was observed did such a flare occur. It is proposed that a phenomenon associated with a major solar flare causes an increase in the trapped particle flux at Io's orbit by an order of magnitude. The posteclipse brightening may be caused by thermoluminescence of Io's surface material upon emergence. Alternatively, it is possible that the increase in trapped particle flux would warm the surface, creating a temporary atmosphere which would precipitate during eclipse cooling and vaporize in the period of warming after reemergence.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 33; Jan. 197
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  • 8
    Publication Date: 2011-08-17
    Description: The ratio for the equivalent widths for the unsaturated H2 quadrupole transitions observed in the Jovian planets is calculated and compared with a large number of observations. The comparison indicates that equilibrium hydrogen may be present in Jupiter and Saturn, while Uranus and Neptune exhibit ratios not in accord with equilibrium hydrogen. Observations which can differentiate among the possible states of H2 are proposed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 33; Jan. 197
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  • 9
    Publication Date: 2011-08-17
    Description: The paper reports JHK colors observed for ten asteroids and synthesized JHK colors for seven meteorite groups, samples of iron and nickel metal, pyroxene, olivine, feldspar, a lunar anorthite and some terrestrial mineral samples. Pronounced differences are apparent between the chondritic and achondritic meteorite classes; the chondritic classes show less subdued trends in J-H color which reflect their metamorphic grade. We find small but significant differences between the JHK colors of the predominant C and S classes of asteroids. All JHK colors of asteroids observed here fall within the limited domain defined by the various chondritic and iron-rich meteorites but are strikingly different from those of most achondritic meteorites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics; 13; Mar. 31
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  • 10
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    Publication Date: 2011-08-18
    Description: The tethered satellite concept provides an ideal platform for the study of the interaction of the atmosphere with satellites of various shapes and surfaces under a wide range of flow conditions. From experiments which would measure the drag, lift, and torque acting on the tethered satellite, important information could be obtained which would have application to satellite lifetime prediction, determination of properties of the upper atmosphere, and scientific information on the interaction of high speed molecules with surfaces (the gas surface interaction). These experiments using the tethered satellite concept are described and would measure the following variables: angle of attack, surface roughness, and flow properties.
    Keywords: AERODYNAMICS
    Type: UAH(NASA Workshop on the Use of a Tethered Satellite System; p 151-155
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  • 11
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    Publication Date: 2011-08-17
    Description: The integral representations approach, for the solution of the Navier-Stokes equations is discussed as well as experience in its development and in applying available finite-difference and finite-element techniques to the treatment of three-dimensional problems, and the computation of turbulent flow. The magnitude of efforts required to develop turbulence models and three-dimensional algorithms indicates that the computational fluid dynamics research must have a broad base. Broader access to modern computing facilities that are in existence within NASA should be promoted for active researchers not directly affiliated with that agency.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Future Computer Requirements for Computational Aerodynamics; p 221-227
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  • 12
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    Publication Date: 2011-08-17
    Description: In their most general form, the Reynolds averaged conservation equations result from ensemble or time averages of the instantaneous Navier-Stokes equations or their compressible counterparts. For these averaging processes to be consistent, the averaging time period must exceed the periods identified with the largest time scales of the turbulence, and yet be shorter than the characteristic times of the flow field. With these equations long period variations in the flow fields are deterministic, provided initial conditions are known. The average dependent variables are sufficiently smooth to be resolvable by finite difference techniques consistent with the size and speed of modern computers.
    Keywords: AERODYNAMICS
    Type: Future Computer Requirements for Computational Aerodynamics; p 239-247
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  • 13
    Publication Date: 2011-08-17
    Description: Technical and economic reasons for accelerating the maturation of the discipline of computational aerodynamics include the cost of conducting the experiments required to provide the empirical data base for new aeronautical vehicles and the limitations in test facilities (Reynolds number, wall and support interferences, aeroelastic distortions, real-gas effects, etc.) for simulating the full-scale vehicle environment. General purpose computers do not have the necessary capability for the next stage of development. Solution of the three dimensional Reynolds averaged Naiver-Stokes equations in a short time to be practical for design purposes will require 40 times the power of current supercomputers. However, it is feasible to construct a special purpose processor that will meet these requirements to enhance the nation's aerodynamic design capability in the 1980's.
    Keywords: AERODYNAMICS
    Type: Future Computer Requirements for Computational Aerodynamics; p 5-30
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  • 14
    Publication Date: 2011-08-17
    Description: The heat transfer to the stagnation point of an ablating carbonaceous heat shield, where both the gas-phase boundary layer and the heterogeneous surface reactions are not in chemical equilibrium, is examined. Specifically, the nonequilibrium changes in the mass fraction profiles of carbon species calculated for frozen flow are studied. A set of equations describing the steady-state, nonequilibrium laminar boundary layer in the axisymmetric stagnation region, over an ablating graphite surface, is solved, with allowance for the effects of finite rate of carbon vaporization.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 16; July 197
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  • 15
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    Publication Date: 2011-08-17
    Description: The difficulty of treating the perturbation of transonic flow, during which shock waves change position, can be overcome by using a distorted coordinate system in which the locations of all shock waves do not change; the distortion is found as part of the solution. This device leads to a relation that allows a range of flows, with differing shock locations, to be related algebraically to two known 'calibration' flows. Results for flows around finite wings, including those with multiple, intersecting shock waves, are presented. A typical computing time for such examples is 0.3 sec on a CDC 7600 computer.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 16; July 197
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  • 16
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    Publication Date: 2011-08-17
    Description: Drift rates for S-burst emissions from Jupiter are studied. The burst spectra, recorded in the frequency range near 32 MHz, provide a qualitative illustration of the behavior of electron bunches shortly after injection into the Io-associated magnetic flux tube. The morphology of the spectra may be taken as support for the hypothesis of an ionospheric acceleration mechanism influencing the flow of electrons.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 272; Mar. 2
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  • 17
    Publication Date: 2011-08-17
    Description: The extensive chaotic and fretted terrains in the equatorial regions of Mars are explained on the basis of the vertical distribution of H2O liquid and ice which once existed in the crust. This account assumes that below the permafrost containing water ice, there was a second zone in which liquid water resided for at least a time. Diagenetic alteration and cementation characterized the material in the subpermafrost zone; above, pristine fragmented material with various ice concentrations was found. Later, the ice-laden zone was stripped away by a number of erosional processes, exposing the former ice-liquid water interface.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 34; June 197
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  • 18
    Publication Date: 2011-08-17
    Description: Spectral reflectance data from the Viking-II Orbiter vidicon cameras have provided a means of mapping and classifying Martian surface materials over about 65% of the planet. The imagery, acquired at three wavelengths, was processed to remove an average Martian photometric function; albedo maps at the three wavelengths were created. Analysis of the imagery showed that the dark region between the equator and about 30 deg S in the Martian highlands consists of ancient ridges, crater rims and rugged plateaus which are very red, and younger intercrater volcanic plains exhibiting mare ridges which are much less red. In addition probable eolian deposits were found in the intermediate and high albedo regions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 34; June 197
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  • 19
    Publication Date: 2011-08-17
    Description: The radar backscattering characteristics of compositional and structural models of Saturn's rings are calculated and compared with observations of the absolute value, wavelength dependence, and degree of depolarization of the rings' radar cross section (reflectivity). The doubling method is used to calculate reflectivities for systems that are many particles thick using optical depths derived from observations at visible wavelengths. If the rings are many particles thick, irregular centimeter- to meter-sized particles composed primarily of water ice attain sufficiently high albedos and scattering efficiencies to explain the radar observations. In that case, the wavelength independence of radar reflectivity implies the existence of a broad particle size distribution; a narrower size distribution is also a possibility. Particles of primarily silicate composition are ruled out by the radar observations. Purely metallic particles may not be ruled out on the basis of existing radar observations. A monolayer of very large ice 'particles' that exhibit multiple internal scattering may not yet be ruled out.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 33; Feb. 197
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  • 20
    Publication Date: 2011-08-17
    Description: The morphology of fresh lunar and Mercurian craters provides insight into processes of crater formation and modification. Measurements determined for Mercurian craters and compared to previously presented lunar data are depth/diameter, central peak and wall-related mass movement frequencies as functions of diameter, crater rim wall width/rim diameter, rim diameter/floor diameter, and central peak height/rim diameter. Two important results are as follows: (1) there is no evidence for direct gravity scaling of crater morphology, although some slight scaling relationship may be indicated, and (2) mass movements are responsible for the change in depth/diameter relationship observed near 2-km depth and 10-km diameter. The latter result is helpful in explaining gravitational and topographic data which suggest low-density regions beneath large fresh craters.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 83; Jan. 10
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  • 21
    Publication Date: 2011-08-17
    Description: Magnitudes and colors on the UBV system are presented for 145 minor planets, including 31 objects in the Eos family, 14 in the Koronis family, 6 in the Nysa family, 11 in the Themis family, 4 Hungarias, 7 Hildas, 8 Trojans, and several objects in unusual orbits. Clearly defined color groups for the Eos, Koronis, Nysa, and Themis family members are strongly suggestive of origin from discrete parent bodies. The Nysas apparently show large light-curve amplitudes. The Mars-orbit crossers 1977RA and 1980 = 1950LA, the earth-orbit crosser 1976UA, and several main-belt asteroids are found to show peculiar colors of unknown significance. The Mars-orbit crosser 1916 = 1953RA appears to be a typical S object, while 1474 Beira and 1977VA show neutral colors. Asteroids at semimajor axis in excess of 4 AU (Trojans preceding and following Jupiter, 279 Thule, and 944 Hidalgo) all belong to a color group centered at B-V = 0.72, U-B = 0.24.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal; 83; June 197
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  • 22
    Publication Date: 2011-08-17
    Description: In the present study, problems of laminar and turbulent two-dimensional flow of a viscous compressible fluid near the trailing edge of a thin flat plate are considered. The complete set of Navier-Stokes equations is solved by the finite-difference method of MacCormack (MacCormack and Baldwin, 1975). It is an explicit, predictor-corrector, time-splitting method of second order acuracy. The computational mesh employed has sufficient resolution for all the characteristic lengths suggested by theory. In the laminar case, the present results are compared with the triple deck solution of Daniels (1974). This comparison indicates that the asymptotic triple deck theory for supersonic trailing edge flow is accurate within five percent for Reynolds numbers greater than 1000. In the turbulent case, the Prandtl-Van Driest-Clauser algebraic eddy viscosity model is used. The numerical results show that the region of upstream influence is approximately of the order of the boundary layer thickness. The solutions for skin-friction, pressure and wake center-line velocity are presented.
    Keywords: AERODYNAMICS
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  • 23
    Publication Date: 2011-08-17
    Description: Collisional accretion appears to be a viable, and seemingly unavoidable, mechanism for intermediate-stage from a swarm of planetesimals into a system containing a few discrete seed planets. Some other mechanism must be invoked to explain growth of condensate grains up to at least tens of meters. Gravitational instability in the particulate disk seems a plausible means of achieving that early-stage growth up to kilometer-scale bodies. The last stage of growth in which the seed planets accrete the remaining material now presents difficulties due to the isolated, circular orbits generated from the intermediate collisional stage.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 24
    Publication Date: 2011-08-17
    Description: The analysis concerns the alterations produced when small amplitude disturbances, including entropy and vorticity disturbances, are imposed on steady potential flows. For the most general nonacoustic incident distortion field that can be imposed on the uniform upstream flow, it is shown that the perturbation velocity at any point of the resulting unsteady compressible and vortical flow consists of a part that is a known function of the imposed upstream distortion field and the mean flow variables and a potential part that can be found by solving a linear inhomogeneous wave equation with a dipole-type source term whose strength is a known function of the imposed upstream distortion field. The theory is applied to the unsteady flow past a corner, and a closed-form analytical solution is found.
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 89; Dec. 13
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  • 25
    Publication Date: 2011-08-17
    Description: Three relatively recently discovered anomalies are considered. The goal of isotopic research is to understand what phenomena are responsible for the observed isotopic anomalies, and thereby to determine the initial solar system isotopic composition. Until recently there has been no measured isotopic ratios which could not be understood in the context of reasonable physical or chemical processes acting to alter a uniform initial solar isotopic composition. This situation changed in 1969 with the discovery by Black and Pepin of an unusual neon isotopic composition in certain carbonaceous meteories. This unusual composition was later designated as Neon E. An unusual or anomalous oxygen isotopic composition was discovered by Clayton et al. (1973). A magnesium isotopic anomaly was discovered by Gray and Compston (1974), and Lee and Papanastassiou (1974). The three isotopic anomalies are discussed, emphasizing particularly the experimental evidence, possible causes for the observed isotopic composition and finally, possible implications of these anomalies with regard to models of solar system formation and evolution.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 26
    Publication Date: 2011-08-17
    Description: Infrared spectral measurements of Mars, Jupiter, and Saturn were obtained from 100 to 470 kaysers and, by taking Mars as a calibration source, brightness temperatures of Jupiter and Saturn were determined with approximately 5 kayser resolution. Internal luminosities were determined from the data and are reported to be approximately 8 times 10 to the minus tenth power of the sun's luminosity for Jupiter and approximately 3.6 times 10 to the minus tenth power of the sun's luminosity for Saturn. Comparison of data with spectra predicted by models suggests the need for an opacity source in addition to gaseous hydrogen and ammonia to help explain Jupiter's observed spectrum in the vicinity of 250 kaysers.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 35; July 197
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  • 27
    Publication Date: 2011-08-17
    Description: Metallography, electron microscopy, and X-ray diffraction techniques were employed to study a fragment of the Tishomingo iron meteorite. The results suggest the following thermal-mechanical history: The fragment was originally a large crystal of taenite (gamma). Cooling through the alpha + gamma phase boundary did not result in accompanying precipitation of kamacite (alpha). Transformation to a martensitic structure initiated between -25 and -65 C. Transformation continued as the temperature fell to -75 to -115 C, resulting in approx 80% martensite (alpha-prime). Subsequent shock deformation and thermal aging processes substantially modified the taenite and martensite microstructures. Twins in the retained taenite phase are attributed to shock deformation at a pressure estimated for a single event at about 170 kbar. The existing complex altered martensite structure containing both taenite and kamacite (3-15% Ni) particles was apparently the product of both shock deformation and thermal aging processes. The maximum temperature reached during thermal aging is estimated to be less than 400 C and perhaps below 310 C.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 42; July 197
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  • 28
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    Publication Date: 2011-08-17
    Description: Small glassy pebbles, called tektites, are found in widely scattered locations around the world. These tektites appear much like volcanic glass obsidian, but their chemical composition is different from that of any terrestrial lava and they contain far less water and none of obsidian's characteristic microcrystals. No one has ever found the mother lode of a field of tektites. They cannot, therefore, be the product of terrestrial volcanism. Recently acquired knowledge about the moon's surface confirms earlier indications that tektites cannot be bits of lunar soil propelled to the earth by the impact of meteorites on the moon. According to one of two remaining possibilities tektites are bits of terrestrial sedimentary rock excavated by meteorites striking the earth's surface, melted by the heat of impact, and congealed into glass as they travel above the atmosphere to the scattered sites where they are found. The other possibility is that tektites are the remains of gobs of lava fired at the earth by volcanic activity on the moon.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Scientific American; 239; Aug. 197
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  • 29
    Publication Date: 2011-08-17
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 83; July 10
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  • 30
    Publication Date: 2011-08-17
    Description: A study of the evidence on accretion in meteorites shows that gross chemical features of chondritic meteorite type were established by accretion of materials with characteristic chemical and isotopic compositions. Some meteorites have been subjected to intensive mechanical and/or thermal processes. Mixing has occurred among meteorite types, presumably late in the accretion sequence. From the materials which appear to have escaped substantial modification it can be concluded that the relative velocities between accreting grains varied but in some cases were very low. Accretion took place after most, if not all, of the gaseous components had been separated from the condensed portion of solar matter.
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  • 31
    Publication Date: 2011-08-17
    Description: Major, minor and trace element analysis as well as noble gas measurements were performed on three Holbrook chondrite samples collected fresh in 1912, in 1931, and in 1968. Decreases in metallic iron and MgO and an increase in total iron were detected. Elemental concentrations of Ti, Ca, Al, P, Mn, Ni, and Cr did not change significantly during weathering. While sodium might have been lost, and K slightly enriched, the trace elements C, Rb, and Sr increased at least two-fold during weathering. Gas abundances decreased, and the concentration ratios of noble gas nuclides varied unpredictably.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics; 13; Sept. 30
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  • 32
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    Publication Date: 2011-08-17
    Description: Reasons for the difference in planetary atmospheres are reviewed. Atmospheric formation by outgassing from terrestrial planets is contrasted with the retention of the primary material by the outer planets. The differences in Venusian, earth, and Martian atmospheres are explained in terms of planet distance from the sun. Data on terrestrial planet pressures, temperatures, and gas compositions, as well as on rates and gas composition of outgassing material are presented. The significance of planet mass is considered.
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  • 33
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    Publication Date: 2011-08-17
    Description: Mariner 10 images of Venus taken at several phase angles were photometrically reduced. The analysis shows that the phase function of the cloud particles is not isotropic, as had been deduced earlier from the brightness distribution on spacecraft images taken at a single phase angle, but has a broad minimum near 60 deg and is forward-scattering. The scattering properties are in quantitative agreement with previous deductions from earth-based polarization measurements by Hansen and his associates.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 5; Dec. 197
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  • 34
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    Publication Date: 2011-08-17
    Description: Experimental results on the Reynolds number influence on the leeside flowfield of planar delta wings at supersonic speeds are presented. Wind tunnel experiments on two delta wing models with straight and sharp leading edges at freestream Mach number of 2.5 and 3.5 and angle of attack between 1 deg and 12.5 deg were carried out. The cross-sectional shape was triangular and the relative height was 0.25. The flow types investigated were to the left and right of the Stanbrook-Squire boundary. Under leading-edge separation conditions, the vortex position and intensity, and thus the suction pressure, vary with Re while the flow type remains nearly unchanged. In the region of separation with embedded shock, Re affects not only the shape of the separation bubble and pressure level near the leading edge but also the type of flow. At sufficiently high Re the flow type of separation with shock changes to one with shock-induced separation.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 16; Dec. 197
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  • 35
    Publication Date: 2011-08-17
    Description: Linearized theory is used to predict the unsteady flow in a supersonic cascade with subsonic axial flow velocity. A closed-form analytical solution is obtained by using a double application of the Wiener-Hopf technique. Although numerical and semianalytical solutions of this problem have already appeared in the literature, this paper contains the first completely analytical solution. It has been stated in the literature that the blade source should vanish at the infinite duct resonance condition. The present analysis shows that this does not occur. This apparent discrepancy is explained in the paper.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 16; Dec. 197
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  • 36
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    Publication Date: 2011-08-17
    Description: The paper describes the theory that underlies the model calculations which show that the far-infrared bands of ammonia are very sensitive to the ammonia distribution above the Jovian atmospheric inversion layer. Observation of the J = 5 and J = 6 ammonia bands at moderate resolution might permit choice between a cold trap model or the irreversible uv photodestruction model for the ammonia distribution. The lack of prominent emission cores in the NH3 rotation-inversion lines only implies that the mixing ratio is low. The ammonia is uniformly mixed if the inversion temperature is low but, at a higher inversion temperature, emission cores will be observed unless the photodissociation is extremely efficient down to at least the inversion layer.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 36; Oct. 197
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  • 37
    Publication Date: 2011-08-17
    Description: The mineral thermodynamic condensation sequence is applied to assemblages in Ca-Al-Ti-rich inclusions in the Allende meteorite, and it is suggested that the total amount of titanium and Ti(3+) contents of aluminous clinopyroxenes (fassaites) are temperature sensitive and that the ratio Ti(3+)/Ti(4+) may be used as a qualitative cosmothermometer. The direct gas-to-solid condensation hypothesis is favored because the predicted thermodynamic sequence is followed. Thermodynamic calculations indicate that the condensation interval of Ti(3+) stabilization is 1647-1125 K, while the titanian-fassaites probably condensed in the interval 1625-1349 K. It is suggested that the Allende meteorite has sampled a spectrum of the condensing solar nebula.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 276; Nov. 16
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  • 38
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    Publication Date: 2011-08-17
    Description: The nonequilibrium chemical processes of nitric oxide formation are computed for the wake of the Tunguska meteor of 1908. The wake characteristics are derived by carrying out an optically-thick radiation field analysis for ablation of the meteoroid. The wake flow field is approximated by a one-dimensional, well-stirred reactor model. Known characteristics of the Tunguska event are imposed as constraints, and three controlling parameters - chemical composition, density, and velocity - are varied over a range around the values derived by Korobeinikov et al. (1976) and Petrov and Stulov (1975). The calculation shows that at least 19 million tons of nitric oxide is produced between the altitudes of 10 and 50 km. The anomalous atmospheric phenomena following the event are attributed to the reactions involving nitric oxide thus produced and atmospheric ozone. It is speculated that the nitric oxide produced by the event fertilized the area near the fall, causing the observed rapid plant growth.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Acta Astronautica; 5; July-Aug
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  • 39
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    Publication Date: 2011-08-17
    Description: An absorption feature centred near 3.0 microns has been discovered in the infrared spectrum of asteroid 1 Ceres. This spectrum has been compared with laboratory spectra of meteorites and shows great similarity to the spectra of type II carbonaceous chondrites. By analogy this suggests the presence of about 10-15 per cent water in the form of water of hydration on the surface of Ceres. This is the first evidence of water in the surface material of an asteroid.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Royal Astronomical Society; vol. 182
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  • 40
    Publication Date: 2011-08-17
    Description: Multiple scattering calculations are performed in order to investigate the nature of the circular polarization of sunlight reflected by planetary atmospheres. Contour diagrams as a function of size parameter and phase angle are made for the integrated light from a spherical but locally plane-parallel atmosphere of spherical particles. To investigate the origin of the circular polarization, results are also computed for second-order scattering and for a simpler semiquantitative model of scattering by two particles. Observations of the circular polarization of the planets are presently too meager for accurate deduction of cloud particle properties. However, certain very broad constraints can be placed on the properties of the dominant cloud particles on Jupiter and Saturn. The cloud particle size and refractive index deduced for the Jupiter clouds by Loskutov, Morozhenko, and Yanovitskii from analyses of the linear polarization are not consistent with the circular polarization. The few available circular polarization observations of Venus are also examined.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 33; Jan. 197
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  • 41
    Publication Date: 2011-08-17
    Description: In connection with a need for more definitive information concerning the composition of Phobos in a study of its origin, an ultraviolet-visible-infrared reflectance spectrum of the Martian satellite was compiled from the Mariner 9 ultraviolet spectrometer, Viking lander imaging, and ground-based photometric data. The probable surface composition of Phobos was deduced by comparing the obtained spectrum with the spectra of asteroids of known composition. The considered data show that the reflectivity of Phobos is flat from 1100 to 400 nm but decreases sharply in the ultraviolet to about 1 percent at 212 nm. The reflectance spectrum is similar to the spectra of asteroids Ceres and Pallas which were found to have surface compositions similar to that of carbonaceous chondrites. It is concluded that the surface composition of Phobos is also similar to that of carbonaceous chondrites. The results of the investigation point to different modes of origin for Mars and Phobos.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 199; Jan. 6
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  • 42
    Publication Date: 2011-08-17
    Description: Viking Orbiter-1 (VO-1) made a series of close flybys of the Martian satellite Phobos in February and May 1977. A description is presented of the results obtained during the flybys in February. The flyby geometries for the encounter period in February are shown in a graph. The trajectory design gave flybys on the illuminated side of Phobos within 80 to 300 km during the entire encounter period. The primary encounter observations of Phobos included visual and infrared imaging as well as radio tracking of VO-1 while it was under the gravitational influence of Phobos. Visual imaging was obtained from two narrow-angle television cameras. Infrared observations were obtained from an infrared thermal mapper. Radio data included S- and X-band Doppler and ranging data to VO-1 with a 10-second Doppler count. Assuming for Phobos a volume of 500 + or - 900 cu km, a mean density of 1.9 + or - 0.6 g/cu cm is obtained for it on the basis of the processed data.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 199; Jan. 6
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  • 43
    Publication Date: 2011-08-17
    Description: Boundary-layer shape measurements at the engine inlet on four different hypersonic aircraft forebody designs (with no engine on the forebody) are reported. The measurements provide a qualitative assessment of the effectiveness of various forebody geometries as engine inlet precompression surfaces. The designs, tested in a hypersonic tunnel at Mach 6 and a nominal freestream Reynolds number of 30,500,000, included a semiconical forebody, a configuration similar to a slab delta wing, a conical nose blended into a flat surface, and a conical, complex forebody shape. Boundary layer height as a function of forebody compression is shown for each design.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 15; Jan. 197
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  • 44
    Publication Date: 2011-08-17
    Description: Relative concentrations of noble gases and C and N are evaluated for the terrestrial planets. Comparisons between amounts of volatile materials in carbonaceous chondrites and on Earth and Mars are presented as support for the accretion model of planetary formation. However, attention is given to the large differences in the C/noble gas ratios on various bodies in the solar system, e.g. the Sun, Venus, Earth, Mars, stressing that the data are too incomplete to provide a reliable model for the sources of volatile and noble elements on the terrestrial planets.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 271; Jan. 12
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  • 45
    Publication Date: 2011-08-17
    Description: The reflectivity of Phobos has been determined in the spectral region from 0.4 to 1.1 micrometers from images taken with a Viking lander camera. The reflectivity curve is flat in this spectral interval and the geometric albedo equals 0.05 + or - 0.01. These results, together with Phobos's reflectivity spectrum in the ultraviolet, are compared with laboratory spectra of carbonaceous chondrites and basalts. The spectra of carbonaceous chondrites are consistent with the observations, whereas the basalt spectra are not. These findings raise the possibility that Phobos may be a captured object rather than a natural satellite of Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 199; Jan. 6
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  • 46
    Publication Date: 2011-08-17
    Description: The International Astronomical Union has endorsed a nomenclature for the albedo features on Mercury. Designations are based upon the mythological names related to the god Hermes; they are expressed in Latin form. The dark-hued albedo features are associated with the generic term Solitudo. The light-hued areas are designated by a single name without generic term. The 32 names adopted are allocated on the Mercury map.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 34; Apr. 197
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  • 47
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    Publication Date: 2011-08-17
    Description: A second-order effect in the relationship between jovian decameter storms and the departure of Io from superior geocentric conjunction is explained on the basis of latitudinal variations in the earth-Jupiter viewing geometry. These variations are defined by the 12-year cycle in the jovicentric declination of the earth. In addition, it is found that the emission of the jovian decameter storm source Io-B (Io-C) is beamed from the northern (southern) magnetic latitudes. These conclusions are compatible with source positions derived from polarimetry and from considerations of planetary-limb shadowing.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 272; Mar. 23
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  • 48
    Publication Date: 2011-08-17
    Description: Photopolarimetric observations of a prominent bright zone and a dark belt of Jupiter in red and blue light are analyzed which were performed by Pioneer 10 at phase angles of 12, 23, 34, 109, 120, 127, and 150 deg. Geometric and photometric reductions of the imaging data are described, the instrument sensitivity at various times is evaluated, and the data are referred to an absolute scale. The observations are analyzed in detail by comparing the data with results of radiative-transfer calculations for specific scattering models of Jupiter's atmosphere. These models include those with a vertical structure consisting of a layer of Rayleigh-scattering gas above a semiinfinite mixture of cloud particles and gas, those having a small quantity of aerosols in the gas above either the diffuse cloud in a reflecting-scattering model or the top cloud of a two-cloud-layer model, those in which a forward-scattering haze is mixed uniformly with gas, and those containing dust layers. It is found that in both the belt and the zone in red as well as blue light, cloud phase functions are required which provide both strong forward scattering and some backscattering.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 33; Mar. 197
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  • 49
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    Publication Date: 2011-08-17
    Description: It is reported that when the star SAO158687 passed behind the Uranus system, its light was occulted twice by the epsilon (fifth) ring of the planet. The first part of the ring to occult was about 100 km wide and the second part was about 40 km wide. The variable width of the ring is accounted for by differences in the orbital eccentricities of the individual particles composing the ring.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 272; Mar. 9
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  • 50
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    Publication Date: 2011-08-17
    Description: The indicial method for calculating flutter derivatives for two-dimensional airfoils at transonic speeds is discussed, with particular attention given to the effect of a moving shock on the flow variables in the indicial method. An expression for the pressure coefficient is developed on the basis of an explicit treatment of the shock motion; the pressure distribution may then be calculated for general oscillations through use of the indicial method. Explicit inclusion of the shock motion is not necessary if only the lift and pitching moment coefficients are desired.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 16; June 197
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  • 51
    Publication Date: 2011-08-17
    Description: Results are reported for two-color (red and blue) high-speed photometric observations of the April 8, 1976, occultation of Epsilon Gem by Mars. The observing system is briefly described, fits to an isothermal atmospheric model of the event are presented, and the blue data are used to derive temperature profiles of the Martian atmosphere in the manner of Wasserman and Veverka (1973). The results are compared with those of Elliot et al. (1977), which were obtained from the NASA Kuiper Airborne Observatory.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal; 83; Apr. 197
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  • 52
    Publication Date: 2011-08-17
    Description: The shape and absolute value of Venus' reflectivity spectrum is measured in the 1.2- to 4.0 micrometer spectral region with a circular variable filter wheel spectrometer having a spectral resolution of 1.5%. Comparing these spectra with synthetic spectra generated with a multiple-scattering computer code, a number of properties of the Venus clouds are inferred. Evidence is obtained indicating that the clouds are made of a water solution of sulfuric acid in their top unit optical depth, and that the clouds are made of this material down to an optical depth of at least 25. In addition, the acid concentration is 84 plus or minus 2% H2SO4 by weight in the top unit optical depth, the total optical depth of the clouds is 37.5 plus or minus 12.5, and the cross-sectional weighted mean particle radius lies between 0.5 and 1.4 micrometers in the top unit optical depth of the clouds. It is found that the average volume mixing ratio of H2SO4 and H2O contained in the cloud material both equal approximately 2 x 10 to the -6. Employing vapor pressure arguments, the acid concentration is shown to equal 84 plus or minus 6% at the cloud bottom and the water vapor mixing ratio beneath the clouds lies between 6 x 10 to the -4 and 10 to the -2.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 34; Apr. 197
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  • 53
    Publication Date: 2011-08-17
    Description: From a comparison of the Mariner 10 third encounter UV spectrometer data with intensities generated from a newly constructed model exosphere, a new value of 4.5 x 10 to the -4th power for the fraction of the solar wind He(++) flux to be intercepted and captured by Mercury's magnetosphere, if the observed He atmosphere is maintained by the solar wind, has been derived. If an internal source for He prevails, the corresponding upper bound for the global outgassing rate is estimated to be 4.5 x 10 to the 22nd power/s. These values differ from those given earlier because of the present use of a surface temperature distribution satisfying the heat equation over Mercury's entire surface which employs Mariner-10-determined mean surface thermal characteristics. The mean standoff distance of Mercury's magnetopause averaged over Mercury's orbit is also used. Agreement between the observed and calculated intensities is found to be good. Minor discrepancies on the nightside of the terminator are explicable in terms of differences between actual and computed temperatures and scale height structure changes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 83; Apr. 1
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  • 54
    Publication Date: 2011-08-17
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 5; Apr. 197
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  • 55
    Publication Date: 2011-08-17
    Description: Calculations have been made to determine the effects of atmospheric drag and gravity on impact ejecta trajectories on Venus, Mars, and earth. The equations of motion were numerically integrated for a broad range of body sizes, initial velocities, and initial elevation angles. A dimensionless parameter was found from approximate analytic solutions which correlated the ejecta range, final impact angle, and final impact velocity for all three planets.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 33; Mar. 197
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  • 56
    Publication Date: 2011-08-17
    Description: An interdisciplinary study of the 65-km diameter Manicouagan ring structure in Quebec was undertaken to gain insight into the integrated effects of impacts on terrestrial planetary bodies. The paper serves as an introduction to several companion papers and summarizes major conclusions. Studies of the 214 m.y. old structure show that the melt rocks are texturally inhomogeneous but chemically homogeneous and can be modeled as a mixture of target lithologies. The melt rocks have a Sr-87/Sr-86 ratio compatible with the melting of crustal rocks. The melt had a two-stage cooling history with clast-melt interactions indicative of mixing superheated silicate liquid with cold clasts. Grain size, clast reactions, and thermal equilibration of clasts and melts are described.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 83; June 10
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  • 57
    Publication Date: 2011-08-17
    Description: Four separable effects of atmospheric turbulence on average refraction angles in occultation experiments are derived from a simplified analysis, and related to more general formulations by B. S. Haugstad. The major contributors are shown to be due to gradients in height of the strength of the turbulence, and the sense of the resulting changes in refraction angles is explained in terms of Fermat's principle. Because the results of analyses of such gradient effects by W. B. Hubbard and J. R. Jokipii are expressed in other ways, a special effort is made to compare all of the predictions on a common basis. We conclude that there are fundamental differences, and use arguments based on energy conservation and Fermat's principle to help characterize the discrepancies.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 34; May 1978
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  • 58
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    Publication Date: 2011-08-17
    Description: Consideration is given to the development of theories concerning the rings of Saturn. Particular attention is given to ring structure, noting its thinness, the separations between rings, and observed variations in brightness. Data gathered via infrared, radio and radar techniques are described in terms of ring particle composition and size. Hypotheses about ring origin and evolution are outlined, including the tidal disruption model, calculations of Saturn's gravitational contraction history, grazing, and meteoroid bombardment. Prospects for future observations of Saturn's rings are reviewed, such as the variation in their radar reflectivity as a function of the tilt of the ring plane.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: American Scientist; 66; Jan
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  • 59
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    Publication Date: 2011-08-17
    Description: The role of Miranda-Ariel orbital resonances in determining the structure of the rings of Uranus is discussed. In particular, it is argued that the three-body orbital resonances of Miranda and Ariel may function as a mechanism for the formation of narrow rings, rather than as a mechanism for trapping freely orbiting particles; the formation of narrow rings, in this hypothesis, would involve an inelastic collision process. The narrowness of the resonances may account for the sharply defined ring boundaries.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 272; Apr. 27
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  • 60
    Publication Date: 2011-08-17
    Description: Solar wind induced magnetic fields may be present in the dayside ionosphere of Venus. A scale analysis and detailed calculations of the effects of different field line orientations on photoelectron transport and electron temperature show that horizontal magnetic fields considerably alter the profiles of electron heating and temperature and photoelectron flux. Direct injection of solar wind electrons has been considered, and the effects are minor. No evidence is found to support the suggestion that a sharp gradient in electron temperature is the cause of certain features in the Mariner-10 electron density profile.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 83; May 1
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  • 61
    Publication Date: 2011-08-17
    Description: The Copernicus Orbiting Astronomical Observatory was used to obtain measurements of Mars Lyman-alpha (1215.671-angstrom) emission at the solar minimum, which has resulted in the first information on atomic hydrogen concentrations in the upper atmosphere of Mars at the solar minimum. The Copernicus measurements, coupled with the Viking in situ measurements of the temperature (170 plus or minus 30 K) of the upper atmosphere of Mars, indicate that the atomic hydrogen number density at the exobase of Mars (250 kilometers) is about 60 times greater than that deduced from Mariner 6 and 7 Lyman-alpha measurements obtained during a period of high solar activity. The Copernicus results are consistent with Hunten's hypothesis of the diffusion-limited escape of atomic hydrogen from Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 200; June 2
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  • 62
    Publication Date: 2011-08-17
    Description: Studies of Phobos and Deimos, the two satellites of Mars, may provide the best observations yet of the material populating the asteroid belt. Viking observations of Phobos showing crater chains and striations are analyzed, and Mariner-9 photometry exhibiting the albedo of the satellite is discussed. A mass determination for Phobos results in a value of 1.1 times 10 to the 19th power g; the mean density of the satellite is set at about 2 g per cu cm, a value suggesting formation of the satellite from material in the asteroid belt.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Royal Astronomical Society; vol. 19
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  • 63
    Publication Date: 2011-08-17
    Description: Methods for obtaining and processing photographs of bright meteors in the United States in the period from 1963 to 1975 are briefly described. Orbital elements and other characteristics are given for 334 bright persistent and long Prairie Network fireballs. The accuracy of the data presented is evaluated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritika; 37, 1; 1978
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  • 64
    Publication Date: 2011-08-17
    Description: A cube-like fragment with an approximately 4 mm edge was taken from the Yamato-74659 meteorite for the mineralogical and crystallographic examination discussed in the present paper. An analysis of powdered fragments by a standard wet chemical method showed that it matched to weathered ureilite. The chemical composition was found to differ from other ureilites in that the FeO content (8.83 wt%) is the lowest among known ureilites and it is richer in SiO2 contents (42.91 wt%).
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 65
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    Publication Date: 2011-08-17
    Description: Impact craters on the moon provided primary pathways for volcanic eruptions through shock-induced fractures that immediately or subsequently tap magma reservoirs. Evidence for this process includes unbreached lava-filled craters and fractured crater floors with associated eruptives. Over 200 craters with floor fractures have been identified on the moon. They commonly occur along the margins of irregular maria, thereby suggesting a link to this important phase of lunar volcanism. Topographic data reveal small elevation differences between the summit of the remnant central peaks and crater rim, and in many cases suggest that floor fracturing resulted from a tabular intrusion localized beneath the crater with uplift of the crater floor. A comparison of lunar and Martian crater photographs shows that some Martian craters also exhibit similar highly localized endogenic modifications.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 66
    Publication Date: 2011-08-17
    Description: The Aioun el Atrouss meteorite is a breccia consisting largely of angular fragments of green orthopyroxene and containing scattered clasts of basaltic composition (mostly pigeonite and calcic plagioclase). It appears to be a physical mixture of two meteorite types - diogenite (hypersthene achondrite) and eucrite (basaltic achondrite). The results of a mineral analysis are tabulated, and typical pyroxene compositions in orthopyroxene (diogenite), subophitic and granoblastic portions of the meteorite are presented.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 67
    Publication Date: 2011-08-17
    Description: A spectrum of Jupiter in the two-micron region has been analyzed to determine the Jovian ammonia abundance. The result is approximately 4 cm-amagat, assuming an airmass factor of 2.5 and a single effective reflecting layer for this wavelength. This is compared with the abundances observed at other wavelengths.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 36; Dec. 197
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  • 68
    Publication Date: 2011-08-17
    Description: Reflectivity spectra of the trailing and leading sides of Io, Europa, Callisto, and Ganymede are analyzed which were obtained at an altitude of 41,000 ft from the Kuiper Airborne Observatory with circular variable filter-wheel spectrometers in the spectral region from 0.7 to 5.5 microns. The data are compared with laboratory spectrum and with synthetic spectra constructed on the basis of simple multiscattering theory. The 2.9-micron feature in Callisto's spectra is attributed primarily to bound water; the fractional amounts of water-ice cover on the trailing and leading sides of Ganymede and on the leading side of Europa are estimated. The bare-ground areas on Ganymede are shown to have reflectivity properties comparable to those of Callisto's surface in the studied spectral region, and the surfaces of both satellites are found to contain significant quantities of bound water. It is suggested that minor but significant amounts of ferrous-bearing material (either ferrous salts or alkali feldspars) can account for the 1.35-micron feature of Io.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 36; Dec. 197
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  • 69
    Publication Date: 2011-08-17
    Description: This paper describes an analysis of carbon-rich separates prepared by demineralization of colloidal fractions after disaggregation of bulk samples of the type C2 meteorites Murray, Murchison, and Cold Bokkeveld, as well as a methanol colloid extracted from acid-resistant residues of the Allende meteorite (type C3V) obtained by dissolution of most of the minerals in HCl and HF acids. The carbonaceous separates, or lAlates (a coined word designating colloids prepared sometimes before and sometimes after acid treatment), are characterized incompletely and with difficulty. A stepwise heating experiment on a Murray lAlate is discussed which revealed bimodal release of all noble gases, with similar patterns for Ar, Kr, and Xe. Chemical reactions are suggested as the likely mechanism for gas release. The results are shown to support the concept of a carbonaceous gas carrier uniformly present in meteorites of various types.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 42; Dec. 197
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  • 70
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    Publication Date: 2011-08-17
    Description: The orbital evolution of Phobos and Deimos is considered from the standpoints of today's orbit, the semimajor axis, and eccentricity and inclination. The synchronous rotations of the moons are discussed, and attention is given to the origin (i.e., accretion and capture) of the moons.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 71
    Publication Date: 2011-08-17
    Description: The paper reports on an analysis of magnetic field observations by the Mariner 10 spacecraft during approximately a one-day period ending a few hours beyond Venus encounter on February 5, 1974. The magnetic field measurements are used to study the downstream region of the solar wind-Venus interaction over a distance of about 100 Venus radii. The study characterizes the various magnetic field regions encountered behind and near the planet; presents an argument that the magnetic field signatures observed are consistent with observation of either a steady or a transient wake, or at least the boundary region of such a wake, interior to a common sheath-like region; examines in detail the fluctuation and discontinuity features of these regions and compares them with those of the interplanetary medium; and summarizes how these new features contribute to the understanding of the solar wind-Venus interaction.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 83; Aug. 1
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  • 72
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    Publication Date: 2011-08-17
    Description: The process by which odd nitrogen species (atomic nitrogen and nitric oxide) are formed during atmospheric entry of meteoroids is analyzed theoretically. An ablating meteoroid is assumed to be a point source of mass with a continuum regime evolving in its wake. The amounts of odd nitrogen species, produced by high-temperature reactions of air in the continuum wake, are calculated by numerical integration of chemical rate equations. Flow properties are assumed to be uniform across the wake, and 29 reactions involving five neutral species and five singly ionized species are considered, as well as vibrational and electron temperature nonequilibrium phenomena. The results, when they are summed over the observed mass, velocity, and entry-angle distribution of meteoroids, provide odd-nitrogen-species annual global production rates as functions of altitude. The peak production of nitric oxide is found to occur at an altitude of about 85 km; atomic nitrogen production peaks at about 95 km. The total annual rate for nitric oxide is 40 million kg; for atomic nitrogen it is 170 million kg.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 83; Aug. 20
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  • 73
    Publication Date: 2011-08-17
    Description: The global density distribution of atomic H in the upper atmosphere of Venus is determined in terms of a global circulation model. It is shown that H produced on the dayside is efficiently advected to the nightside by the major gas CO2 where it is then convected to lower altitudes and recombines. A maximum night/day H density ratio of about 5 is derived, in which case exospheric return flow from night to day strongly limits the nightside density enhancement. A previously postulated constraint connecting the eddy diffusion coefficient with the escape flux of H in one dimensional models is no longer required when global circulation of H is considered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 5; Aug. 197
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  • 74
    Publication Date: 2011-08-17
    Description: Results are presented for two laboratory measurements of the intensity and central frequency of the (4, 0) S(1) quadrupole line of H2, which were made at pressures of 2.658 and 1.494 atm through a 0.456-km path length. It is found that the absolute line intensity is significantly lower than the value predicted from theoretical matrix elements but is essentially identical to the value derived by Rank et al. (1966). The central-frequency results are shown to verify the pressure shift predicted by McKellar (1974). It is concluded that hydrogen abundances estimated from the equivalent width of the (4,0) S(1) quadrupole line in the spectra of the outer planets will have to be revised upward by nearly a factor of 2.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal; vol. 224
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  • 75
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    Publication Date: 2011-08-17
    Description: The spectrum of a fast (63 km/s) sporadic meteor for which altitude and orbit data are available is reported. The -6 mag meteor occurred on January 5, 1976, over southern New Mexico. Fifty features have been identified in the spectrum. The spectrum is essentially identical to that of Perseid meteors of similar brightness. It is shown that heavy-particle collisions do not dominate bright meteor spectra lacking time resolution. Low-energy electron excitation of Ca II is strongly indicated in the wake to such an extent as to strongly affect spectra of this type lacking time resolution.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal; vol. 224
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  • 76
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    Publication Date: 2011-08-17
    Description: Viking Orbiter observations of Phobos and Deimos are presented with attention to physical dimension and surface features. Both satellites are approximately 1.4 times as long as they are wide; Phobos having a length of 27 km, while Deimos is half that size. In addition, both satellites are tidally locked, as is earth's moon, and are held together by cohesive forces as well as by gravity. Phobos and Deimos are both heavily cratered, and Phobos has deep (30 m) grooves in the vicinity of its largest crater, Stickney; indicating surface fracturing under meteorite impact. The craters on Deimos are largely filled with a fine-grained substance, probably crater ejecta.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Sky and Telescope; 56; Sept
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  • 77
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    Publication Date: 2011-08-17
    Description: During the past decade, significant advances in the in situ measurements of planetary magnetic fields have been made. The U.S.A. and U.S.S.R. have conducted spacecraft investigations of all the planets, from innermost Mercury out to Jupiter. Unexpectedly, Mercury was found to possess a global magnetic field but neither the Moon nor Venus do. The results at Mars are incomplete but if a global field exists, it is clearly quite weak. The main magnetic field of Jupiter has been measured directly for the first time and confirms, as well as augments appreciably, the past 2 decades of ground-based radio astronomical studies which provided indirect evidence of the field. Progress in developing analytically complete models of the dynamo process suggests a possible common origin for Mercury, earth and Jupiter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Moon and the Planets; 18; June 197
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  • 78
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    Publication Date: 2011-08-17
    Description: Present-day knowledge about the planetary magnetic field and interior of Mercury is reviewed. Radar observations are discussed which delineated the correct rotation rate of Mercury (58.646 days) and the planet's 3:2 spin-orbit resonance. The data obtained in Mariner 10 magnetic-field observations during the first and third encounters with Mercury are examined in detail, and theoretical studies of the planet's interior are summarized, including both steady-state models and those describing the thermal evolution of the planet. Two possible source mechanisms for the observed intrinsic planetary magnetic field are evaluated: an active dynamo and a passive paleomagnetic field frozen into the planet's outer layers at an earlier epoch. It is noted that neither the available magnetic-field data nor models of the planetary interior permit one to distinguish uniquely between the two mechanisms. The spin-orbit commensurability of Mercury is explained in the framework of the solar tides induced in the body of the planet, a nonaxisymmetric moment of inertia, and the highly eccentric orbit of the planet.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Space Science Reviews; 21; Mar. 197
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  • 79
    Publication Date: 2011-08-17
    Description: The author develops the idea that the formation of the solar system was triggered by the explosion of a supernova near a compressed interstellar cloud, which was further compressed by the supernova ejecta until it went over the threshold for gravitational collapse. During the collapse it is expected that the cloud would fragment into much smaller pieces. The principle source of friction in the collapsing nebula is taken to be turbulent viscosity, the required stirring having been supplied possibly by meridional circulation currents. The theory can be shown to account for how a great deal of condensed matter in the form of cometary bodies could be put into elliptical orbits extending toward 100,000 AU, the region of the Oort reservoir.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 80
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    Publication Date: 2011-08-17
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 35; Sept
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  • 81
    Publication Date: 2011-08-17
    Description: Results of UBV photometry and polarimetry of 1580 Betulia during its 1976 apparition are presented. The synodic period of rotation is found to be 6.130 hr. The linear phase coefficient and absolute magnitude of the primary maximum in V are 0.032 mag/deg and 14.88, respectively. No color variations with rotation or solar phase angle were detected, the mean colors being B-V = 0.66 and U-B = 0.24. Betulia's light curve is unique among asteroids studied to date in that it displays three maxima and three minima within one rotational cycle, indicative of a region of greater roughness and/or a dark spot on one of its broad faces. Polarization results indicate a low albedo and a mean diameter of about 7 km, establishing Betulia as the first C-type asteroid to be found among the Mars crossers. A model accounting for most features of Betulia's light curve is given by a prolate spheroid rotating about one of its shorter axes having an axis ratio of 1:1.21 with a major topographic feature on one of its broad faces.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 35; Sept
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  • 82
    Publication Date: 2011-08-17
    Description: Various measurements were made to determine the temperature and attitude of the gondola and the status of primary power and control equipment. Bead thermistors were used to measure temperatures at selected points throughout the gondola. A two-axis magnetometer and a two-axis pendulum were used to measure gondola attitude. Voltage and current measurements indicated the status of the primary power sources and associated power converters.
    Keywords: AERODYNAMICS
    Type: NASA. Goddard Space Flight Center STRATCOM 8 Data Workshop and Suppl.; p 24-31
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  • 83
    Publication Date: 2011-08-17
    Description: The STRATCOM (STRATospheric COMposition) is a long term multipurpose program for integrated, correlated measurements of stratospheric parameters related to composition, thermodynamics, and radiative balance. Balloon 8-b, carrying a solar-pointing grating infrared spectrometer, two CO2 thermal emission radiometers and two in-situ air temperature sensors was launched at 1251 MST on 28 September 1977 to float at an altitude of 39 km from 1521 MST with the instruments making measurements at that altitude through the time of sunset at 1822 MST. Balloon 8-a lifted a payload consisting of four UV filter photometers, two UV spectrometers, two chemiluminescent ozonesondes, dasibi ozone monitor, 14 tube cryogenic sampler, two aluminum oxide H2O sensors, four air temperature sensors, atmospheric pressure sensor, infrared and visible pyranometers, downward-looking camera, blunt-kryton lamp-Gerdien condenser probe, three component anemometer, balloon apex-plate payload and three parachute-borne dropsondes.
    Keywords: AERODYNAMICS
    Type: NASA. Goddard Space Flight Center STRATCOM 8 Data Workshop and Suppl.; p 10-23
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  • 84
    Publication Date: 2011-08-17
    Description: During the scientific commissioning phase of IUE several spectra were acquired from objects residing in the Solar System. The activities focused on testing numerous parameters which would indicate the usefulness of IUE for planetary science. It seems that IUE can successfully tackle many important questions and the data analysis and interpretation of the initial set of observations has begun.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 275; Oct. 5
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  • 85
    Publication Date: 2011-08-17
    Description: Power spectrum analysis of Mariner 10 images for planetary zonal wavenumbers no less than 3 and for latitudes in the range 55 deg S to 25 deg N yields spectra which show a systematic and apparently significant variation with latitude. Accordingly, average spectra are determined for three latitude zones: an equatorial region, a midlatitude region, and an intermediate zone. A comparison of the results for Venus with brightness distribution spectra for terrestrial clouds reveals similarities between the Venus midlatitude region spectrum and that for the equatorial region of the earth. The only indication of a departure from a general power law behavior for the Venus spectra is a flattening of the equatorial spectrum in the region of wavenumbers 3 and 4. The characteristics of the Venus image spectra appear to be compatible with the interpretation that the observable clouds lie in a region of high static stability with the inertial eddy motions corresponding to two-dimensional turbulence.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 35; Sept
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  • 86
    Publication Date: 2011-08-17
    Description: On the basis of a linear theory it is shown that wind-induced diffusion associated with large-scale circulation in the Venus atmosphere leads to nighttime bulges in O, He, and H. The effect on He is very large with a 243-day rotation period of the atmosphere, yielding an upper limit for the maximum/minimum diurnal density ratio of approximately 1000. This ratio is much smaller for H (max/min of about 4) due to the greater importance of exospheric flow, which acts (as for He) as a damping mechanism. For the faster rotation period of 4 days consistent with the motions of the cloud tops, the diurnal variation of O is significantly reduced, contributing to an increase by a factor of two in the horizontal wind velocity. The same effect significantly reduces the He variations to an increase by a factor of 7 from day to night. The results suggest that composition and wind measurements provide valuable information on the rotation rate of the Cytherean thermosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 83; Sept. 1
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  • 87
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    Publication Date: 2011-08-17
    Description: On the basis of a presented theory, it is suggested that Venus' current rotation is a stable balance between atmospheric and solar body tides. The theory is concerned with Venus' atmospheric tides, driven by solar heating, and how these tides could serve as a third torque to balance the effects of solar body torque and to maintain a stable equilibrium resonance with regard to the earth's gravitational effects. In the absence of the atmospheric tidal torque, or some other torque, it would be expected that Venus would be despun until synchronous rotation (one side always facing the sun) is attained, rather than retain the retrograde rotation period of 243 days.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 275; Sept. 7
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  • 88
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    Publication Date: 2011-08-17
    Description: A new scenario is offered for the origin of the moon. It is assumed that the earth formed initially with about the maximum amount of angular momentum consistent with dynamical stability. This state is approximated by the secularly unstable Maclaurin spheroids (highly flattened hamburger-shaped bodies). It is shown that the earth cannot depart from this state at a reasonable rate as long as its viscosity is in the range of liquid rock. Since core formation supplies about 1600 kJ/kg, the earth will not leave this state until core formation is complete. When cooling produces a rise in viscosity, the earth will necessarily evolve along a path which is approximated by the Riemann ellipsoids (which have rapid internal motion). The evolution is toward a Jacobi ellipsoid, but it is intercepted by the development of a third-harmonic (pear-shaped) instability, which is catastrophic and leads to fission. The process of fission itself may be fundamentally analogous to the breaking of a wave in water. We cannot exclude the possibility that some other planets evolved similarly.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 35; Aug. 197
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  • 89
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    Publication Date: 2011-08-17
    Description: Pioneers 10 and 11 have transmitted seven images of the Galilean satellites with surface resolutions on the order of several hundred kilometers. Because the point-spread function is well determined, it has been possible to measure the radius of each of the four satellites to a precision of typically plus or minus 30 km. The method used fits a semicircle to the illuminated limb by varying the center coordinates and radius until the best-fit criteria are satisfied. Careful attention is given to locating the true edge position within the blurred image. The radius determinations and corresponding densities for the satellites are: Io (1840 plus or minus 30, 3.41 plus or minus 0.19), Europa (1552 plus or minus 20, 3.06 plus or minus 0.15), Ganymede (2650 plus or minus 25, 1.90 plus or minus 0.06), and Callisto (2420 plus or minus 20, 1.81 plus or minus 0.05), where the units are in kilometers and grams per cubic centimeters, respectively.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 35; Aug. 197
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  • 90
    Publication Date: 2011-08-17
    Description: A detailed analysis of the published Venus IR maps has been performed and a number of new results have been obtained. The global contour map of the average temperature variations in the vicinity of 6120 km reveals the existence of saddle points along the equator at dawn, at noon, and just before sunset. The hot spots observed at 4:30-4:40 A.M. at 65 deg to 68 deg S latitude appear to be in the vicinity of the coldest region from which the 8- to 14-micron emissions originate. At large earth zenith angles the limb darkening curves show a hump which is attributed primarily to a single patchy haze layer in the vicinity of 6123 km and with a thickness of the order of 3 km. An average IR source region temperature of 250 K is obtained at the equator. At the poles the same altitude region is 8 K cooler.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 83; July 1
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  • 91
    Publication Date: 2016-06-07
    Description: Saturn missions have the following principal goals, in order of importance: (1) Intensive investigation of the atmosphere of Saturn; (2) determination of regional surface chemistry and properties of the surface features of satellites and properties of ring particles; (3) intensive investigation of Titan; and (4) atmospheric dynamics and structure of Saturn satellites and Saturn rings.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL The Saturn System; p 407-420
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  • 92
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    In:  CASI
    Publication Date: 2016-06-07
    Description: A hot-air balloon, with the air heated by natural sources, is described. Buoyancy is accomplished by either solar heating or by utilizing the IR thermal flux of the planet to heat the gas in the balloon. Altitude control is provided by a valve which is opened and closed by a barometer. The balloon is made of an organic material which has to absorb radiant energy and to emit as little as possible.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL The Saturn System; p 385-393
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  • 93
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    In:  CASI
    Publication Date: 2016-06-07
    Description: The similarities and differences of atmosphere entry probe mission designs and sciences appropriate to certain solar system objects, are reviewed. Candidate payloads for Saturn and Titan probes are suggested. Significant supporting research and technology efforts are required to develop mission-peculiar technology for probe exploration of the Saturnian system.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL The Saturn System; p 361-378
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  • 94
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    In:  CASI
    Publication Date: 2016-06-07
    Description: The described Saturn orbiter dual probe mission and spacecraft combines three systems into a multi-purpose Saturn exploration package. The spacecraft consists of: (1) Saturn orbiter; (2) Saturn probe; and (3) Titan probe or lander. This single spacecraft provides the capability to conduct in situ measurements of the Saturn and Titan atmospheres, and, possibly the Titan surface, as well as a variety of remote sensing measurements. The remote sensing capabilities will be used to study the surfaces, interiors and environments of Saturn's satellites, the rings of Saturn, Saturn's magnetosphere, and synoptic properties of Saturn's atmosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Its The Saturn System; p 345-360
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  • 95
    Publication Date: 2016-06-07
    Description: Voyager will use dual-frequency 3.5 and 13 cm wavelength radio occultation techniques to study the atmospheres and ionospheres of Saturn and Titan, and the rings of Saturn. At Titan radio occultation is predicted to probe the atmosphere to the surface. The existence of a surface could be confirmed by detection of an obliquely scattered echo. At Saturn the two Voyager encounters will provide occultation measurements of temperate and equatorial regions of the atmosphere and ionosphere, and of the rings. The atmosphere will also be probed in polar regions during the deepest portions of the occultation. Both frequency and intensity data will be collected and jointly analyzed to study temperature-pressure profiles, and to derive information on atmospheric shape, turbulence, and weather. For the rings, Voyager will provide measurements of the complex (amplitude and phase) radio extinction and angular scattering functions of the ring particles as a function of wavelength, polarization, and radial distance from Saturn.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL The Saturn System; p 317-330
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  • 96
    Publication Date: 2016-06-07
    Description: The Voyager infrared investigation uses a Michelson interferometer (IRIS) covering the spectral range from 200 to 3000 cm/1 (3.3 to 50 micrometers) and a bore sighted radiometer covering the range from 5000 to 25000 cm/1 (0.4 to 2 micrometers). The spectral resolution of the interferometer is 4.3 cm/1 and the field of view is 0.25 deg. Scientific results anticipated from the investigation of the Saturnian system are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL The Saturn System; p 309-316
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  • 97
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    In:  CASI
    Publication Date: 2016-06-07
    Description: A brief review of the objectives and capabilities of the Voyager mission at Saturn is provided. In addition to a description of the eleven Voyager investigations and the Saturn encounter geometry, the scientific capabilities are discussed in the areas of atmospheric, satellite, magnetospheric, and ring studies.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL The Saturn System; p 285-299
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  • 98
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    In:  CASI
    Publication Date: 2016-06-07
    Description: The Voyager imaging science experiment objectives at Saturn include exploratory reconnaissance of Saturn, its satellites and its rings. The imaging cameras are described, along with an abbreviated discussion of specific objectives.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL The Saturn System; p 301-308
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  • 99
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Models of the Saturnian magnetosphere based on the application of magnetospheric scaling relations to a spin-aligned planetary magnetic dipole, that produces a surface equatorial field strength in the range 0.5 to 2 gauss, exhibit the following properties: (1) The orbit of Titan lies inside of the magnetosphere essentially all of the time, even when variations in the size of the magnetosphere resulting from solar wind pressure changes are taken into account; (2) the Brice-type planetary plasmasphere reaches a peak density of about 10 protons cm/3 at L approximately 7 (L = planetocentric distance in units of planetary radii); (3) Saturn's rings have a profound effect on the energetic particle population and the plasmaspheres derived from interstellar neutrals and Titan's torus; (4) the model calculation suggests that the Titan-derived plasmasphere may be self-amplifying with a feed-back factor greater than unity, which implies the possibility of a non-linearly saturated, highly inflated Saturnian magnetosphere; and (5) this same source can have important eroding effects on the outer edge of the rings determined by Brown-Lauzerotti sputtering rates.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL The Saturn System; p 265-284
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  • 100
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Direct, strong evidence for non-thermal radio emission from Saturn exists in the hectometric data observed by Imp 6. The planet has been tentatively identified as a decametric source, but the most sensitive and most recent data fail to confirm this. At metric or decimetric wavelengths Saturn has no non-thermal emission like Jupiter's synchrotron sources. Finally, a comparative study of Earth and Jupiter radio emissions suggests lightning discharges.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL The Saturn System; p 251-263
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