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  • Inorganic Chemistry  (785)
  • LUNAR AND PLANETARY EXPLORATION  (715)
  • FLUID MECHANICS AND HEAT TRANSFER
  • 2015-2019
  • 1995-1999
  • 1985-1989  (1.891)
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  • 1985  (1.891)
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  • 2015-2019
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  • 1
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    The Venus ionosphere (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Physical properties of the Venus ionosphere obtained by experiments on the US Pioneer Venus and the Soviet Venera missions are presented in the form of models suitable for inclusion in the Venus International Reference Atmosphere. The models comprise electron density (from 120 km), electron and ion temperatures, and relative ion abundance in the altitude range from 150 km to 1000 km for solar zenith angles from 0 to 180 deg. In addition, information on ion transport velocities, ionopause altitudes, and magnetic field characteristics of the Venus ionosphere, are presented in tabular or graphical form. Also discussed is the solar control of the physical properties of the Venus ionosphere.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Advances in Space Research (ISSN 0273-1177); 5; 11, 1
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  • 2
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    Particulate matter in the Venus atmosphere (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The paper presents a summary of the data currently available (June 1984) describing the planet-enshrouding particulate matter in the Venus atmosphere. A description and discussion of the state of knowledge of the Venus clouds and hazes precedes the tables and plots. The tabular material includes a precis of upper haze and cloud-top properties, parameters for model-size distributions for particles and particulate layers, and columnar masses and mass loadings.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Advances in Space Research (ISSN 0273-1177); 5; 11, 1
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  • 3
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    Models of Venus neutral upper atmosphere - Structure and composition (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Models of the Venus neutral upper atmosphere, based on both in situ and remote sensing measurements, are provided for the height interval from 100 to 3500 km. The general approach in model formulation was to divide the atmosphere into three regions: 100-150 km, 150-250 km, and 250-3500 km. Boundary conditions at 150 km are consistent with both drag and mass spectrometer measurements. A paramount consideration was to keep the models simple enough to be used conveniently. Available observations are reviewed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Advances in Space Research (ISSN 0273-1177); 5; 11, 1
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  • 4
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    The interplanetary micrometeoroid flux and lunar primary and secondary microcraters (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: It is proposed that considerable care is required to properly interpret either spacecraft in situ data or lunar crater data as well as near-earth data; in the case of the former, complications may arise which may be attributed to secondary lunar ejecta impacts, in the latter, they may result from impacting earth-orbiting debris. Experimental evidence suggests that most impact pits on lunar rocks with pit diameters smaller than 7 micrometers have been generated by lunar secondary ejecta impacts and not by primary meteoroid impacts. It is also found that lunar crater production rates are more accurate when deduced from meteoroid space experiments and not from solar flare track ages. It is concluded that in so far as all of the above qualifications are taken into account, a self-consistent meteoroid flux versus mass distribution is obtained.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
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  • 5
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    Simulation as an aid to phenomenological modeling (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Certain difficulties arise in connection with the development of models for the prediction of turbulent flow characteristics. The present paper is mainly concerned with an approach which provides an aid in such development work by making it possible to test Reynolds average turbulence models. This approach is based on full and large eddy simulations of turbulent flows. Attention is given to details regarding Reynolds average turbulence models, mixing length models, two equation (k-epsilon) models, Reynolds stress models, and passive scalars. It is shown that a great deal about modeling can be learned from simulations of turbulent flows. There is reason to believe that these results will lead to improvements in the quality of predictions of turbulent flows.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 6
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    Energy conversion processes in the outer planets (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Energy conversion processes which are potentially important in the outer planets at pressures greater than obut 0.1 bar are reviewed. Generation of buoyancy contrasts by condensation of various constituents is discussed with emphasis on the possible significance of phase changes in substances such as Si and Mg compounds at deep levels. It is demonstrated that, in the absence of nonequilibrium thermodynamic processes, strong kinetic energy generation must accompany the transport of heat out of the high temperature planetary interiors. The possibly dominant role of lagged parahydrogen conversion in the convective transport of heat at levels where T is less than 300 K is discussed. Measurements which may ultimately contribute to a better understanding of energy conversion processes are summarized.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
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  • 7
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    Photochemistry and clouds of Jupiter, Saturn and Uranus (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Photochemistry of ammonia, methane, phosphine, hydrogen sulfide, methylamine, hydrogen cyanide and carbon monoxide in the atmospheres of Jupiter, Saturn and Uranus is discussed. Condensation of ammonia, ammonium hydrosulfide, water, methane, ethane and acetylene below and near the tropopause of these planets is formulated. Whenever necessary, new calculations are included. Candidates for the upper atmospheric hazes, and the reddish-brown chromosphore in the clouds of Jupiter and Saturn are discussed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
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  • 8
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    Mars missions and bases - A recent look (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: This paper discusses some of the key options for Mars programs, missions, bases, elements, and systems. Program and mission options include Mars flyby, orbiting, and landing missions; they include near-term 'sortie' missions, and later, longer-duration Mars-base missions. Key program and mission parameters include the mix of manned/unmanned elements, the number and types of space vehicles used, types of science done, trajectory options and implications launch timing and schedules, etc. The key mission parameters strongly affect the nature, sizing, and quantity of earth-to-orbit (ETO) vehicles. On-orbit assembly of space vehicles (SVs) is also an important related consideration. The potential degree of utilization of the Space Station (SS) and other then-existing elements is a key question, and several possibilities are discussed in this paper. Several configurations of SVs are provided. Several options are identified for the Mars base infra-structure, and parametric data is shown for buildup of bases as a function of mission and vehicle type. Technologies required for the missions are also discussed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
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  • 9
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    Lava tubes - Potential shelters for habitats (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Natural caverns occur on the moon in the form of 'lava tubes', which are the drained conduits of underground lava rivers. The inside dimensions of these tubes measure tens to hundreds of meters, and their roofs are expected to be thicker than 10 meters. Consequently, lava tube interiors offer an environment that is naturally protected from the hazards of radiation and meteorite impact. Further, constant, relatively benign temperatures of -20 C prevail. These are extremely favorable environmental conditions for human activities and industrial operations. Significant operational, technological, and economical benefits might result if a lunar base were constructed inside a lava tube.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
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  • 10
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    Solar and thermal radiation in the Venus atmosphere (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Attention is given to the solar and thermal radiation fields of Venus. Direct measurements and the results of numerical models based on direct measurements are presented. Radiation outside the atmosphere is considered with emphasis placed on global energy budget parameters, spectral and angular dependences, spatial distribution, and temporal variations of solar and thermal radiation. Radiation fluxes inside the atmosphere below 90 km are also considered with attention given to the solar flux at the surface, solar and thermal radiation fluxes from 100 km to the surface, and radiative heating and cooling below 100 km.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Advances in Space Research (ISSN 0273-1177); 5; 11, 1
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  • 11
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    Models of the structure of the atmosphere of Venus from the surface to 100 kilometers altitude (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: From a critical comparison and synthesis of data from the four Pioneer Venus Probes, the Pioneer Venus Orbiter, and the Venera 10, 12, and 13 landers, models of the lower and middle atmosphere of Venus are derived. The models are consistent with the data sets within the measurement uncertainties and established variability of the atmosphere. The models represent the observed variations of state properties with latitude, and preserve the observed static stability. The rationale and the approach used to derive the models are discussed, and the remaining uncertainties are estimated.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Advances in Space Research (ISSN 0273-1177); 5; 11, 1
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  • 12
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    On a class of TVD schemes for gas dynamic calculations (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The purpose of this paper is to review a class of explicit and implicit second-order accurate Total Variation Diminishing (TVD) schemes and to show by numerical experiments, the performance of these schemes to the Euler equations of gas dynamics. The method of constructing these second-order accurate TVD schemes is sometimes known as the modified flux approach.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 13
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    A Lagrangian method for the shallow water equations based on a Voronoi mesh - Flows on a rotating sphere (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A Lagrangian scheme using the Voronoi mesh is applied to study shallow water flow on a sphere. Discrete approximations to the shallow water equations are obtained for the surfaces of a nonrotating and a rotating sphere, and discrete differential operators are defined for the gradient and the divergence on the sphere. Dissipation is put into the model, when needed, by merging fluid points when they get too close to each other. The full numerical scheme is described and results of numerical computations on various test cases are given, including zonal flow and the Riemann problem.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 14
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    Atmospheric circulation of Venus (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Observational data of Venus are utilized to study rotational effects on atmospheric circulations. The high surface temperature and planetary-scale turbulent motion at cloud tops, and the relation between energy and momentum budget are examined. The limited amount of data available on the vertical and horizontal distribution of net radiative heating, the zonal wind structure, and waves affects the study of the temperature and motion on Venus. The limitations of the scaling analysis used to estimate the properties of the circulation as regards the cyclostrophic balance, the extent of the Hadley circulation, large-scale wave transport, vertical propagation of waves, convection, and turbulence are considered. Hypotheses concerned with the deep, cloud-level, and upper atmospheres of Venus are proposed. Future research in the areas of propagating planetary- scale waves, zonal flow and planetary-scale wave instability processes, and convection is suggested.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
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  • 15
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    Simultaneous measurements of temperature, density, and pressure in a supersonic turbulent flow using laser-induced fluorescence (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A pulsed laser-induced fluorescence technique is described that provides simultaneous measurements of temperature, density, and pressure in low-temperature, turbulent flows. The measurements are made with spatial and temporal resolution comparable to that obtained with modern laser anemometer techniques used for turbulent boundary layer research. The capabilities of the method are briefly described and its demonstration in a simple two-dimensional turbulent boundary layer at Mach 2 is reported. The results are compared with conventional hot-wire anemometer data obtained in the same flow.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 16
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    The use of radar and visual observations to characterize the surface structure of the planet Mercury (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: An analysis is conducted of available topographic profiles and scattering parameters derived from earth-based S- and X-band radar observations of Mercury, in order to determine the nature and origin of regional surface variations and structures that are typical of the planet. Attention is given to the proposal that intercrater plains on Mercury formed from extensive volcanic flooding during bombardment, so that most craters were formed on a partially molten surface and were thus obliterated, together with previously formed tectonic features.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
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  • 17
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    Evolution of a vortical structure associated with the bursting event in a channel flow (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The temporal evolution of a horseshoe vortex structure in a channel is investigated by a numerical simulation. A spectral numerical method is employed to integrate the time-dependent, three-dimensional Navier-Stokes equations. The initial vortical structure is obtained by applying a conditional sampling technique to a data base generated from a direct simulation of a turbulent channel flow. The evolution of this vortical structure under the influence of the self-induced motion and the mean shear is presented. It is shown that the initial sheet-like vortical structure rolls up into a vortex tube as it is convected downstream. Turbulence structures associated with the vortex stretching are investigated. Production of vorticity stretching is high inside the vortex legs, although it is also substantial in the tip region and above the legs. High Reynolds shear stress is produced near the tip of the vortex.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 18
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    Advanced geologic exploration supported by a lunar base - A traverse across the Imbrium-Procellarum region of the moon (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: An example of extended traverse of a lunar region, the Imbrium-Procellarum, for the purpose of geological exploration is described. The necessary field support is discussed, including transportation and logistical support, analytical instrumentation, and field equipment. The various sites of special geological interest in the region are mentioned individually in the order in which they would be visited, indicating what questions are of particular scientific interest at each site.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
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  • 19
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    Simulation of turbulent mixing layers (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A hybrid numerical scheme, combined with a scalar convection scheme, is used to compute turbulent mixing layers. The hybrid scheme is used to solve the vorticity equation by dividing the domain into two regions, applying a Lagrangian method in one region and an Eulerian method in the other. The scalar convection scheme is used to track an interface which separates a dyed fluid from a dye-free fluid, thereby distinguishing the fluid that starts on the high speed side from the fluid that starts on the low speed side. A two-dimensional mixing layer has been simulated using this new method; the roll up of a vortex sheet into structures that interact and pair is observed. The growth of the momentum thickness and the development of the mean turbulence statistics are found to be consistent with experimental observations. Forcing of the layer at moderate and low frequencies shows a dramatic effect on the growth of the momentum thickness and the entrainment ratio. Low frequency forcing enhances the growth of the layer; moderate frequency forcing inhibits the growth.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 20
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    Mass extinctions and cosmic collisions - A lunar test (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The possibility has been considered that some or all major mass extinctions in the geologic record of earth are caused by the collision of massive, cosmic objects. Thus, it has been proposed that the unusual concentration of siderophile elements in strata at which the boundary between the Cretaceous (K) and Tertiary (T) geologic time periods has been placed must represent the remnants of a gigantic meteorite. However, a large 65-m.y.-old crater which could have been the result of the impact of this meteorite is not presently known on earth. One approach to evaluate the merits of the collisional hypothesis considered is based on the study of the probability of collision between a cosmic object of a suitable size and the earth. As moon and earth were subject to the same bombardment history and the preservation of craters on the moon is much better than on earth, a consideration of the lunar cratering record may provide crucial information.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
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  • 21
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    Saturn's rings - Particle size distributions for thin layer model (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A model incorporating limited interaction between the incident energy and particles in the ring is considered which appears to be consistent with the multiple scattering process in Saturn's rings. The model allows for the small physical thickness of the rings and can be used to relate Voyager 1 observations of 3.6- and 13-cm wavelength microwave scatter from the rings to the ring particle size distribution function for particles with radii ranging from 0.001 to 20 m. This limited-scatter model yields solutions for particle size distribution functions for eight regions in the rings, which exhibit approximately inverse-cubic power-law behavior.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Icarus (ISSN 0019-1035); 64; 531-548
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  • 22
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    Supersonic meteorology of Io - Sublimation-driven flow of SO2 (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The horizontal flow of SO2 gas from the day side to the night side of IO is calculated on the basis of a hydrodynamic model. The flow speed is found to be supersonic for all realistic values of the parameters. The surface pressure follows the frost vapor pressure within a factor of 2 in spite of day-night pressure ratios of 10,000 or more. Atmospheric temperature is generally below the surface temperature due to decompression in the expanding flow. The greatest sensitivity of the solution is connected with the frost temperature at the subsolar point. The quantities that involve the mass of the atmosphere (density, pressure, mass transport, and condensation rate) all vary as the vapor pressure of the frost, which is a sensitive function of frost temperature.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Icarus (ISSN 0019-1035); 64; 375-390
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  • 23
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    The effects of compliant walls on transition and turbulence (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Two theoretical approaches to the phenomenon of drag reduction by a compliant wall are proposed. One is to study the limit cycle oscillations of the Navier-Stokes equations for a boundary layer flow over a compliant wall or a Poiseuille flow in a channel with a compliant wall. The other is a complementary study of a simpler, sequential model, which partially decouples the fluid and wall motions. In this approach, a 'Total Model' is constructed from suitable component models. While the first study is more rigorously based, it will be initially limited, by computational constraints, to relatively low Reynolds numbers. The second, more approximate approach, will allow consideration of a fully developed turbulent flow. The Total Model will predict the compliant wall motion accurately, but will not per se be sufficient to predict the skin friction drag. However, once the wall motion is known, the skin friction drag and the pressure drag can be computed separately, using one of the existing models.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 24
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    Empirical model of the composition of the Venus ionosphere Repeatable characteristics and key features not modeled (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: In-situ measurements of positive ion composition of the ionosphere of Venus are combined in an empirical model which is a key element for the Venus International Reference Atmosphere (VIRA) model. The ion data are obtained from the Pioneer Venus Orbiter Ion Mass Spectrometer (OIMS) which obtained daily measurements beginning in December 1978 and extending to July 1980 when the uncontrolled rise of satellite periapsis height precluded further measurements in the main body of the ionosphere. For this period, measurements of 12 ion species are sorted into altitude and local time bins with altitude extending from 150 to 1000 km. The model results exhibit the appreciable nightside ionosphere found at Venus, the dominance of atomic oxygen ions in the dayside upper ionosphere and the increase in prominence of atomic oxygen and deuterium ions on the nightside. Short term variations, such as the abrupt changes observed in the ionopause, cannot be represented in the model.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Advances in Space Research (ISSN 0273-1177); 5; 9, 19
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  • 25
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    Thermal net flux measurements on the Pioneer Venus entry probes (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Corrected thermal net (upward minus downward flux) radiation data from four Pioneer Venus probes at latitudes of 4 deg and 60 deg N, and 27 deg and 31 deg S, are presented. Comparisons of these fluxes with radiative transfer calculations were interpreted in terms of cloud properties and the global distribution of water vapor in the lower atmosphere of Venus. The presence of an as yet undetected source of IR opacity is implied by the fluxes in the upper cloud range. It was also shown that beneath the clouds the fluxes at a given altitude increase with latitude, suggesting greater IR cooling below the clouds at high latitudes and a decrease of the water vapor mixing ratios toward the equator.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Advances in Space Research (ISSN 0273-1177); 5; 9, 19
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  • 26
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    The thermal release of Hg from chondrites and their thermal histories (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A quantitative treatment and implications of isothermal and linear heating data on Hg in meteorites are given as a sequel to a more qualitative analysis of meteorite thermal histories (Reed and Jovanovic, 1968). Studies of Hg in terrestrial metamorphic rocks establish that thermal events to which meteorites were subjected fall in the same temperature range, of 400-900 C, as exists during terrestrial metamorphism. Hg diffusion parameters based on data from the linear and isothermal heating experiments are calculated. The conclusions are: (1) Meteorites experienced thermal events of the same magnitude as those measured by primarily mineralogical metamorphic indicators reviewed by Dodd (1969); (2) no correspondence with mineralogical-petrological metamorphic grade is evident; (3) Hg data for some chondrites correlate with shock facies (non-thermal) indicators (Dodd and Jarosewich, 1979); (4) small Hg activation energies (6-14 kcal/mole) require that the meteorites must have been stored in closed systems until low temperatures were attained. Hg must be presented as an involatile mineral(s) or as a substituent in a host phase at temperatures below 100 C. Consistent with this interpretation is the fact that despite diffusion times of 100-1,000,000 years at 200 K, Hg was retained in small objects over cosmic ray exposure periods of a hundred-million years.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 49; 1743-175
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  • 27
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    Analysis of buoyancy effect on fully developed laminar heat transfer in a rotating tube (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Laminar heat transfer is analyzed in a tube rotating about an axis perpendicular to the tube axis. The solution applies for flow that is either radially outward from the axis of rotation, or radially inward toward the axis of rotation. The conditions are fully developed, and there is uniform heat addition at the tube wall. The analysis is performed by expanding velocities and temperature in power series using the Taylor number as a perturbation parameter. Coriolis and buoyancy forces caused by tube rotation are included, and the solution is calculated through second-order terms. The secondary flow induced by the Coriolis terms always tends to increase the heat transfer coefficient; this effect can dominate for small wall heating. For radial inflow, buoyancy also tends to improve heat transfer. For radial outflow, however, buoyancy tends to reduce heat transfer; for large wall heating this effect can dominate, and there is a net reduction in heat transfer coefficient.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: ASME, Transactions, Journal of Heat Transfer (ISSN 0022-1481); 107; 338-344
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  • 28
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    Shape instability in thin viscous films and jets (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The theory of viscous liquid films and thin jets as two- and one-dimensional continua is examined. Theoretical results are presented concerning a special type of instability which leads to the loss of smoothness of the shape (wrinkling) and associated with the failure of hyperbolicity of the governing equations. The conditions for different types of such an instability are formulated in the closed analytical form.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Acta Mechanica (ISSN 0001-5970); 55; 33-50
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  • 29
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    Pole orientation of 16 Psyche by two independent methods (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Nineteen new lightcurves of 16 Psyche are presented along with a pole orientation derived using two independent methods, namely, photometric astrometry and magnitude-amplitude-shape-aspect. The pole orientations found using these two methods agree to within 4 deg. The results from applying photometric astrometry were prograde rotation, a sidereal period of 0.1748143 days + or - 0.0000003 days, and a pole at longitude 223 deg and latitude +37 deg, with an uncertainty of 10 deg, and, from applying magnitude-amplitude-shape-aspect a pole at 220 + or - 1 deg, +40 + or - 4 deg, and a modeled triaxial ellipsoid shape (a greater than b greater than c) and a/b = 1.33 + or - 0.07. The discrepancy between the high-pole latitude found here and the low latitudes reported by Lupishko et al. (1982) and Zhou and Yang (1982) is discussed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Icarus (ISSN 0019-1035); 61; 241-251
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  • 30
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    Chemical zoning and homogenization of Pasamonte-type pyroxene and their bearing on thermal metamorphism of a howardite parent body (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The Mg-Fe zoning of pyroxenes in Pasamonte and Juvinas eucrites is examined in order to gain a better understanding of the metamorphism in the surface layer of a eucrite/howardite parent body. Three distinct types of Ca-Mg-Fe zoning of Pasamonte pyroxenes are identified. The wide compositional range of the zoned pyroxenes suggests that Pasamonte is less metamorphosed than previously believed. It is also found that a Pasamonte-type pyroxene may yield a Juvinas-type pyroxene by thermal metamorphism. Calculations imply that the homogenization of Juvinas pyroxenes may have occurred during later reheating events rather than during initial cooling.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 90; C629-C63
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  • 31
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    Bibliography (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Articles entered into the data base and Lunar and Planetary Institute Library in the period from May to October, 1983 are listed in annotated bibliography. The topics of the articles include asteroids, comets, and meteorites.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Earth, Moon, and Planets (ISSN 0167-9295); 32; 193-237
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  • 32
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    Conjecture about a hurricane system in the Jovian atmosphere (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Arguments are presented in support of the hypothesis that the Great Red Spot (GRS) of Jupiter is a giant hurricane, and that the same decription might apply to the smaller vortices such as the white and brown ovals (barges) on the surface of Jupiter. Estimates of the spin-down times constants for the white and brown oval vortices, indicate that the motions must be sustained by the continued release of internal energy. In analogy with the CISK mechanism for terrestrial hurricanes, transport of water vapor is identified as a possible latent energy source. On the basis of the large size and long life time of the GRS, (indicating extreme depth), it is suggested that the hurricane GRS hurricane may have been induced by meteor impact. Voyager 1 images of the GRS are provided.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Earth, Moon, and Planets (ISSN 0167-9295); 32; 183-192
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  • 33
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    Gravity field of the Jovian system from Pioneer and Voyager tracking data (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Data sets from the Voyager and Pioneer flybys of Jupiter and the Galilean satellites are employed to characterize the Jovian magnetic field and the effects of the Io torus on transmissions. Both optical and Doppler radio data are considered, except for periods when the Jovian radiation environment disturbed the oscillator stability of the radio transmitters. Account is taken of small accelerations of the spacecraft by tidal forces of a single rising satellite, density differences in the Great Red Spot producing a columnar gravitational change, and three unknown objects in the inner Jovian system. Correction parameters are developed for the effects on the S-band data induced by the Jovian plasmasphere inwards from the Io torus. Calculations are then made of the planet and satellite masses, gravity harmonic coefficients, and orientation of the rotational pole. Large reductions in the uncertainties in previous mass estimates are obtained.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Astronomical Journal (ISSN 0004-6256); 90; 364-372
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  • 34
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    Features of a reattaching turbulent shear layer in divergent channel flow (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Experimental data have been obtained in an incompressible turbulent flow over a rearward-facing step in a diverging channel flow. Mean velocities, Reynolds stresses, and triple products that were measured by a laser Doppler velocimeter are presented for two cases of tunnel wall divergence. Eddy viscosities, production, convection, turbulent diffusion, and dissipation (balance of kinetic energy equation) terms are extracted from the data. These data are compared with various eddy-viscosity turbulence models. Numerical calculations incorporating the k-epsilon and algebraic-stress turbulence models are compared with the data. When determining quantities of engineering interest, the modified algebraic-stress model (ASM) is a significant improvement over the unmodified ASM and the unmodified k-epsilon model; however, like the others, it dramatically overpredicts the experimentally determined dissipation rate.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 23; 163-171
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  • 35
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    Large arcuate scars: A geological legacy of the Earth's accretionary past (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Immediately following accretion, the surface of the Earth was densely patterned with circular scars which were the surface expressions of 3-D craterform structures. In the course of geological time these structures would have become less and less visible due to the workings of the Earth's atmosphere, surface waters, and plate tectonics regime but there is no compelling reason to assume that they have been entirely eradicated. Furthermore, a very imperfect analogy with the other inner planets suggests that geological processes may not in fact be capable of totally erasing such deep features. Some illustrative examples of arcuate scars are discussed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 71-73
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  • 36
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    Lunar and Martian impact basins: Exposed records of terrestrial bombardment? (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The unrecycled surfaces of the Moon, Mercury, and Mars preserve the very early history of impact bombardment and its effect on crustal evolution. Previous studies indicated that the post accretion impact flux by large bodies on Mars may have been dificient, but systematic studies recently have revealed that this deficiency is largely the result of active erosional and depositional processes during the first 0.8 by. Ancient Martian impact basins larger than 300 km in diameter are revealed by subtle but unequivocal topographic and structural control of drainage patterns. In addition, the largest basins have left a deep seated imprint of concentric and radial structural patterns that control the occurrence of most Martian volcanic and tectonic provinces. If 10(-6)/km(2) is considered to be a reasonable approximation for the density of impact basins ( 300 km) of the Moon and Mars, then the Earth should have recorded more than 500 impacts that resulted in basins larger than 300 km in diameter over its post accretion geologic history. If calibrated with the Moon, then most of these impacts occurred prior to 3.8 by.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 74-75
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  • 37
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    Water loss from Venus: Implications for the Earth's early atmosphere (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The atmosphere of Venus outgassed rapidly as a result of planetary heating during accretion, resulting in massive water loss. The processes affecting atmospheric chemistry following accretion have consisted largely of hydrogen escape and internal re-equilibrium. The initial bulk composition of Venus and Earth are assumed to have been roughly similar. Chemical speciation on Venus was controlled by the temperature and oxygen buffering capacity of the surface magma. It is also assumed that the surfaces of planetary bodies of the inner solar system were partly or wholly molten during accretion with a temperature estimated at 1273 to 1573 K. To investigate the range of reasonable initial atmospheric compositions on Venus, limits have to be set for the proportion of total hydrogen and the buffered fugacity of oxygen. Using the C/H ratio of 0.033 set for Earth, virtually all of the water generated during outgassing must later have been lost in order to bring the current CO2/H2O ratio for Venus up to its observed value of 10 sup 4 to 10 sup 5. The proportion of H2O decreases in model atmospheres with successfully higher C/H values, ultimately approaching the depleted values currently observed on Venus. Increasing C/H also results in a rapid increase in CO/H2O and provides an efficient mechanism for water loss by the reaction CO+H2O = CO2 + H2. This reaction, plus water loss mechanisms involving crustal iron, could have removed a very large volume of water from the Venusian atmosphere, even at a low C/H value.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 65-67
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  • 38
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    The origin of continental crust: Outlines of a general theory (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The lower continental crust, formerly very poorly understood, has recently been investigated by various geological and geophysical techniques that are beginning to yield a generally agreed on though still vague model (Lowman, 1984). As typified by at least some exposed high grade terranes, such as the Scottish Scourian complex, the lower crust in areas not affected by Phanerozoic orogeny or crustal extension appears to consist of gently dipping granulite gneisses of intermediate bulk composition, formed from partly or largely supracrustal precursors. This model, to the degree that it is correct, has important implications for early crustal genesis and the origin of continental crust in general. Most important, it implies that except for areas of major overthrusting (which may of course be considerable) normal superposition relations prevail, and that since even the oldest exposed rocks are underlain by tens of kilometers of sial, true primordial crust may still survive in the lower crustal levels (of. Phinney, 1981).
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 54-56
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  • 39
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    Implications for the Earth of the early dynamical environment (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The formation of the Earth, was mainly from sizeable bodies: perhaps moon sized. Models of interaction among small planetesimals which take into account only close encounters all lead to the formation of moon sized objects, thus leading to several 100 in the inner solar system. Longer term interactions, such as secular resonance sweepings, are needed to get these planetesimals together to form the observed terrestrial bodies. After the accumulation of the Earth, during which core formation certainly occurred, further impacts probably influenced the locations of rifting centers in the system of mantle convection and crustal differentiation. They may have affected craton stabilization by promoting lateral heterogeneity, but had little influence on the key problem of early recycling of sial.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 45-47
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  • 40
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    A review of tectonic aspects of the Limpopo belt and other Archean high-grade gneissic terranes (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Published information on the Archean high grade terrains varies a great deal in the detail available. Such information as exists indicates marked differences in the lithic types and proportions present in the central Limpopo belt compared with the better studies of the other Archean high grade terrains. These differences may be important because they are expressed by the presence in the Limpopo belt of subordinate, but significant quantities (about 5% each) of two rock suites likely to have formed on a shallow marine platform of significant size (Eriksson and Kidd, in prep.). These suites consist of thick sections dominantly consisting of either carbonate and calc-silicate, or of pure metaquartzites, often fuchsite bearing, whose lithic characters are unlike those expected for metacherts but are very like those expected for platform arenites. Isotopic ages suggest these sediments are probably older than 3.3 Ga and younger than 3.5 Ga. Studies lead to the conclusions that (1) continental fragments large enough to provide a substrate for significant platform arenite and carbonate sedimentation existed by 3.3 to 3.5 Ga ago; (2) Wilson cycle tectonics seems to adequately explain most major features of the Archean gneissic terranes; and (3) Tibetan-Himalayan style collisional tectonics 2.6 Ga and older accounts for the large scale relationships between the Limpopo belt and the adjacent Archean greenstone granitoid terrane cratons. By inference, other more fragmentary Archean gneissic terranes may have once been part of such collisional zones.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 48-49
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  • 41
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    Anorthositic oceanic crust in the Archean Earth (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Ultrapure minerals separated from eclogite inclusions in kimberlites were analyzed for Sm, Nd, Sr, and oxygen isotopes and for major and trace elements. Clinopyroxene (cpx) and garnet (gnt) are the only primary mineral phases in these rocks, and mineral phases and their alteration products. The WR sub calc. is the reconstructed bulk composition excluding all the contamination influences. Two groups of eclogites: are distinguished: (1) type A Noritic-anorthositic eclogites; and (2) type B Ti-ferrogabbroic eclogites. The oxygen isotopes are primary mantle-derived features of these rocks and are not caused by posteruption processes, as they were measured on unaltered, clean mineral separates and show a correlation with REE pattern and Sr and Nd isotopes. It is suggested that the variation of the oxygen isotopes are caused by crustal-level fluid-rock interaction at relatively low temperature. It is shown that oxygen isotopes variation in MORB basalts caused by the hydrothermal system are in the same range as the observed oxygen isotope variation in eclogites. A model to explain the new set of data is proposed. It is thought that some of these eclogites might be emplaced into the upper lithosphere or lower crust at the time corresponding to their internal isochron age. The calculated WR composition was used to estimate model ages for these rocks.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 40-41
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  • 42
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    Noble gases and the early history of the Earth: Inappropriate paradigms and assumptions inhibit research and communication (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The development of models as tracers of nobel gases through the Earth's evolution is discussed. A new set of paradigms embodying present knowledge was developed. Several important areas for future research are: (1) measurement of the elemental and isotopic compositions of the five noble gases in a large number of terrestrial materials, thus better defining the composition and distribution of terrestrial noble gases; (2) determinations of relative diffusive behavior, chemical behavior, and the distribution between solid and melt of noble gases under mantle conditions are urgently needed; (3) disequilibrium behavior in the nebula needs investigation, and the behavior of plasmas and possible cryotrapping on cold nebular solids are considered.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 37-38
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  • 43
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    Constraints on the development of the early continental crust from isotopic data (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Aspects of the origin and development of the early (AE) continential crust are addressed by radiogenic isotope and trace element studies. The most important ones are: (1) at what time did the earliest continental crust form; (2) what was its composition; (3) by what processes did it grow and by what processes was it destroyed; (4) what were the rates of production and destruction as a function of time during this time period? Nd is isotopic data on the oldest terrestrial rocks indicate that the mantle at this time had already suffered substantial depletion in incompatible elements due to earlier continent forming events. Isotopic data on young volcanic rocks derived from the depleted mantle show no evidence of this early history. The observed isotopic patterns of Nd, Sr, Hf and Pb through time together with the presently observed age spectrum of crustal rocks are considered. These patterns can be modelled by a transport model in which the continental growth and destruction rates are allowed to vary as a function of time. It is suggest that the mass of the continents at 3.8 AE ago was about 25% of the current continental mass. However, due to the very high recycling rates obtained in the early Archean only a few percent of this crust has been preserved up to the present.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 39
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  • 44
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    Submarine hydrothermal environments as sites for the origin and evolution of life (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: That life formed and evolved in hydrothermal environments is proposed. This hypothesis is plausible in terms of the tectonic, paleontological, and degassing history of the Earth. Submarine hydrothermal vents are the only contemporary geological environment which may truly be called primeval and which today continue to be a major source of gases and dissolved elements to the ocean. The microbial assemblages in present day hydrothermal systems therefore could be living analogues of the earliest microbial communities to develop on Earth. The evidence for the hypothesis is reviewed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 34-36
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  • 45
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    The degassing history of the Earth: Noble gas studies of Archaean cherts and zero age glassy submarine basalts (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Recent noble gas studies suggests the Earth's atmosphere outgassed from the Earth's upper mantle synchronous with sea floor spreading, ocean ridge hydrothermal activity and the formation of continents by partial melting in subduction zones. The evidence for formation of the atmosphere by outgassing of the mantle is the presence of radionuclides H3.-4, Ar-040 and 136 Xe-136 in the atmosphere that were produced from K-40, U and Th in the mantle. How these radionuclides were formed is reviewed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 28-30
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  • 46
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    The 3.5 b.y. old Onverwacht Group: A remnant of ancient oceanic crust (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The interaction between seawater and submarine volcanic rock has had important consequences for the chemistry of the ocean during the Phanerozoic. Most extant terranes have been regionally metamorphosed to the amphibolite and granulite facies, so that their precursor lithologies and structures are not readily determinable. However, the 3.5 b.y. old supracrustal rocks of the Barberton Mountain Land, South Africa, have not been subjected to high grade regional metamorphism, and therefore there was reason to hope that a laboratory investigation might reveal the extent to which these rocks had been exposed to subseafloor hydrothermal activity. Hart and de Wit describe bulk geochemical evidence from the entire suite as well as field evidence which support the concept of hydrothermal activity in the Barberton Mountain Land. Mineralogical and textural features which unequivocally mark it as a submarine sequence emplaced in a midocean ridge/fracture zone or back arc/fracture zone environment are briefly discussed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 31-33
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  • 47
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    Considerations of large scale impact and the early Earth (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Bodies which have preserved portions of their earliest crust indicate that large scale impact cratering was an important process in early surface and upper crustal evolution. Large impact basins form the basic topographic, tectonic, and stratigraphic framework of the Moon and impact was responsible for the characteristics of the second order gravity field and upper crustal seismic properties. The Earth's crustal evolution during the first 800 my of its history is conjectural. The lack of a very early crust may indicate that thermal and mechanical instabilities resulting from intense mantle convection and/or bombardment inhibited crustal preservation. Whatever the case, the potential effects of large scale impact have to be considered in models of early Earth evolution. Preliminary models of the evolution of a large terrestrial impact basin was derived and discussed in detail.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 23-24
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  • 48
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    The problem of the Earth's CO2 content and the iron core (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The near absence of metallic iron and the presence of magnetite and FeS in the C-1 chondrites imply that metallic iron was a minor phase present during the accretion process that formed the C-1 chondrites. If the C-1 chondrites provided the bulk of the initial planetary growth materials, the carbon reduction model is favored. The above estimates suggest that some 1240 to 227 times as much CO2 may have been produced during the formation of the core than can be accounted for in the crust and mantle. This discrepancy taken to the extreme suggests either that: (1) the Earth has lost more than 99 percent of its initial CO2 during early differentiation (this is highly unlikely) or: (2) the Earth has acquired some 90 percent of its present mass by the accretion of debris from previously reduced and differentiated but subsequently disrupted planetary bodies whereby the associated CO2 would not be captured, or: (3) the C-1 chondrites represent only a trivial fraction of the initial accretion materials present in the nebular cloud or: (4) condensed iron and anhydrous silicate phases were preferentially accreted during the initial formation of the planetary bodies.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 20-22
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  • 49
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    Developments in the simulation of compressible inviscid and viscous flow on supercomputers (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: In anticipation of future supercomputers, finite difference codes are rapidly being extended to simulate three-dimensional compressible flow about complex configurations. Some of these developments are reviewed. The importance of computational flow visualization and diagnostic methods to three-dimensional flow simulation is also briefly discussed.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 50
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    The problem of water on Mars (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
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    Effects of wall curvature on turbulence statistics (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A three-dimensional, time-dependent, direct numerical simulation of low-Reynolds number turbulent flow in a mildly curved channel was performed, and the results examined to determine the mechanism by which curvature affects wall-bounded turbulent shear flows. A spectral numerical method with about one-million modes was employed, and no explicit subgrid scale model was used. The effects of curvature on this flow were determined by comparing the concave and convex sides of the channel. The observed effects are consistent with experimental observations for mild curvature. The most significant difference in the turbulence statistics between the concave and convex sides is in the Reynolds shear stress. This is accompanied by significant differences in the terms of the Reynolds shear stress balance equations. In addition, it was found that stationary Taylor-Goertler vortices were present and that they had a significant effect on the flow by contributing to the mean Reynolds shear stress, and by enhancing the difference between the wall shear stresses.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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    Structure of turbulence in the presence of uniform shear (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The structure of the vorticity field in homogeneous turbulent shear flow is analyzed using a database generated by direct numerical solution of the unsteady Navier-Stokes equations with up to 128x128x128 grid points. For two Reynolds numbers, the probability distribution of the inclination angle of the vorticity vectors, two-point correlations of the velocity and vorticity fields, and the instantaneous vorticity vectors and vortex lines in three-dimensional space were examined. It is shown that homogeneous turbulent shear flow contains a large number of horseshoe vortices. These vortices are most often found in planes inclined at 45 deg to the flow direction and are formed from the roll-up of sheets of transverse vorticity. These findings and similar results obtained in turbulent channel flow, lead to the conclusion that hairpin vortices are the characteristic vortical structures in all turbulent shear flows.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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    Direct numerical simulation of equilibrium turbulent boundary layers (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: This paper describes the simulation of turbulent boundary layers by direct numerical solution of the three-dimensional, time-dependent Navier-Stokes equations, using a spectral method. The flow is incompressible, with Re sub delta = 1000. The equations are written in the self-similar coordinate system and periodic streamwise and spanwise boundary conditions are imposed. A family of nine 'equilibrium' boundary layers, from the strongly accelerated 'sink' flow to Stratford's separating boundary layer is treated. Good general agreement with experiments is observed. The effects of pressure gradients on the structures and statistics, both in the wall and wake regions are discussed.
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    Electrolytic currents in Europa (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The transverse electric (TE) and transverse magnetic (TM) currents at the Europan surface are calculated. The study was performed because of the proximity of Europa to Jupiter, which has a strong magnetic field, and the presence of a conductor (water ice) in copious quantities on the Europan surface. The moon is assumed to have a silica interior, an ice layer and, in places, an intermediate liquid layer. Account is taken of surface eddy currents, the maximum current density in the surface and a saline liquid layer, and the TM magnitudes with different liquid layer thicknesses. The effects of random appearances of vertical cracks in the ice are also considered. The calculations indicate that the surface currents could be higher on Europa than on Io, but may be too weak to produce heating effects sufficient to prevent refreezing of a crack.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Icarus (ISSN 0019-1035); 63; 39-44
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    On the proposed triggering of Jovian radio emissions (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Calvert (1985) has proposed that a solar type III radio bursts can trigger the onset of certain Jovian hectometer wavelength emissions. It is shown, using the data obtained by the Voyager Planetary Radio Astronomy experiment, that this triggering hypothesis is not supported statistically. Furthermore, the causality of this proposed triggering is questioned because much of the Jovian hectometer emission is due to a quasi-continuous radio source rotating, in lighthouse fashion, with Jupiter. Thus, an observed 'onset' of emission is simply a function of the observer's position in local time around Jupiter.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Geophysical Research Letters (ISSN 0094-8276); 12; 621-624
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    Lunar sample 14425 - Corrected analysis (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A polished section of lunar sample 14425, an 8 mm glass bead, was studied using a scanning electron microscope and energy-dispersive X-ray analyzer. The silicon, aluminum, iron, magnesium, calcium, sodium, potassium, titanium, and chromium contents of the glass were determined. Two types of glass are visible in the polished section. One is clear and almost devoid of metallic spherules, while the other is cloudy and contains numerous metallic spherules, some less than one micron in size. Both glass types are homogeneous and identical in composition. This composition closely matches that of some Apollo 14 breccias or glass found in the breccias. The apparent similarity in composition between lunar sample 14425 and the high-magnesium microtektites found in a previous study was probably due to charging effects during analyses in which the sample was uncoated.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Science (ISSN 0036-8075); 220; 1410
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    Magnetic field properties of Jupiter's tail at distances from 80 to 7500 Jovian radii (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The results of a detailed study of the magnetic field data on the near and distant Jovian magnetotail from both Voyager 1 and 2 are presented. The spacecraft trajectories and the data are reviewed, and four distant tail encounters are examined and compared with the corresponding Voyager 1 interplanetary data sets. A power spectral analysis of both the near and distant tail intervals is given, and some of the differences between the tail encounters and the power spectra of these control data sets are discussed. Two solar wind or magnetosheath data sets obtained when Voyager 2 was not in the distant tail are analyzed. These more 'normal' solar wind conditions are contrasted with those reflected in both the Voyager 2 distant tail encounters and the conditions monitored by Voyager 1 farther downstream.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 90; 8223-823
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  • 58
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    Enthalpy damping for the steady Euler equations (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: For inviscid steady flow problems where the enthalpy is constant at steady state, it was previously proposed to use the difference between the local enthalpy and the steady state enthalpy as a driving term to accelerate convergence of iterative schemes. This idea is analyzed, both on the level of the partial differential equation and on the level of a particular finite difference scheme. It is shown that for the two-dimensional unsteady Euler equations, a hyperbolic system with eigenvalues on the imaginary axis, there is no enthalpy damping strategy which moves all the eigenvalues into the open left half plane. For the numerical scheme, however, the analysis shows and examples verify that enthalpy damping is potentially effective in accelerating convergence to steady state.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Applied Numerical Mathematics (ISSN 0168-9274); 1; 417-432
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    Double-diffusive convection with sidewalls (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Stommel et al. (1956) have first described an instability, known as thermosolutal convection, thermohaline convection, or double-diffusive convection. This instability may occur in the case of a fluid in a gravitational field with two diffusing components present. The present study is concerned with the effect of sidewalls on flow in the fingering regime in the absence of applied horizontal gradients. The work was motivated by numerical results obtained on the basis of a simulation of thermosolutal convection occurring during the unidirectional solidification of a binary alloy. In this case, the unperturbed solute field in the liquid ahead of the solidifying planar interface has an exponential vertical profile because of the rejection or preferential incorporation of solute by the solid phase.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 28; 2716-272
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    Bending waves and the structure of Saturn's rings (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The surface mass density profiles at four locations within Saturn's rings are calculated using Voyager spacecraft images of spiral bending waves. The identification of a feature in Saturn's outer B ring as Mimas's 4:2 bending waves is confirmed, and these 4:2 waves are analyzed to determine the surface density in Saturn's B ring. A fourth set of bending waves, the Mimas 7:4, located in the inner A ring, is identified and analyzed. Mimas's 5:3 and 8:5 bending waves, observed in the middle and outer A ring respectively, are reanalyzed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Icarus (ISSN 0019-1035); 62; 433-447
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    Bolometric albedos of Titan, Uranus, and Neptune (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The energy budgets of Titan, Uranus, and Neptune are reevaluated using new observational data on energy input as well as unpublished data on energy output. The bolometric geometric albedo of each object was determined, and preliminary determinations of the phase functions were used to compute the Bond albedos and effective temperatures. The values for the latter are 83 + or - 2 K for Titan, 57 + or - 2 K for Uranus, and 47 + or - 2 K for Neptune. The effective temperature of Titan is greater than the observed brightness temperatures in the thermal infrared region of the spectrum, indicating that the emissivity is less than unity for this part of the spectrum. An internal luminosity of (3.9 + or 1.1) x 10 to the 15th W is found for Neptune, and an upper limit of (0.6 + or - 1.4) x 10 to the 15th W is found for Uranus.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Icarus (ISSN 0019-1035); 62; 425-432
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    Internal combustion engine combustion chamber process studies at NASA Lewis Research Center (1985)
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Propulsion and Power (ISSN 0748-4658); 1; 351-353
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    Radial diffusion in magnetodiscs (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The orbits of charged particles in magnetodiscs are considered. The bounce motion is assumed adiabatic except for transits of a small equatorial region of weak magnetic field strength and high field curvature. Previous theory and modeling have shown that particles scatter randomly in pitch angle with each passage through the equator. A peaked distribution thus diffuses in pitch angle on the time scale of many bounces. It is argued in this paper that spatial diffusion is a further consequence when the magnetodisc has a longitudinal asymmetry. A general expression for DLL, the diffusion of equatorial crossing radii, is derived. DLL is evaluated explicitly for ions in Jupiter's 20-35 radii magnetodisc, assumed to be represented by Connerney et al.'s (1982) Voyager model plus a small image dipole asymmetry. Rates are energy, species, and space dependent but can average as much as a few tenths of a planetary radius per bounce period.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 90; 7587-759
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    Venus nightside ionospheric troughs - Implications for evidence of lightning and volcanism (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The inferred presence of lightning has been a potentially very important result from the in situ exploration of the environment of Venus by the Pioneer Venus Orbiter (PVO). The evidence for lightning has been derived from impulsive low-frequency plasma wave events recorded by the Orbiter electric field detector. The present paper is concerned with an alternative interpretation of the plasma results. It is shown that prominent examples of the plasma waves which have previously been specifically attributed to lightning are associated with distinct nightside ionization troughs. It is suspected that many of the plasma wave disturbances are not due to lightning but rather result from energetic and dynamic processes to be expected in the vicinity of the magnetic field and plasma configurations involved.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 90; 7415-742
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    Atmospheric temperature profiles of Uranus and Neptune (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Far-infrared spectrophotometry of Uranus and Neptune in the 30-55 micron spectral range is presented. The measurements in the present six independent spectral bands allow the derivation of atmospheric temperature profiles for these planets. Both planets are found to have tropopause temperatures near 53 K, with Neptune having a stronger stratospheric temperature inversion than Uranus. Effective temperatures of 57.7 + or - 1.8 K and 58.2 + or - 1.9 K are obtained for Uranus and Neptune, respectively, confirming the large internal heat source in Neptune.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 292; L83-L86
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    The moons of Uranus, Neptune and Pluto (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Voyager 2, launched in August 1977, will fly by Uranus in January, 1986, passing within 29,000 km of that planet's innermost moon, Miranda. It will subsequently encounter Neptune in August 1989, flying within 10,000 km of its inner satellite, Triton; images made of this moon by a high resolution camera are expected to reveal surface features as small as a few hundred meters in diameter. The composition of the Uranian moons will br inferred from their near-IR reflectance spectra and mean densities. While the spacecraft will not fly by Pluto, it is expected that the lessons learned from the Voyager encounters with Neptune and Uranus will expand current understanding of Pluto and its moon, Charon.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Scientific American (ISSN 0036-8733); 253; 38-47
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    Wavy edges suggest moonlet in Encke's gap (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Voyager images have revealed radial undulations of the inner and outer edges of the 325 km wide Encke gap in Saturn's A ring. These waves are present at some, but not all, longitudes. Their locations and wavelengths provide strong indirect evidence for the presence of at least one dominant moonlet of about 10 km radius orbiting near the center of the gap. Implications for 'shepherding' theory are discussed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 292; 276-290
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    Liquid management in low gravity using baffled rotating containers (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Possible static configurations of liquids in rotating cylindrical containers with baffles evenly spaced in the axial direction are found. The force balance is among surface tension, centrifugal force and gravity. Two instabilities are found in this parameter space: type 1 is the inability of the liquid to form an interface attached to the baffles; type 2 is the inability for multi-baffled configurations to sustain interfaces between each pair of baffles. The type 1 analysis is confirmed through laboratory based equipment. Applications to orbiting containers are discussed.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Spacecraft and Rockets (ISSN 0022-4650); 22; 287
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    The atmosphere of Saturn - An analysis of the Voyager radio occultation measurements (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The Voyager 1 and 2 probes' radio links were used to study both the northern and southern latitudes of Saturn during occultation by that planet, yielding electron number density profiles for the ionosphere, and gas refractivity, number density, pressure, temperature, and ammonia abundance data for the troposphere and stratosphere. From the vertical pressure profiles obtained at different latitudes, it is possible to determine the size and shape of Saturn's isobaric surfaces.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Astronomical Journal (ISSN 0004-6256); 90; 1136-114
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    Navier-Stokes calculations for unsteady three-dimensional vortical flows in unbounded domains (1985)
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 23; 868-874
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    Some morphologic systematics of complex impact structures (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Current measurements of the horizontal dimensions of complex meteorite structures are summarized. The measurements were used in a least squares analysis of correlations among the dimensions of the crater rings and central peaks of compact meteorites. Some geometric similarities between terrestrial complex impact structures and the large multiring basin of the planets are demonstrated, and the possible physical constraints on ring formation are discussed.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Meteoritics (ISSN 0026-1114); 20; 49-68
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    Response of earth and Venus ionospheres to corotating solar wind stream of 3 July 1979 (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Corotating solar wind stream interactions are examined for the earth and Venus in light of data from the plasma detectors aboard ISEE-3, the Pioneer Venus Orbiter (PVO), and Helios-A, as well as in situ ion composition measurements taken by the mass spectrometers aboard the PVO and Atmosphere Explorer-E spacecraft. During May-July 1979, a sequence of distinct, recurrent coronal regions developed at the sun; their analysis indicates a corresponding sequence of corotating streams. Although the planetary environments are distinctly different, it is noted that pronounced and analogous ionospheric responses to the stream passage were observed at both the earth and Venus. The response to the intercepted stream is consistent with independent investigations showing the importance of the variability of the solar wind momentum flux in the solar wind-ionosphere interaction at both planets.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Earth, Moon and Planets (ISSN 0167-9295); 32; 275-290
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    A finite difference method for solving unsteady viscous flow problems (1985)
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 23; 659-668
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    Terrestrial impactors at geological boundary events - Comets or asteroids? (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: In the present evaluation of evidence presented to date for a 26-28 million year periodicity in the extinction record and the age of large, well dated terrestrial impact craters, it is noted that no simple, one-to-one relationship emerges between major asteroid and/or comet impacts, siderophile anomalies, and biological extinction events. While impacts may indeed be the major extinction-triggering event in some or even most cases, either other major events, or secondary effects of the impacts, may be the actual extinction-causing mechanism. Long term obscuration of insolation, planetary cooling, or lethal atmospheric pollution may vary among extinctions, depending on the actual state of the planet and its biota during the geological period in question. The source of 28 million year-period asteroidal impactors, moreover, remains unknown and thereby casts doubt on the entire periodicity scenario.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Nature (ISSN 0028-0836); 314; 517
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    Computing three-dimensional incompressible flows with vortex elements (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The techniques, capabilities and applicability of numerical models of three-dimensional, unsteady vortical flows with high Re are assessed. Vorticity is calculated only in appropriate regions and the velocity field is derived from the boundary conditions. Vorticity is assumed to take the shape of tubes with uniform core structures in the case of turbulence. The efforts being made to simplify equations for dense collections of vortex filaments in order to make them tractable to computer simulations are described. The effectiveness of vorticity arrow representations for accurately describing vorticity fields near surfaces is discussed, along with Lagrangian vortex elements, which may be of use in modelling the rotational part of flows around bluff bodies, nonuniform density flows and chemically reacting flows.
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    Aerodynamics of sports balls (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.
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    Sizing up the planets (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Visual, scaled comparisons are made among prominent volcanic, tectonic, crater and impact basin features photographed on various planets and moons in the solar system. The volcanic formation Olympus Mons, on Mars, is 27 km tall, while Io volcanic plumes reach 200-300 km altitude. Valles Marineris, a tectonic fault on Mars, is several thousand kilometers long, and the Ithasa Chasma on the Saturnian moon Tethys extends two-thirds the circumference of the moon. Craters on the Saturnian moons Tethys and Mimas are large enough to suggest a collision by objects which almost shattered the planetoids. Large meteorite impacts may leave large impact basins or merely ripples, such as found on Callisto, whose icy surface could not support high mountains formed by giant body impacts.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Sky and Telescope (ISSN 0037-6604); 69; 404
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    What color is the solar system? (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Estimates are made of the true visual colors of various planets and moons in the solar system. Account is taken of the components of perceived color, i.e., hue, saturation and lightness. Earth is a blue planet while most of the others, including Mars, are yellow and differ only in their lightness. Widely disseminated Voyager images of Jupiter have been computer-enhanced to highlight details. A reflectance spectrum established by the International Commission on Illumination provides reference lines which are measured and compared with reference colors which would be seen on earth in normal daylight. Uranus is actually a light aqua color due to its absorption of 6190 A light and reflectance of 5000 A blue green light.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Sky and Telescope (ISSN 0037-6604); 69; 399-402
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  • 79
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    Venus gravity - A harmonic analysis and geophysical implications (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: An improved theoretical model of Venusian global gravity has been obtained by fitting a tenth degree spherical harmonic series to 78 orbital arcs of Doppler tracking data from the Pioneer Venus Orbiter. Maps of the free-air anomaly and its formal error are presented. Isostatic anomaly and 'Geoid' maps are also presented, and their geophysical implications are discussed in details. Comparison with equivalent resolution topographic models reveals a strong correlation between long wavelength gravity and the topography of Venus. Analysis of the second degree harmonics showed two aspects of the orientation of the inertial axes of Venus: (1) a significant (about three degrees) departure of the axis of greatest inertia from the rotational axis; and (2) a near alignment of the axis of least inertia with the location of the subterrestrial point at the time of the next inferior conjunction with earth (December 16, 2101). A series of contour maps of the Venusian free-air anomalies is provided.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 90; C739-C75
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  • 80
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    Isotope analysis of crystalline impact melt rocks from Apollo 16 stations 11 and 13, North Ray Crater (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The North Ray Crater Target Rock Consortium was formed to study a large number of rake samples collected at Apollo 16 stations 11 and 13 with comparative chemical, mineralogical, and chronological techniques in order to provide a larger data base for the discussion of lunar highland evolution in the vicinity of the Apollo 16 landing region. The present investigation is concerned with Rb-Sr and Sm-Nd isotopic analyses of a number of whole-rock samples of feldspathic microporhyritic (FM) impact melt, a sample type especially abundant among the North Ray crater (station 11) sample collection. Aspects of sample mineralogy and analytical procedures are discussed, taking into account FM impact melt rocks 6715 and 63538, intergranular impact melt rock 67775, subophitic impact melt rock 67747, subophitic impact melt rock 67559, and studies based on the utilization of electron microscopy and mass spectroscopy.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 90; C431-C44
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  • 81
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    The depths of the mare basalt source region (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Chemical data for the parental magmas of the nine known VLT Array I pyroclastic glasses show statistically significant trends due to olivine (approximately Fo83) control during their formation by partial melting. The compositional scatter is largely due to compositional variations in the source regions on the + or - 1 percent level. This compositional scatter is small when one considers that the scale of the source region is up to 1000 km, but is sufficient to make positive identification of the residual phase(s) in the source regions difficult. Nevertheless, when the effects of the scatter are properly modeled, it is relatively clear that olivine is the residual phase in the source region. Hence these data and additional constraints indicate that the source regions are at shallow depths in the moon.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 90; C396-C40
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  • 82
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    Oscillations of a compound drop system undergoing rotation (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A compound liquid-drop system is comprised of three immiscible concentric fluids: a core fluid of density p(i) surrounded by a shell of density p(s) which is embedded in a medium of density p(o). In this analysis, the fluids are incompressible and inviscid. The effect of rotation upon the modes of oscillation of a compound drop is investigated. Rotation rate is considered as a small perturbation of the normal modes of the compound drop, thus introducing the effects of a Coriolis force and a centrifugal distortion.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 28; 1023-102
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  • 83
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    Fault type predictions from stress distributions on planetary surfaces - Importance of fault initiation depth (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The prediction of fault type on planetary surfaces from model stresses calculated at depth is discussed. These fault-type predictions yield different faults than those predicted using the surface criteria commonly employed in geophysical models. For elastic-plate flexure models of mascon loading on the moon, stresses calculated at the surface predict the occurrence of strike-slip faulting at the radial distance where grabens are found. Normal faults bounding lunar grabens and thrust faults responsible for wrinkle ridges are analyzed. It is found that the former initiate at the mechanical discontinuity that separates the breccia of the megaregolith from in situ fractured rock and that the latter initiate at the mechanical discontinuity between basalt layers and the underlying basin floor. The difference between elastic constants for the outer few kilometers of brecciated megaregolith and the underlying lunar lithosphere are evaluated. Superposing nonisotropic stresses resulting from the weight of overburden to the depth of the relevant mechanical discontinuity yield stresses that predict wrinkle ridges in the basin centers and grabens outside the basin margin, and eliminate the predicted zone of strike-slip faults.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 90; 3065-307
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  • 84
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    Spectral and other physicochemical properties of submicron powders of hematite (alpha-Fe2O3), maghemite (gamma-Fe2O3), magnetite (Fe3O4), goethite (alpha-FeOOH), and lepidocrocite (gamma-FeOOH) (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The spectral properties (0.35-2.20 microns) of submicron powders of hematite, maghemite, magnetite, goethite, and lepidocrocite are determined. Other physicochemical data are obtained for the powders in order to determine if deviations from stoichiometry occur due to their small particle size, to determine their state of chemical and phase purity, and to determine the physical characteristics of the individual powders. The physicochemical data obtained include mean particle diameter, discrete particle shape, chemical composition, crystallographic phase, magnetic parameters, and Moessbauer parameters. The positions of the spectral features for the hematite, maghemite, and magnetite powders are independent of temperature over the interval between about +20 and -110 C. For the goethite and lepidocrocite powders, a small shift of about 0.02 micron to shorter wavelengths is observed for some of the features after cooling to about -110 C. The spectral properties of the iron oxides and oxyhydroxides are important not only for understanding the basic physics and chemistry of the compounds but also for applications such as the remote sensing of the earth and Mars.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 90; 3126-314
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  • 85
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    Aerodynamic effect of combustor inlet air pressure on fuel jet atomization (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Propulsion and Power (ISSN 0748-4658); 1; 137-142
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  • 86
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    Impact of computational fluid dynamics on development test facilities (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Aircraft (ISSN 0021-8669); 22; 182-187
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  • 87
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    The temperature distribution within a sphere placed in a directed uniform heat flux and allowed to radiatively cool (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The temperature field within a sphere is found when the sphere is heated by a directed heat flux and cooled by blackbody radiation. For small heat fluxes, the analytic solution is obtained by transform methods. For large heat fluxes, the solution is computed numerically.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: ASME, Transactions, Journal of Heat Transfer (ISSN 0022-1481); 107; 28-32
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  • 88
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    Vortex motion in wall-bounded viscous flow (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A factor of general interest in a broad class of wall-bounded flows is the dynamic evolution of vortical structures through the flow. The structures are three-dimensional, and an overall mathematical description of such entities has not yet been formulated. One of the objectives of the present investigation is concerned with the establishment of a framework, based on first principles, which may form a basis for more detailed analytical studies. Another aim is related to the establishment of boundary and initial conditions in numerical experiments. The mathematical framework employed involves the method of matched asymptotic expansions, and an inner solution field is constructed which consists of a two-dimensional vortical structure. The outer solution field is taken to be an otherwise undisturbed laminar two-dimensional parallel or self-similar viscous flowfield.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Proceedings, Series A - Mathematical and Physical Sciences (ISSN 0080-4630); 397; 1813,
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  • 89
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    Thickness of ice on perennially frozen lakes (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A simple energy-balance model for the perenially frozen lakes of Antarctica's southern Victoria Land is presented which, using the measured ablation rate of 30 cm/yr, can explain the observed ice thickness. Some speculations are presented on the ice cover that could have existed on possible former lakes in the equatorial regions of Mars.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Nature (ISSN 0028-0836); 313; 561
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  • 90
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    A perspective of theoretical and applied computational fluid dynamics (1985)
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 23; 328-341
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  • 91
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    Turbulence structures associated with the bursting event (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Turbulence structures in a wall bounded shear layer during the bursting event detected by a conditional sampling technique are investigated using data obtained from large eddy simulation of turbulent channel flow. Streamlines are constructed from the ensemble-averaged velocity field to illustrate the flow patterns associated with the bursting event. The splatting motions during the sweep event and the existence of a pair of counterrotating streamwise vortices during the ejection process are exhibited.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 28; 52-58
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  • 92
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    A model for diagenesis in proto-planetary bodies (1985)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A model is proposed which eases the thermal constraints imposed by earlier models of low-temperature aqueous alteration in primitive extraterrestrial materials in which formation of an aqueous medium promoting these alterations required complete melting of the water-ice. It is argued that low-temperature alterations in a protoplanetary body such as the formation of hydrated silicates will occur because of the presence of an interfacial water layer.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Nature (ISSN 0028-0836); 313; 293
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  • 93
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    Global map of eolian features on Mars (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A variety of common eolian features on Mars have been identified from a survey of Mariner 9 and Viking orbiter images, and their regional and global distributions and orientations are discussed. Ten features have been mapped including: light and dark streaks, splotches, barchan and transverse dunes, crescentric and anomalous dunes, yardangs, wind grooves, and deflation pits. The north polar region shows a complex wind regime. Dunes and other ephemeral features reveal winds from the northwest and northeast. In the middle and low northern latitudes, northeasterly winds are the most effective winds. Southeast winds are the effective winds in most southern latitudes. Erosional features in bedrock indicate long-term and perhaps ancient wind trends, whereas depositional features may record relatively more recent winds. Deflation pits in the mantled terrain may contain the best record of both ancient and present-day winds.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 90; 2038-205
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  • 94
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    Impact cratering history of the Saturnian satellites (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The impact flux history of the Saturn system has been modelled, and absolute ages estimated. The model assumes that the general history of impact flux was similar to that of the inner solar system and that the dominant source of material in the postaccretionary phases was external to the Saturn system. Population I and II craters represent the synheavy and postheavy bombardment periods, respectively. Observed crater densities are representative of the actual ages and do not appear to be saturation-equilibrium surfaces. It is concluded that some of the satellites have geologic histories which extend to about 3.5 b.y. Significant endogenic resurfacing has occurred on several satellite surfaces, which indicates that thermal conditions and material compositions are more complicated than might have been anticipated prior to Voyager encounters.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 90; 2029-203
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  • 95
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    Magnetic field in the wake of Venus and the formation of ionospheric holes (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Magnetic field structures are analyzed for both the ionospheric hole region and the magnetosheath/ionosphere interaction region of the nightside of Venus, in search of possible coupling between these two regimes. A magnetic coordinate system based on the directions of the solar wind and the interplanetary magnetic field is found to order the data reasonably well, allowing consistent superposition of observational data from individual passes of the Pioneer Venus orbiter. The results indicate that the magnetosheath plasma flow in the wake region plays an important role in forming the ionospheric holes through deformation of the nightside ionopause. The results are combined in a model of the three-dimensional magnetic field structure around the ionosphere of Venus.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 90; 1385-139
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  • 96
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    Analytical model for large-scale turbulence (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The paper presents an analytical model for large-scale turbulence, based on a new closure which depends on the growth rate of the instability-generating turbulence. For convection in stars the results of the mixing-length theory are recovered, and for laboratory convection the N = R to the 1/3 power law is recovered. The present model can readily be extended to include magnetic fields and rotation.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physical Review Letters (ISSN 0031-9007); 54; 430-433
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  • 97
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    Large-amplitude MHD waves upstream of the Jovian bow shock Reinterpretation (1985)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Observations of large amplitude magnetohydrodynamic (MHD) waves upstream of the Jovian bow shock were previously interpreted as arising from a resonant electromagnetic ion beam instability. That interpretation was based on the conclusion that the observed fluctuations were predominantly right elliptically polarized in the solar wind rest frame. Because it was noted that the fluctuations are, in fact, left elliptically polarized, a reanalysis of the observations was necessary. Several mechanisms for producing left hand polarized MHD waves in the observed frequency range were investigated. Instabilities excited by protons appear unlikely to account for the observations. A resonant instability excited by relativistic electrons escaping from the Jovian magnetosphere is a likely source of free energy consistent with the observations. Evidence for the existence of such a population of electrons was found in both the Low Energy Charged Particle experiments and Cosmic Ray experiments on Voyager 2.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 90; 302-310
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  • 98
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    Rift systems on Venus: An assessment of mechanical and thermal models (1985)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The formation and distribution of major tectonic features on Venus are closely linked to the dominant mechanism of lithospheric heat loss. Among the most spectacular and extensive of the major tectonic features on Venus are the Chasmata, deep linear valleys generally interpreted to be the products of lithospheric extension and rifting. Systems of chasmata and related features can be traced along several tectonic zones up to 20,000 km in linear extent. Mechanical and thermal models for terrestrial continental-rifting are applied to the rift systems of Venus. The models are tested against known topographic and tectonic characteristics of Venus chasmata as well as independent information on the physical properties of the Venus crust and lithosphere.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 138 - 141
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  • 99
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    Extensional tectonics of the Saturnian Satellites (1985)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The saturnian satellites were imaged by the Voyager spacecraft at sufficient resolutions to reveal landforms that indicate histories of extensional tectonics for several of these bodies. The relationships among landforms on various satellites imply that extensional tectonism is a consequence of several different energy sources. Case histories of several satellites are discussed to illustrate the interaction of various phenomena associated with extensional tectonism.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 91-92
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  • 100
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    Hot-spot tectonics on Io (1985)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: The thesis is that extensional tectonics and low-angle detachment faults probably occur on Io in association with the hot spots. These processes may occur on a much shorter timescale on Ion than on Earth, so that Io could be a natural laboratory for the study of thermotectonics. Furthermore, studies of heat and detachment in crustal extension on Earth and the other terresrial planets (especially Venus and Mars) may provide analogs to processes on Io. The geology of Io is dominated by volcanism and hot spots, most likely the result of tidal heating. Hot spots cover 1 to 2% of Io's surface, radiating at temperatures typically from 200 to 400 K, and occasionally up to 700K. Heat loss from the largest hot spots on Io, such as Loki Patera, is about 300 times the heat loss from Yellowstone, so a tremendous quantity of energy is available for volcanic and tectonic work. Active volcanism on Io results in a resurfacing rate as high as 10 cm per year, yet many structural features are apparent on the surface. Therefore, the tectonics must be highly active.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 76-80
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