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  • General Chemistry  (1,723)
  • GEOPHYSICS  (1,328)
  • LUNAR AND PLANETARY EXPLORATION  (1,153)
  • 2015-2019
  • 1995-1999
  • 1980-1984  (4,204)
  • 1983  (2,032)
  • 1981  (2,172)
Collection
Keywords
Publisher
Years
  • 2015-2019
  • 1995-1999
  • 1980-1984  (4,204)
Year
  • 1
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    Curatorial functions and the U.S. Antarctic meteorite program (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The discovery of concentrations of meteorites in Antarctica by Japanese field parties in 1969, and subsequently by joint U.S.-Japanese and U.S. field parties since 1976 has provided a significant new resource for understanding the origin and evolution of the solar system. The number of meteorites as well as the variety of meteorites has increased dramatically, and substantial amounts of data derived from their study has begun to appear in the scientific literature. The U.S. program of investigation has drawn on curatorial experience derived from the lunar program to: (1) develop specific collection and preliminary examination protocols; (2) provide documented samples for scientific investigations in response to specific requests; and (3) coordinate research by scientific consortia. The productivity of scientific research is significantly enhanced by these management approaches. Some of the results of the curatorial program for Antarctic meteorites carried out over the past three years are described.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: National Institute of Polar Research, Memoirs (ISSN 0386-0744); 20, D
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  • 2
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    The tectonics of anorthosite massifs (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Anorthosite massifs developed approximately 1.4 to 1.5 billion years ago along an arch which developed parallel to a zone of continental separation as a block which included North America, Europe, and probably Asia separated from a block which included parts of South America, Africa, India, and Australia. Anorthosite massifs also developed at the same time along a belt which runs through the continents which comprise Gondwanaland (South America), Africa, India, Australia, and Antarctica. This was a zone of continental separation which subsequently became a zone of continental collision about 1.2 billion years ago. The northern anorthosite belt also parallels an orogenic belt which was active between 1.8 and 1.7 billion years ago. Heat generated during this mountain building period helped in the formation of the anorthosites.
    Keywords: GEOPHYSICS
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 29 p
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  • 3
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    Low-energy electron flux and its reaction to active experimentation of Spacelab (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: An instrument capable of observing the natural electron flux in the energy range from 0.1 to 12.0 kiloelectron volts is discussed for use in an experiment intended as a forerunner of a method that will utilize artificially accelerated electrons as tracer particles for electron fields parallel to the magnetic field. Effects that are of importance either as means of detecting the echo beam or as causes of beam perturbations (e.g., spacecraft charging effects and electron background) are to be studied. The use of electron accelerators as a tool to probe magnetospheric processes rather than to modify them is planned.
    Keywords: GEOPHYSICS
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 4
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    Atmospheric emission photometric imaging (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: A dual-channel video system mounted on a stabilized two-axis gimbal system (mounted on the pallet) with associated optics and data handling electronics described the low light flux observations are required for: (1) investigating ionospheric transport processes by observing Mg+ ions; (2) supporting magnetospheric electron bounce experiments; (3) measuring electron cross sections for selected atmospheric species; (4) detecting small particle contamination; and (5) studying natural auroras.
    Keywords: GEOPHYSICS
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 4 p
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  • 5
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    DC-magnetic field vector measurement (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: A magnetometer experiment was designed to determine the local magnetic field by measuring the total of the Earth's magnetic field and that of an unknown spacecraft. The measured field vector components are available to all onboard experiments via the Spacelab command and data management system. The experiment consists of two parts, an electronic box and the magnetic field sensor. The sensor includes three independent measuring flux-gate magnetometers, each measuring one component. The physical background is the nonlinearity of the B-H curve of a ferrite material. Two coils wound around a ferrite rod are necessary. One of them, a tank coil, pumps the ferrite rod at approximately 20 kilohertz. As a consequence of the nonlinearity, many harmonics can be produced. The second coil (i.e., the detection coil) resonates to the first harmonic. If an unknown dc or low-frequency magnetic field exists, the amplitude of the first harmonic is a measure for the unknown magnetic field. The voltages detected by the sensors are to be digitized and transferred to the command and data management system.
    Keywords: GEOPHYSICS
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 2 p
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  • 6
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    Investigation on Atmospheric H and D through the measurement of their Lyman-alpha emissions (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: Study of sources of Lyman-alpha emission in the atmosphere, in the interplanetary medium, and perhaps in the galactic medium is planned. Sources of Lyman-alpha emission are described and a schematic of the instrument presented.
    Keywords: GEOPHYSICS
    Type: NASA Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 7
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    Space experiments with particle accelerators (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: The purpose of space experiments with particle accelerators (SEPAC) is to carry out active and interactive experiments on and in the Earth's ionosphere and magnetosphere. It is also intended to make an initial performance test for an overall program of Spacelab/SEPAC experiments. The instruments to be used are an electron beam accelerator, magnetoplasma dynamic arcjet, and associated diagnostic equipment. The accelerators are installed on the pallet, with monitoring and diagnostic observations being made by the gas plume release, beam-monitor TV, and particle-wave measuring instruments also mounted on the pallet. Command and display systems are installed in the module. Three major classes of investigations to be performed are vehicle charge neutralization, beam plasma physics, and beam atmosphere interactions. The first two are mainly onboard plasma physics experiments to measure the effect of phenomena in the vicinity of Spacelab. The last one is concerned with atmospheric modification and is supported by other Spacelab 1 investigations as well as by ground-based, remote sensing observations.
    Keywords: GEOPHYSICS
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 4 p
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  • 8
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    Ozone and aircraft operations (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The cabin ozone problem is discussed. Cabin ozone in terms of health effects, the characteristics of ozone encounters by aircraft, a brief history of studies to define the problem, corrective actions taken, and possible future courses of action are examined. It is suggested that such actions include avoiding high ozone concentrations by applying ozone forecasting in flight planning procedures.
    Keywords: GEOPHYSICS
    Type: NASA. Marshall Space Flight Center Proc.: 5th Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 40-44
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  • 9
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    Development of a window protection assembly for a shuttle experiment (1981)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A window environmental protection assembly developed for the shuttle infrared leeside temperature experiment is described. The assembly consists of a carbon phenolic composite window mount which contains two silicon windows, a fibrous environmental protection plug to protect the windows during launch operations and ascent heating, a release mechanism used to jettison the plug just prior to atmospheric entry, and two pin puller mechanisms which retain the plug. The plug is released from the window mount assemblies using pneumatic pin pullers and separation springs in the release mechanism. The assembly was designed and tested to withstand the severe mechanical and thermal environments which could be experienced at the top of the shuttle orbiter vertical stabilizer during the ascent, on-orbit, and entry periods of the shuttle trajectory.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA. Marshall Space Flight Center The 15th Aerospace Mech. Symp.; p 303-329
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  • 10
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    Comparisons of global ozone trends inferred from the BUV experiment on Nimbus 4 and the ground-based network (1981)
    In:  CASI
    Details
    Publication Date: 2006-03-27
    Description: Preliminary comparisons between global ozone burdens derived from the backscattered ultraviolet (BUV) experiment on Nimbus 4 and those inferred from an analysis of ground-based network data seem to indicate significant differences in the inter-annual variability of ozone. Some of the observed differences may be due to improper weighting of the ground-based network data, slowly changing planetary wave structure over the fixed station, of small inter-annual changes in meridional transport parameters. There is also some evidence which indicates that the polar stratosphere at high latitudes may represent an important ozone storage resevoir which tends to compensate for large scale changes observed in the regions outside of the polar stratosphere. Possible consequences of this are that the global trends derived from ground based ozone measurements may not be valid and furthermore that the current satellite techniques by themselves may be sufficient. An ozone monitoring system which includes observations from satellites, ground-based stations, balloons and rockets may be necessary.
    Keywords: GEOPHYSICS
    Type: Goddard Lab. for Atmospheric Sci., Collected Reprints, 1978 - 1979, Vol. 1; p 279
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  • 11
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    Measurement of trace levels of chlorine in the stratosphere (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Mathematical models of stratospheric ozone have predicted a reduction in the total ozone due to chlorofluoromethanes released into the atmosphere. Analytical procedures for the collection of air in the stratosphere and for analysis of these air samples for trace levels of chlorine, regardless of the state of chemical composition were developed. Calibration experiments are conducted in order to validate all methods and procedures. Results of neutron activation analysis calibration procedures using standard chlorine gases are included.
    Keywords: GEOPHYSICS
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 15 p
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  • 12
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    GRM - Observing the terrestrial gravity and magnetic fields in the 1990's (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: NASA is proposing to launch a new geopotential fields exploration system called the Geopotential Research Mission (GRM). Two spacecraft will be placed in a circular polar orbit at 160 km altitude. Distances between these satellites will vary from 100 to 600 km. Both scalar and vector magnetic fields will be measured by magnetometers mounted on a boom positioned in the forward direction on the lead satellite. Gravity data will be computed from the measured change in distance between the two spacecraft. This quantity, called the range-rate, will be determined from the varying frequency (Doppler shift) between transmitter and receiver on each satellite. Expected accuracies (at the one-sigma level) are: gravity field, 1.0 milliGal, 5 cm geoid height; magnetics, scalar field 2 nT, vector to 20 arcsec, both resolved to less than 100 km. With these more accurate and higher resolution data, it will be possible to investigate the earth's structure from the crust (with the shorter wavelength gravity and magnetic anomalies) through the mantle (from the intermediate wavelength gravity field) and into the core (using the longer wavelength gravity and magnetic fields).
    Keywords: GEOPHYSICS
    Type: EOS (ISSN 0096-3941); 64; 609-611
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  • 13
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    Measurements of stratospheric SO2 after the EL Chichon eruptions (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Samples of stratospheric trace gases were obtained on eight flights of NASA high-altitude aircraft from April 16 through December 13, 1982. The sampling occurred at altitudes from 15 to 22 km, latitudes from 23 to 52 deg N, and longitudes from 108 to 130 deg W. The cryogenically concentrated samples were analyzed by gas chromatography for SO2, a primary precursor of the gas-to-particle conversion process. The measured mixing ratio of SO2 varied between 8 and 132 pptv. Evidence from aerosol measurements indicates that a few of our early samples may have been collected in the fringes of the volcanic cloud from El Chichon. Samples obtained on some later flights may have been from the eruption cloud but were taken at times when most of the volcanically injected SO2 should have been converted to H2SO4.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; 1045-104
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  • 14
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    Effect of the eruption of El Chichon stratospheric aerosol size and composition (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Dominant effects of the El Chichon eruption on stratospheric aerosols at 19.8 to 20.7 km are: (1) vapor depositional growth of the small-aerosol (background) mode; (2) development of a large-particle mode by sedimentation from the highest altitudes in the cloud; (3) a change in the large-particle mode from sulfate-coated silicates to sulfate aerosols, some with silicate cores; (4) a 100-fold increase in sulfate mass in the large particle mode. Terminal velocities of large silicate particles, maximum r = 2.3 micron, sampled 1 month after eruption, and calibrated with the aid of lidar data, indicate initial injection to 26 to 27 km. Smaller velocities of sulfate aerosols, median r = 0.5 micron, are compatible with major growth in 2 to 3 months at 27 to 28 km. Aerosol settling accounts for the descent of the main lidar return to 26.5 km in August and to 20 to 21 km in December.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; 1021-102
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  • 15
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    Possible effects of the El Chichon volcanic cloud on the radiation budget of the northern tropics (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A series of calculations with a one-dimensional, time-marching, radiative-convective model are performed to assess the impact of the El Chichon volcanic cloud on the radiation budget of the northern tropics during the 6-month period following the injection of volcanic material into the stratosphere. Extensive measurement of the cloud obtained from airborne, spacecraft, and ground platforms were used to define the model parameters and to test the predictions of the model. The El Chichon cloud is predicted to have caused an increase in planetary albedo of 10 percent, a decrease in total solar radiation of 2-3 percent at the ground on cloudless days, and an increase in temperature of 3.5 K at the 24-km (30-mb) level. These predictions are compatible with relevant observations, within their respective error bars.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; 1057-106
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  • 16
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    Solar system history as recorded in the Saturnian ring structure (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Holberg's analysis of the Voyager Saturn photographs in reflected and transparent light, and occultation data of stars seen through the rings are discussed. A hyperfine structure with 10,000 ringlets can be explained by the Baxter-Thompson negative diffusion. This gives the ringlets a stability which makes it possible to interpret them as fossils which originated at cosmogonic times. It is shown that the bulk structure can be explained by the combined cosmogonic shadows of the satellites Mimas and Janus and the Shepherd satellites. This structure originated at the transition from the plasma phase to the planetesimal phase. The shadows are not simple void regions but exhibit a characteristic signature. Parts of the fine structure, explained by Holberg as resonances with satellites, are interpreted as cosmogonic shadow effects. However, there are a number of ringlets which can neither be explained by cosmogonic nor by resonance effects. Analysis of ring data can reconstruct the plasma-planetesimal transition with an accuracy of a few percent. Previously announced in STAR as N84-12013
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysics and Space Science (ISSN 0004-640X); 97; 1, No; 79-94
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  • 17
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    Stability of streams and lakes on Mars (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The freezing of small Martian streams is modelled for a variety of climatic conditions, on the supposition that the Martian atmosphere may have been considerably thicker in the past, at the time of the formation of the valley networks. This model examines the energy balance at the upper and lower surfaces of ice on streams, in order to determine the rate at which ice thickens with time. Results indicate that freezing rates are not strongly dependent on atmospheric pressure, and, under windy conditions, dependence on atmospheric pressure is even weaker. It is noted that the main problem in valley formation is in initiating the flow. Groundwater seepage alone is inadequate, due to the difficulty of groundwater system replenishment.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 476-495
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  • 18
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    A revised thermospheric model based on mass spectrometer and incoherent scatter data - MSIS-83 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is noted that the model presented here extends the previous description of neutral parameters to the base of the thermosphere in a continuous manner while maintaining the basic structure of the MSIS model at higher altitudes. As the altitude decreases, the composition approaches lower atmosphere values, whereas yearly, and to a lesser extent daily, variations in temperature and density are in reasonable agreement with earlier results for the lower thermosphere. An alternate description is given of magnetic storm variations on the basis of the three hour ap indices and an 8- to 10-hour exponential decay in thermospheric density and temperature response after a heating event. Additional coefficients are included for the time independent and magnetic activity terms, among them a longitudinally dependent seasonal magnetic activity effect. The description of molecular oxygen derives from mass spectrometer and EUV absorption measurements rather than ion chemistry.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 10170-10
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  • 19
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    Large amplitude MHD waves upstream of the Jovian bow shock (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Observations of large amplitude MHD waves upstream of Jupiter's bow shock are analyzed. The waves are found to be right circularly polarized in the solar wind frame, which suggests that they are propagating in the fast magnetosonic mode. A complete spectral and minimum variance eigenvalue analysis of the data was performed. The power spectrum of the magnetic fluctuations contains several peaks. The fluctuations at 2.3 MHz have a direction of minimum variance anti-parallel to the direction of the average magnetic field. Several harmonics at 6, 9, and 12 MHz are also present. The direction of minimum variance of these fluctuations lies at approximately 40 deg to the magnetic field. It is argued that these fluctuations are waves excited by protons reflected off the Jovian bow shock. The inferred speed of the reflected protons is about two times the solar wind speed in the solar wind frame. A linear instability analysis is presented that suggests an explanation for many of the observed features of the observations. The fluctuations apparently contain a significant fraction of magnetic energy that is linearly polarized and in the Alfven mode.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 9989-999
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  • 20
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    Response of the mobile VLBI design to error sources (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The response of Mobile VLBI design to error sources is addressed. The sensitivity of the hydrogen maser to variations in ambient temperature is discussed, with an example of drifts in the frequency system causing excursions in the time-delay observable exceeding + or - 200 cm. It is shown that baselines determined only from S-band data can contain errors in excess of 30 cm during periods of high ionospheric activity. The effect of the troposphere on baseline solutions is examined by comparing calibrations from the Water Vapor Radiometer (WVR) to those from a surface model. The apparent ability of the WVR to track relatively short-period fluctuations in water vapor is noted. Finally, consideration is given to the effects of source structure and the technique of monitoring closure of the time-delay observable around a closed figure of baselines.
    Keywords: GEOPHYSICS
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  • 21
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    Stratospheric condensation nuclei and possible solar influences (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Balloon-borne measurements of condensation nuclei and H2SO4 molecules in large negative ion clusters have been made in the stratosphere at around 30 km altitude. The nuclei observed were in the 0.01-0.1 micron diameter range. Consideration was given to sunspot activity as a triggering event for ionization of upper atmospheric H2SO4 species and subsequent formation of the nuclei. A numerical model was defined for a steady state between the H2SO4 association and ion recombination in order to determine a critical nucleation rate. It is concluded that condensation nuclei are produced in ion nucleation in an H2SO4 supersaturated polar cloud chamber, with the process being initiated by solar flare particle ionization.
    Keywords: GEOPHYSICS
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  • 22
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    A study of solar activity-ozone relationship from Nimbus-4 BUV data (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The total O3 and the O3 mixing ratio at various pressure levels in the stratosphere measured from the Nimbus-4 BUV experiment over a 7-yr period (1970 to 1977) comprises a comprehensive data base available to study the possible effects of solar variability on stratospheric O3. It is shown that with the decrease in solar activity from 1970 to 1976, the globally averaged O3 inferred from Nimbus-4 data decreases from about 10 to 12 percent in the upper stratosphere to about 1 to 3 percent in the lower stratosphere. The systematic decrease in O3 seems to be correlated with the conventional indices of solar activity; however, it is difficult to account for the observed changes at various pressure levels with the current understanding of the photochemical models and the solar UV flux variations over a solar cycle.
    Keywords: GEOPHYSICS
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  • 23
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    Delta function excitation of waves in the earth's ionosphere (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Excitation of the earth's ionosphere by delta function current sheets is considered, and the temporal and spatial evolution of wave packets is analyzed for a two-component collisional F2 layer. Approximations of an inverse Fourier-Laplace transform via saddle point methods provide plots of typical wave packets. These illustrate cold plasma wave theory and may be used as a diagnostic tool since it is possible to relate specific features, e.g., the frequency of a modulation envelope, to plasma parameters such as the electron cyclotron frequency. It is also possible to deduce the propagation path length and orientation of a remote radio beacon.
    Keywords: GEOPHYSICS
    Type: Radio Science (ISSN 0048-6604); 18; 1337-135
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  • 24
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    Light element geochemistry and spallogenesis in lunar rocks (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Abundance and isotopic compositions are measured for the very volatile elements carbon, nitrogen and sulfur in 11 lunar rocks representing a wide spectrum of textures and compositions. Samples were combusted sequentially at three temperatures in order to remove terrestrial contaminants before melting the lunar rock and liberating lunar volatiles. The combustion results indicate very little terrestrial sulfur contamination, with sulfur contents correlated with the TiO2 contents of the basalts analyzed. Sulfur isotopic compositions are remarkably uniform and similar to the Canon Diablo meteorite standard. Nitrogen levels are found to be no greater than those obtained with procedural blanks, corresponding to abundances less than 0.1 microg/g. Stable nitrogen isotope measurements indicate a spallogenic N-15 production rate of 4.1 x 10 to the -6th microg N-15/g sample/million years, in agreement with previous estimates. No indigenous carbon in excess of procedural blank levels of about 0.7 microg/g is found in lunar basalts. Levels of 1 to 5 microg/g found in highland rocks may derive from meteoritic or terrestrial sources. The average measured spallogenic C-13 production rate is 4.1 x 10 to the -6th microg C-13/g sample/million years.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 47; 1769-178
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  • 25
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    Normal mode study of the earth's rigid body motions (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In this paper it is shown that the earth's rigid body (rb) motions can be represented by an analytical set of eigensolutions to the equation of motion for elastic-gravitational free oscillations. Thus each degree of freedom in the rb motion is associated with a rb normal mode. Cases of both nonrotating and rotating earth models are studied, and it is shown that the rb modes do incorporate neatly into the earth's system of normal modes of free oscillation. The excitation formula for the rb modes are also obtained, based on normal mode theory. Physical implications of the results are summarized and the fundamental differences between rb modes and seismic modes are emphasized. In particular, it is ascertained that the Chandler wobble, being one of the rb modes belonging to the rotating earth, can be studied using the established theory of normal modes.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 9437-944
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  • 26
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    A mechanism for plasma waves at the harmonics of the plasma frequency in the electron foreshock boundary (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A bump-on-tail unstable reduced velocity distribution, constructed from data obtained at the upstream boundary of the electron foreshock by the GSFC electron spectrometer experiment on the ISEE-1 satellite, is used as the initial plasma state for a numerical integration of the 1D-Vlasov-Maxwell system of equations. The integration is carried through the growth of the instability, beyond its saturation, and well into the stabilized plasma regime. A power spectrum computed for the electric field of the stabilized plasma is dominated by a narrow peak at the Bohm-Gross frequency of the unstable field mode but also contains significant power at the harmonics of the Bohm-Gross frequency. The harmonic power is in sharp peaks which are split into closely spaced doublets. The fundamental peak at the Bohm-Gross frequency is split into a closely spaced triplet. The mechanism for excitation of the second harmonic is shown to be second order wave-wave coupling. Previously announced in STAR as N83-17315
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 9081-909
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  • 27
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    The flux and source of energetic protons in Saturn's inner magnetosphere (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The flux of energetic protons in Saturn's inner magnetosphere was observed in two channels from 48 to 63 and 63 to 160 MeV. Absorption features due to the G ring and the satellites Enceladus and Mimas were easily identifiable. The flux observed in the absorption slot of Mimas can be maintained by the decay of a cosmic ray albedo neutron flux of 0.007/sq cm/s/sr. This flux is entirely consistent with calculations of the neutron flux produced by galactic cosmic ray interactions with the rings of Saturn. The omnidirectional proton flux of 0.0082/sq cm/s at 2.734 R sub s requires a residence time of 30 years. Both the residence time and the energy spectrum are comparable to those found in the inner radiation belt of the Earth. The angular distribution is nearly isotropic in the Mimas slot and beyond 4R sub s. Otherwise the pitch angle distribution is pancake and is approximated by sin(n)theta with n in the range 2 to 7. This distribution is consistent with an isotropic neutron source in the ring plane. Previously announced in STAR as N83-22084
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8923-893
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    Survey of low-energy plasma electrons in Saturn's magnetosphere - Voyagers 1 and 2 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The low energy plasma electron environment within Saturn's magnetosphere was surveyed by the Plasma Science Experiment (PLS) during the Voyager encounters with Saturn. Over the full energy range of the PLS instrument (10 eV to 6 keV) the electron distribution functions are clearly non-Maxwellian in character; they are composed of a cold (thermal) component with Maxwellian shape and a hot (suprathermal) non-Maxwellian component. A large scale positive radial gradient in electron temperature is observed, increasing from less than 1 eV in the inner magnetosphere to as high as 800 eV in the outer magnetosphere. Three fundamentally different plasma regimes were identified from the measurements: (1) the hot outer magnetosphere, (2) the extended plasma sheet, and (3) the inner plasma torus. Previously announced in STAR as N83-34872
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8847-887
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    The Z3 zonal harmonic model of Saturn's magnetic field Analyses and implications (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The planetary magnetic field of Saturn has been studied by the spacecraft Pioneer 11 in 1979, Voyager 1 in 1980, and Voyager 2 in 1981. The field is found to be primarily dipolar and axially coincident with the rotation axis, but with significant quadrupole and octupole moments. The harmonic terms are g1(0) = 21535 nT, g2(0) = 1642 nT, and g3(0) = 2743 nT. This model field, Z3, in conjunction with a model for an equatorial ring current, represents very precisely the in situ magnetic-field measurements and data on charged-particle absorption by satellites and rings within 8 Saturn radii of the planet. However, this axisymmetric model fails to explain the periodic modulation of Saturn's kilometric radiation or Saturn's electrostatic discharges. This enigma of Saturn's magnetosphere remains unsolved in spite of extensive reconsideration of all available data bearing on this issue.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8771-877
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    Photometry and polarimetry of Saturn at 2640 and 7500 A (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Voyager 2 photometric and polarimetric data are reduced and tabulated, with spatially resolved limb-to-terminator scans across Saturn's equatorial zone providing information on the altitude distribution of UV-absorbing hazes, together with the phase function and polarizing properties of stratospheric and tropospheric aerosols. It is found that the UV photometry and polarimetry are best fit by Rayleigh's phase matrix. A stratospheric haze of small particles is allowed as long as the optical depth is near unity or less, and the center of the haze layer is in the 30 to 70 mbar region. The altitudes presently derived for three latitudes agree with those obtained by ground-based methane band studies and analyses from Pioneer 11. A high altitude absorber is abundant in the polar regions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8679-869
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    Medium scale disturbances in total ozone during Southern Hemisphere summer (1983)
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    Publication Date: 2011-08-18
    Description: Distinct medium scale disturbances in Southern Hemisphere total ozone were observed by the Nimbus 7 Total Ozone Mapping Spectrometer during the 1979 FGGE observing period. These disturbances are shown to be a result of advection by the zonal harmonic wave five which is centered near the tropopause (Salby, 1982). The contribution to the total ozone field by vertical advection due to this wave is shown to be nearly equal to that due to horizontal advection.
    Keywords: GEOPHYSICS
    Type: American Meteorological Society, Bulletin (ISSN 0003-0007); 64; 1358-136
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    Isotopic evidence from the eastern Canadian shield for geochemical discontinuity in the Proterozoic mantle (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Nd and Sr isotopic compositions presently reported for anorthosites and related rocks from the Grenville and Nain Provinces of the eastern Canadian shield indicate that the massifs were delivered from at least two distinct mantle source regions which were established before 1650 Myr ago. These regions were episodically involved in magmatism over about 500 Myr. One reservoir was isotopically similar to the depleted, modern midocean ridge basalt source. The other reservoir was chondritic-to-moderately-enriched, and is most easily identified in the Nain Province, but may have occurred scattered throughout Superior Province, as well.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 306; 679
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    Distribution, abundance and carbon isotopic composition of gaseous hydrocarbons in Big Soda Lake, Nevada - An alkaline, meromictic lake (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The study of the distribution and isotopic composition of low molecular weight hydrocarbon gases at the Big Soda Lake, Nevada, has shown that while neither ethylene nor propylene were found in the lake, ethane, propane, isobutane and n-butane concentrations all increased with water column depth. It is concluded that methane has a biogenic origin in both the sediments and the anoxic water column, and that C2-C4 alkanes have biogenic origins in the monimolimnion water and shallow sediments. The changes observed in delta C-13/CH4/ and CH4/(C2H6 + C3H8) with depth in the water column and sedimeents are probably due to bacterial processes, which may include anaerobic methane oxidation and different rates of methanogenesis, and C2-to-C4 alkane production by microorganisms.
    Keywords: GEOPHYSICS
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 47; 2107-211
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    Autoregressive harmonic analysis of the earth's polar motion using homogeneous International Latitude Service data (1983)
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    Publication Date: 2011-08-18
    Description: The homogeneous set of 80-year-long (1900-1979) International Latitude Service (ILS) polar motion data is analyzed using the autoregressive method (Chao and Gilbert, 1980), which resolves and produces estimates for the complex frequency (or frequency and Q) and complex amplitude (or amplitude and phase) of each harmonic component in the data. The ILS data support the multiple-component hypothesis of the Chandler wobble. It is found that the Chandler wobble can be adequately modeled as a linear combination of four (coherent) harmonic components, each of which represents a steady, nearly circular, prograde motion. The four-component Chandler wobble model 'explains' the apparent phase reversal during 1920-1940 and the pre-1950 empirical period-amplitude relation. The annual wobble is shown to be rather stationary over the years both in amplitude and in phase, and no evidence is found to support the large variations reported by earlier investigations. The Markowitz wobble is found to be marginally retrograde and appears to have a complicated behavior which cannot be resolved because of the shortness of the data set.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 10299-10
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    Morphology and chemistry of projectile residue in small experimental impact craters (1983)
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    Publication Date: 2011-08-18
    Description: Small-scale impact craters (5-7 mm in diameter) were produced with a light gas gun in high purity Au and Cu targets using soda lime glass (SL) and man-made basalt glass (BG) as projectiles. Maximum impact velocity was 6.4 km/s resulting in peak pressures of approximately 120-150 GPa. Copious amounts of projectile melts are preserved as thin glass liners draping the entire crater cavity; some of this liner may be lost by spallation, however. SEM investigations reveal complex surface textures including multistage flow phenomena and distinct temporal deposition sequences of small droplets. Inasmuch as some of the melts were generated at peak pressures greater than 120 GPa, these glasses represent the most severely shocked silicates recovered from laboratory experiments to date. Major element analyses reveal partial loss of alkalis; Na2O loss of 10-15 percent is observed, while K2O loss may be as high as 30-50 percent. Although the observed volatile loss in these projectile melts is significant, it still remains uncertain whether target melts produced on planetary surfaces are severely fractionated by selective volatilization processes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 88; B353-B36
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    Comparison of Yamato and Victoria Land polymict eucrites - A view from mineralogical and isotopic studies (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: New interior samples of four Yamato polymict eucrites (Y74159, Y74450, Y75011, and Y75015) have been studied by electron microprobe, transmission electron microscope, and X-ray diffraction techniques, and compared with several samples of the Victoria Land polymict eucrites. These same samples have been analysed using Rb-Sr and Nd-Sm isotopic systematics. Several grains of inverted pigeonite, with blebby augite similar to those in Binda and Moama, have been identified in all four Yamato eucrites. Coarse-grained meso-stasis-rich subophitic basalts, which contain Mg-rich pigeonite (with Fe-rich olivine veinlets) zoned outward to a subcalcic ferroaugite rims, have also been found. These unique clasts were not found in ALH76005, 77302, 78040, 7858, and 78165 and EET eucrites. The tight grouping of Rb/Sr and Sm/Nd ratos, and similar modal compositions of the Yamato group indicate that they are most likely to be pieces from a single fall, and distinct from the ALH and EET groups. However, the Yamato, Allan Hills, and Elephant Moraine groups may sample a few distinct magmas or similar but different source regions on the same parent body.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 88; B245-B25
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    The production curve for agglutinates in planetary regoliths (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Models for the production of agglutinates are developed that can be applied to the lunar surface or to any planetary or asteroidal body lacking an atmosphere. Models are developed using rate equations for progressively more complex situations and range from Model 1, which is a simple linear increase of agglutinate content with time, to Model 4, which includes provision for recycling of existing agglutinates and replenishment and burial of exposed soil. Model 4 has some aspects of a steady state because, depending on the rate constants, agglutinate content may be limited to an intermediate value, even for long exposure times. In an extreme case, agglutinate content may be limited to a value near zero. These models predict that agglutinates should be low in abundance in areas of thin regolith, such as the Lunokhod-2 site on the moon, and on asteroids. The models may also help explain the apparent low agglutinate abundances of lunar regolith breccias and meteorite regolith breccias.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 88; B193-B19
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    Ancient crustal components in the Fra Mauro breccias (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Texturally pristine clasts preserve primary petrographic relationships and mineral compositions, yielding insights into igneous processes of the early lunar crust that cannot be gained from highly shocked and brecciated 'chemically pristine' samples. The use of texture as a prime criterion allows for expansion of the data base derived solely from chemical criteria, and provides complementary data. Texturally pristine clasts from the Apollo 14 site studied here include anorthosite, troctolites, gabbronorites, and basalts. Alkali anorthosites are plagioclase orthocumulates and may form by flotation in Mg-suite plutons. Ferroan anorthosite was cataclastically deformed and metamorphosed to granulite facies. Troctolites include both 01 + Plg and 01 + En + Plg cumulates. Major and trace element analyses of two troctolites reveal 'eastern' geochemical affinities that contrast other 'western' troctolites. Gabbronorites are Pig + Plg + or - Sp cumulates whose parent magmas may range from high-Al to intermediate-Ti mare basalt. At least three varieties of mare basalt are found at Apollo 14: high-Al, low-Ti; low-Al, intermediate-Ti; and low-Al, Ti VHK basalt. VHK (Very High Potassium) basalt is a new variety indigenous to Apollo 14.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 88; B177-B19
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    An upper bound on the radius of a highly electrically conducting lunar core (1983)
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    Publication Date: 2011-08-18
    Description: Parker's (1980) nonlinear inverse theory for the electromagnetic sounding problem is converted to a form suitable for analysis of lunar day-side transfer function data by: (1) transforming the solution in plane geometry to that in spherical geometry; and (2) transforming the theoretical lunar transfer function in the dipole limit to an apparent resistivity function. The theory is applied to the revised lunar transfer function data set of Hood et al. (1982), which extends in frequency from 10 to the -5th to 10 to the -3rd Hz. On the assumption that an iron-rich lunar core, whether molten or solid, can be represented by a perfect conductor at the minimum sampled frequency, an upper bound of 435 km on the maximum radius of such a core is calculated. This bound is somewhat larger than values of 360-375 km previously estimated from the same data set via forward model calculations because the prior work did not consider all possible mantle conductivity functions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 88; B97-B102
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    SERIES - Satellite Emission Range Inferred Earth Surveying (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Satellite Emission Range Inferred Earth Surveying (SERIES) concept is based on the utilization of NAVSTAR Global Positioning System (GPS) radio transmissions without any satellite modifications and in a totally passive mode. The SERIES stations are equipped with lightweight 1.5 m diameter dish antennas mounted on trailers. A series baseline measurement accuracy demonstration is considered, taking into account a 100 meter baseline estimation from approximately one hour of differential Doppler data. It is planned to conduct the next phase of experiments on a 150 m baseline. Attention is given to details regarding future baseline measurement accuracy demonstrations, aspects of ionospheric calibration in connection with subdecimeter baseline accuracy requirements of geodesy, and advantages related to the use of the differential Doppler or pseudoranging mode.
    Keywords: GEOPHYSICS
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    Calculated stormtime variations in plasmaspheric thermal ion composition (1983)
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    Publication Date: 2011-08-18
    Description: Model calculations describing stormtime variations in the earth's dayside plasmasphere are used to examine variations in ion composition. The model storm is initiated by high-latitude thermospheric heating that generates meridional winds that carry neutral species, momentum, and energy equatorward. The thermosphere acts on the plasmasphere through collisional transfer of momentum and through chemical reactions between neutral species and ions. Over latitudes near the region of thermospheric heating, the thermosphere-plasmasphere coupling processes cause enhancement in the density of oxygen ions while protons are being lost. Meanwhile, densities of oxygen ions and protons near the equator are increasing together, almost in phase. The largest enhancements in ion density develop at latitudes near 45 deg invariant for both oxygen and hydrogen.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 10233-10
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  • 42
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    Atmospheric tides on Venus. III - The planetary boundary layer (1983)
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    Publication Date: 2011-08-18
    Description: Diurnal solar heating of Venus' surface produces variable temperatures, winds, and pressure gradients within a shallow layer at the bottom of the atmosphere. The corresponding asymmetric mass distribution experiences a tidal torque tending to maintain Venus' slow retrograde rotation. It is shown that including viscosity in the boundary layer does not materially affect the balance of torques. On the other hand, friction between the air and ground can reduce the predicted wind speeds from about 5 to about 1 m/sec in the lower atmosphere, more consistent with the observations from Venus landers and descent probes. Implications for aeolian activity on Venus' surface and for future missions are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 165-175
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    Structure and dynamics of Saturn's outer magnetosphere and boundary regions (1983)
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    Publication Date: 2011-08-18
    Description: In 1979-1981, the three USA spacecraft Pioneer 11 and Voyagers 1 and 2 discovered and explored the magnetosphere of Saturn to the limited extent possible on flyby trajectories. Considerable variation in the locations of the bow shock (BS) and magnetopause (MP) surfaces were observed in association with variable solar wind conditions and, during the Voyager 2 encounter, possible immersion in Jupiter's distant magnetic tail. The limited number of BS and MP crossings were concentrated near the subsolar region and the dawn terminator, and that fact, together with the temporal variability, makes it difficult to assess the three dimensional shape of the sunward magnetospheric boundary. The combined BS and MP crossing positions from the three spacecraft yield an average BS-to-MP stagnation point distance ratio of 1.29 +/- 0.10. This is near the 1.33 value for the Earth's magnetosphere, implying a similar sunward shape at Saturn. Study of the structure and dynamical behavior of the outer magnetosphere, both in the sunward hemisphere and the magnetotail region using combined plasma and magnetic field data, suggest that Saturn's magnetosphere is more similar to that of Earth than that of Jupiter. Previously announced in STAR as N83-30346
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8791-880
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    Channels and valleys on Mars (1983)
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    Publication Date: 2011-08-18
    Description: Tentative conclusions about the origins of channels and valleys on Mars based on the consensus of investigators who have studied the problem are presented. The morphology of outflow channels is described in detail, and the morphology, distribution, and genesis of Martian valleys are addressed. Secondary modification of channels and valleys by mass-wasting phenomena, eolian processes, cratering, and mantling by lava flows is discussed. The physics of the flows needed to account for the immense volumes of Martian outflow channels is considered in detail, including the possible influence of debris flows and mudflows, glaciers, and ice sheets. It is concluded that Mars once probably possessed an atmosphere with higher temperatures and pressures than at present which played an essential role in an active hydrological cycle.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geological Society of America, Bulletin (ISSN 0016-7606); 94; 1035-105
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    A model study of the effects of intermittent loss on odd nitrogen concentrations in the lower troposphere (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A time-dependent box model of the lower troposphere which includes a description of photochemical and physical processes has been developed. This model has been applied to the calculation of nitric acid and NO(x)(NO + NO2) concentrations over a diurnal cycle which includes precipitation. Nitric acid concentrations and the HNO3/NO(x) ratio are found to be highly variable under the assumptions regarding the frequency, duration, and intensity of precipitation employed in this model. The chemistry of odd nitrogen compounds during the night is potentially important in establishing the level of nitric acid in the lower troposphere. These calculations also indicate that relatively large errors may occur when the continuity equation describing nitric acid variations is averaged over a diurnal cycle which includes precipitation. Interpretation of simultaneous measurements of HNO3 and NO(x) will require some knowledge of the history of the observed air mass and may require an improved understanding of nighttime odd nitrogen chemistry.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 10697-10
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    Observation of wave-wave interactions in the stratosphere (1983)
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    Publication Date: 2011-08-18
    Description: Data from the LIMS instrument for January 1979 are used to provide further evidence for the often observed vacillation between the amplitudes of waves 1 and 2 in the stratosphere. The vacillation is shown to result primarily from nonlinear wave-wave interactions within the stratosphere. Two ways of interpreting nonlinearity are discussed. In the first, the basic state is defined to include large amplitude waves as well as the mean zonal wind. A forced wave propagates with respect to this asymmetric basic state, which can lead to changes in the conventional zonal wavenumber measured at one latitude. The other view of nonlinearity, interaction of wave with the zonal flow and with other wavenumbers are considered separately. Wave-wave interactions among waves 1, 2 and 3 are calculated. The derivation and computation of wave-wave interaction terms in the potential enstrophy balance are given. The observations indicate that enstrophy transfer among waves can be substantial even when the amplitude of one of the contributing waves is small. The computed enstrophy balance also demonstrates that wave-wave interactions can have a large effect on the interaction of waves with the mean flow.
    Keywords: GEOPHYSICS
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 40; 2484-249
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    Three Mars years - Viking Lander 1 imaging observations (1983)
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    Publication Date: 2011-08-18
    Description: The Mutch Memorial Station (Viking Lander 1) on Mars acquired imaging and meteorological data over a period of 2245 martian days (3.3 martian years). This article discusses the deposition and erosion of thin deposits (ten to hundreds of micrometers) of bright red dust associated with global dust storms, and the removal of centimeter amounts of material in selected areas during a dust storm late in the third winter. Atmospheric pressure data acquired during the period of intense erosion imply that baroclinic disturbances and strong diurnal solar tidal heating combined to produce strong winds. Erosion occurred principally in areas where soil cohesion was reduced by earlier surface sampler activities. Except for redistribution of thin layers of materials, the surface appears to be remarkably stable, perhaps because of cohension of the undisturbed surface material.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 222; 463-468
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  • 48
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    Stratospheric temperature profile from balloon-borne measurements of the 10.4-micron band of CO2 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The technique of nonlinear least squares spectral curve fitting has been used to derive the stratospheric vertical temperature profile from balloon-borne measurements of the 10.4 micron band of CO2. The spectral data were obtained at sunset with the approximately 0.02 per cm resolution University of Denver interferometer system from a float altitude of 33.5 km near Alamogordo, New Mexico, on 23 March 1981. The r.m.s. deviation between the retrieved temperature profile and correlative radiosonde measurements is 2.2 K.
    Keywords: GEOPHYSICS
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer (ISSN 0022-4073); 30; 327-334
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    Electric field measurements at the magnetopause. I Observation of large convective velocities at rotational magnetopause discontinuities (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Large convective electric fields of the order of 10 mV/m (sometimes as high as 22 mV/m) are observed at rotational magnetopause discontinuities. These observations were made with the long cylindrical (179-m base line) probes carried on the ISEE 1 satellite. These electric field observations yield convective velocity magnitudes (equal to the cross product of the vector E and the vector B, the latter divided by the square of the magnitude of B) of the order of 150 km/s. In this format for the convective velocity magnitudes, some of these observations are similar to the high speed plasma velocity observations that were made at the magnetopause with the plasma experiment carried on the ISEE 1 satellite. It is shown that, for many of these magnetopause crossings, there exists a special moving coordinate system where the observed electric fields vanish. Such a unique reference system is often used in theoretical studies of magnetic discontinuities. This special coordinate system does not move at the local plasma velocity but moves instead at a velocity intermediate between the convective velocity and the local Alfven velocity. It is used here as a diagnostic tool for the experimental investigation of rotational discontinuities at the magnetopause.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 10000-10
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    Stability and capture of asteroids (1983)
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    Publication Date: 2011-08-18
    Description: The problem of stability of asteroids is treated from the point of view of Hill's stability-concept and using Lyapunov's Characteristic Numbers. The quantitative measure of stability (S) introduced earlier is evaluated for over 300 asteroids and a surprisingly simple relation is established between the semi-major axes of some of the asteroids' orbits and S. A detailed analysis is presented of the Lyapunov Characteristic Numbers for two minor planets and the time-variation of these numbers is discussed. The technology of capture of asteroids is vitally dependent on their orbital stability, therefore, these two problems, i.e., capture and stability, are closely related. In fact, some predictable instabilities may be properly utilized to capture and/or change asteroidal orbits to accomplish collisions with the Earth.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Sao Paulo Univ. The Motion of Planets and Nat. and Artificial Satellites, Volume 2; p 39-46
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    A Sr and Nd isotopic study of five Yamato polymict eucrites and a comparison to other Antarctic and ordinary eucrites (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Sr and Nd isotopic analysis of five Yamato polymict eucrites indicate that these samples formed at about 4.6 Ga ago with initial Sr and Nd ratios essentially the same as the analyzed non-Antarctic eucrites. The Yamato eucrites have Sr, Sm, and Nd concentrations that consistently lie among the highest found in eucritic samples. This characteristic identifies these Yamato samples as a closely related group. Comparisons between these Yamato samples and other Antarctic polymict eucrites clearly estabishes that they all share some characteristic trace element features. Comparisons of Antarctic polymict eucrites with non-Antarctic ordinary eucrites reveal consistent differences. The most obvious is an enrichment of Rb in the polymict eucrites. These comparisons suggest that the Antarctic polymict eucrites belong to a single large family of material that is itself fairly diverse and distinct from the non-Antarctic eucrites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: National Institute of Polar Research, Memoirs, Special Issue (ISSN 0386-0744); 30, D
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    Estimation of lower crust magnetization form satellite derived anomaly field (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Various lines of evidence point to the lower crust as the source of the long-wavelength magnetic anomaly field measured by the POGO and Magsat satellites. Using seismically determined lower crust thicknesses and equivalent source inversion of the satellite anomaly data, magnetization for the lower crust for much of the United States has been calculated. The average magnetization for two hundred sixty-six 150 x 150 km areas is 3.5 A/m with a standard deviation of 1.1 A/m. These values are consistent with laboratory measurements of mafic-ultramafic rocks expected in the lower crust, and in agreement with previous estimates of lower crust magnetization based on long-wavelength aeromagnetic data. Average lower crust thickness for the same areas is 18.2 km (sigma = 6.4). Thus, over large regions, it appears that variation in magnetization and variation in magnetic layer thickness contribute almost equally in causing the anomaly field variation at satellite altitude.
    Keywords: GEOPHYSICS
    Type: Tectonophysics (ISSN 0040-1951); 93; 33-45
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    Condensation of chondrules (1983)
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    Publication Date: 2011-08-19
    Description: Analysis of current experimental results concerned with the kinetic constraints on chondrule formation showed that the major physical properties of chondrules could have been produced by direct condensation of metastable liquid silicates droplets from a hot gas in the primordial nebula. It is argued that such a condensation process would have to be followed by crystallization, accretion, and partial comminution of the droplets. The chemical mechanisms driving this process are described, including: nucleation constraints on comminution and crystallization; slow transformations and chemical reactions in chain silicates; and the slow diffusion of ions. It is shown that the physical mechanisms for chondrule condensation are applicable to a broad spectrum of chondrule sources.
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    External control of planetary radio emission (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent studies using data from Voyagers 1 and 2 to correlate variations in the Saturn kilometric radiation (SKR) with changes in solar-wind properties are summarized and illustrated with graphs. Best SKR correlations have been obtained with the solar-wind ram pressure and the related kinetic energy flux. It is pointed out that the related phenomenon on earth, the auroral kilometric radiation, occurs mainly in the nightside auroral region (as opposed to the dayside cleft region for SKR) and is best correlated with solar-wind velocity and inverted-V electron-precipitation events, implying a different stimulation process. The evidence for solar-wind control of the non-Io-related decametric radiation of Jupiter is also reviewed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Oesterreichische Akademie der Wissenschaften, mathematisch-naturwissenschaftliche Klasse, Sitzungsberichte, Abteilung 2 (ISSN 0723-9319); 192; 8-10,
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  • 55
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    Cold plasma distribution above a few thousand kilometers at high latitudes (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Great advances with respect to the study of the earth's magnetosphere could be achieved in connection with the launch of the Dynamics Explorer (DE) 1 and 2 spacecraft. These advances were made possible partly because of the unique combination of coplanar orbits which simultaneously sample the low altitude ionospheric and atmospheric signature (DE-2) and the high altitude phenomena of the inner magnetosphere (DE-1). It was, thus, feasible to obtain new measurements of the coupling of plasmas and fields between these fundamentally important regions. One basic element of the coupling involves the interchange of low energy plasma between the ionosphere and magnetosphere. The flow characteristics of the low energy plasma are indicators of the magnetospheric and ionospheric electric fields which drive the current system. The Retarding Ion Mass Spectrometer (RIMS) instrument has been designed for conducting measurements regarding this plasma population. Attention is given to details regarding RIMS, an example RIMS orbit, plasma trough characteristics, and polar cap phenomena.
    Keywords: GEOPHYSICS
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    Atmospheric density, temperature and wind measurement techniques during the 1980 Energy Budget Campaign (1981)
    In:  CASI
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    Publication Date: 2011-12-30
    Description: Super Loki rocketsonde systems are described. The datasonde telemeters data to a ground station where ambient temperatures are calculated between 20 and 70 km. The sphere is a passive, radar tracked system which allows density to be calculated between 30 and 90 km. When flown simultaneously the systems give redundant data in the altitudes between 30 and 70 km. The datasonde has a balloon parachute that descends more slowly than a conventional parachute and is more stable. Because of launch constraints the datasondes reached very high apogees, leading to very fast descent velocities. Aerodynamic heating reduced thermistor sensitivity. Anomalous parachute behavior influenced wind sensing until a denser layer was reached. The spheres collapsed above 60 km altitude, but their data, combined with dropsonde data give significant results for 21 flights. These show that the stratosphere is colder than Cospar 72 model predictions and the mesosphere is warmer.
    Keywords: GEOPHYSICS
    Type: Wuppertal Univ. Sounding Rocket Program Aeronomy Project: Energy Budget Campaign 1980. Expt. Summary; p 382-396
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    The Galilean satellites (1981)
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    Publication Date: 2011-08-18
    Description: The general characteristics of the Galilean satellites, as determined from Voyager data, are described. Attention is then given to the characteristics (surface features, colors, compositions, and geophysical and geochemical processes) of the particular satellites. Particular consideration is given to the nature of Io's atmosphere and to magnetospheric interactions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    Atmospheres of the terrestrial planets (1981)
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    Publication Date: 2011-08-18
    Description: The paper reviews current knowledge of the characteristics of atmospheres surrounding the terrestrial planets; attention is given to composition, temperature, characteristics of the upper atmospheres, and meteorology. In addition, the long-term history of the atmospheres is discussed, along with some of the major climatic changes that have occurred. Finally, consideration is given to future efforts that will enhance the understanding of these subjects.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 59
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    Radiative-photochemical response of the mesosphere to dynamical forcing (1981)
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    Publication Date: 2011-08-18
    Description: Combination of the chemical continuity equation for odd oxygen with the second law of thermodynamics yields analytic solutions which describe the coupled behavior of temperature and ozone perturbations in response to an externally specified forcing. The results appear in a form which allows easy physical interpretation of the coupling between radiative and photochemical processes. When the forcing is chosen to mimic a planetary scale wave, the theory shows that photochemical acceleration of radiative damping reduces the amplitude of the temperature perturbation by an amount which increases with the wave period. Although ozone fluctuations are anti-correlated with those in temperature, minima in ozone do not coincide exactly in longitude with temperature maxima. The percentage variation in ozone increases upward and is always larger than that in temperature at the same pressure. This demonstrates that variations in ozone on constant pressure surfaces may serve as a sensitive indicator of wave activity in the mesosphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 86; June 20
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  • 60
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    Particles above the tropopause - Measurements and models of stratospheric aerosols, meteoric debris, nacreous clouds, and noctilucent clouds (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An outline is presented of the present status of knowledge of stratospheric aerosols, meteoric debris, nacreous clouds, and noctilucent clouds. Considerable progress has been made in studies of these particles during the previous decade and it is appropriate to synthesize the information to provide a background for studies planned for the 1980s. Numerical models of the formation, growth, and evolution are considered and a description is given of the physical processes involved, taking into account aspects of nucleation, coagulation, condensational growth, sedimentation, and questions of dynamical transport. A schematic outline of the physical and chemical processes included in a model of stratospheric aerosols is provided.
    Keywords: GEOPHYSICS
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    Near-infrared spectrophotometry of the satellites and rings of Uranus (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: New spectrophotometry from 1.5 to 2.5 microns is reported for the Uranian satellites Titania, Oberon, and Umbriel. A spectrum of the rings of Uranus from 2.0 to 2.4 microns is also reported. No evidence is found for frost covering the surface of the ring material, consistent with the low albedo of the rings previously reported by Nicholson and Jones (1980). The surfaces of the satellites are found to be covered by dirty water frost. Assuming albedos of the frost and gray components covering the Uranian satellites to be the same as the light and dark faces of Iapetus, radii are derived that are roughly twice those inferred from the assumption of a visual albedo of 0.5.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 45; Mar. 198
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  • 62
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    The CAMEO barium release - E/parallel/ fields over the polar cap (1981)
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    Publication Date: 2011-08-18
    Description: Four successive thermite barium releases at an altitude of 965 km over polar cap invariant latitudes 84 to 76 deg near magnetic midnight were conducted from the orbiting second stage of the vehicle that launched Nimbus 7; the releases were made as part of the CAMEO (Chemically Active Material Ejected in Orbit) program. This was the first opportunity to observe the behavior of conventional barium release when conducted at orbital velocity in the near-earth magnetic field. The principal unexpected characteristic in the release dynamics was the high, 1.4 to 2.6 km/s, initial Ba(+) expansion velocity relative to an expected velocity of 0.9 km/s. Attention is also given to neutral cloud expansion, initial ion cloud expansion, convective motion, and the characteristics of field-aligned motion. The possibility of measuring parallel electric fields over the polar cap by observing perturbations in the motion of the visible ions is assessed.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 86; May 1
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  • 63
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    Temporal and spatial variations observed in the ionospheric composition of Venus - Implication for empirical modelling (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The distributions of several ion species in a data base obtained by in situ measurements of the thermal ion composition of the ionosphere of Venus by the Pioneer Venus Orbiter have been sorted to identify temporal and spatial variations and determine the feasibility of an analytical representation of the experimental results. The first results from the sorting of several prominent ions including O(+), O2(+), and H(+) and several minor ions including CO2(+), C(+), and H2(+) reveal significant diurnal variations which consist of strong day to night contrast in the ion concentrations, with differences of one to two orders of magnitude, depending upon ion mass and altitude. It is suggested that repeatable day to night gradients in the ion distribution are adaptable to parametric modeling.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 64
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    Very low frequency waves stimulated by an electron accelerator in the auroral ionosphere (1981)
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    Publication Date: 2011-08-18
    Description: The sounding rocket, Polar 5, carrying a 10 keV electron accelerator in a mother-daughter configuration and other diagnostic instruments, was launched into a slightly disturbed ionosphere with weak auroral activity on February 1, 1976 from Northern Norway to study VLF wave phenomena. The rocket trajectory crossed two auroral regions: one, between 86 and 111 s flight time, and a secondary region between 230 and 330 s. The daughter, carrying the accelerator, was separated axially from the mother in a forward direction at an altitude of 90 km. The VLF experiment, carried by the mother payload, recorded both electromagnetic and electrostatic waves. The receiving antenna was an electric dipole, 0.3 m tip-to-tip, oriented 90 degrees to the rocket spin axis. The onboard particle detector recorded increased electron fluxes in the two auroral regions. A double peaked structure was observed in the fluxes of 4-5 and 12-27 keV electrons within the northern auroral form. The number density of thermal plasma varied during the flight, with maximum density within the main auroral region. To the north of this aurora a slow, steady decrease in the density was observed, with no enhancement in the region of the second aurora.
    Keywords: GEOPHYSICS
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    An analytic formulation for heating source memory in the thermospheric composition (1981)
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    Publication Date: 2011-08-18
    Description: Numerical calculations from a spectral circulation model are utilized to construct an analytic Green's function formulation describing the meridional, time-dependent thermospheric composition and temperature response during magnetic storms. The purpose is to develop a formulation that embodies source memory while being sufficiently simple to serve as a heuristic guide for empirical modeling. By passing from the discrete Fourier series representation, utilized for the numerical circulation model, to a continuous Fourier integral representation, explicit waves are obtained for the thermospheric response times. The response times are altitude and species dependent and can exceed two days below 200 km. Thus, for certain storm scenarios, pronounced source memory signatures for the composition and temperature are predicted. Response times obtained from the formulation are shown to give a response consistent with previously published neutral composition data from AE-C for the February 1974 storm when an ap dependent heat source is employed.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 86; May 1
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    Semiempirical modeling of thermospheric magnetic storms (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An improved formulation for empirical modeling of magnetic storm effects in neutral thermospheric composition and temperature is utilized in a study of two disturbed periods. The formulation, which incorporates the prior history of the heat input rather than a single phase delay, is based on a Fourier integral representation of an existing theoretical model. This results in an improved representation of the detailed time variations and a better carry-over of model parameters from one storm to the other and provides a basis for theoretical interpretation.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 86; May 1
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    Inference of the ring current ion composition by means of charge exchange decay (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The analysis of data from the Explorer 45 (S3-A) electrostatic analyzer in the energy range 5-30 keV has provided some new results on the ring current ion composition. It has been well established that the storm time ring current has a decay time of several days, during which the particle fluxes decrease nearly monotonically. By analyzing the measured ion fluxes during the several day storm recovery period and assuming that beside hydrogen other ions were present and that the decays were exponential in nature, three separate lifetimes for the ions were established. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H(+), O(+) and He(+) in the energy and L value range of the data.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 86; May 1
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  • 68
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    Dynamic variations observed in thermal and superthermal ion distributions in the dayside ionosphere of Venus (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In-situ measurements of the ion composition and concentration of the ionosphere of Venus are obtained with the Bennett RF ion mass spectrometer (OIMS) on the Pioneer Venus Orbiter (PVO). Dayside ion profiles exhibit considerable variability in the height of the ionopause as well as the scale heights of the ion constituents, which reflect the compression and expansion of the ionosphere in response to solar wind variations. Near the dayside upper boundary of the thermal O+ distribution, super-thermal ions are detected by the OIMS, presenting a complication for identifying the ion signature of the ionopause. Correlated with the presence of the superthermal ions, the ac electric field detector (OEFD) detects regions of intensified signals, with peak response in the 100 Hz frequency channel. It is expected that further analysis of the superthermal ion-electric field signatures will contribute to a clearer understanding of the physical processes underlying the formation of the ionopause.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    The electrodynamic interaction of Io with Jovian magnetosphere (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    Bidirectional reflectance spectroscopy. II - Experiments and observations (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Aspects of the theoretical bidirectional reflectance expression derived by Hapke (1981) are studied experimentally, and it is shown that the expression describes satisfactorily the measured angular scattering and spectral properties of a cobalt glass powder in which the two properties vary greatly with wavelength. The theoretical reflectance function also describes measured distributions of intensity across the surfaces of planets, except near the sunlit limb, where the macroscopic roughness influences the brightness.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 86; Apr. 10
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    Observations of Martian tides over two annual cycles (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The first four diurnal surface pressure harmonics have been analyzed over major portions of two Martian annual cycles (Mars years) at the two Viking lander sites. The diurnal harmonics of surface wind have also been analyzed at one of the sites. Since the atmospheric tides have previously been shown to provide a good indication of Martian global dust storms, these results provide a basis for comparing dust storm activity in the two years. Two global dust storms occurred during the first year. During the second year, there was only one major storm, and it closely followed the pattern of the first storm of the first year. A significant feature of the results is the brief, but nearly complete, vanishing of the diurnal pressure tide at the onset of one of the global dust storms. It is proposed that this may have been due to interference between the normal westward-propagating diurnal tide and a topographically forced eastward propagating tide, and that the latter may have helped initiate the global storm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 38; Jan. 198
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    A Martian general circulation experiment with large topography (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A three-layer general circulation model of the Martian atmosphere is described, and the assumptions governing the model are discussed. The simulated, zonally averaged circulation is found to have only limited sensitivity to differences between this model and an earlier general circulation model; this circulation compares reasonably well with observations. It is also found that the meridional mass flow produced by the seasonal condensation of CO2 in the winter polar region has a major influence on the circulation; owing to the weak influence of atmospheric heat transport, however, the mass flow is governed almost entirely by radiation. Quasi-barotropic stationary waves, which are forced kinematically by the topography and which resemble topographically forced terrestrial planetary waves, are generated by the model in the winter hemisphere region of strong eastward flow, while baroclinic stationary waves are thermally forced by topography in the tropics and summer subtropics. It is also concluded that transient baroclinically unstable waves, of somewhat lower dominant wavenumber than those found on the earth, are generated in winter midlatitudes; their amplitudes, wavenumbers, and phase speeds closely agree with what has been deduced from the Viking lander observations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 38; Jan. 198
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    Meteoric ion production near Jupiter (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Meteoric ion layer formation within the Jovian atmosphere is examined with attention to metallic ion production in the lower ionosphere. The Fe(+) impact ionization rate within the Jovian atmosphere peaks above the mesopause with a magnitude of approximately 0.5 cu cm/sec and is much less than the ambient ionosphere photoionization rates near the late afternoon Pioneer 10 ionosphere occultation. Charge exchange of the ablated neutral Fe atoms with ambient ions can result in an Fe(+) production rate of about 10 cu cm/sec. Ignoring transport, steady state Fe(+) density maxima of about 10,000 or 1,000,000 cu cm can be maintained when Fe(+) loss is through radiative association or radiative recombination respectively. Even if an estimated lower limit to the incident meteoroid flux is used based on a meteoroid spatial density which does not vary with distance from the sun, the corresponding Fe(+) peak densities are 1,000 and 500,000 cu cm, respectively. Meteoric ion densities may thus be important in the Jovian lower ionosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 86; Mar. 1
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    SAS 2 observations of the earth albedo gamma radiation above 35 MeV (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The earth albedo gamma radiation above 35 MeV in the equatorial region is investigated using observations from the second Small Astronomy Satellite. The zenith angle distribution of the gamma radiation has a peak toward the horizon which is about an order of magnitude more intense than the radiation coming from the nadir, and nearly two orders of magnitude more intense than the gamma radiation from most parts of the sky. The gamma radiation originating from the western horizon is a factor of four more intense than the radiation from the eastern horizon and a factor of three more intense than that from the northern and southern directions. This reflects the geomagnetic effects on the incident cosmic rays whose interactions produce the albedo gamma rays. The variation of the upcoming gamma ray intensity with vertical cutoff rigidity is consistent with the empirical relationship found by Gur'yan et al. (1979).
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 86; Mar. 1
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    Discovery of natural gain amplification in the 10-micrometer carbon dioxide laser bands on Mars - A natural laser (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Fully resolved intensity profiles of various lines in the carbon dioxide band at 10.4 micrometers have been measured on Mars with an infrared heterodyne spectrometer. Analysis of the line shapes shows that the Mars atmosphere exhibits positive gain in these lines. The detection of natural optical gain amplification enables identification of these lines as a definite natural laser.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 212; Apr. 3
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    Coherent- and incoherent-scatter radar (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The ionized regions of the atmosphere were studied using high power backscatter radars at VHF and UHF frequencies were studied. The first year of data from the Urbana coherent-scatter radar were analyzed. It is suggested that the VHF scattered power profile from the mesosphere over Urbana depends on the existence of short vertical wave length tidal components to generate turbulence. Short period altitude and amplitude variations are believed to be due to gravity wave interacting with the tidal components.
    Keywords: GEOPHYSICS
    Type: Res. in Aeronomy; p 47-81
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    Partial reflection (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Differential-absorption electron concentration and drifts wind data were collected on a daily basis along with daily winds data. The daily winds data are compared with the daily electron concentration data on the meridional prevailing wind are compared with the electron concentration. Results are briefly discussed.
    Keywords: GEOPHYSICS
    Type: Res. in Aeronomy; p 24-29
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    Laser radar (1981)
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    Publication Date: 2011-08-18
    Description: A laser radar system to measure the altitude distribution of atmospheric sodium in the 80 to 100 km altitude region was constructed. The system consists of a high power pulsed dye laser, large aperture receiving telescope, and photon counting and signal processing equipment. The receiving system development, and the construction and development of the dye laser are discussed. Spatial and temporal filtering of the data to enhance the resolution of the sodium lidar profiles is described as well as computer model studies of the sodium density response to gravity wave perturbations.
    Keywords: GEOPHYSICS
    Type: Res. in Aeronomy; p 82-94
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    Meteor radar (1981)
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    Publication Date: 2011-08-18
    Description: Experimental and theoretical studies of the dynamics of the meteor region (75-105 km) were conducted using a meteor radar system. The radar was operated for approximately 700 hours. The data were fully analyzed to yield the north/south and east/west horizontal wind components, and curve fitting routines are used to yield the daily mean winds, and the diurnal and semidiurnal tides.
    Keywords: GEOPHYSICS
    Type: Res. in Aeronomy; p 30-46
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    Rocket experiments (1981)
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    Publication Date: 2011-08-18
    Description: Payloads designed to study the ionization and the ionizing sources (energetic particles) during periods of auroral activity are described. These include a probe experiment to measure the variation in electron concentration, to measure electron temperature, and to measure the vehicle potential; a propagation experiment to obtain the electron concentration and the electron collision frequency; and an energetic particle experiment to measure particle energy spectra.
    Keywords: GEOPHYSICS
    Type: Res. in Aeronomy; p 6-23
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  • 81
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    X-band atmospheric noise temperature statistics at Goldstone, DSS 13, 1979 and 1980, and clear air noise temperature models for Goldstone (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Superhigh frequency (X band) noise temperature data are presented which illustrate the noise temperature increase above quiescent baseline for the years 1979 and 1980. Clear air models are also given which shows the seasonal noise temperature effects of changing surface water vapor densities for a particular atmospheric model.
    Keywords: GEOPHYSICS
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 161-167
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    A frequency and timing subsystem for the ORION mobile unit (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A mobile surveying instrument in support of the crustal dynamics program measures the length and direction of the distance between sites on the Earth's surface using VLBI techniques operating at microwave frequencies and extragalactic radio sources. The frequency and timing subsystem uses as a frequency standard the hydrogen maser. An important part of the subsystem is a sophisticated automatic system to monitor frequency stability and accumulated clock error.
    Keywords: GEOPHYSICS
    Type: Telecommun. and Data Acquisition; p 3-10
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  • 83
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    Calculation of atmospheric loss from microwave radiometric noise temperature measurements (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Microwave propagation loss in the atmosphere can be inferred from microwave radiometric noise temperature measurements. The relevant equations are given and a derivation and calculation is made assuming various physical models. Comparison is made with the commonly used lumped element atmospheric model (isothermal and uniform loss) and the model with linear temperature and exponential loss distributions. The results are useful for estimating the integral inversion differences due to the model selection. This indicates that the commonly used lumped element atmospheric model is a very good approximation with judicious choice of the effective physical temperature. For the worst case comparison, the lumped element model agrees with the variable parameter model within 0.2 dB up to a propagation loss of 3 dB.
    Keywords: GEOPHYSICS
    Type: Telecommun. and Data Acquisition; p 73-80
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  • 84
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    Earthquakes - on the moon (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Information obtained with the Apollo lunar seismic stations is discussed. The four types of natural seismic sources that have been identified are described, viz., thermal moonquakes, deep moonquakes, meteoroid impacts, and shallow moonquakes. It is suggested that: (1) the thermal quakes represent the slow cracking and movement of surface rocks; (2) the deep quakes are induced by the tide-generating force of the earth's gravity; (3) the meteoroids responsible for most of the observed impacts are in the mass range from 1 to 100 kg and are clustered in groups near the earth's orbit; and (4) the shallow quakes are similar to intraplate earthquakes and indicate that the moon is as seismically active as the interior regions of the earth's tectonic plates. The structure of the lunar interior as inferred from seismic signals due to both the last three natural sources and 'artificial' impacts of used spacecraft is examined in detail.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Discovery; 6; 1, 19; 1981
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  • 85
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    The atmosphere and ionosphere of Jupiter (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The thermal structure of the upper atmosphere of Jupiter, the composition of the atmosphere and the strength of mechanical mixing, and sources and sinks of ionization in the Jupiter ionosphere are described from Voyager UV spectrometer, radio, IR, and imaging data. A topside ionospheric temperature of 1300 K was observed, along with an energy equilibrium between the plasma and neutral gas in the upper atmosphere. A composite thermal structure is provided, noting a close similarity to earth conditions at upper levels, and enhanced thermal behavior has been detected between the times of solar minimum and maximum activity. Ammonia photochemistry is examined, and measured concentrations of H2, CH4, C2H6, and C2H2 as a function of height are outlined. Eddy diffusion coefficient calculations are carried out, yielding a highest Ly-alpha intensity of 100 million sq cm/sec. The increased exospheric temperature between 1973 and 1980 is stressed to have no known satisfactory explanation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Vistas in Astronomy; 25; pt. 3
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  • 86
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    Martian channels and valleys - Their characteristics, distribution, and age (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The distribution and ages of Martian channels and valleys, which are generally believed to have been cut by running water, are examined with particular emphasis on the small branching networks referred to as runoff channels or valley networks. Valleys at latitudes from 65 deg S to 65 deg N were surveyed on Viking images at resolutions between 125 and 300 m. Almost all of the valleys are found in the old cratered terrain, in areas characterized by high elevations, low albedos and low violet/red ratios. The networks are deduced to have formed early in the history of the planet, with a formation rate declining rapidly shortly after the decline of the cratering rate 3.9 billion years ago. Two types of outflow channels are distinguished: unconfined, in which broad swaths of terrain are scoured, and confined, in which flow is restricted to discrete channels. Both types start at local sources, and have formed episodically throughout Martian history. Fretted channels, found mainly in two latitude belts characterized by relatively rapid erosion along escarpments, are explained by the lateral enlargement of other channels by mass wasting.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 48; Oct. 198
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  • 87
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    Venus nightside ionospheric holes - The signatures of parallel electric field acceleration regions (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Attention is given to the existence of 'holes', that is, regions of density depletion in the nightside Venus ionosphere associated with regions of radial magnetic fields. The properties of the electrons within the core of these holes are thought to suggest an acceleration process along the magnetic field lines, a process also suggested by the Venera 9 and 10 observations of energetic ions in the Venus tail. On the basis of the observational information, these Venusian plasma depletions are attributed to the presence of parallel electric fields similar to those observed in the terrestrial auroral ionosphere. The resulting electric field accelerates electrons down the field lines, heating the depleted thermal electron population within the hole and producing ionization below the hole. At the same time, ionospheric ions are accelerated outward toward the plasmasheet.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 8; Dec. 198
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  • 88
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    Influence of gravity field uncertainties on the results from POGO and Magsat geomagnetic surveys (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Errors in the gravity models used in satellite position calculations are examined as a possible source of the 0 to 100% variance found between POGO and Magsat magnetic data and the extrapolations of aerial magnetic survey data to satellite heights. For POGO data obtained over the New York Bight region using a relatively poor gravity field (a hybrid spherical harmonic model of degree 7 and order 6 with three higher order resonance terms), the magnitude of the error in the satellite height component is found to be sufficient to account for the amplitude of the discrepancy, however the frequency of the quasi-periodic orbital error is too large to explain the localized nature of the differences. For the case of the Magsat satellite, in which a more accurate gravity model was used, it is found that a 30 mgal gravitational anomaly distributed over a 5 x 5 deg area will produce insufficiently large position errors to account for the variations. The agreement between the two sets of satellite data in the New York Bight region suggests either a consistent error in satellite measurements, or problems with the reduction and processing of the aeromagnetic data.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 8; Dec. 198
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  • 89
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    Stratospheric measurements of continuous absorption near 2400 per cm (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Measurements of continuous absorption near 2400 per cm by N2 and CO2 over long path lengths in the lower stratosphere are presented. The continua were measured in a stratospheric solar spectrum obtained during sunset with a balloon-borne Michelson interferometer in the 2380-2500 per cm region, and transmittances were calculated by ratioing the amplitudes to those of a high-sun spectrum in order to eliminate the wavelength dependence of the measured flux. Comparison of the measured transmittances with those calculated for a multilayered atmospheric model using laboratory absorption measurements results in a fair agreement, and reveals the primary component of the absorption throughout most of the range to be N2, with the CO2 contribution equal to that of N2 only at the CO2 band head. In this region, the shape of the continuum is very sensitive to the sub-Lorentzian line shape assumed in the calculations, and so, if the shape of the N2 continuum at low temperatures can be determined through laboratory measurements, may be used to infer air-broadened far-wing CO2 line shape.
    Keywords: GEOPHYSICS
    Type: Applied Optics; 20; Dec. 15
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  • 90
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    Fresnel zone structure in planetary occultations (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The structures of the Fresnel zones of an occulting body with a substantial atmosphere are analyzed. The first Fresnel zone is defined as the set of all contiguous points connected to the transmitter and receiver via paths with a combined length within one half wavelength of the stationary value, and calculated by the application of the Huygens-Fresnel principle to a wave front frozen in time as it traverses the region of interest, taking into account wave front curvature of waves undergoing refraction. Calculations of the Fresnel zones of a planet determined by the meeting of wave fronts represented as tori reveal that the zone along the propagation path traversing the nearest portion of the limb to the transmitter has a shape similar to an ellipse, while that of the far zone resembles the letter X. The phase delay along the farside path is found to be a stationary point rather than a minimum, since delay is distributed in the form of a hyperbolic paraboloid near the ray and in the form of a torus intersection for greater separations. Examples are presented for S band propagation deep in the atmospheres of Venus and Jupiter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Radio Science; 16; Nov
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  • 91
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    Topography of Venus and earth - A test for the presence of plate tectonics (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Comparisons of earth and Venus topography by use of Pioneer/Venus radar altimetry are examined. Approximately 93% of the Venus surface has been mapped with a horizontal resolution of 200 km and a vertical resolution of 200 m. Tectonic troughs have been indicated in plains regions which cover 65% of Venus, and hypsometric comparisons between the two planets' elevation distributions revealed that while the earth has a bimodal height distribution, Venus displays a unimodal configuration, with 60% of the planet surface within 500 m of the modal planet radius. The effects of mapping the earth at the same resolution as the Venus observations were explored. Continents and oceans were apparent, and although folded mountains appeared as high spots, no indications of tectonic activity were discernible. A NASA Venus Orbiting Imaging radar is outlined, which is designed to detect volcanoes, folded mountain ranges, craters, and faults, and thereby allow definition of possible plate-tectonic activity on Venus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: American Scientist; 69; Nov
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  • 92
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    Evidence for 18.6 year Mn signal in temperature and drought conditions in North America since AD 1800 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is found that, since 1800, the mean discrepancy in epoch between maxima in temperature and maxima in the Drought Area Index (DAI) for the western United States with respect to maxima in the lunar modal tide is 0.9 and 0.1 year, respectively. It is suggested, in light of the fact that a cluster of nine stations in western Canada yields the 18.6-year lunar nodal term out of phase with 30 stations in eastern North America, that (1) enhanced drought conditions in the western United States are neither recurrent nor rhythmic on a time scale of 20 years, but rather periodic with a period of 18.6 years, and (2) the Rocky Mountain system is an influence for atmospheric tidal phenomena at epochs of maximum in the lunar nodal tide as well as for maxima in the temperature records of the DAI.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 86; Nov. 20
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  • 93
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    Atmospheric carbon dioxide and chlorofluoromethanes - Combined effects on stratospheric ozone, temperature, and surface temperature (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The effects of combined CO2 and CFCl3 and CF2Cl2 time-dependent scenarios on atmospheric O3 and temperature are described; the steady-state levels of O3 and surface temperature, to which the chlorofluoromethane scenario tends in the presence of twice and four time ambient CO2, are examined; and surface temperature changes, caused by the combined effects, are established. A description of the model and of the experiments is presented. Results indicate that (1) the total ozone time history is significantly different from that due to the chlorofluoromethane alone; (2) a local ozone minimum occurs in the upper stratosphere about 45 years from the present with a subsequent ozone increase, then decline; and (3) steady-state solutions indicate that tropospheric temperature and water vapor increases, associated with increased infrared opacity, cause significant changes in tropospheric ozone levels for 2 x CO2 and 4 x CO2, without the addition of chlorofluoromethanes.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 8; June 198
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  • 94
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    Observations of Saturn in the 5- to 8-micron spectral region (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A spectrum of Saturn obtained from the Kuiper Airborne Observatory exhibits an emission peak at 6.8 microns attributed to ethane, but is otherwise dominated by absorption from 5.3 to 7.2 microns. While the large absorption in this spectral region is consistent with the presence of ammonia gas or ammonia ice, or both, such an explanation is inconsistent with the lack of a major absorption near 3.0 microns.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 45; Mar. 198
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  • 95
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    Deconvolution of wide field-of-view radiometer measurements of earth-emitted radiation. I - Theory (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The theory of deconvolution of wide field-of-view (WFOV) radiometer measurements of earth-emitted radiation provides a technique by which the resolution of such measurements can be enhanced to provide radiant exitance at the top of the atmosphere with a finer resolution than the field of view. An analytical solution for the earth-emitted radiant exitance in terms of WFOV radiometer measurements is derived for the nonaxisymmetric (or regional) case, in which the measurements and radiant exitance are considered to be functions of both latitude and longitude. This solution makes it possible to deconvolve a set of WFOV radiometer measurements of earth-emitted radiation and obtain information with a finer resolution than the instantaneous field of view of the instrument. It is shown that there are tradeoffs involved in the selection between WFOV and scanning radiometers.
    Keywords: GEOPHYSICS
    Type: Journal of the Atmospheric Sciences; 38; Mar. 198
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  • 96
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    Artificial particle and wave stimulation in the Trigger experiment (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Trigger experiment, designed to test the response of the auroral ionosphere to an impulsive release of a hot, dense plasma, and consisting of a sounding rocket payload (launched on February 11, 1977) divided into two parts, an instrumented diagnostic section and a cesium-doped high-explosive canister, is described. When the two sections were separated by about 1 km, the cesium high-explosive was ignited and the plasma around the payload was observed to increase briefly by a factor of 4 in density and a factor of 2 in temperature, upon which various particle and field phenomena occurred in rapid succession. A large increase in the field-aligned charged particle flux was observed over the approximate energy range of 10 eV to more than 300 keV, starting about 150 ms after the release and lasting about 1 second. A second particle burst started one second after the release and lasted for tens of seconds. A transient electric field pulse of 200 mV/m appeared just before the particle flux increase began.
    Keywords: GEOPHYSICS
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  • 97
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    Deconvolution of wide field-of-view radiometer measurements of earth-emitted radiation. II - Analysis of first year of Nimbus 6 ERB data (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The theory of deconvolution considered by Smith and Green (1981) is applied to Nimbus 6 data in order to interpret the data with the maximum obtainable resolution. Attention is given to the data sample, sun-contaminated measurements, the measurement model, the deconvolution, the degree variance, the spherical harmonic coefficients, the geographical distribution of longwave radiation, time histories of zonal coefficients, and the effect of a grid system. Degree variance plots for 12 months of longwave radiation data show that the limit for a spherical harmonic representation of the Nimbus 6 wide field-of-view longwave data is 12th degree. The degree variance plots also reveal that most of the power is in the lower degree terms. Contour maps of the radiation field show the geographical distribution of earth emitted radiant exitance for each month.
    Keywords: GEOPHYSICS
    Type: Journal of the Atmospheric Sciences; 38; Mar. 198
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  • 98
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    Water vapor in the stratosphere - Preliminary results of the LIMS experiment aboard Nimbus 7 (1981)
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    Publication Date: 2011-08-18
    Keywords: GEOPHYSICS
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  • 99
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    Simultaneous measurements of NO/x/, NO, and O3 production in a laboratory discharge - Atmospheric implications (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Simultaneous measurements of NO(x) (NO + NO2), NO, and O3 production in a laboratory discharge show that within the uncertainties of the experiment, all of the NO(x) produced was NO, and no detectable enhancement of O3 after the discharge was observed. The laboratory experiments described gave an NO production rate of 5 + or - 2 x 10 to the 16th molecules/joule mole for a 100,000-1,000,000 joules/m spark. Assuming that the global dissipation of lightning energy is about 10 to the -8th joules/sq cm per sec (Dawson, 1980; and Hill et al., 1980), the NO production rate results in a global source of NO due to lightning of about 1.8 Mt(N)/yr, which is considerably lower than earlier estimates. This lower value for NO(x) production by lightning suggests that NO(x) emissions from anthropogenic sources, estimated to be at least 20 MT(N)/yr, may be the dominant source of NO(x) to the global troposphere. Furthermore, since most of the anthropogenic sources of NO(x) are located in the Northern Hemisphere, this new interpretation of the relative source strengths of this species favors a highly skewed asymmetric distribution of NO(x).
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 8; Apr. 198
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  • 100
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    Martian ages (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Four discussions are conducted: (1) the methodology of relative age determination by impact crater statistics, (2) a comparison of proposed Martian impact chronologies for the determination of absolute ages from crater frequencies, (3) a report on work dating Martian volcanoes and erosional features by impact crater statistics, and (4) an attempt to understand the main features of Martian history through a synthesis of crater frequency data. Two cratering chronology models are presented and used for inference of absolute ages from crater frequency data, and it is shown that the interpretation of all data available and tractable by the methodology presented leads to a global Martian geological history that is characterized by two epochs of activity. It is concluded that Mars is an ancient planet with respect to its surface features.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 86; Apr. 10
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