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  • Other Sources  (1,175)
  • LUNAR AND PLANETARY EXPLORATION  (726)
  • GEOPHYSICS  (449)
  • Inorganic Chemistry
  • 1975-1979  (1,175)
  • 1976  (1,175)
  • 1
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    Mathematical modelling of undrained clay behavior (1976)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: The proposed general analytical model describes the anisotropic, elastoplastic, path-dependent, stress-strain properties of inviscid saturated clays under undrained conditions. Model parameters are determined by using results from strain-controlled simple shear tests on a saturated clay. The model's accuracy is evaluated by applying it to predict the results of other tests on the same clay, including monotonic and cyclic loading. The model explains the very anisotropic shear strength behavior observed for weak marine clays.
    Keywords: GEOPHYSICS
    Type: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 95-102
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  • 2
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    Geodynamics experiment MA-128 (1976)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The Apollo Soyuz Test Project Geodynamics Experiment was performed to assess the feasibility of tracking and recovering high frequency components of the earth gravity field by utilizing a synchronous orbiting tracking station such as Applications Technology Satellite 6. Two prime areas of data collection were selected for this experiment. The first area is the center of the African continent, and the second area is the Indian Ocean depression centered at latitude 5 N and longitude 75 E. Preliminary results show that the detectability objective of the experiment has been achieved in both areas as well as in several additional anomalous areas around the globe. Gravity anomalies of the Karakoram and Himalayan mountain ranges of ocean trenches, and of the Diamantina depth are specific examples.
    Keywords: GEOPHYSICS
    Type: Apollo-Soyuz Test Project; 16 p
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  • 3
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    Doppler tracking experiment MA-089 (1976)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The Doppler tracking experiment was designed to test the feasibility of improved mapping of earth gravity field anomalies by means of the low-low satellite-to-satellite tracking method. All prescribed data have been retrieved and are currently being reduced and analyzed. Baseline data taken while the docking module was still attached to the command and service module indicated that the equipment operated satisfactorily. The efficacy of the two frequency ionospheric correction method has been demonstrated, and preliminary reduction of a data sample has successfully removed extraneous signatures down to the 50-millihertz level, where the rotational motion of the docking module is revealed. Photographs of the docking module, taken shortly after jettison, show that its rotation was stable.
    Keywords: GEOPHYSICS
    Type: NASA. Lyndon B. Johnson Space Center Apollo-Soyuz Test Project; 31 p
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  • 4
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    Earth's bowshock and its vicinity (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Phenomena associated with the bowshock, such as its thickness, velocity, and associated waves are described. There are transverse waves radiating away from the shock and at times stationary waves fixed to it. Reflected protons generate waves far upstream. Electrostatic waves occur in the shock.
    Keywords: GEOPHYSICS
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  • 5
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    Exploration of the giant planets by infrared spectroscopy (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The infrared spectrometer and radiometer for the Mariner-Jupiter-Saturn mission is described. Results of Nimbus and Mariner 9 IR spectroscopy of earth and Mars are used as examples to demonstrate the power and diversity of the technique. Determinations of planetary surface compositions, surface temperatures, vertical temperature profiles, surface pressures, and atmospheric constituents are summarized. Applications to Jupiter and Saturn are briefly mentioned.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 6
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    Heat budget of ionospheric electrons (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Heat input calculations were detached from solar extreme UV data and monatomic oxygen densities were derived from simultaneously measured data sets (ion composition 146-191 km) in a study of the heat budget of ionosphere electrons. Earlier inferences that cooling predominates over heating are supported. A search for additional heat sources or a revision of the cooling rates is recommended, by way of balancing the heat budget. Importance is attached to electron cooling by fine structure excitation of monatomic oxygen.
    Keywords: GEOPHYSICS
    Type: Annales de Geophysique; 32; Oct
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  • 7
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    The mesosphere (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The mesosphere is an atmospheric region characterized by a negative gradient of solar energy absorption and temperature. Although the distribution of most minor constituents is dominated by photochemistry, vertical transport does have a pronounced effect on many of them. The basic dynamic principles are discussed along with their application to the important mesospheric motions: acoustic-gravity waves, tides, planetary-scale waves, and eddy motions. Oxides of nitrogen and hydrogen are also examined which strongly influence the balance of odd oxygen (O and O3). Brief discussions of the chemistry of carbon compounds and of excited species are also included. The chemistry of ionic species in the mesosphere is very important because it strongly influences the propagation and absorption of radio waves. Because of ion clustering and negative-ion formation, such chemistry is extremely complex. The current state of knowledge is discussed in some detail. The principles involved in constructing models for predicting the distribution of minor constituents, both neutral and ionic, are presented.
    Keywords: GEOPHYSICS
    Type: Geophysical Surveys; 2; 1976
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  • 8
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    Coincident observations of ionospheric troughs and the equatorial plasmapause (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Electron-density observations made in the topside ionosphere by the Ariel 4 and Isis 2 satellites are examined in conjunction with results obtained by Explorer 45 when it traversed the near-equatorial plasmapause with one hour (both UT and MLT) of the Ariel and Isis traversals of the same L coordinate. Both dusk and night observations are analyzed, and an attempt is made to show that depressions in ionospheric electron density occur in the vicinity of the plasmapause field line. It is concluded that the electron distributions observed in the electron-density troughs at 550 km near dusk by Ariel and at 1400 km near midnight by Isis do not always parallel variations in the light-ion distribution inferred from the Explorer plasmapause traversals and that there appears to be no specific feature of the main ionospheric trough which can be used to identify the plasmapause field line except in a statistical sense.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 24; Dec. 197
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  • 9
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    Some aspects of the stratospheric Cl-ClO-Cl cycle - Possible roles of ClO, ClNO3 and HOCl (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The possible inhibitory effect of excited ClO produced during chlorine-sensitized ozone decomposition on the stratospheric Cl-ClO-Cl cycle is investigated. Collisional deactivation of excited ClO is discussed, chemical reactions involving excited ClO are examined, and the possible roles of HO2 and NO2 in weakening the Cl-ClO-Cl cycle are evaluated. It is noted that the formation of HOCl through a reaction between ClO and HO2 implies that the Cl-ClO-Cl cycle has not been completed.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 24; Dec. 197
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  • 10
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    Effects of the atmosphere on remote sensing (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The interaction between electromagnetic radiation and the earth's atmosphere is considered, taking into account windows in the electromagnetic spectrum, solar and terrestrial radiation, physical properties of the atmosphere, and clouds. The characteristics of upwelling radiation in the visible wavelengths are discussed along with infrared radiation and microwaves. Attention is given to radiant emittance, radiance, contrast, effects of atmospheric turbulence, ocean color, and questions concerning the classification of surface features with the aid of computers.
    Keywords: GEOPHYSICS
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  • 11
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    Magnetospheric whistler ducts observed by ISIS satellites (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The latitudinal width of the magnetospheric whistler duct has been estimated by the first and final invariant latitudes of whistler echoes and the conservation of the magnetic flux for the centered dipole field, using 105 whistler echoes in ISIS VLF data received at Kashima, Japan for 1972-1973. The latitudinal distribution of whistler duct occurrence shows a maximum at invariant latitudes of 40-45 degrees near the maximum occurrence latitude of ground whistlers. The radial width of magnetospheric whistler duct in the geomagnetically equatorial plane increases with invariant latitude of the geomagnetic flux tube in which whistlers propagate.
    Keywords: GEOPHYSICS
    Type: Radio Research Laboratories; vol. 23
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  • 12
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    Terrestrial kilometric radiation. I - Spatial structure studies (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Observations of lunar occultations of earth at 250 kHz, obtained with the Radio Astronomy Explorer 2 satellite, have been used to derive two-dimensional maps of the location of the sources of terrestrial kilometric radiation (TKR). By examining the two-dimensional source distributions as a function of the observer's location (lunar orbit) with respect to the magnetosphere, the average three-dimensional location of the emission regions can be estimated. Although TKR events at 250 kHz can often be observed at projected distances corresponding to the 250-kHz electron gyro or plasma level (about 2 earth radii), many events are observed much farther from earth (about 5 to 15 radii). On the dayside, emission was apparently observed in the region of the polar cusp and the magnetosheath at a magnetic latitude of about 70 deg; in the night hemisphere, emission is found to be associated with regions of the magnetotail at latitudes of at least 70 deg. The nightside emission is suggestive of a mechanism involving plasma-sheet electron precipitation in the premidnight sector.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Dec. 1
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  • 13
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    Structure of Mars' atmosphere up to 100 kilometers from the entry measurements of Viking 2 (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Viking 2 entry data on the structure of Mars' atmosphere up to 100 kilometers define a morning atmosphere with an isothermal region near the surface; a surface pressure 10% greater than that recorded simultaneously at the Viking 1 site; and a thermal structure to 100 kilometers at least qualitatively consistent with pre-Viking modeling of thermal tides. The temperature profile exhibits waves whose amplitude grows with altitude, to about 25 K at 90 kilometers. The atmosphere is stable against convection, except possibly in some very local regions. Temperature is everywhere appreciably above the carbon dioxide condensation boundary at both landing sites, precluding the occurrence of carbon dioxide hazes in northern summer at latitudes to at least 50 deg N. Thus, ground-level mists seen in these latitudes would appear to be condensed water vapor.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 194; Dec. 17
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  • 14
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    Scientific results of the Viking missions (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The two Viking missions to Mars have been extraordinarily successful. Thirteen scientific investigations yielded information about the atmosphere and surface. Two orbiters and landers operating for several months photographed the surface extensively from 1500 kilometers and directly on the surface. Measurements were made of the atmospheric composition, the surface elemental abundance, the atmospheric water vapor, temperature of the surface, and meteorological conditions; direct tests were made for organic material and living organisms. The question of life on Mars remains unanswered. The Viking spacecraft are designed to continue the investigations for at least one Mars year.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 194; Dec. 17
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  • 15
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    Estimated grain saltation in a Martian atmosphere (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Mariner 9 spacecraft images showing evidence of variable surface features and surface erosion resulting from atmospheric wind on Mars have caused a renewed interest in the eolian mechanics of saltating grains. To study this phenomenon, both experimental investigation in an atmospheric wind tunnel and numerical solutions of the equations of motion of a single grain under Martian surface conditions were conducted. The numerical solutions for earth were used and empirically adjusted to correlate with existing experimental data for Mars. These modified equations were then solved to estimate grain motion for Mars. These calculations show the importance of a lifting force on the grain to initiate motion in both earth and Mars calculations. Major findings include a comparison of earth and Mars grain trajectories that show Mars length scales to be longer and to fall with a higher terminal grain velocity. The grains in the Mars calculation also made a smaller collision angle with the surface on rebound.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 81; Nov. 10
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  • 16
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    Al-26 in Kenna and other ureilites (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A description is presented of the results of a nondestructive analysis conducted with a 42-g slice of the Kenna ureilite. The sample was analyzed in a gamma-gamma coincidence counting system, using a dual-parameter, 4096-channel pulse height analyzer. Data concerning Al-26 and Ne-22/Ne-21 in ureilites and Chassigny are presented in a table. A graph shows the ratio of measured Al-26 activity to that calculated from elemental production rates vs spallation Ne-22/Ne-21 for ureilites and Chassigny. The significance of the data with respect to findings reported by Wilkening et al. (1973) is discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 40; Dec. 197
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  • 17
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    On the energy deposition of photoelectrons in the atmosphere of Venus (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Vertical components of photoelectron fluxes in the atmosphere of Venus are computed by solving an appropriate form of the Boltzmann equation in the cases where there is no flux of either photoelectrons or solar-wind particles across the ionopause and where photoelectrons are free to escape from the atmosphere. It is assumed that Venus has no magnetic field and that the atmosphere is composed of carbon dioxide, atomic oxygen, and helium. The results are plotted as a function of altitude for several energies in the range from 100 eV to a cutoff of the order of 1 eV. Heating rates for the two upper boundary conditions and the case of no spatial transport are determined which show that transport effects dominate at altitudes greater than about 200 km. Electron temperatures are calculated for the adopted model atmosphere and ionosphere by solving the pertinent conservation equation, and excitation rates are computed for the CO Cameron band as well as the CO2(+) A and B bands.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 81; Oct. 1
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  • 18
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    Thermospheric storms and related ionospheric effects (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A comparative study of thermospheric storms for equinox and winter conditions is presented based on neutral-composition measurements from the Aeros-A neutral-atmosphere temperature experiment. The main features of the two storms as inferred from changes in N2, Ar, He, and O are described, and their implications for current theories of thermospheric storms are discussed. On the basis of the study of the F-region critical frequency measured from a chain of ground-based ionospheric stations during the two storm periods, the general characteristics of the ionospheric storms and the traveling ionospheric disturbances are described. It is suggested that the positive and negative phases of ionospheric storms are different manifestations of thermospheric storms.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Oct. 1
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  • 19
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    The 'soil' of Mars /Viking 1/ (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The immediate environs of the Viking 1 lander are described, and the techniques employed to deduce the properties of the two different 'soil' types there are summarized. It is shown that the surface in the immediate vicinity of the lander consists of an area with fine-grained materials ('Sandy Flats') and a rocky area set in a matrix of finer-grained material ('Rocky Flats'). Estimates are given for the bulk density, particle density, particle size distribution, cohesion, angle of internal friction, and penetration resistance of the surface layer in each area. Footpad penetration into the surface layer is discussed, and wind removal of particles is examined. It is concluded that the surface layer of the Viking 1 landing site contains loess, dune sand, lunar nominal soil, lag gravel, and bare rock.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 194; Oct. 1
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  • 20
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    Status of the Viking missions (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A chronology of Viking 1 lander activities is presented for the first 43 sols (Martian days) of surface sampling and analysis. The orbital insertion of the second Viking spacecraft is reviewed along with the search for the second landing site. A general assessment of the planet is made on the basis of the data thus far obtained. Some of the findings reported are that: (1) there is extensive evidence of volcanism, fluvial and aeolian erosion, and deposition over the entire surface; (2) the floor of Vallis Marineris is significantly younger than the planet's surface; (3) the morphology of Martian crater ejecta is indicative of surface flow rather than ballistic deposition; (4) the rocks in the immediate vicinity of the lander are all covered by a layer of fine red dust; (5) the atmosphere is optically thick and well mixed, with suspended particles giving the sky a pink color; (6) the N and Ar isotopic ratios are different from those on earth; (7) atmospheric water vapor varies with both time of day and location; (8) the summer northern polar regions have a high water concentration in the atmosphere; (9) a large fraction of magnetic material resides in the surface; and (10) no complex organic compounds have been detected in the two samples analyzed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 194; Oct. 1
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  • 21
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    Venus' night side ionosphere - Its origin and maintenance (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A substantial nightside ionosphere has been observed on Venus by both Mariner 5 and Mariner 10. Major dayside ionic species such as O2(+) and other molecular ions have chemical lifetimes much shorter than the 244.3-day rotation period of the planet. Rapid transport of ions from the dayside to the nightside to the extent required seems most unlikely. Consequently, possibilities are investigated for local production of ions on the nightside itself. Constraints imposed by chemical lifetimes require atomic ions with low ionization potentials. It is suggested that metallic ions of meteoric origin are the positive charge carriers, and the plausibility of this mechanism is demonstrated. Other possibilities are examined and shown to be less likely. Meteor ablation on Venus, the aeronomy of metallic species, and the role of negative ions near the electron peaks of the atmosphere are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 81; Sept. 1
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  • 22
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    The Viking landing sites - Selection and certification (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: During the past several years the Viking project developed plans to use Viking orbiter instruments and earth-based radar to certify the suitability of the landing sites selected as the safest and most scientifically rewarding using Mariner 9 data. During June and July 1976, the earth-based radar and orbital spacecraft observations of some of the prime and backup sites were completed. The results of these combined observations indicated that the Viking 1 prime landing area in the Chryse region of Mars is geologically varied and possibly more hazardous than expected, and was not certifiable as a site for the Viking 1 landing. Consequently, the site certification effort had to be drastically modified and lengthened to search for a site that might be safe enough to attempt to land. The selected site considered at 47.5 deg W, 22.4 deg N represented a compromise between desirable characteristics observed with visual images and those inferred from earth-based radar. It lies in the Chryse region about 900 kilometers northwest of the original site.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 193; Aug. 27
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  • 23
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    The Halley rendezvous via solar sailing mission description (1976)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The possibility of using solar sails to achieve a rendezvous with Halley's Comet is explored. Rendezvous trajectories are calculated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Proc. of the Shuttle-Based Cometary Sci. Workshop; p 251-256
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  • 24
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    QH observations (1976)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A model of the dissociative lifetime of the hydroxyl radical is computed where the H2O and OH velocities are vectorially added. A lifetime of approximately 3 x 100,000 seconds is determined.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA. Marshall Space Flight Center Proc. of the Shuttle-Based Cometary Sci. Workshop; p 222-226
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  • 25
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    The Nimbus 4 infrared spectroscopy experiment. III - Observations of the lower stratospheric thermal structure and total ozone (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Dec. 20
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  • 26
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    High resolution spectral analysis of the Jovian decametric radiation. II - The band-like emissions (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Analysis of the bandlike Jovian decametric emission is presented. A model for the active region that accounts for the observed radiation characteristics is described using the measured parameters of the bandlike emission and a model of the Jovian magnetic field. The active region is characterized not only by the fact that an upward-flowing electron stream is caused to radiate in this region, but the stream itself is broken into radiating electron bunches within the active region. Observed undulations of the emission band on the time-frequency plane are interpreted as motions of the active region along a flux tube. The instantaneous location of the active region along the flux tube shows a dependence on the density of the stream entering the active region. The mechanism responsible for density modulation of the stream appears to be common to both the bandlike and simple-S-burst emission types.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 29; Dec. 197
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  • 27
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    High resolution spectral analyses of the Jovian decametric radiation. I - Burst morphology and drift rates (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Morphological analyses of high-resolution spectral recordings of Jovian decametric radiation show a regime of phenomena not seen at lower resolutions. Observed emissions range from narrow-band (50 kHz) simple quasi-periodic bursts to wide-band emissions (extending over a 500-kHz passband) exhibiting complex structural detail. Assuming gyroemission from electrons in a dipole field for which the magnetic moment is 10 Gauss Jupiter-radius-cubed, drift-rate measurements of the bursts indicate that the source size is of the order of 600 km and its location is near 1.3 Jupiter radii at a colatitude of 27.3 deg. The measurements suggest that the emitting electrons belong to a population having a very specific equatorial pitch angle near 3.5 deg. This study concludes that it may be possible to verify gyroemission as the mechanism responsible for the decametric radiation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 29; Dec. 197
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  • 28
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    The occultation of Mariner 10 by Mercury (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Analysis of Mariner 10 dual-frequency radio-occultation recordings has yielded new information on the radius and atmosphere of Mercury. The ingress measurements, which were conducted near 1.1 deg north latitude and 67.4 deg east longitude on the night side of the planet, gave a value for the radius of 2439.5 + or - 1 km. Egress near 67.6 deg north latitude and 258.4 deg east longitude on the sunlit side yielded a radius of 2439.0 + or - 1 km. The atmospheric measurements showed the electron density to be less than 1000 per cu cm on both sides of the planet. From the latter result one may infer an upper limit to the dayside surface gas density of 1 million molecules per cu cm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 29; Dec. 197
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  • 29
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    Relation of a contracting earth to the apparent accelerations of the sun and moon (1976)
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    Publication Date: 2011-08-17
    Description: It has been concluded that the theoretical ratio of the apparent secular accelerations of the moon and the sun implied by tidal theory is far higher than the ratio of observed values. This paper shows that the discrepancy can be entirely removed within the range of uncertainty of the various quantities involved if terms making allowance for a secularly decreasing terrestrial moment of inertia are included in the dynamical equations for the apparent secular accelerations. Such a decrease has already been predicted on the basis of the phase-change hypothesis for the nature of earth's core. The development of this hypothesis is reviewed, the modified dynamical equations are derived, and values of tidal couples implied by existing observational data are examined. The numerically determined rate of decrease of earth's moment of inertia is found to be in close agreement with that predicted by the phase-change hypothesis. The results indicate that a diminishing gravitational constant is unlikely, that the moon would have been in close proximity to earth only 1 billion years ago, and that earth's rotation period at that time would have been about 5 hr.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: The Moon; 16; Dec. 197
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  • 30
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    Observational and theoretical temperatures for a total lunar eclipse (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Temperature profiles from seven regions of the moon were recorded during a total eclipse using an infrared radiometer and telescope. The eclipse was visible from beginning to end. Target areas chosen range from mare areas to mountainous highlands. Theoretical temperature curves were calculated using a thermophysical model in which the lunar material properties are variable. These curves are compared with the experimental data. A description of the instrumentation, observations, calibration, signal reduction, and the theoretical model is given. The results show excellent agreement between the observational and theoretical temperatures during the eclipse. The apparent differences between the observed and calculated temperatures during pre- and post-eclipse are minimal after directional radiation is taken into account.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: The Moon; 15; June-Jul
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    Floor-fractured lunar craters (1976)
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    Publication Date: 2011-08-17
    Description: Observational data concerning floor-fractured craters on the lunar near and far sides are examined, including the morphologic classification of the craters, their spatial and size distributions, and their floor, peak, and rim elevations relative to the maria. Six morphologic classes and two subclasses are delineated on the basis of fracture pattern, crater floor depth, and floor type. These data are used to reconstruct a history of crater modification which accounts for the large differences in affected crater size and age, the small peak-rim elevation differences, remnant central peaks within mare-flooded craters and ringed plains, ridged and flat-topped rim profiles of heavily modified craters and ringed plains, as well as the absence of positive gravity anomalies in most floor-fractured craters and some large mare-filled craters. The results indicate that: (1) impact craters became centers of intrusions and volcanism generally related to periods of basin inundation by mare basalts; (2) some light-plains units in the highlands may be due to both impact ejecta and extrusions of light-colored lava or ash; (3) floor-fractured craters may have become important volcanic vents that contributed to the inundation of the lunar surface by mare basalts; and (4) the lunar highlands probably did not fully escape the epochs of mare flooding.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: The Moon; 15; June-Jul
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    Field-aligned currents observed by the Ogo 5 and Triad satellites (1976)
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    Publication Date: 2011-08-17
    Description: The Triad (at a height of 800 km) and Ogo 5 (in the high altitude magnetosphere) magnetic field observations have shown the existence of a field-aligned current system consisting of currents flowing in the polar cap boundary layer and those flowing in another layer located equatorward of the former. In the polar cap boundary layer (identified as the high-latitude boundary of the plasma sheet in the nightside magnetosphere), the current flows into the ionosphere on the morning side and away from the ionosphere on the afternoon side. In the lower-latitude layer, the current directions are reversed. The current in the polar cap boundary layer is considered as the primary field-aligned current system.
    Keywords: GEOPHYSICS
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    The chemistry of planetary atmospheres (1976)
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    Publication Date: 2011-08-17
    Description: Present knowledge concerning the chemistry of planetary atmospheres is reviewed along with the theories which attempt to explain observational data. The known gross atmospheric compositions of the terrestrial and giant planets are listed, differences between the atmospheres of earth and Venus are discussed, and the atmospheres of the giant planets are described. The origin and evolution of the atmospheres of earth, Venus, Mars, Jupiter, Saturn, and Uranus are outlined, and chemical processes in the atmospheres are examined, particularly cloud formation. The question of organic synthesis and evolution in the reducing atmospheres of the giant planets is considered. It is noted that laboratory work on the individual chemical processes and reactions involved in the evolution of organic compounds in planetary atmospheres, comets, and interstellar space points to the inevitability of organic-compound synthesis in all these situations and to the pervasiveness of organic chemistry throughout the universe.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Chemical Education; 53; Apr. 197
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    Geomagnetic storm effects on the thermosphere and the ionosphere revealed by in situ measurements from OGO 6 (1976)
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    Publication Date: 2011-08-17
    Description: The temporal response of the densities of upper-atmospheric ion and neutral constituents to a particular geomagnetic storm is studied using simultaneous ion and neutral-composition data obtained by the OGO 6 satellite during consecutive orbits at altitudes greater than 400 km. The investigated constituents include H(+), O(+), N2, O, He, and H. Derivation of the H density is reviewed, and the main effects of the storm are discussed, particularly temporal and global variations in the densities. It is found that: (1) the H and He densities began to decrease near the time of sudden commencement, with the decrease amounting to more than 40% of the quiet-time densities during the maximum stage at high latitudes; (2) the O and N2 densities exhibited an overall increase which began later than the change in H and He densities; (3) the H(+) density decreased differently in two distinct regions separated near the low-latitude boundary of the light-ion trough; and (4) the O(+) density showed an increase during earlier stages of the storm and decreased only in the Northern Hemisphere during the recovery phase. Certain physical and chemical processes are suggested which play principal roles in the ionospheric response to the storm
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 24; Nov. 197
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  • 35
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    Mars dynamics, atmospheric and surface properties - Determination from Viking tracking data (1976)
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    Publication Date: 2011-08-17
    Description: Approximately three months of radio tracking data from the Viking landers have been analyzed to determine the lander locations, the orientation of the spin axis of Mars, and a first estimate from Viking data of the planet's spin rate. Preliminary results have also been obtained for atmospheric parameters and radii at occultation points and for properties of the surface in the vicinity of lander 1.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 194; Dec. 17
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    Viking magnetic properties investigation - Further results (1976)
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    Publication Date: 2011-08-17
    Description: The amounts of magnetic particles held on the reference test chart and backhoe magnets on lander 2 and lander 1 are comparable, indicating the presence of an estimated 3 to 7 percent by weight of relatively pure, strongly magnetic particles in the soil at the lander 2 sampling site. Preliminary spectrophotometric analysis of the material held on the backhoe magnets on lander 1 indicates that its reflectance characteristics are indistinguishable from material within a sampling trench with which it has been compared. The material on the RTC magnet shows a different spectrum, but it is suspected that the difference is the result of a reflectance contribution from the magnesium metal covering on the magnet. It is argued that the results indicate the presence, now or originally, of magnetite, which may be titaniferous.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 194; Dec. 17
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  • 37
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    Spiral structure as an explanation for the asymmetric brightness of Saturn's A ring (1976)
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    Publication Date: 2011-08-17
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 264; Nov. 25
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  • 38
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    Diffusive isothermal partitioning in a layered medium with geologic applications (1976)
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    Publication Date: 2011-08-17
    Description: The diffusive isothermal partitioning of solute in a layered two-phase material has been analyzed to help elucidate the phenomenon of solute partitioning in multiphase lunar and terrestrial materials and to estimate the cooling history of samples. After reviewing the physical chemistry of partitioning and the case of an infinite one-dimensional diffusion couple, we solve in analytic form the case of a finite one-dimensional couple. The solution can be used to estimate cooling histories or to interpret laboratory experiments on partitioning. A sample calculation is included.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Nov. 10
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  • 39
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    Tektites and their origin (1976)
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    Publication Date: 2011-08-17
    Description: Questions concerning the tektite distribution are examined, taking into account the Australasian strewn field, the Ivory Coast strewn field, the Moldavite strewn field, the North American strewn field, the Libyan desert glass, the Aouelloul crater glass, and amerikanites. Attention is given to the shapes of tektites, the internal structure of tektites, the physical properties of tektite glass, the chemical composition of tektites, isotopes, fission tracks, cosmic ray tracks, and arguments in favor and against the terrestrial origin of tektites. It is concluded that tektites cannot be terrestrial in origin. They are probably volcanic ejects, of geologically recent epochs, from one or a number of lunar volcanoes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 40
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    On the magnetic mirroring as the basic cause of parallel electric fields (1976)
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    Publication Date: 2011-08-17
    Description: Among the different proposed mechanisms for generating parallel electric fields, magnetic mirroring of charged particles seems to be the most plausible. In the present paper, it is suggested that magnetic mirroring is the basic cause of parallel electric fields in the magnetosphere and that the magnetic mirroring effect may be able to form the basis of an auroral theory that can remove a major portion of the ambiguity of observations. In the model proposed, the parallel electric field is due to a magnetic confinement of a negatively charged hot collision-free plasma. A transfer of electron gyroenergy into wave energy tends to weaken this confinement; if this energy transfer becomes too strong, the parallel potential gradient will break down. Hence, from this model, in contrast to certain other models of parallel electric fields, only a small fraction of the total auroral particle energy may be expected to be transformed into electromagnetic wave energy during the acceleration process.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Nov. 1
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  • 41
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    Viking to Mars - Profile of a space expedition (1976)
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    Publication Date: 2011-08-17
    Description: The Viking spacecraft, operations, and findings are reviewed and numerous pictures are presented in an attempt to capture the atmosphere of the Viking expedition. The details of the two Viking spacecraft, each consisting of an orbiter and lander combination launched a Titan III/Centaur are described and illustrated, along with the Viking ground-data and communications system. The principal conclusions of the Viking mission to date are: detection of nitrogen, argon, krypton, and xenon; determination of isotopic ratios of carbon, nitrogen, oxygen, and argon; uniform diurnal meteorological conditions; determination of major elemental abundances; complex surface chemistry; no ubiquitous organic material; 4 to 7% of the sampled surface material is magnetic; discovery of ancient extensive fluvial activity; north permanent polar cap made of water ice; and significant variations of the atmospheric water vapor, the summer hemisphere being much more humid than the winter hemisphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronautics and Aeronautics; 14; Nov. 197
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  • 42
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    An example of a thermally metamorphosed agglutinate (1976)
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    Publication Date: 2011-08-17
    Description: The nature and properties of lunar agglutinates in relation to the kind of metamorphism described by Albee et al. (1973) are briefly considered. The properties of the agglutinates are compared with those of a lunar metaclastic particle which is believed to be the product of the extreme thermal metamorphism of an agglutinate. The results of electronprobe microanalyses of selected agglutinitic glasses are presented in a table. Attention is also given to the bulk chemical composition of some noritic metaclastic rocks and several highland rock types.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics; 11; Sept. 30
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  • 43
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    Energetics of the midlatitude thermosphere (1976)
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    Publication Date: 2011-08-17
    Description: Thermospheric energetics is examined from the point of view of atomic and molecular processes which convert solar EUV radiative energy into kinetic energy of the ambient electron, ion, and neutral gases. The energy flow from photon to photoelectron-ion pair through energy loss and ion-molecule transfer to eventual electron-ion recombination is traced in detail. Upper and lower bounds are placed on the efficiency of conversion of radiative to thermal energy. Implications for the question of consistency of measured solar EUV fluxes and ionospheric models are discussed.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 38; Aug. 197
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  • 44
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    Dynamical effects in the distribution of helium in the thermosphere (1976)
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    Publication Date: 2011-08-17
    Description: The paper discusses some phenomena, mainly observed by satellites, which illustrate the use of helium as a tracer for studying the morphology and history of atmospheric responses to energy inputs of varying amplitudes and durations. The effects observed include (1) the annual north-south excursion of the sub-solar point producing the winter helium bulge, (2) the 24-hour diurnal variation, where the helium density peak is phase-shifted to the morning in the lower thermosphere, (3) high latitude magnetospheric heating of the thermosphere, with helium indicating regions of probable upwelling of the heated gas, and (4) gravity wave formation and propagation, with the attendant implications for transport of energy from one region of the atmosphere to another.
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 38; Aug. 197
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  • 45
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    Unlimbering Viking's scoop (1976)
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    Publication Date: 2011-08-17
    Description: A number of difficulties which were encountered in deploying the Viking 1 lander's surface-sampler arm are discussed. When the surface sampler jammed during its initial operation, the problem was studied with the aid of tests on a full-scale lander mock-up. It was found that the difficulty was caused by a boom latch pin which had failed to fall clear. The surface-sampler arm could subsequently be freed by modifying the original command sequence. Another difficulty could be overcome by a similar approach.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: IEEE Spectrum; 13; Oct. 197
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  • 46
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    A radar study of the backup Martian landing sites (1976)
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    Publication Date: 2011-08-17
    Description: The Goldstone radar system at DSS 14 was used to probe the Martian surface at 8495 MHz in a narrow strip between -6 deg and -2 deg latitude. The Viking C landing sites lie in this strip, and their altitudes, rms surface slope, and reflectivity are presented.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: The Deep Space Network; p 49-52
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  • 47
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    A geological basis for the exploration of the planets: Introduction (1976)
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    Publication Date: 2011-08-17
    Description: The geological aspects of solar-system exploration were considered by first showing how geologic data are related to space science in general, and, second, by discussing the approach used in planetary geology. The origin, evolution, and distribution of matter condensed in the form of planets, satellites, comets, and asteroids were studied. Terrestrial planets, comets, and asteroids, and the solid satellites of the outer planets are discussed. Jupiter and Saturn, in particular, have satellites of prime importance. Geophysics, geochemistry, geodesy, cartography, and other disciplines concerned with the solid planets were all included.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: A Geol. Basis for the Exploration of the Planets; p 1-12
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  • 48
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    Algorithms for computing the geopotential using a simple density layer (1976)
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    Publication Date: 2011-08-16
    Description: Several algorithms have been developed for computing the potential and attraction of a simple density layer. These are numerical cubature, Taylor series, and a mixed analytic and numerical integration using a singularity-matching technique. A computer program has been written to combine these techniques for computing the disturbing acceleration on an artificial earth satellite. A total of 1640 equal-area, constant surface density blocks on an oblate spheroid are used. The singularity-matching algorithm is used in the subsatellite region, Taylor series in the surrounding zone, and numerical cubature on the rest of the earth.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Sept. 10
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  • 49
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    Molecular oxygen abundances in the thermosphere from atmosphere Explorer-C ion composition measurements (1976)
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    Publication Date: 2011-08-16
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Sept. 1
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  • 50
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    Viking magnetic properties investigation - Preliminary results (1976)
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    Publication Date: 2011-08-16
    Description: Three permanent-magnet arrays are aboard the Viking lander. By sol 35, one array, fixed on a photometric reference test chart on top of the lander, has clearly attracted magnetic particles from airborne dust; two other magnet arrays, one strong and one weak, incorporated in the backhoe of the surface sampler, have both extracted considerable magnetic mineral from the surface as a result of nine insertions associated with sample acquisition. The loose Martian surface material around the landing site is judged to contain 3 to 7 per cent highly magnetic mineral which, pending spectrophotometric study, is thought to be mainly magnetite.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 194; Oct. 1
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  • 51
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    Search for the Viking 2 landing site (1976)
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    Publication Date: 2011-08-16
    Description: The search for the landing site of Viking 2 is reviewed, emphasizing the characteristics of the various candidate sites and reasons for rejecting unsuitable sites. It is shown that the B3 site in Utopia Planitia was selected because the B latitude band (40 to 50 deg N) was of the highest scientific interest, the site appeared to be smoothed by uniform mantling, and the additional data analysis and acquisition required to land at any other site could have resulted in a landing delay and significant additional operational complexity. It is tentatively concluded that the Viking 2 lander rests in a deflation hollow.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 194; Oct. 1
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  • 52
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    V.L.F. emission from ring-current electrons (1976)
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    Publication Date: 2011-08-16
    Description: Characteristics of VLF emissions detected by satellite in association with enhancements of ring-current electrons during magnetic storms and substorms are described along with the associated enhancements in electron intensities and the anisotropies of the ring-current electron distribution. It is shown that the emissions are observed only when the satellite is outside the plasmasphere, that the beginning of the emissions coincides with the satellite's encounter with the large electron fluxes in that region, and that the increase in electron intensities associated with the observed emissions is limited only to low-energy electrons. The frequency distributions of emissions with peak frequencies above and below half the electron gyrofrequency at the equator is analyzed. The bimodal frequency distribution of the equatorial whistler-mode emissions is explained in terms of different production regions for emissions at frequencies above and below half the equatorial electron gyrofrequency.
    Keywords: GEOPHYSICS
    Type: Nature; 263; Sept. 2
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  • 53
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    Lidar measurement of stratospheric dust from St. Augustine Volcano (1976)
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    Publication Date: 2011-08-17
    Description: The detection of a stratospheric dust layer of probable volcanic origin over Hampton, Va., on the evening of Jan. 28, 1976, with a 20-inch lidar system is reported. A digitized cathode-ray-tube trace of a return signal from altitudes of 12 to 24 km on January 28 is provided, and it is shown that 38% of the return was due to stratospheric aerosol. Noting that measurements on January 22 and February 2 showed no traces of this stratospheric dust layer, trajectories of dust-laden air parcels are followed from initiation at 0000 GMT on January 24 at the St. Augustine Volcano on Augustine Island, Alaska (59 deg N, 153 deg W). Analysis of the trajectories indicates that dust injected into the stratosphere at 59 deg N, 153 deg W could have been transported to Virginia in about 4 days. It is concluded that if the St. Augustine Volcano was the source of the dust, at least 23 deg of meridional transport from polar latitudes was observed.
    Keywords: GEOPHYSICS
    Type: American Meteorological Society; vol. 57
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  • 54
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    Mapping of lunar surface from side-looking orbital radar images (1976)
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    Publication Date: 2011-08-17
    Description: Side-looking spacecraft radar imagery has thus far been produced only from an orbit around the moon. This was a part of the Apollo Lunar Sounder Experiment (ALSE) of the Apollo 17 mission in December 1972. This paper reports results of a radargrammetric evaluation of overlapping Apollo 17 synthetic-aperture radar images (wavelength 2 m). The potential to map from single images and to reconstruct three-dimensional stereoscopic models is studied. The relative height accuracy achieved is about + or - 100 m and is thus competitive with that obtained with the vidicon camera presently used for planetary exploration.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: The Moon; 15; June-Jul
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  • 55
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    Composition effects in thermospheric gravity waves (1976)
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    Publication Date: 2011-08-17
    Description: Classical linearized gravity wave theory is employed to derive relationships between amplitude ratios and phase angles of atmospheric constituents undergoing acoustic-gravity wave oscillations. These results are compared with recently reported Atmospheric Explorer-C satellite data. Calculated amplitude and phase characteristics, for a large class of pure internal gravity wave oscillations, are in accord with the AE-C satellite measurements.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 3; Dec. 197
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  • 56
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    Martian north pole summer temperatures - Dirty water ice (1976)
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    Publication Date: 2011-08-17
    Description: Broadband thermal and reflectance observations of the Martian north polar region in late summer yield temperatures for the residual polar cap near 205 K with albedos near 43 percent. The residual cap and several outlying smaller deposits are water ice with included dirt; there is no evidence for any permanent carbon dioxide polar cap.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 194; Dec. 17
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  • 57
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    The Viking seismic experiment (1976)
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    Publication Date: 2011-08-17
    Description: A three-axis short-period seismometer is now operating on Mars in the Utopia Planitia region. The noise background correlates well with wind gusts. Although no quakes have been detected in the first 60 days of observation, it is premature to draw any conclusions about the seismicity of Mars. The instrument is expected to return data for at least 2 years.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 194; Dec. 17
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  • 58
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    Discovering Jupiter. I (1976)
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    Publication Date: 2011-08-17
    Description: The current state of knowledge regarding the planet Jupiter is examined, taking into account data obtained with the aid of the spacecraft Pioneer 11. A description is given of Jupiter's weather. The Pioneer 11 pictures show that the planet's banded cloud structure breaks down above 50 deg latitude, and turns into relatively small, mostly circular cloud features in the polar regions. Attention is given to Jupiter's heat balance, aspects of internal heat flow, questions of atmospheric circulation, the turbulence in Jupiter's atmosphere, the effects of coriolis forces, Jupiter's upper atmosphere, the Great Red Spot, and the Jovian magnetosphere and radiation belts.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Spaceflight; 18; Dec. 197
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  • 59
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    OH emission intensity measurements during the 1969 NASA Airborne Auroral Expedition (1976)
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    Publication Date: 2011-08-17
    Description: Absolute intensity measurements of the (8, 6) OH band obtained during 10 flights of the December 1969 NASA Auroral Airborne Expedition are presented. Nightglow intensities higher by a factor of 2 than the usual values are recorded during flights 8, 14, and 15. The OH variations are compared with the evolution of the green line and O2(1 Delta g) emissions measured by other experimenters on board the aircraft. Before sunrise the twilight variations of OH down to a solar depression angle of 5 deg show a rapid decrease. A theoretical prediction of the OH, O I 5577 A, and O2(1 Delta g) emissions is evaluated by means of an extensive time-dependent oxygen-hydrogen model of the 25- to 150-km region. Twilight decrease of the OH emission is interpreted in terms of mesospheric ozone photodissociation. Nighttime variations of the emissions may be reproduced if modifications of the dynamic regime are introduced into the model.
    Keywords: GEOPHYSICS
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  • 60
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    Topside optical view of the dayside cleft aurora (1976)
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    Publication Date: 2011-08-17
    Description: Photometers on the ISIS-II spacecraft provide a view of the atomic oxygen 5577-A and 6300-A emissions and the N2(+) 3914-A emission detected as dayside aurora in the magnetospheric cleft region. The 6300-A emission forms a continuous and permanent band across the noon sector, at about 78 deg invariant latitude, with a defined region of maximum intensity that is never less than 2 kR (uncorrected for albedo) and is centered near magnetic noon. There are significant differences in the intensity patterns on either side of noon and their responses to geomagnetic activity. Discrete 3914-A auroral forms appear within this region at preferred locations that cannot be precisely specified but which tend to the poleward edge of the 6300-A emission in the evening and the equatorward edge in the morning, where the difference between the two emissions is greatest. It is concluded that the discrete auroras observed by all-sky cameras in the day sector follow the 6300-A emission through the cleft region, though a definite cleft boundary is not defined.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 24; Oct. 197
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    Stratigraphy and structural geology (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The immediate goal of stratigraphy and structural geology is to reduce the enormous complexity of a planetary surface to comprehensible proportions by dividing the near-surface rocks into units and mapping their distribution and attitude.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: A Geol. Basis for the Exploration of the Planets; p 13-32
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    Geophysics (1976)
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    Description: Four areas of investigation, each dealing with the measurement of a particular geophysical property, are discussed. These properties are the gravity field, seismicity, magnetism, and heat flow. All are strongly affected by conditions, past or present, in the planetary interior; their measurement is the primary source of information about planetary interiors.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: A Geol. Basis for the Exploration of the Planets; p 63-74
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    Geodesy and cartography (1976)
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    Publication Date: 2011-08-17
    Description: Geodesy and cartography provide the geometric framework on which most investigations of planets are ultimately based. Specifically, the products of these disciplines provide information on the following: (1) the dimensions of the planet, (2) a mathematical figure of reference for the planet, (3) the orientation of the body in the celestial coordinate system, (4) the rotational constants, (5) a defined system of coordinates, (6) the location of surface points in the defined coordinate system, (7) the gravity potential expressed in spherical harmonics, (8) topographic and thematic maps, and (9) surface albedo in various wavelengths. The relevance of geodesy and cartography to planetology is discussed, and the requirements of data acquisition and mission design are considered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA Ames Res. Center A Geol. Basis for the Exploration of the Planets; p 75-84
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    Geochemistry (1976)
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    Publication Date: 2011-08-17
    Description: The most effective strategy for the geochemical study of a planet is to proceed systematically with the mineralogical and chemical characterization of its materials in accordance with geologically determined priorities. It is insufficient merely to analyze chemically the surface rocks. To appreciate the meaning of a chemical analysis, some assessment must be made of the geologic history of the sample - what its source and mode of origin are and what processes have operated upon the sample to cause chemical fractionation. Determination of mineralogy, texture, lithology, and other properties of the rock that might be relevant to origin is, therefore, necessary.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA Ames Res. Center A Geol. Basis for the Exploration of the Planets; p 33-62
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    Photometry of Venus from Mariner 10 (1976)
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    Publication Date: 2011-08-16
    Description: Photometry of the upper atmosphere of Venus from Mariner 10 on February 5, 1974 is discussed with respect to in-flight verification of camera linearity, shading, and absolute photometric calibration. Among photometric results are the following: (1) temporal brightness variations were observed in the UV greater than 10% over a few hours due to the rapid rotation of the upper atmosphere, (2) the observed terminator was 4 degrees past the geometric terminator due to detached haze layers at altitudes around 85 km, (3) there were no indications of cloud top elevation variations greater than a few hunderd meters, and (4) in the UV, the bright and dark regions both had low albedos in all scales, showing that the UV absorber is not confined just to dark markings.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 33; Sept
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    Jupiter at five microns (1976)
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    Publication Date: 2011-08-16
    Description: The paper summarizes the information obtained in recent maps of Jupiter at 5 microns, a frequency at which the gases in Jupiter have a relatively low opacity. It is highly possible that 5-micron hot spots are breaks in the cloud deck permitting observation of the hot lower layers of the atmosphere. Many 5-micron sources coincide with blue visual features, but the details of the correspondence need further investigation. Large-scale changes in the appearance of the planet occur at 5 microns on time scales of months; these changes are sufficiently dramatic to produce detectable variations in the whole-disk flux from the planet. Their correspondence to large-scale changes in visual features is not yet determined.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    Effect of nearby supernova explosions on atmospheric ozone (1976)
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    Publication Date: 2011-08-16
    Description: An investigation has been conducted of the probable effects of a nearby supernova event on the ozone layer of the earth. It is found that the ozone depletion, although smaller than that estimated by Ruderman (1974), is still significant, and could, as a result of cosmic rays, extend over periods of time from 1000 to 10,000 years. However, the probability of the occurrence of such an event within the past 100 million years appears to be low. The calculated ozone depletion seems to be the major effect of a supernova on a earth-like planet at a distance in the range from 5 to 10 pc.
    Keywords: GEOPHYSICS
    Type: Nature; 263; Sept. 30
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    Evolution of the ionosphere (1976)
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    Publication Date: 2011-08-16
    Description: Studies were made of the electron density profiles at various stages of atmospheric evolution, with the assumption that the atmospheric composition has changed due to the gradual increase of oxygen while the nitrogen level has remained constant. The result of model calculations indicates that when the oxygen content is less than about 1% of the present earth's atmosphere level, the major ions in the F2 region will change from O(+) to N(+). The maximum number density of N(+) ions reaches approximately 10 million per cu cm because of the absence of a rapid loss mechanism for N(+). The height of the N(+) ion density peak is much lower than the height of the F2 layer peak of the current ionosphere.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Sept. 1
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    Ion chemistry of N2/+/ and the solar ultraviolet flux in the thermosphere (1976)
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    Publication Date: 2011-08-16
    Description: We have analyzed daytime composition measurements in the thermosphere from Atmosphere Explorer-C by use of a theory of the ion chemistry. Predicted and measured N2(+) densities are compared to infer global variation of the solar ionizing flux. Results indicate that the solar flux of Hinteregger measured on Atmosphere Explorer-C provides an adequate basis for the calculation of solar ultraviolet photoionization rates. The role of metastable species is examined, and theoretical O+(2D) densities are presented.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Aug. 1
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    Bow shock and magnetosheath waves at Mercury (1976)
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    Publication Date: 2011-08-16
    Description: Mariner 10 measurements at the Mercury bow shock provide examples where the magnetic field is approximately parallel or perpendicular to the bow shock normal. Upstream of a broad irregular parallel shock, left-hand circularly polarized waves are observed which cut off very sharply at about 4 Hz. Upstream of a perpendicular shock, righ-hand circularly polarized waves are observed which persist up to the Nyquist frequency of 12 Hz. Determination of the wave propagation vector as a function of frequency helps to identify conclusively the waves as whistler mode waves propagating from the shock. The magnetosheath downstream of the parallel shock is disturbed more than that downstream of the perpendicular shock, particularly below 1 Hz. In the latter case, regular left-hand-polarized waves observed slightly above the proton gyrofrequency are identified as ion cyclotron waves with wavelengths of about 300 km which have been Doppler shifted up to their observed frequency.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 81; Aug. 1
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    Mars - Wind friction speeds for particle movement (1976)
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    Publication Date: 2011-08-16
    Description: Wind friction threshold speeds for particle movement were determined in a low pressure boundary layer wind tunnel at an atmospheric pressure of 5.3 mb. The results imply that for comparable pressures on Mars, the minimum wind friction threshold speed is about 2.5 m/sec, which would require free-stream winds of 50 to 135 m/sec, depending on the character of the surface and the atmospheric conditions. The corresponding wind speeds at the height of the Viking lander meteorology instrument would be about a factor of two less than the free-stream wind speed. The particle size most easily moved by winds on Mars is about 160 microns; particles both larger and smaller than this (at least down to about 5 microns) require stronger winds to initiate movement.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 3; Aug. 197
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  • 72
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    The interpretation of ionospheric radio drift measurements. IX - Direct comparisons between field-aligned ion drifts by incoherent scatter and Kinesonde measurements (1976)
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    Publication Date: 2011-08-16
    Keywords: GEOPHYSICS
    Type: Journal of Atmospheric and Terrestrial Physics; 38; July 197
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    The first Viking mission to Mars (1976)
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    Publication Date: 2011-08-16
    Description: The paper outlines the major goals and present achievements of the Viking 1 mission to Mars. The construction and instrumentation of the orbiter and lander are described. The criteria used to select the optimum landing site are discussed together with orbit adjustments and the landing process. Special attention is given to constraints on surface coverage and observation conditions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 193; Aug. 27
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    A new estimate of volatile outgassing on Mars (1976)
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    Publication Date: 2011-08-16
    Description: The presence of 28% argon on Mars, as calculated by Levine and Riegler (1974) and indirectly inferred from Soviet Mars-6 lander data, has important implications for the outgassing history of H2O, CO2, and N2 on Mars. Even if the terrestrial volatile outgassing ratio is only approximately valid for Mars, then large quantities of H2O (of the order of 100,000 g/sq cm), about 10,000 g/sq cm of CO2 (about 1000 times more CO2 than found at present in the Martian atmosphere), and some 450 g/sq cm of N2 may have outgassed over the history of Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 28; June 197
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    On the calculation of cosmic-ray exposure ages of stone meteorites (1976)
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    Publication Date: 2011-08-16
    Description: Abundances of cosmic ray-produced noble gases and Al-26, including some new measurements, have been compiled for some 23 stone meteorites with exposure ages less than 3,000,000 yr. Concentrations of cosmogenic He, Ne, and Ar in these meteorites have been corrected for differences in target element abundances by normalization to L-chondrite chemistry. Combined noble gas measurements in depth samples of the Keyes and St. Severin chondrites are utilized to derive equations for normalizing the production rates of cosmogenic He-3, Ne-21, and Ar-38 in chondrites to an adopted 'average' shielding. The measured unsaturated AL-26 concentrations and the calculated equilibrium Al-26 for these meteorites are combined to estimate exposure ages. These exposure ages are statistically compared with chemistry- and shielding-corrected concentrations of cosmogenic He, Ne, and Ar to derive absolute production rates for these nuclides, which are found to be roughly 25% higher than production rates used in the past. From these production rates and relative chemical correction factors, production rates for other classes of stone meteorites are derived.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 40; July 197
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    Representation of magnetic fields in space (1976)
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    Publication Date: 2011-08-16
    Description: Several mathematical methods which are available for the description of magnetic fields in space are reviewed. Examples of the application of such methods are given, with particular emphasis on work related to the geomagnetic field, and their individual properties and associated problems are described. The methods are grouped in five main classes: (1) methods based on the current density, (2) methods using the scalar magnetic potential, (3) toroidal and poloidal components of the field and spherical vector harmonics, (4) Euler potentials, and (5) local expansions of the field near a given reference point. Special attention is devoted to models of the magnetosphere, to the uniqueness of the scalar potential as derived from observed data, and to the L parameter.
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics and Space Physics; 14; May 1976
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    Possibility of detecting magnetospheric radio bursts from Uranus and Neptune (1976)
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    Publication Date: 2011-08-16
    Description: The intensity of magnetospheric radio bursts (MRBs) is scaled to solar-wind input into planetary magnetospheres and the frequency of emission is scaled to polar surface magnetic-field strength in order to estimate the possibility of detecting MRBs from Uranus and Neptune. A scaling law is derived which relates the ratio of power radiated in MRBs to the solar-wind input for earth, Jupiter, and Saturn. Power-flux spectra of MRBs from these three planets are plotted, and it is shown that Jupiter and Saturn may radiate 1% to 5% of the solar-wind energy input into their magnetospheres. The properties of MRBs from Uranus and Neptune are estimated by assuming a conversion efficiency of 1% to 5%, a bandwidth of half the peak frequency, and conformity of Uranus' and Neptune's dipole moments with the magnetic Bode's law. Based on the results, it is suggested that detection of MRBs from these two planets may be a reasonable cruise-mode radio-astronomy objective on future missions to the outer solar system.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 261; May 27
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    Stratospheric ozone as viewed from the Chappuis band (1976)
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    Publication Date: 2011-08-16
    Description: Total stratospheric ozone values above high-altitude stations in southern California from 1912 to 1950 and northern Chile from 1918 to 1948 are determined using data obtained by the Smithsonian Astrophysical Observatory, including transmission measurements made in the Chappuis band (0.5 to 0.7 micron). The results show that at both sites, total ozone amounts commonly exhibit variations of as much as 20% to 30% on time scales ranging from months to decades. Consideration of the amount of incident solar energy absorbed by the Chappuis band suggests that ozone acts as a shutter on the incoming solar radiation and provides a trigger mechanism between solar activity and climatic change.
    Keywords: GEOPHYSICS
    Type: Nature; 261; May 27
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    Aliphatic amines in the Murchison meteorite (1976)
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    Publication Date: 2011-08-16
    Description: The paper reports on the determination of aliphatic amines in water extracts of the Murchison meteorite. The amines were analyzed by gas chromatography both as the free amines and as 2,4-dinitrophenyl (DNP) derivatives. The results give evidence for the presence of all of the possible primary aliphatic monoamines (eight) with fewer than five carbon atoms. Two of the seven possible secondary or tertiary aliphatic monoamines were identified. The identified primary amines total 80 nmol per g meteorite, and seem to be chemically or physically trapped in the meteorite. Similarities between the water-extractable amines and amino acids suggest that (1) a simple carbon compound, methane, for example, is the precursor of meteorite amines and amino acids, and (2) both amines and amino acids are extracted from the meteorite both as such and in the form of acid-hydrolyzable derivative or precursor species.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 261; May 13
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    Polarization of the reflected light of asteroid 433 Eros (1976)
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    Publication Date: 2011-08-16
    Description: Linear polarizations measured for asteroid 433 Eros at various wavelengths and at solar phase angles ranging from 9 to 53 deg are presented. The polarization results are entirely typical of main-belt S asteroids, and indicate a dusty surface with geometric albedo 0.20. The derived effective diameter at photometric maximum is 21 km. Eros is quite uniform polarimetrically; no dependence on aspect is detected, and the polarization is shown to be constant during a single rotation with a precision of one part in forty.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 28; May 1976
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    Lightcurves and the axis of rotation of 433 Eros (1976)
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    Publication Date: 2011-08-16
    Description: Ten lightcurves and UBV photometry of 433 Eros were obtained between August 1972 and May 1975. The absolute magnitude of the lightcurve maximum is 10.75 and the phase coefficient is 0.025 mag/deg. There may be a small difference in B-V color between the northern and southern hemispheres. The pole of the axis of rotation is directed toward 16 deg, ecliptic longitude and 12 deg ecliptic latitude, respectively, and the rotation is direct with a sidereal period of 5 hr 16 min 13.4 sec. The dimensions derived from the polarimetric albedo and the lightcurve amplitudes are 12 km by 12 km by 31 km for a smooth cylinder with hemispherical ends.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 28; May 1976
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    Investigation of a new stony meteorite from Mauritania with some additional data on its find site - Aouelloul crater (1976)
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    Publication Date: 2011-08-16
    Description: The Zerga meteorite, a small stony meteorite found at Aouelloul crater, is a fragment of a larger mass with a pre-atmospheric radius between 20 and 125 cm. The meteorite is a typical amphoterite, with monomict brecchia which has undergone at least one recrystallization episode. The terrestrial age of the meteorite is roughly an order of magnitude smaller than the K-Ar gas-retention age (about 3.1 million years) of the glassy impactite found at the crater, which is close to the age of the nearby Tenoumer crater (about 2.5 million years). The similar ages of the two craters, together with their alignment with the Temimichat Ghallaman crater, suggest a simultaneous triple impact following the disruption of a large meteorite moving on a very shallow earth trajectory. The unusually shallow original depths inferred for two of the craters may be explained by low impact angles.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 30; 2, Ma; May 1976
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    Physical properties of asteroid 433 Eros (1976)
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    Publication Date: 2011-08-16
    Description: Newly available photometric, polarimetric, spectroscopic, thermal-radiometric, radar, and occultation results are synthesized in order to derive a coherent model for Eros. The geometric albedo is 0.19 plus or minus 0.01 at the visual wavelength, and the overall dimensions are approximately 13 by 15 by 36 km. The rotation is about the short axis, in the direct sense, with a sidereal period of 5 hr 16 min 13.4 sec. The pole of rotation lies within a few degrees of ecliptic coordinates 16 deg longitude and beta = +11 deg latitude. Eros is uniformly coated with a particulate surface layer several millimeters thick. It has an iron-bearing silicate composition, similar to that of a minority of main-belt asteroids, and probably identifiable with H-type ordinary chondrites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 28; May 1976
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    Nitric oxide formation by meteoroids in the upper atmosphere (1976)
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    Publication Date: 2011-08-16
    Description: The process of nitric oxide formation during atmospheric entry of meteoroids is analyzed theoretically. An ablating meteoroid is assumed to be a point source in a uniform flow with a continuum regime evolving in its wake. The amount of nitric oxide produced by high-temperature reactions of air in the continuum regime is calculated by numerical integration of chemical-rate equations. The results, when summed over the observed mass, velocity, and entry-angle distributions of meteoroids, provide annual global production rates of nitric oxide as a function of altitude. The peak production of nitric oxide is found to occur at altitudes between 90 and 100 km, the total annual rate being about 40 million kg. The present results suggest that the large concentration of nitric oxide observed below 95 km could be attributed to meteoroids instead of photodissociation of nitrogen.
    Keywords: GEOPHYSICS
    Type: Atmospheric Environment; 10; 7, 19; 1976
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    Martian atmospheric lee waves (1976)
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    Publication Date: 2011-08-16
    Description: Areas of extensive mountain lee wave phenomenon in the northern midlatitudes during late winter are observed in Mariner 9 television pictures of Mars. The lee wave pattern is due to the discrete spectrum of waves generated by a crater ridge in an airstream. The cloud patterns resulting from the waves generated by the flow across a mountain or crater are dependent on the velocity profile of the airstream and the vertical stability of the atmosphere. A two-layer velocity model of the airstream is used in calculations based on the theory of mountain lee waves. Regardless of the simple model used for the airstream, the calculations appear to be capable of reproducing the observed wave patterns. The many observations of lee waves suggest that the near surface wind speeds as implied by the lower stream velocities do not greatly exceed, and most of the time are less than, 40 m/sec in the northern midlatitudes during late winter except possibly on a very localized scale. Results are in agreement with circulation models, especially the Leovy and Mintz (1969) two-layer numerical model.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 27; Apr. 197
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    Thermal emission spectra of 24 asteroids and the Galilean satellites (1976)
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    Publication Date: 2011-08-16
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 27; Apr. 197
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    Field-aligned fluxes in the geomagnetic equator (1976)
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    Publication Date: 2011-08-16
    Description: During 12 electron injection events observed by Explorer 45 during the December, 1971, and February, 1972, in magnetic storms it was found that the lowest observable pitch angle particles (down to 7 degrees in one case) arrived first. Pitch angle dispersion and shell-splitting effects are shown to be inadequate explanations for most of these pitch angle distributions. It is suggested that parallel electric fields may be supplying 1- to 5-keV electrons to the magnetosphere from the ionosphere. Various models of parallel electric fields are discussed.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Apr. 1
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    Radiometric diameter and albedo of the remarkable asteroid 1976AA (1976)
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    Publication Date: 2011-08-16
    Description: It is pointed out that the minor planet 1976AA discovered on January 7, 1976, is the first asteroid found with an orbital period of less than a year. A description is given of a study in which the diameter and the albedo of the asteroid were determined with the aid of infrared radiometry. It is concluded that on the basis of its albedo 1976AA can probably be classed with the stony group of asteroids.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 260; Apr. 22
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    New theory of the Great Red Spot from solitary waves in the Jovian atmosphere (1976)
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    Publication Date: 2011-08-16
    Description: It is shown that many characteristics of the Great Red Spot (GRS) and numerous other features that have been observed on Jupiter can be explained by solitary waves on a horizontally sheared zonal flow in a rotating, stratified atmosphere. Streamline patterns for waves corresponding to combined depression-elevation solitary waves (D-E solitrons) show a strong resemblence to the flow around the GRS. The morphology and flow pattern of the South Tropical Disturbance indicate that it was a D solitron. Numerous spot-like features situated in regions between cloud bands where horizontal shear forces might be expected have the morphology of E solitrons. Restrictions placed on the atmospheric parameters by the model are consistent with available models and observations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 260; Apr. 8
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    Cyclotron side-band emissions from ring-current electrons (1976)
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    Publication Date: 2011-08-16
    Description: The paper examines temporal variations in electron energy spectra and pitch-angle distributions during a VLF-emission event observed by Explorer 45 in the main phase of a magnetic storm. It is noted that the observed event occurred outside the plasmasphere on the night side of the magnetosphere and that the dusk-side plasmapause had a double structure during the event. It is found that the VLF emissions consisted of two frequency bands, corresponding to the whistler and electrostatic modes, and that there was a sharp band of 'missing emissions' along frequencies equal to half the equatorial electron gyrofrequency. A peculiar pitch-angle distribution for high-energy electrons (50 to 350 keV) is noted. It is concluded that the VLF-producing particles were enhanced low-energy (about 5 keV) ring-current electrons which penetrated into the night side of the magnetosphere from the magnetotail plasma sheet and which drifted eastward after encountering the steep gradient of the geomagnetic field.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 24; Apr. 197
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  • 91
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    Deuteron whistler and trans-equatorial propagation of the ion cyclotron whistler (1976)
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    Publication Date: 2011-08-16
    Description: The paper investigates two unusual types of ion cyclotron whistlers that were found in the low-latitude topside ionosphere by analyzing ISIS VLF electric-field data received at Kashima, Japan. One type is characterized by an asymptotic frequency equal to one half the local proton gyrofrequency; the asymptotic frequency of the other type corresponds to the minimum proton gyrofrequency along the geomagnetic field line passing through the satellite. The observations are compared with theoretical spectrograms of the ion cyclotron whistlers computed for appropriate model distributions of electrons and ions in the topside ionosphere. It is found that the whistlers with the asymptotic frequency of one half the local proton gyrofrequency are deuteron whistlers and that the other whistlers are due to the transequatorial propagation of proton or deuteron whistlers originating in the southern hemisphere.
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science; 24; Apr. 197
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  • 92
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    Minor planets and related objects. XIX - Shape and pole orientation of /39/ Laetitia (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results are reported for analyses of UBV photoelectric photometric data and light curves of the asteroid Laetitia. The pole orientation is determined using a technique for reducing the scatter in the magnitude-phase relation. No significant variations in color are found over the surface, and the light curves are found to indicate topographic elements (peaks, scarps, or depressions) approximately 10 km in radius. It is shown that the light-curve amplitudes as well as the wide scatter in observed magnitude and phase relation can be explained by a triaxial ellipsoidal figure with a dimensional ratio of about 15:9:5. It is concluded that the size, shape, and composition of this asteroid are highly suggestive of a major collisional fragment from a substantially more massive differentiated parent body.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal; 81; Jan. 197
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  • 93
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    Diurnal tide in the Martian atmosphere (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Classical atmospheric tidal theory is extended to include the effects of large-amplitude planetary-scale variations of the terrain height. Utilizing simple models of the thermotidal forcing, the resulting technique is used to compute the diurnal tide in both the dust-free and the dust-laden Martian atmosphere. The main effect of the Martian variable terrain is to drive topographic tidal modes which can propagate vertically and to excite the possibly resonant diurnal Kelvin mode. The resulting surface wind can exceed 20 m/sec and may determine the preferred location for the initiation of global dust storms. In the middle Martian atmosphere (30-80 km) static and shear instabilities embedded within the tidal fields will generate extensive, though variable, regions of turbulence. Vertical mixing by this turbulence and transport by the tide itself may help to stabilize the middle Martian atmosphere against photolysis.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 33; Feb. 197
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  • 94
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    A parameterization for the absorption of solar radiation by water vapor in the earth's atmosphere (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A parameterization for the absorption of solar radiation as a function of the amount of water vapor in the earth's atmosphere is obtained. Absorption computations are based on the Goody band model and the near-infrared absorption band data of Ludwig et al. A two-parameter Curtis-Godson approximation is used to treat the inhomogeneous atmosphere. Heating rates based on a frequently used one-parameter pressure-scaling approximation are also discussed and compared with the present parameterization.
    Keywords: GEOPHYSICS
    Type: Journal of Applied Meteorology; 15; Jan. 197
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  • 95
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    Composition waves in the thermosphere (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Neutral-composition waves excited by auroral heat sources are investigated. For horizontal wavelengths of the order of 1000 km, it is concluded that diffusion processes (1) play a significant role such that deviations from diffusive equilibrium prevail for He throughout the thermosphere; (2) produce phase differences of about 220 deg (or -140 deg) between He and N2, and (3) account for He amplitudes comparable to those of N2. These results basically explain recent AE-C satellite measurements which have revealed an anticorrelation between the heavier and lighter constituents of the thermosphere. The calculations also indicate that temperature and N2 concentration are generally out of phase by about 100 deg.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Feb. 1
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  • 96
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    Apollo 16 far ultraviolet imagery of the polar auroras, tropical airglow belts, and general airglow (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Far-ultraviolet imagery of the earth in the wavelength ranges from 1050 to 1600 A and from 1250 to 1600 A was obtained from the lunar surface during the Apollo 16 mission on Apr. 21, 1972. The images have an angular resolution of about 2 arcmin (230-km linear resolution) and have been quantitatively analyzed to obtain absolute intensities and spatial distributions of the polar auroras (both wavelength ranges), the day and night airglow, and tropical airglow belts (1250-A to 1600-A wavelength range). The observations are consistent with previous results obtained from the OGO-4 spacecraft, but they have also provided details on the spatial distributions of the various emissions over an entire hemisphere at a single time. A general night airglow, at least in the Northern Hemisphere, is indicated.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Feb. 1
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  • 97
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    New vistas in planetary radio astronomy (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Recent progress in planetary radio astronomy is reviewed, where the most significant advances have come from spacecraft observations. The low-frequency radio spectra of the earth, Jupiter, and Saturn are compared, and the striking similarity in shapes is noted. New radio data are examined which provide a way to compare the magnetic field strengths of the planets. More detailed information on the radio structures of Jupiter and Saturn, and possibly on Uranus, is expected from the 1977 Mariner Jupiter-Saturn mission.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Sky and Telescope; 51; Mar. 197
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  • 98
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    Perturbation theory in thermosphere dynamics (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: It is shown that density and pressure throughout the thermosphere can be adequately described in a logarithmic expansion that provides a sound basis for the application of perturbation theory. This expansion eliminates most of the important nonlinearities associated with density variations. On the basis of this expansion, the validity of perturbation theory can be extended to cover a large variety of atmospheric conditions in which the relative temperature amplitude is less than 0.5 and wind velocities are significantly less than the speed of sound.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Mar. 1
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  • 99
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    Wind-enhanced escape with application to terrestrial helium (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: We derive a simple expression for the escape flux which takes into account horizontal winds at the exobase. The escape flux is shown to increase with the wind velocity and becomes much larger than the Jeans escape flux for velocities approaching the thermal velocity. This model is applied to terrestrial He-4, where we determine the conditions required for wind-enhanced escape to contribute to the overall He-4 budget. For completeness, we also derive an expression for the escape flux when only a vertical wind is present at the exobase.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 81; Mar. 1
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  • 100
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    Early lunar magnetism (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A new method (Shaw, 1974) for investigating paleointensity (the ancient magnetic field) was applied to three subsamples of a single, 1-m homogeneous clast from a recrystallized boulder of lunar breccia. Several dating methods established 4 billion years as the age of boulder assembly. Results indicate that the strength of the ambient magnetic field at the Taurus-Littrow region of the moon was about 0.4 oersted at 4 billion years ago. Values as high as 1.2 oersted have been reported (Collison et al., 1973). The required fields are approximately 10,000 times greater than present interplanetary or solar flare fields. It is suggested that this large field could have arisen from a pre-main sequence T-Tauri sun.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 260; Mar. 18
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