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  • LUNAR AND PLANETARY EXPLORATION  (552)
  • 1980-1984  (552)
  • 1925-1929
  • 1983  (552)
  • 1
    Publication Date: 2013-08-31
    Description: The discovery circumstances are analyzed for all Earth-approaching asteroids detected in the last twenty-four years. In particular, topocentric angular velocities, opposition distance, geocentric and heliocentric distances, phase angle, and lunar phase at discover were calculated in an effort to separate any selection effects between chance and purposeful (i.e., as the result of a systematic search) discoveries. Another motivation was the possibility of discerning useful clues how to search more efficiently for such objects. There are 60 minor planets in the sample. The principal result is that the discovery of Earth-approaching asteroids is dominated by serendipity. Therefore, searching for them at the current relatively bright limits at less than a very high rate seems pointless.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.26:174327 , NASA-CR-174327
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  • 2
    Publication Date: 2013-08-31
    Description: A bow wave was previously observed in the solar wind upstream of each of the first six planets. The observed properties of these bow waves and the associated plasma flows are outlined, and those features identified that can be described by a continuum magnetohydrodynamic flow theory. An account of the fundamental concepts and current status of the magnetohydrodynamic and gas dynamic theories for solar wind flow past planetary bodies is provided. This includes a critical examination of: (1) the fundamental assumptions of the theories; (2) the various simplifying approximations introduced to obtain tractable mathematical problems; (3) the limitations they impose on the results; and (4) the relationship between the results of the simpler gas dynamic-frozen field theory and the more accurate but less completely worked out magnetohydrodynamic theory. Representative results of the various theories are presented and compared.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-174135 , NAS 1.26:174135
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  • 3
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    In:  CASI
    Publication Date: 2013-08-31
    Description: The 4.8 micron flux from the Galilean satellite Io was shown to fluctuate with an amplitude of approximately 10 percent on time scales of every 28 seconds, 40 minutes, night-to-night, and perhaps year-to-year. Such behavior was found to be the result of random fluctuations for which the mean square fluctuation varies inversely with frequency for constant bandwidth measurement. The theory developed for thermionic emission from barium oxide cathodes in vacuum tubes might be applicable to this situation. If so, the fluctuations in the flux from Io's volcanoes may be caused by diffusion of hot convective cells onto the surface of Io. Long term fluctuations may furnish a means by which the Io volcanism can shut down and conserve energy. Thus the discrepancy that exists between measurements of the current heat flow from Io and calculations of tidal dissipation may be resolved. Tests for rapid flickering at 10 microns showed no fluctuations greater than one percent. This agrees with the prediction of the flow model theory in which the 10 microns volcanic thermal emission arises from cooling of old flows.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-173447 , NAS 1.26:173447
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  • 4
    Publication Date: 2013-08-31
    Description: The low energy plasma electron environment within Saturn's magnetosphere was surveyed by the Plasma Science Experiment (PLS) during the Voyager encounters with Saturn. Over the full energy range of the PLS instrument (10 eV to 6 keV) the electron distribution functions are clearly non-Maxwellian in character; they are composed of a cold (thermal) component with Maxwellian shape and a hot (suprathermal) non-Maxwellian component. A large scale positive radial gradient in electron temperature is observed, increasing from less than 1 eV in the inner magnetosphere to as high as 800 eV in the outer magnetosphere. Three fundamentally different plasma regimes were identified from the measurements: (1) the hot outer magnetosphere, (2) the extended plasma sheet, and (3) the inner plasma torus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85086 , NAS 1.15:85086
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  • 5
    Publication Date: 2013-08-31
    Description: The results of an experimental comparison between palagonites and a smectite (montmorillonite) in the simulation of the Viking Biology Labeled Release (LR) experiment and conclusions regarding their suitability as MarSAMs are reproved. It was found that palagonites do not cause formate decomposition and C-14 release in their natural form or after acidification and thus cannot be a completely satisfactory analog to the Mars soil studied by Viking.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-84361 , A-9320 , NAS 1.15:84361
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  • 6
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    In:  CASI
    Publication Date: 2013-08-31
    Description: The data collection and the interpretation with respect to the mineralogy of meteoritic and terrestrial samples are summarized. The key conclusion is that the Moon underwent a series of melting episodes with complex crystal-liquid differentiation. It was not possible to determine whether the Moon melted completely or only partially. The stage is now set for a systematical geochemical and geophysical survey of the Moon. Emphasis was moved to meteorites in order to sort out their interrelationships from the viewpoint of mineral chemistry. Several parent bodies are needed for the achondrites with different chemical properties. Exploration of Mars is required to test ideas based on the possible assignment of shergottites, nakhlites and chassignite to this planet. Early rocks on the Earth have properties consistent with a heavy bombardment and strong volcanic activity prior to 4 billion years ago.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-170345 , NAS 1.26:170345
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  • 7
    Publication Date: 2013-08-31
    Description: The radicals and ions observed in comets result from photodissociation and photoionization of molecules. According to current models, a comet is composed chiefly of a large, solid nucelus of frozen gases (parent molecules) such as H2O, HCN, and NH3. It is believed comets were formed at the same time and in the same region of space as the major planets and that their chemical composition is the same as that of the early solar system. As the comet nears the Sun, the surface heats up, liberating the frozen gases as well as dust particles. Solar radiation photodissociates the parent molecules into fragments that are observed by resonance fluorescence. Both polyatomic molecules, present in the interstellar medium, and cometary radicals were observed. Using laboratory photo-dissociation data and computer models, astronomers are attempting to identify the parent molecules that account for all observed radicals and ions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.26:170215 , NASA-CR-170215
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  • 8
    Publication Date: 2013-08-31
    Description: Disk average brightness temperatures of Mercury were obtained using a 4.6 m radio telescopes. The data was searched for periodicities which correlate with phase angle, hermocentric longitude and beat frequencies produced by modulations of various celestial mechanical parameters. Spectral line observations were made of Venus with the NRAO 11 m radio telescope. The total CO content and the CO vertical profile, and their variability were observed. Large scale thermophysical properties of the surface of Mars were studied.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-169867 , NAS 1.26:169867
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  • 9
    Publication Date: 2013-08-31
    Description: The rate constant is measured over the temperature interval 218-456 K using the technique of flash photolysis-laser-induced fluorescence. NH2 radicals are produced by the flash photolysis of ammonia highly diluted in argon, and the decay of fluorescent NH2 photons is measured by multiscaling techniques. For each of the five temperatures employed in the study, the results are shown to be independent of variations in PH3 concentration, total pressure (argon), and flash intensity. It is found that the rate constant results are best represented for T between 218 and 456 K by the expression k = (1.52 + or - 0.16) x 10 to the -12th exp(-928 + or - 56/T) cu cm per molecule per sec; the error quoted is 1 standard deviation. This is the first determination of the rate constant for the reaction NH2 + PH3. The data are compared with an estimate made in order to explain results of the radiolysis of NH3-PH3 mixtures. The Arrhenius parameters determined here for NH2 + PH3 are then constrasted with those for the corresponding reactions of H and OH with PH3.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.15:85063 , NASA-TM-85063
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  • 10
    Publication Date: 2013-08-31
    Description: When high resolution measurements of the phase variation of the lunar disk center brightness temperature revealed that in situ regolith electrical losses were larger than those measured on returned samples by a factor of 1.5 to 2.0 at centimeter wavelengths, the need for a refinement of the regolith model to include realistic treatment of scattering effects was identified. Two distinct scattering regimes are considered: vertial variations in dielectric constant and volume scattering due to subsurface rock fragments. Models of lunar regolith energy transport processes are now at the state for which a maximum scientific return could be realized from a lunar orbiter microwave mapping experiment. A detailed analysis, including the effects of scattering produced a set of nominal brightness temperature spectra for lunar equatorial regions, which can be used for mapping as a calibration reference for mapping variations in mineralogy and heat flow.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-174577 , SAI-1-141-00-0374-00 , NAS 1.26:174577
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  • 11
    Publication Date: 2013-08-31
    Description: A review is provided of current concepts concerning the formation of the Saturn system and the subsequent history of the planet, its satellites, and rings. Emphasis is placed upon numerical models of Saturn's evolution and interior models of its satellites. Alternative theories are presented and assessed for the origins of the Saturn system, the rings of Saturn, and the atmosphere of Titan.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.15:85847 , A-9485 , NASA-TM-85847
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  • 12
    Publication Date: 2013-08-31
    Description: Similarities between the Saturnian and terrestrial outer magnetosphere are examined. Saturn, like Earth, has a fully developed magnetic tail, 80 to 100 RS in diameter. One major difference between the two outer magnetospheres is the hydrogen and nitrogen torus produced by Titan. This plasma is, in general, convected in the corotation direction at nearly the rigid corotation speed. Energies of magnetospheric particles extend to above 500 keV. In contrast, interplanetary protons and ions above 2 MeV have free access to the outer magnetosphere to distances well below the Stormer cutoff. This access presumably occurs through the magnetotail. In addition to the H+, H2+, and H3+ ions primarily of local origin, energetic He, C, N, and O ions are found with solar composition. Their flux can be substantially enhanced over that of interplanetary ions at energies of 0.2 to 0.4 MeV/nuc.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85105 , NAS 1.15:85105
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  • 13
    Publication Date: 2013-08-31
    Description: The possibility of detecting IR molecular line emission from cometary parent molecules is explored. Due to the non-LTE conditions in the inner coma and the large amount of near IR solar flux, IR fluorescence will be a significant source of cometary emission and, in fact, will dominate the grain radiation in a sufficiently high resolution instrument. The detection of this line emission will be difficult due to absorption in the terrestrial atmosphere, but it appears possible to measure cometary H2O emission from airplane altitudes. As IR molecular line emission represents one of the few promising methods of detecting cometary parent molecules directly, further research on this problem should be vigorously pursued.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85067 , NAS 1.15:85067
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  • 14
    Publication Date: 2013-08-31
    Description: During the outbound leg of its passage through the Jovian magnetosphere in the Voyager 2 spacecraft observed 50 traversals of the magnetotail current sheet during a 10 day period at distances between 30 and 130 R sub j. Analysis of these observations shown that the Jovian tail sheet tends to lie approximately parallel to the ecliptic plane and to oscillate about the tail axis with the 10 hour planetary rotation period. The magnetic structure near and within the current sheet was variable with time and distance from Jupiter, but generally corresponded to one of the following: (1) simple rotation of field across the sheet, with an approximately southward direction in the sheet (generally northward beyond a distance from Jupiter of approximately 84 R sub j; (2) field having a southward component in a broad region near the sheet, but northward in a restricted region at the sheet itself; or (3) a clear bipolar variation of the sheet normal field component as the sheet was crossed (i.e., the field became northward and then southward, or vice versa, in crossing the sheet).
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85014 , NAS 1.15:85014
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  • 15
    Publication Date: 2013-08-31
    Description: This collection of Viking Orbiter photomosaics is designed to facilitate identification and location of the various pictures with respect to the surface of Mars. Only a representative set of the nearly 50,000 images taken by the two Viking Orbiters, and computer-processed prior to December 1978, are contained in the mosaics and in the picture listings.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.61:1093 , NASA-RP-1093
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  • 16
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    In:  CASI
    Publication Date: 2013-08-31
    Description: New areas of meteorite concentration were discovered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85261 , NAS 1.15:85261
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  • 17
    Publication Date: 2013-08-31
    Description: It is shown that if Io-injected plasma is lost via a planetary wind-fixed Birkeland current system may result. This is due to the fact that the azimuthal centrifugal current flows across a density gradient produced by the loss of plasma through the planetary wind in the tail. The divergent centrifugal current is connected to field-aligned Birkeland currents which flow into the ionosphere at dawn and out of it at dusk. The closure currents in the ionosphere require a dawn to dusk electric field which at the orbit of Io is estimated to have a strength of 0.2 mV/m. However, the values of crucial parameters are not well known and the field at Io's orbit may well be significantly larger. Independent estimates derived from the local time asymmetry of the torus UV emission indicate a field of 1.5 mV/m.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-166463 , U-OF-IOWA-83-4 , NAS 1.26:166463
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  • 18
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Research on this task consisted of the development and initial application of photometric and photoclinometric models using interactive computer image processing and graphics. New programs were developed to compute viewing and illumination angles for every picture element in a Voyager image using C-matrices and final Voyager ephemerides. These values were then used to transform each pixel to an illumination-oriented coordinate system. An iterative integration routine permits slope displacements to be computed from brightness variations, and correlated in the cross-sun direction, resulting in two dimensional topographic data. Figure 1 shows a 'wire-mesh' view of an impact crater on Ganymede, shown with a 10-fold vertical exaggeration. The crater, about 20 km in diameter, has a central mound and raised interior floor suggestive of viscous relaxation and rebound of the crater's topography. In addition to photoclinometry, the computer models that have been developed permit an examination on non-topographically-derived variations in surface brightness.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.26:174574 , NASA-CR-174574
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  • 19
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Meteorites from the 1981 and 1982 Antarctic collection are listed showing classification, weight, degree of weathering, degree of fractionation, % Fa, and % Fs. Physical and petrigraphic characteristics are described for 23 samples from the Allan Hills, Thiel Mountains, the Pecora Escarpment, and the Elephant Moraine locations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85408 , NAS 1.15:85408
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  • 20
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Topics discussed include: (1) Martian global tectonics; (2) the origin and evolution of a circular and an irregular lunar mare; (3) stratigraphy of Oceanus Procellarum basalts: sources and styles of emplacement; (4) the tectonic evolution of the Oceanus Procellarum Basin; (5) charting the Southern Seas: the evolution of the Lunar Mare Australe; (6) the stratigraphy of Mare Imbrium; and (7) Storms and rains: a comparison of the Lunar Mare Imbrium and Oceanus Procellarum.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.15:85630 , NASA-TM-85630
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  • 21
    Publication Date: 2013-08-31
    Description: Observations of large amplitude magnetohydrodynamics (MHD) waves upstream of Jupiter's bow shock are analyzed. The waves are found to be right circularly polarized in the solar wind frame which suggests that they are propagating in the fast magnetosonic mode. A complete spectral and minimum variance eigenvalue analysis of the data was performed. The power spectrum of the magnetic fluctuations contains several peaks. The fluctuations at 2.3 mHz have a direction of minimum variance along the direction of the average magnetic field. The direction of minimum variance of these fluctuations lies at approximately 40 deg. to the magnetic field and is parallel to the radial direction. We argue that these fluctuations are waves excited by protons reflected off the Jovian bow shock. The inferred speed of the reflected protons is about two times the solar wind speed in the plasma rest frame. A linear instability analysis is presented which suggests an explanation for many of the observed features of the observations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85005 , NAS 1.15:85005
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  • 22
    Publication Date: 2013-08-31
    Description: The infrared spectra of H2O ice VII and D2O ice VII were studied and techniques were developed for measuring adiabats of phases of NH3-H2O to 5 GPa. A mixing system for pressurized fluids was constructed in which liquid solutions of definite compositions can be prepared and loaded reliably into diamond cells in a project which seeks to determine the properties and boundaries of several high pressure phases of the H2-He-H2O-NH3-CH4 system. These data are needed to constrain theoretical models of the interiors of the major planets.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.26:170303 , NASA-CR-170303
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  • 23
    Publication Date: 2013-08-31
    Description: Important properties of the recently discovered Saturn electrostatic discharges are entirely consistent with an extended lightning storm system in Saturn's atmosphere. The presently favored B-ring location is ruled out.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-84966 , NAS 1.15:84966 , REPT-695
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  • 24
    Publication Date: 2013-08-31
    Description: The refractive index of planetary atmospheres at microwave frequencies is discussed. Physical models proposed for the refractive irregularities in the ionosphere and neutral atmosphere serve to characterize the atmospheric scattering structures, and are used subsequently to compute theoretical scintillation spectra for comparison with the Voyager occultation measurements. A technique for systematically analyzing and interpreting the signal fluctuations observed during planetary occultations is presented and applied to process the dual-wavelength data from the Voyager radio occultations by Jupiter, Saturn, and Titan. Results concerning the plasma irregularities in the upper ionospheres of Jupiter and Saturn are reported. The measured orientation of the irregularities is used to infer the magnetic field direction at several locations in the ionospheres of these two planets; the occultation measurements conflict with the predictions of Jovian magnetic field models, but generally confirm current models of Saturn's field. Wave parameters, including the vertical fluxes of energy and momentum, are estimated, and the source of the internal gravity waves discovered in Titan's upper atmosphere is considered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: SU-SR-D208-1983-1 , NAS 1.26:175554 , NASA-CR-175554
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  • 25
    Publication Date: 2013-08-31
    Description: The Plasma Science Experiment (PLS) on the Voyager spacecraft provide data on the plasma ions and electrons in the interplanetary medium and the magnetospheres of the giant planets Jupiter and Saturn. A description of the analysis used to obtain electron parameters (density, temperature, etc.) from the plasma science experiment PLS electron measurements which cover the energy range from 10 eV to 5950 eV is presented. The electron sensor (D cup) and its transmission characteristics are described. A derivation of the fundamental analytical expression of the reduced distribution function F(e) is given. The electron distribution function F(e), used in the moment integrations, can be derived from F(e). Positive ions produce a correction current (ion feedthrough) to the measured electron current, which can be important to the measurements of the suprathermal electron component. In the case of Saturn, this correction current, which can either add to or subtract from the measured electron current, is less than 20% of the measured signal at all times. Comments about the corrections introduced by spacecraft charging to the Saturn encounter data, which can be important in regions of high density and shadow when the spacecraft can become negatively charged are introduced.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85037 , NAS 1.15:85037
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  • 26
    Publication Date: 2013-08-31
    Description: Progress is reported in the development of the P-T-X diagram for 0 less than or = X less than or = 0.50 and in the development of techniques for measuring adiabats of phases of NH3-H2O. The partial phase diagram is presented, investigations of the compositions of ammonia ices are described, and methods for obtaining the infrared spectra of ices are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.26:173278 , NASA-CR-173278
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  • 27
    Publication Date: 2013-08-31
    Description: Graphical data necessary for the analysis of planetary exploration missions to Saturn are presented. Positional and geometric information spanning the time period from 1985 through 2020 is provided. The data and their usage are explained.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL-PUB-82-44-VOL-5 , NASA-CR-173195 , NAS 1.26:173195
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  • 28
    Publication Date: 2013-08-31
    Description: Graphical data necessary for the analysis of planetary exploration missions to Jupiter are presented. Positional and geometric information spanning the time period from 1985 through 2020 is provided. The data and their usage are explained.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL-PUB-82-44-VOL-4 , NAS 1.26:173194 , NASA-CR-173194
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  • 29
    Publication Date: 2013-08-31
    Description: Graphical data necessary for the analysis of planetary exploration missions to Venus are presented. Positional and geometric information spanning the time period from 1988 through 2020 is provided. The data and the usage are explained.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: JPL-PUB-82-44-VOL-2 , NASA-CR-173192 , NAS 1.26:173192
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  • 30
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Surface properties derived from IRTM data are correlated to derive interpretations of the surface geology on Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-173197 , NAS 1.26:173197
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  • 31
    Publication Date: 2013-08-31
    Description: Dark haloed craters and regions of the Moon which were sites of ancient volcanism were remotely sensed as well as KREEP deposits in the Inbrium region. The relationship between geology and geochemistry in the Undarum/Spumans region was also examined. Results are summarized for observations of the Reiner Gamma formation, studies of impact cratering mechanics and processes, spectral variations of asteroidal surfaces, albedo and color variations on Ganymede, and studies of lunar impact structures.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-173216 , NAS 1.26:173216
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  • 32
    Publication Date: 2013-08-31
    Description: During the two Voyager encounters with Saturn, radio bursts were detected which appear to have originated from atmospheric lightning storms. Although these bursts generally extended over frequencies from as low as 100 kHz to the upper detection limit of the instrument, 40 MHz, they often exhibited a sharp but variable low frequency cutoff below which bursts were not detected. We interpret the variable low-frequency extent of these bursts to be due to the reflection of the radio waves as they propagate through an ionosphere which varies with local time. We obtain estimates of electron densities at a variety of latitude and local time locations. These compare well with the dawn and dusk densitis measured by the Pioneer 11 Voyager Radio Science investigations, and with model predictions for dayside densities. However, we infer a two-order-of-magnitude diurnal variation of electron density, which had not been anticipated by theoretical models of Saturn's ionosphere, and an equally dramatic extinction of ionospheric electron density by Saturn's rings.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85121 , NAS 1.15:85121
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  • 33
    Publication Date: 2013-08-31
    Description: Graphical data necessary for the analysis of planetary exploration missions to Mars are presented. Positional and geometric information spanning the time period from 1990 through 2020 is provided. The data and usage are explained.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.26:173193 , JPL-PUB-82-44-VOL-3 , NASA-CR-173193
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  • 34
    Publication Date: 2013-08-31
    Description: An analysis of the electron absorption signature observed by the Cosmic Ray System (CRS) on Voyage 2 near the orbit of Mimas is presented. We find that these observations cannot be explained as the absorption signature of Mimas. Combing Pioneer 11 and Voyager 2 measurements of the electron flux at Mimas's orbit (L=3.1), we find an electron spectrum where most of the flux above approx 100 keV is concentrated near 1 to 3 MeV. The expected Mimas absorption signature is calculated from this spectrum neglecting radial diffusion. A lower limit on the diffusion coefficient for MeV electrons is obtained. With a diffusion coefficient this large, both the Voyager 2 and the Pioneer 11 small-scale electron absorption signature observations in Mimas's orbit are enigmatic. Thus we refer to the mechanism for producing these signatures as the Mimas ghost. A cloud of material in orbit with Mimas may account for the observed electron signature if the cloud is at least 1% opaque to electrons across a region extending over a few hundred kilometers.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: ATR-83(9990)-3 , NASA-CR-174596 , NAS 1.26:174596
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  • 35
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    In:  CASI
    Publication Date: 2013-08-31
    Description: The planets and their satellites were observed at high resolution at millimeter wavelengths with the Hat Creek Interferometer. Instrumentation and observations are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-173042 , NAS 1.26:173042
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  • 36
    Publication Date: 2013-08-31
    Description: Magnetospheric radio emissions, Saturn electrostatic discharges, inferred source locations, and emission theories are addressed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85023 , NAS 1.15:85023
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  • 37
    Publication Date: 2013-08-31
    Description: In 1979-1981, the three USA spacecraft Pioneer 11 and Voyagers 1 and 2 discovered and explored the magnetosphere of Saturn to the limited extent possible on flyby trajectories. Considerable variation in the locations of the bow shock (BS) and magnetopause (MP) surfaces were observed in association with variable solar wind conditions and, during the Voyager 2 encounter, possible immersion in Jupiter's distant magnetic tail. The limited number of BS and MP crossings were concentrated near the subsolar region and the dawn terminator, and that fact, together with the temporal variability, makes it difficult to assess the three dimensional shape of the sunward magnetospheric boundary. The combined BS and MP crossing positions from the three spacecraft yield an average BS-to-MP stagnation point distance ratio of 1.29 +/- 0.10. This is near the 1.33 value for the Earth's magnetosphere, implying a similar sunward shape at Saturn. Study of the structure and dynamical behavior of the outer magnetosphere, both in the sunward hemisphere and the magnetotail region using combined plasma and magnetic field data, suggest that Saturn's magnetosphere is more similar to that of Earth than that of Jupiter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85065 , NAS 1.15:85065
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  • 38
    Publication Date: 2013-08-31
    Description: Formation mechanisms of nonequilibrium 10 micron CO2 molecule radiation and the possible existence of a natural laser effect in the upper atmospheres of Venus and Mars are theoretically studied. An analysis is made of the excitation process of CO2 molecule vibrational-band levels (with natural isotropic content) induced by direct solar radiation in bands 10.6, 9.4, 4.3, 2.7 and 2.0 microns. The model of partial vibrational-band temperatures was used in the case. The problem of IR radiation transfer in vibrational-rotational bands was solved in the radiation escape approximation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: PREPRINT-207 , NAS 1.15:85057 , NASA-TM-85057
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  • 39
    Publication Date: 2013-08-31
    Description: A model of Saturn's magnetospheric magnetic field is obtained from the Voyager 1 and 2 observations. A representation consisting of the Z sub 3 zonal harmonic model of Saturn's planetary magnetic field together with an explicit model of Saturn's planetary magnetic field and a model of the equatorial ring current fits the observations well within r 20 R sub S, with the exception of data obtained during the Voyager 2 inbound pass.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.15:85055 , NASA-TM-85055
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  • 40
    Publication Date: 2013-08-31
    Description: The NLTE radiative transfer problem is solved to obtain the 00 deg 1 vibrational state population. This model successfully reproduces the existing center-to-limb observations, although higher spatial resolution observations are needed for a definitive test. The model also predicts total fluxes which are close to the observed values. The strength of the emission is predicted to be closely related to the instantaneous near-IR solar heating rate.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.15:85045 , NASA-TM-85045
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  • 41
    Publication Date: 2013-08-31
    Description: Observations of the total flux and center to limb dependence of the nonthermal emission occurring in the cores of the 9.4 and 10.4 micrometers CO2 bands on Mars are compared to a theoretical model based on this mechanism. The model successfully reproduces the observed center to limb dependence of this emission, to within the limits imposed by the spatial resolution of the observations of Mars and Venus. The observed flux from Mars agrees closely with the prediction of the model; the flux observed from Venus is 74% of the flux predicted by the model. This emission is used to obtain the kinetic temperatures of the Martian and Venusian mesospheres. For Mars near 70 km altitude, a rotational temperature analysis using five lines gives T = 135 + or - 20 K. The frequency width of the emission is also analyzed to derive a temperature of 126 + or - 6 K. In the case of the Venusian mesosphere near 109 km, the frequency width of the emission gives T = 204 + or - 10 K.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.15:85044 , NASA-TM-85044
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  • 42
    Publication Date: 2013-08-31
    Description: Results are presented of a series of numerical experiments in which an upper ocean model is driven by surface heat fluxes and stress fields derived from the FGGE SOP-1 GLAS analysis/forecast system (Halem, et al., 1982). The model results show that most changes in the mixed layer height and horizontal velocity occurs in the first days. On the other hand, changes in the temperature field take a longer time to develop. In the most realistic case (real initial conditions, instantaneous forcing fields from the atmospheric analysis), the resulting changes in temperature were larger than observed and the correlation between observed and predicted changes was poor. The deficiency in the forecast of SST changes may be due to several factors: lack of sufficient ocean resolution, improper initialization, lack of feedback between the ocean and the atmosphere and the absence of transports by the strong boundary currents, and perhaps unrealistic surface fluxes of heat and momentum. Unless these problems are alleviated it is not reasonable to perform coupled atmospheric ocean forecasts.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-85038 , NAS 1.15:85038
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  • 43
    Publication Date: 2013-08-31
    Description: Analyses of data from Voyager 2 experiments provide evidence for, and characteristics of, a Jovian magnetotail extending at least to 9,000 Jovian radii from the planet. During approximately (25 day) periodic sightings of the tail, the magnetic field tended to point radially towards or away from Jupiter, indicating preservation to large distances of the bipolar, lobe like structure observed near the planet. This periodicity, along with various properties of the solar wind at this time, indicates that the tail is apparently influenced by recurrent solar wind features. Anomalous magnetic fields, not aligned with the nominal tail axis, also exist within the tail, especially in the low density, central (core) region, indicating some complexity of internal structure.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: MIT-CSR-P-83-1 , NAS 1.15:85054 , NASA-TM-85054
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  • 44
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    Publication Date: 2013-08-31
    Description: The light produced by the atoms and ions of Jupiter's luminous, heavy particle environment was studied. High resolution spectrophotometry is discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NAS 1.26:169860 , NASA-CR-169860
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  • 45
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    In:  CASI
    Publication Date: 2018-06-06
    Description: Venus before Pioneer, the Pioneer Venus mission, Pioneer Venus spacecraft, scientific investigation, mission to Venus scientific results, and results of Soviet studies of Venus are addressed. A chronology of exploration of Venus from Earth before the Pioneer Venus mission and Venus nomenclature and mythology are provided.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-SP-461 , NAS 1.21:461
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  • 46
    Publication Date: 2017-10-02
    Description: Solar-wind plasma data from the ISEE-3 and Helios 2 spacecraft were examined in order to explain a uniquely rapid 10 deg turning of the plasma tail of comet Bradfield 1979l on 1980 February 6. An earlier study conducted before the availability of in situ solar-wind data (Brandt et al., 1980) suggested that the tail position angle change occurred in response to a solar-wind velocity shear across the polar component changed by approximately 50 km/s. The present contribution confirms this result and further suggests that the comet-tail activity was caused by non-corotating, disturbed plasma flows probably associated with an Importance 1B solar flare.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: CONF-821159-6 , NASA-TM-85617 , NAS 1.15:85617 , DE83-011332 , LA-UR-83-1023 , Solar Wind 5 proceedings
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  • 47
    Publication Date: 2016-06-07
    Description: Approximately 46% of the lunar sample (10084,151), 125.42 mg, was solubilized in 680 ml 0.01 M salicylic acid. Atomic absorption spectroscopic analysis of the solubilized lunar sample showed the following amount of metal ions: Ca, 3.1; Mg, 4.0; K, 0.09; Na, 0.67; Fe, 7.3; Mn, 1.6; Cu, Ni, Cr, less than 0.1 each. All are in ppm. Salicylic acid used to solubilize the lunar sample was highly inhibitory to the growth of mixed soil microbes. However, the mineral part of the lunar extract stimulated the growth. For optimal growth of the soil microbes the following nutrients must be added to the moon extract; sources of carbon, nitrogen, sulfur, phosphorus, and magnesium in addition to water.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA. Johnson (Lyndon B.) Space Center The 1983 NASA/ASEE Summer Faculty Fellowship Research Program Research Reports; NASA. Johnson (Lynd
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  • 48
    Publication Date: 2016-03-09
    Description: Various topics in the areas of planetary composition and differentiation, planetary surfaces and interiors, lunar rocks, lunar regoliths, and meteorites and tektites are discussed and some experimental studies are presented. Individual subjects addressed include: Stillwater anorthosites, origin of palimpsests and anomalous pit craters on Ganymede and Callisto, the chemistry of the Apollo 11 Highland component, and many others.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: (ISSN 0148-0227)
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  • 49
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    Publication Date: 2016-03-09
    Description: The present conference concerning the study of Venus discusses stellar magnitude and albedo data for the planet, radio astronomical studies, results of the Venera 13 and 14 missions, Venus optical properties, topography, surface properties and tectonic evolution, the tectonic implications of the interior of Venus, the thermal structure, photochemistry, composition, general circulation, and electrical activity of the Venus atmosphere, and the thermal balance of the lower, middle and upper atmoshere of Venus. Also discussed are the observation and interpretation of the Venus ionosphere, its model calculation, the interaction of the solar wind with the ionosphere of Venus in light of flow field models, the origin and evolution of the Venus atmosphere, and the problem posed by rare gases in the atmosphere of Venus.
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  • 50
    Publication Date: 2011-08-19
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: National Institute of Polar Research, Memoirs, Special Issue (ISSN 0386-0744); 30, D
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  • 51
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    Publication Date: 2011-08-19
    Description: Analysis of current experimental results concerned with the kinetic constraints on chondrule formation showed that the major physical properties of chondrules could have been produced by direct condensation of metastable liquid silicates droplets from a hot gas in the primordial nebula. It is argued that such a condensation process would have to be followed by crystallization, accretion, and partial comminution of the droplets. The chemical mechanisms driving this process are described, including: nucleation constraints on comminution and crystallization; slow transformations and chemical reactions in chain silicates; and the slow diffusion of ions. It is shown that the physical mechanisms for chondrule condensation are applicable to a broad spectrum of chondrule sources.
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  • 52
    Publication Date: 2011-08-19
    Description: The effectiveness of dynamic recrystallization experiments to reconstruct chondrule textures is evaluated. Consideration is given to the results of several experimental simulations of the silicate spheres of pyroxene-olivine chondrules, Si-rich chondrules, chondrites, droplet chondrules, and microporphyritic chondrules. It is shown that many chondrules have textures consistent with heating to 1400-1600 C, and cooling rates from a few degrees to several thousands of degrees per hour. It is shown that this physical constraint effectively rules out mechanisms for chondrule genesis which do not require instantaneous or very slow cooling. Analysis of the available textural, chemical, and isotopic data suggest that chondrules were generated from primordial particles, and several mechanisms might have assisted in chondrule heating as they settled down toward the median plane of the nebula. The most important of these mechanisms appear to be friction with the nebular gas and heating by flares.
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  • 53
    Publication Date: 2011-08-19
    Description: Sr and Nd isotopic analysis of five Yamato polymict eucrites indicate that these samples formed at about 4.6 Ga ago with initial Sr and Nd ratios essentially the same as the analyzed non-Antarctic eucrites. The Yamato eucrites have Sr, Sm, and Nd concentrations that consistently lie among the highest found in eucritic samples. This characteristic identifies these Yamato samples as a closely related group. Comparisons between these Yamato samples and other Antarctic polymict eucrites clearly estabishes that they all share some characteristic trace element features. Comparisons of Antarctic polymict eucrites with non-Antarctic ordinary eucrites reveal consistent differences. The most obvious is an enrichment of Rb in the polymict eucrites. These comparisons suggest that the Antarctic polymict eucrites belong to a single large family of material that is itself fairly diverse and distinct from the non-Antarctic eucrites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: National Institute of Polar Research, Memoirs, Special Issue (ISSN 0386-0744); 30, D
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  • 54
    Publication Date: 2011-08-19
    Description: Xe-129 - Xe-128 and Ar-40 - Ar-39 analyses has been performed on two Antarctic enstatite meteorites, the chondrite Y-691 and the aubrite (enstatite achondrite) ALH-78113. Both meteorites have complex Ar-40 - Ar-39 release patterns to which no unambiguous age assignment is possible. Both give apparently satisfactory Xe-129 - Xe-128 correlations corresponding to unusual ages. The I-Xe age of the chondrite Y-691 is 16 Ma after Bjurbole, not unusual for chondrites in general but 10 Ma later than previously known ages for enstatite chondrites. The I-Xe age of the aubrite ALH-78113 is 210 Ma after Bjurbole, the latest age (rather than a limit) so far observed by the I-Xe technique, but this age assignment must be considered tentative because of the possibility that it is significantly influenced by terrestrial I contamination.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: National Institute of Polar Research, Memoirs, Special Issue (ISSN 0386-0744); 30, D; 275-291
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  • 55
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    Publication Date: 2011-08-19
    Description: The carbon-14 terrestrial ages of four Yamato meteorites are measured and compared with the C-14 terrestrial ages of eighteen meteorites from Victoria Land. The youngest Yamato meteorite, Y-75102, is 4300 + or - 1000 yr; the oldest, Y-74459, is 24,000 + or - 2000 yr. The Yamato meteorite site is collecting recent falls, less than 25,000 yr, at a more rapid rate than the Victoria Land sites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: National Institute of Polar Research, Memoirs, Special Issue (ISSN 0386-0744); 30, D
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  • 56
    Publication Date: 2011-08-19
    Description: Mineralogical examination of thin sections of non-Antarctic and Antarctic HED (howardite, eucrite, diogenite) achondrites indicates that they contain a variety of lithic components. Some of these components occur both as monomict meteorites and as clasts in polymict meteorites, whereas others occur only as clasts in some polymict breccias. The components may be classified by the degree of homogenization of the pyroxene present. In order of increasing homogeneity these are: (1) Y-75011-type basalt clasts; (2) Pasamonte; (3) Y-790266-type clasts; (4) Stannern and Nuevo Laredo; (5) Juvinas and Haraiya; and (6) Ibitira. Type 1 has been least modified by post-igneous thermal annealing, while types 5 and 6 were thoroughly metamorphosed. Three types of cumulate eucrites are recognized and are believed to represent (a) cumulates from thick lava flows or layered intrusions; (b) lunar highlands type crust; and (c) differentiation products of diogenitic magmas.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: National Institute of Polar Research, Memoirs, Special Issue (ISSN 0386-0744); 30, D; 181-205
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  • 57
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    Publication Date: 2011-08-19
    Description: Chondrules are igneous-textured, millimeter-sized, spherical to irregularly-shaped silicate objects which constitute the major component of most chondrites. There is agreement that chondrules were once molten. Models for chondrule origin can be divided into two categories. One involves a 'planetary' setting, which envisages chondrules forming on the surfaces of parent bodies. Melting mechanisms include impact and volcanism. The other category is concerned with a cosmic setting in the solar nebula, prior to nebula formation. Aspects regarding the impact on planetary surfaces are considered, taking into account chondrule abundances, the abundancy of agglutinates on the moon, comminution, hypervelocity impact pits, questions of age, and chondrule compositions. Attention is also given to collisions during accretion, collisions between molten planetesimals, volcanism, and virtues of a nebular setting.
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  • 58
    Publication Date: 2011-08-19
    Description: Carbonaceous chondrites (groups CO and CV) contain three types of ferromagnesian chondrules that can be distinguished on the basis of mineralogy and texture. Statistical analysis of the bulk chemical compositions of these chondrule types suggest that two of the three types are genetically related. The chondrules in carbonaceous chondrites can thus be separated into two populations. These populations are also apparently distinct in terms of redox state and oxygen isotopic composition. The more abundant population (I) is clearly different from chondrules in unequilibrated ordinary chondrites, but the minor population (II) is similar to them in many respects. These chondrule populations may have formed by melting of solid, locally homogeneous precursor materials in different regions of the nebula, and were mixed after solidification was complete.
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  • 59
    Publication Date: 2011-08-19
    Description: Recent SEM observations of the Allende chondrules and matrix are reported. Intergrowths of both Fe-rich olivine (with a composition near Fa50), and clinoenstatite (with a composition of about Fs2). All of the clinoenstatite was involved in associations along the outer margins, grain boundaries, and internal crack surfaces of the chondrule. Most of the chondrules also contain abundant opaque inclusions which must have been strongly altered and partially replaced before chondrule formation. It is suggested that the Fe-rich olivine formed from the clinoenstatite by a reaction of the type Fe + 1/202 + MgSiO3 to (Fe,Mg)2SiO4. It is argued that a variation of the small, internally-heated planetesimal provides the most plausible environment for the chemical reaction.
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  • 60
    Publication Date: 2011-08-19
    Description: The petrogenetic properties of chondrules in different unequilibrated ordinary chondrites (UOCs) are compared to averaged chondrule-suite values obtained from recent analyses of several H-group, L-group, and LL-group chondrites. The purpose of the study was to develop a data base for future statistical analyses of chondrite characteristics. Mean end-member compositions of olivine (mol percent Fa) and pyroxene (mol percent Fs) were used as indices of the relative degree of 'equilibration' of each chondrule suite. It is found that the bulk chondrule geometric-mean abundances of Na, Mg, and Ni are the same from one UOC to another, and show no major systematic trends related to the H-group, L-group, of LL-group parentage of the host chondrites. The patterns of rare-earth element abundances in the chondrules are also examined, and the results are compared with statistical analyses. It is concluded that multivariate statistical analysis of pooled UOC chondrule data is justified for chondrule bulk compositions, as long as the statistical results are not misinterpreted as the primary petrogenetic features of chondrules.
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  • 61
    Publication Date: 2011-08-19
    Description: The ferromagnesian chondrules in Allende follow a trend in the oxygen three-isotope plot that diverges significantly from the 16-O mixing line defined by light and dark inclusions and the matrix of the meteorite. The trend probably results from isotopic exchange with an external gaseous reservoir during the process of chondrule formation sometime after the establishment of the isotopic compositions of the inclusions and matrix. The Allende chondrules approach, but do not reach, the isotopic compositions of chondrules in unequilibrated ordinary chondrites, implying exchange with a similar ambient gas, but isotopically different solid precursors for the two types of meteorite.
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  • 62
    Publication Date: 2011-08-18
    Description: The fine-grained matrices (less than 150 microns) of 14 gas-rich ordinary chondrile regolith breccias were studied in an attempt to decipher the nature of the lithification process that converted loose regolith material into consolidated breccias. It is found that there is a continuouos gradation in matrix textures from nearly completely clastic (class A) to highly cemented (class C) breccias in which the remining clasts are completely surrounded by interstitial, shock-melted material. It is concluded that this interstitial material is formed by shock melting in the porous regolith. In general, the abundances of solar-wind-implanted He-4 and Ne-20 are inversely correlated with the abundance of intenstitial, shock-melted, feldspathic material. Chondrites with the highest abundance of interstitial, melted material (class C) experienced the highest shock pressures and temperatures and suffered the most extensive degassing. It is this interstitial, feldspathic melt that lithifies and cements the breccias together; those breccias with very little interstitial melt (class A) are the most porous and least consolidated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters (ISSN 0012-821X); 66; 1-10
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  • 63
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    Publication Date: 2011-08-18
    Description: A bibliography of articles entered into the data base at the Lunar and Planetary Institute Library from November 1982 through January 1983 is presented. An abstract of each article is given. The subjects covered by the articles include: the motion of the moon and dynamics of the earth-moon system: shape and gravity field of the moon; the physical structure of the moon, its thermal and stress history; the morphology of the lunar surface, the origin and stratigraphy of lunar formations, and mapping of the moon; the chemical composition of the moon, lunar petrology, mineralogy, and crystallography; electromagnetic properties of the moon; the planets; and other objects, including asteroids, comets, meteorites, and cosmic dust.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Moon and the Planets (ISSN 0165-0807); 29; 237-327
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  • 64
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    Publication Date: 2011-08-18
    Description: Because sulfuric acid does not wet sulfur, composite drops in the atmosphere of Venus cannot have sulfur 'cores', but must instead have sulfur coats. Both components then communicate with the vapor phase. Drops that are fully coated with sulfur are immune to coalescence; this sets a limit to growth that may explain 'Mode 3' particles. The sulfur coating is probably responsible for the anomalously low refractive indices derived from entry-probe nephelometer data. There appears to be about an order of magnitude less elemental sulfur than sulfuric acid in the clouds.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 568-577
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  • 65
    Publication Date: 2011-08-18
    Description: A 100-m resolution has been obtained in the radial direction, across the entire Saturn ring system, in Voyager 2 photopolarimeter observations of Delta Scorpii as it was occulted by the rings. An automatic search with finite Fourier transforms located 13 density waves excited by resonances with Saturn's satellites. Although strong density waves can be easily located, no waves have been identified which have predicted torques/surface mass density values lower than 4 x 10 to the 16th cu cm/sec-squared. This suggests a limit of less than 100 waves to be found in the Saturn rings. Total ring mass is estimated as 5 x 10 to the -8th of the mass of Saturn. The power spectrum for the rings shows no dominant individual wavelengths. The majority of ring structures and most variance in ring optical depth are not explainable by currently entertained physical mechanisms.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 439-452
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  • 66
    Publication Date: 2011-08-18
    Description: High resolution spectroscopic observations of asteroid 2 Pallas from 1.7-3.5 microns are reported. These data are combined with previous measurements from 0.4-1.7 microns to interpret Pallas' surface mineralogy. Evidence is found for low-Fe(2+) hydrated silicates, opaque components, and low Fe(2+) anhydrous silicates. This assemblage is very similar to carbonaceous chondrite matrix material such as is found in type CI and CM meteorites, but it has been subjected to substantial aqueous alteration and there is a major extraneous anhydrous silicate component. This composition is compared to that of asteroid 1 Ceres. Although there are substantial differences in their broad band spectral reflectances it appears that both asteroids are genetically related to know carbonaceous chondrites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 398-408
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  • 67
    Publication Date: 2011-08-18
    Description: The spectral properties from 0.4 to 3 microns of montmorillonite plus dark carbon grains (called opaques) of various sizes are studied as a function of the weight fraction of opaques present. The reflectance level and band depths of the 1.4-, 1.9-, 2.2-, and 2.8-micron water and/or OH absorption features are analyzed using derived empirical relationships and scattering theory. It is found that the absorption band depths and reflectance level are a very nonlinear function of the weight fraction of opaques present but can be predicted in many cases by simple scattering theory. The 2.8-micron bound water fundamental band is the most difficult absorption feature to suppress. The overtone absorptions are suppressed a greater amount than the fundamental but are still apparent even when 10-20 wt pct opaques are present. The relationships observed and the simple scattering theory presented show that quantitative compositional remote sensing studies are feasible for surfaces containing complex mineral mixtures.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 10635-10
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  • 68
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    Publication Date: 2011-08-18
    Description: This paper presents the results of a study of local vortices, and dust devils, on Mars as observed by Viking Landers 1 and 2. It is found that these vortices are most common during Martian spring and summer, as occurs on earth. Seven of the vortices involve wind speeds that may raise dust from the Martian surface. There is no indication that these possible dust devils contribute to the planet-wide spread of major dust storms. However, it appears that they may help in maintaining the atmospheric dust content. The data indicate that there is no preference in rotation direction, at least to core diameters of 300 m (corresponding to a region of influence of about 3 km diameter).
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 11005-11
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  • 69
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    Publication Date: 2011-08-18
    Description: Many of the moons of the outer planets in the solar system consist to a substantial degree of water and other ices. Such ices are thought to make up at least half, by mass, of all condensed material in the outer solar system. The surfaces and interiors of these icy satellites have undergone considerable geologic evolution, and in some cases may still be active today. So that these processes can be understood, certain critical data on the behavior of water and other ices at low (ca. 100 K) temperatures and high (ca. 10 kbar) pressures are needed. Given such data, various techniques for modeling planetary interiors can be tested to see which models best describe the conditions observed on these bodies; such models may then be used to study larger, terrestrial planets.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: (ISSN 0022-3654)
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  • 70
    Publication Date: 2011-08-18
    Description: The energy densities epsilon(P) of the low energy ions measured by the Low Energy Charged Particle experiment on Voyager 1 and 2 are compared to the magnetic field energy densities derived from the magnetometer instrument during the crossing of the dayside Saturn magnetopause. The ratios of the proton to magnetic field energy densities are greater than about 0.5 during the Voyager 2 crossing when the magnetopause was at about 18 R(s). During the Voyager 1 crossing of the magnetopause at about 23 R(s), the ratios were about 0.1, although they approached one as the spacecraft entered the region near 18 R(s). The observations show that the dayside Saturnian magnetopause can at times have high beta plasma conditions, similar to the situation found at Jupiter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; 1200-120
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  • 71
    Publication Date: 2011-08-18
    Description: The results of a detailed photogeologic analysis and classification of ridge-fault cross-cutting relationships on ridged plains units of the Tharsis region is reported. The problems involved in using the morphology of ridge-fault intersections to determine relative timing of structural events are discussed. The implications of using intersection angles as well as morphology to determine possible age relationships for the tectonic history of the region are presented. It is concluded that the major ridge-forming events in the Tharsis region were roughly coincident with, and possibly prior to, the extensional events that produced the faulting of the Tempe and Mareotis regions, the Coprates and Memnonia regions, and the rifting of the Valles Marineris. The compressional events that formed most of the ridges are restricted in time both by their relationship to regional extensional events and by the age of the units on which they formed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 278-298
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  • 72
    Publication Date: 2011-08-18
    Description: It is noted that the near-forward scattering functions of particles in Saturn ring features are related to 3.6 cm radio occultation power spectra by a Fredholm integral equation of the first kind. The equation reduces to an algebraic system of equation whose solution by usual inversion techniques (that is, least mean squares) is ruled out by the near singularity of the forward transformation matrix. A combination of constrained linear inversion and a filtering algorithm based on eigenvector decomposition of the matrix reduces the instabilities; this yields derived phase functions valid over the range of zero to about 12 mrad. It is noted that these functions represent the collective forward diffraction lobe of particles greater than about 1 m in radius. Since multiple scattering of the signal is a significant effect, the measured phase functions must be adjusted to obtain the singly scattered component. This single-scattering correction is examined for two physical models, namely the monolayer and the classical discrete random slab; in addition, the fraction of opacity in submeter particles for each model for particular ring features is estimated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 209-228
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  • 73
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    Publication Date: 2011-08-18
    Description: A method for estimating radial gravity anomalies from line-of-sight acceleration data, their interpolation, and the use of iteration for improved radial anomaly estimates is outlined. Results based on spherical harmonic coefficients for Venus' gravitational field are first discussed, and the procedure is then presented for determining radial acceleration estimates from the line-of-sight vectors and for interpolating the results at preselected locations using the method of objective mapping. A preliminary gravity anomaly map of much of the surface of Venus based on the first estimation step of this technique is presented, and the results are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 345-371
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  • 74
    Publication Date: 2011-08-18
    Description: It is pointed out that the Voyager flybys of Jupiter produced remarkable images of Europa, one of the four large Galilean satellites. Taking into account information provided by these Voyagers flybys and other data and investigations, a study is conducted regarding the suitability of Europa as a habitat for living organisms. The performed calculations indicate, that for a plausible physical model of Europa, the general conditions for the survival of biological organisms could exist, at least in some regions, highly restricted in both space and time.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 246-254
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  • 75
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    In:  Other Sources
    Publication Date: 2011-08-18
    Description: A report on the continuing investigation of Io is presented. Gravitational resonance is discussed as the cause of Io's volcanism, and the volcanic activity is explained in terms of sulfur chemistry. Theories concerning the reasons for the two main types of volcanic eruptions on Io are advanced and correlated with geographical features of the satellite. The sulfur and silicate models of the calderas are presented, citing the strengths and weaknesses of each. Problems of the gravitational resonance theory of Io's heat source are then described. Finally, observations of Io planned for the Galileo mission are summarized.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Scientific American (ISSN 0036-8733); 249; 56-67
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  • 76
    Publication Date: 2011-08-18
    Description: The partition coefficients between synthetic whitlockite (beta Ca-phosphate) and coexisting silicate melts are determined for the actinide elements Th, U and Pu. Experiments were performed at 1 bar pressure and 1250 C at oxygen fugacities from 10 to the -8.5 to 10 to the -0.7 bars, and partitioning was determined from trace element radiography combined with conventional electron microprobe analysis. Results show Pu to be more readily incorporated into crystalline phases than U or Th under reducing conditions, which is attributed to the observation that Pu exists primarily in the trivalent state, while U and Th are tetravalent. Corrected partition coefficients for whitlockite of 3.6, less than or equal to 0.6, 1.2, 0.5 and less than or equal to 0.002 are estimated for Pu(+3), Pu(+4), Th(+4), U(+4) and U(+6), respectively. Experiments performed at trace levels and percent levels of UO2 indicate that Si is involved in U substitution in whitlockite, and show a reduced partition coefficient at higher concentrations of U that can be explained by effects on melt structure or the fraction of tetravalent U.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 47; 1695-170
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  • 77
    Publication Date: 2011-08-18
    Description: A carbon-chromite fraction from the Allende C3V chondrite shows strikingly large isotopic enrichments of neodymium-142 (0.47 percent) and neodymium-143 (36 percent). Both apparently formed by alpha decay of samarium-146 and samarium-147 (half-lives 1.03 x 10 to the 8th and 1.06 x 10 to the 11th years), but the isotopic enrichment was greatly magnified by recoil of residual nuclei into a carbon film surounding the samarium-bearing grains. These data provide an improved estimate of the original abundance of extinct samarium-146 in the early solar system, Sm-146/Sm-144 = (4.5 + or - 0.5) x 10 to the -3rd, higher than predicted by some models of p-process nucleosynthesis. It may be possible to use this isotopic pair as a chronometer of the early solar system.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 222; 1015-101
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  • 78
    Publication Date: 2011-08-18
    Description: Carbon and chromite fractions from the Allende meteorite that contain isotopically anomalous xenon-131 to xenon-136 (carbonaceous chondrite fission or CCF xenon) at up to 5 x 10 to the 11th atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently the CCF xenon and its carbonaceous carrier are relics from stellar nucleosynthesis.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 222; 1013-101
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  • 79
    Publication Date: 2011-08-18
    Description: A set of spectra has been obtained of the Jovian equatorial zone central meridian 6190 A CH4 and 6450 A NH3 bands on the nights of February 26, 27, and 28, 1980, a year after the data reported by Cochran and Cochran (1980), in order to check the previous results and search for possible temporal variations. The new data confirm the results of the previous study. A correlation of the NH3 and CH4 equivalent widths, as well as a lack of any strong correlation of red continuum reflectivity with equivalent width, are found. Longitude regions of larger or smaller than average equivalent width still seem to exist a year later, with some slight drift in longitude. An increase in the average CH4 and NH3 equivalent width over the entire planet was detected during the one year interval. This is easily understood as the result of a global decrease in the mean altitude of the NH3 cloud.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 116-121
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  • 80
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    Publication Date: 2011-08-18
    Description: A simple one-dimensional cooling analysis is used to consider the cooling of a flow of pure sulfur on the Ionian surface by a combination of upward radiation and downward conduction, and some speculations on the nature of surface structures and optical properties for such a flow are made. It is concluded that surface folding caused by compressive stresses, crustal foundering due to tensile fracturing and density inversions, and local turbulence may result in regularly spaced surface ridges periodically interrupted by upwellings of liquid sulfur onto the frozen surface of the flow. The model suggests that although the color of the surface crust of a quickly quenched sulfur flow will not necessarily reflect the local internal temperature of the flow, diapiric upwellings and convection from beneath this crust should indicate the progressive cooling of the inner, more fluid zones of the flow.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 38-50
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  • 81
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    Publication Date: 2011-08-18
    Description: A tabulation is given of line intensities for the nu(2) band of CH3D which have absolute accuracies of + or - 3 percent. Using these intensities, some of the previous Jovian D/H determinations are reinterpreted.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 273; L47-L49
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  • 82
    Publication Date: 2011-08-18
    Description: The analysis of the near-infrared spectrum of monodeuterated methane (CH3D) near 6400/cm and 5100/cm is presented. Three new parallel bands which have locally perturbed upper states connecting with the ground state are identified, and approximate rotational constants are derived. The band centered near 6425/cm and the 9613 A band previously analyzed by Lutz, Danehy, and Ramsay (1978) are found to form an apparent vibrational progression with the nu2 fundamental at 2200/cm, and vibrational assignments of 3nu2 and 5nu2, respectively, are proposed. Detailed comparison of the rotational constants of the states involved is shown to support these assignments.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 273; 397-409
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  • 83
    Publication Date: 2011-08-18
    Description: Precise measurements of the half-life of I-129 in three different meteorites and one lunar surface rock are reported. The meteorite source of I-129 was produced by cosmic ray secondary neutron reactions on Te, while the source in lunar materials in spallation on barium and rare earth elements. The Abee, Allende, and Dhajala meteorites were examined, together with the lunar rock 14310. Details of the process used to extract the iodine are provided. The Abee and Allende samples exhibited a production of 0.5 atom/min per gm of Te from the (n,2n) reaction and 0.05 atom/min/gm for the (n,gamma) reaction. The I-129 is concluded to be a viable tool for long-lived cosmogenic nuclide studies. Further work to extend the data to include the constancy of the cosmic ray flux, the meteorite bombardment history, and the cosmic exposure age dating by means of the I-129 and Xe-129 method is indicated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 305; 611
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  • 84
    Publication Date: 2011-08-18
    Description: Voyagers 1 and 2 provided images of sufficient resolution for morphologic and photometric studies of Saturn's small satellites. These objects, all very difficult to observe from earth, orbit Saturn at distances of 2.3 to 6.3 Saturn radii (just outside the A ring to the orbit of Dione) and range in mean diameter from 22 to 188 km. All are irregularly shaped (long/short axis ratios range from 1.4 to 2.0) and probably heavily cratered. While impacts have apparently been important in shaping these objects, observed crater densities suggest that the present forms may have survived for about 4 billion years. Geometric albedos vary from 0.4 to at least 0.8. These albedos and the few color data available are similar to those of larger Saturn satellites which are known to have surfaces made predominantly of water ice. The range of observed albedos could be explained by minor variations in the amount of dark, opaque contaminants.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8743-875
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  • 85
    Publication Date: 2011-08-18
    Description: A sharp stratospheric emission feature at 667/cm in the Voyager infrared spectra of Titan is associated with the nu2 Q branch of CO2. A coupling of photochemical and radiative-transfer theory yields an average mole fraction above the 110 mbar level of (1.5 + 1.5 or - 0.8) x 10 to the -9th, with most of the uncertainty being due to imprecise knowledge of the vertical distribution. CO2 is found to be in a steady state, with its abundance being regulated principally by the 72 K cold trap near the tropopause and secondarily by the rate at which water-bearing meteoritic material enters the top of the atmosphere. An influx of water about 0.4 times that at the top of the terrestrial atmosphere is consistent with a combinati