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  • LUNAR AND PLANETARY EXPLORATION  (723)
  • Animals
  • 1980-1984
  • 1975-1979  (723)
  • 1925-1929
  • 1977  (723)
Collection
Keywords
Years
  • 1980-1984
  • 1975-1979  (723)
  • 1925-1929
Year
  • 201
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    Thermal radiation from Titan's atmosphere (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The temperature-inversion model of Titan's atmosphere is modified to include the thermal emission from a plausible amount of C2H2. Infrared photometry of Titan from 8 to 14 microns agrees with model calculations for 0.5 cm-atm C2H6 and 1.0 cm-atm C2H2 and an optically thin dust layer in a temperature-inversion region at 160 K. The random band approximation used to calculate C2H6 opacity has been verified by laboratory transmission measurements. Measurements of the C2H2 emission at 13.7 microns may provide an indirect check on the presence of H2 on Titan. Existing observations of Titan appear to be fully consistent with the inversion model if the surface radius equals 2700 km, the atmospheric radius equals 2900 km, and the surface temperature equals 78 K. The energy balance depends sensitively on these three parameters.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 202
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    The Kramer Creek, Colorado meteorite - A new L4 chondrite (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Results of bulk chemical analyses and mineralogical and petrographic studies of a chondrite found at Kramer Creek, Colorado, are reported. The meteorite has been classified as an L-group chondrite on the basis of its bulk chemistry, the fayalite content of its olivine (21.7%) and the ferrosilicate content of its pyroxene (18.3%). The presence of interstitial glass and the iron oxide percent mean deviations for olivine and low-Ca pyroxene (2.4 and 4.6%) place the specimen in petrologic group 4 of the Van Schmus and Wood classification (1967)
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics; 12; June 30
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  • 203
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    Observations of Uranus occultation events (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: An analysis of photometric data obtained during the Uranus appulse to SAO 158687 shows three occultation events which appear to coincide with portions of the Uranian ring system. Two occultation events were associated with the alpha ring and one with the beta ring of the planet; the alpha ring event suggests a ring model with a random distribution of occulting bodies of about 1 km diameter, and an areal density of about 50% over a band 10 km wide. Calculations indicate that neither the inner nor outer rings of the planet are truly concentric circles (to within their radius). In addition, determination of the ring centers can be used to locate the center of mass of the planet, and an upper limit of 26,300 km can be assigned to its radius.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 268; July 7
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  • 204
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    Study of lunar librations using differential very-long-baseline observations of ALSEPs (1977)
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    Publication Date: 2019-06-27
    Description: Observations of signals from the ALSEP transmitters via differential very-long-baseline interferometry (VLBI) are being made to determine the relative selenocentric coordinates of the ALSEPs and the motion of the moon about its center of mass. By VLBI the relative positions of the ALSEPs can be determined with uncertainties less than 5 meters, and the orientation of the moon within 0.5 second of selenocentric arc.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 205
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    The sodium and hydrogen gas clouds of Io (1977)
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    Publication Date: 2019-06-27
    Description: Models are developed to describe the spatial distribution of gases emitted by Io and are applied to recent observations which indicate extensive gas clouds of hydrogen and sodium in orbit around Jupiter. Hydrogen and sodium atoms are emitted from Io with velocities in the range from 2 to 3 km/sec, with fluxes of about 10 billion and 100 million per sq cm/sec for hydrogen and sodium, respectively. Hydrogen atoms may be formed by photodecomposition of gases such as NH3 or H2S released from the satellite surface and may escape thermally from an exosphere whose temperature is about 500 K. Sodium may be ejected from the surface by energetic particles or by ultraviolet radiation, and it appears that a nonthermal mechanism drawing energy from Jupiter's magnetic field is required in order to account for its release to space.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Planetary and Space Science; 25; May 1977
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  • 206
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    Cratering and obliteration history of Mars (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The review presented is based mainly on the pre-Viking literature. Early interpretations of the Mariner 4 pictures of Martian craters are considered along with interpretations of Mariner 9 pictures. A description of cratering/obliteration models is presented and aspects of obliteration episode interpretation are discussed, taking into account large, intermediate, and small craters. Alternative interpretations of Martian cratering are also considered and questions of absolute chronology are investigated. The geomorphological processes described include exogenic, aeolian, and aqueous processes. The significance of the various processes and activities for the geomorphological evolution of Mars is evaluated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 207
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    On the 6825 A band of methane as observed in Uranus and Neptune (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A high-resolution spectrum of the series of lines near 6825 A presumably due to CH4 has been obtained for Uranus. The line spacings are in agreement with the previous observations of Owen (1966), Bergstralh (1975), and Belton and Hayes (1975) but not with the laboratory observations reported by Lutz and Owen (1976). It is proposed that the transitions identified by Lutz and Owen are not correlated one-to-one with those features observed in the planets. Wavelength differences of up to 0.8 A are found between the laboratory and planetary features, where the resolving power allows one to specify the line positions to better than + or - 0.07 A. The spectrum obtained for Neptune is in essential agreement with that for Uranus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal; vol. 215
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  • 208
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    Comment on low energy electron measurements in the Jovian magnetosphere (1977)
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    Publication Date: 2019-06-27
    Description: It is suggested that the low energy electrons reported by Intriligator and Wolfe (1974) in the outer magnetosphere of Jupiter may actually be photoelectrons and/or secondary electrons from the Pioneer spacecraft surfaces. The electron spectrum is similar to the observed photoelectron spectrum on earth-orbiting satellites where differentially charged surfaces have deflected the electrons into particle detectors.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 4; June 197
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  • 209
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    Comment on 'The Venus bow shock - Detached or attached' by C. T. Russell (1977)
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    Publication Date: 2019-06-27
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; June 1
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  • 210
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    Measures of Jupiter photographs - 1974/75 apparition (1977)
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    Publication Date: 2019-06-27
    Description: The 1974/75 Jupiter apparition is described. Photographic images have been measured and zonal velocities are given for all spots observed on four or more dates. Global and localized zonal flow patterns are graphically presented. Methane absorption band imagery at 890 nm indicates that white ovals and red spots are high in altitude, and blue features are cloud-free areas. The motions of blue features are complex and unlike the motions of other features. Interactions or associations between spots at five adjacent atmospheric currents have been observed. Zonal motion within an equatorial plume has been observed. Evidence is presented for a probable source of red spots in the North Tropical Zone.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 31; May 1977
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  • 211
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    Io's surface composition based on reflectance spectra of sulfur/salt mixtures and proton-irradiation experiments (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Available full-disk reflectance spectra of Io in the range 0.3 to 2.5 microns have been used to determine a surface compositional model for Io that is consistent with Io's other known chemical and physical properties. Results indicate that the surface of Io contains abundant dehydrated salts of high Na, Mg, and Fe(3+) content such as bloedite and ferrous iron sulfate. Experiments were performed studying the irradiation damage effects from low-energy proton bombardment, since Io is immersed in Jupiter's magnetosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 31; May 1977
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  • 212
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    The distribution of ammonia and its photochemical products on Jupiter (1977)
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    Publication Date: 2019-06-27
    Description: Altitude profiles of ammonia and its photochemical products are generated in the light of measurements of the Jovian temperature structure, eddy transport coefficient, improved chemical scheme, and rate constants. Realistic limits are placed on the concentration of hydrazine which may participate in the recycling of ammonia on Jupiter. The maximum hydrazine-ice production rate is calculated to be about 1.3 mg/sq m per Jovian day. The distribution of nitrogen gas is presented with and without supersaturation of hydrazine. The nitrogen mixing ratio near the ammonia cloud top is estimated to be in the range between 10 to the -9th and 10 to the -11th power. An appreciable latitudinal variation in the ammonia concentration is expected.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 31; July 197
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  • 213
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    'Mysterite' - A late condensate from the solar nebula (1977)
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    Publication Date: 2019-06-27
    Description: An attempt is made to clarify the nature of 'mysterite', a material that had been postulated to explain the overabundance of Tl, Bi, and Ag in certain chondrites. Four dark clasts and a vein sample from the H6 chondrite Supuhee were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Ni, Os, Rb, Re, Sb, Se, Te, Tl, and Zn. One of the clasts is enriched in all volatile elements, while the other four samples are enriched only in the siderophile volatiles Ag, Bi, and Tl. The enrichments range up to 100 times typical H6 chondrite abundances. The proportions of Ag, Bi, and Tl suggest the presence of at least two, Tl-rich and Tl-poor, varieties of mysterite. The former seems to dominate in Supuhee and Krymka, and the latter in Mezo-Madaras. Apparently mysterite is a late condensate from the solar nebula that collected volatiles left behind by earlier generations of chondrites. It was incorporated in Supuhee and perhaps in other chondrites (mainly of low petrologic types) during brecciation events.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 41; July 197
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  • 214
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    The critical velocity phenomenon and the origin of the regular satellites (1977)
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    Publication Date: 2019-06-27
    Description: A theory is developed for the formation of the satellite systems which are likely to have been formed in situ, that is, not by capture of the satellite by the central planet. The foundation of the theory is the observation of the similarity between the band structure of such satellites and the band structure of cosmically abundant elements. That means that the values of the quantity log Gamma, where Gamma is the ratio of the mass of the central body to the orbital radius of the secondary body, are grouped into three bands which can be identified with the three bands into which are grouped the values of the ratio of the mass of a central body to the distance at which the kinetic energy of a freely falling cloud of atoms of a given kind equals the ionization energy. A coherent series of processes that could have led to the formation of satellites is outlined. The theory is valid also for planets, since the above-mentioned band structure is noted for the sun-planets system also.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 215
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    Consequences and inferences from tidal interactions in the solar system (1977)
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    Publication Date: 2019-06-27
    Description: A general theory of the rotation of solid bodies in the solar system leads to the following conclusions: No special initial conditions on the primordial rotation states of most tidally evolved bodies are necessary to account for their present rotation. The possible exception is the rotation of Venus, which must have been initially retrograde unless a liquid core-solid mantle interaction or an accelerating atmospheric tide could dominate the ordinary gravitational tides. Tides eventually drive all bodies in precessing orbits to 'Cassini states', where the spin vector, normal to the orbit and normal to the invariable plane remain coplanar as the first two precess about the latter. The constant obliquity in this configuration, together with the lowest order gravitational harmonics and the amplitude of the physical libration allows the determination of the central condensation and the extent of a liquid-core for Mercury. Criteria for the existence of observable amplitudes of the free wobble, free precession and libration of the moon are established which do not exclude current, non-zero values.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 216
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    Io's surface and the histories of the Galilean satellites (1977)
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    Publication Date: 2019-06-27
    Description: Similarities and differences among the Galilean satellites are discussed. A hypothesis is offered that the surface of Io is largely covered by 'evaporite' salts produced by defluidization of Io's interior, migration of salt-saturated solutions to Io's surface, and subsequent H2O loss to space. Laboratory reflectance studies show that evaporites constitute a good match to Io's spectrum in the infrared, in contrast to ices or frosts, the presence of which is not considered likely in view of the absence of near IR ice bands in Io's surface spectrum. Likely coloring agents in the blue include elemental sulfur, which may be produced from sulfates by proton irradiation or other processes, and F-centers produced by irradiation with magnetospheric protons. Preferential irradiation of material in the polar regions may account for Io's peculiar dark polar caps.
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  • 217
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    Wave optics of the central spot in planetary occultations (1977)
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    Publication Date: 2019-06-27
    Description: The detection of a bright central spot during the occultation of epsilon Geminorum by Mars demonstrates that an exponentially-stratified planetary atmosphere can act as a lens providing very high resolution of distant objects (e.g., quasars, white dwarfs, and pulsars). The diffraction nature of the central occultation spot is investigated, with special reference to Mars and Venus. In practice, however, central occultations by these planets are seldom observable from the earth's surface, and spacecraft would have to be used to obtain a suitable orientation for observers. Further difficulties may be encountered in image deconvolution needed for extended objects, in location of the image of a true point source, and in compensation for peculiarities of planets and their atmospheres.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 268; July 7
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  • 218
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    Observations of the sodium emission from Jupiter, region C (1977)
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    Publication Date: 2019-06-27
    Description: Observations of the sodium emission near Jupiter made while testing an interferometric imaging device are discussed. The results obtained suggest that the sodium emission detected in the region (designated C2) between 3 and 7.5 arcmin (9 and 23 Jupiter radii) from the planet may be no more than terrestrial airglow. It is concluded that region C2 is implausible on theoretical grounds and would need very solid observational support for its existence to be accepted.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Planetary and Space Science; 25; June 197
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  • 219
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    Evidence for two major changes in the Venus aerosol distribution - 1972-1975 (1977)
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    Publication Date: 2019-06-27
    Description: High-spatial-and-spectral-resolution observations of Venus CO2 line profiles taken over a three-year interval are analyzed using inhomogeneous atmospheric models with anisotropic scattering. The data exhibit two sudden significant changes in the structure of the atmosphere, one occurring near April 1973, and the other near November 1974. Two models are developed to describe the vertical cloud structure of the atmosphere of Venus in the more quiescent periods after these changes. For each model, the CO2 specific abundance must decrease with increasing atmospheric pressure; i.e., the clouds are thinnest high in the atmosphere and become denser with depth. No evidence is found that the cloud particles must change their scattering phase function with altitude.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomy and Astrophysics; 58; 3, Ju; June 197
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  • 220
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    Phosphate in Angra dos Reis - Structure and composition of the Ca3/PO4/2 minerals (1977)
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    Publication Date: 2019-06-27
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 35; 2, Ju; June 197
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  • 221
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    Isotopic and chemical investigations on Angra dos Reis (1977)
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    Publication Date: 2019-06-27
    Description: Isotope ratios and chemical abundance measurements for a variety of elements are reported for total meteorite and mineral separates of the Angra dos Reis achondrite. U-Pb, Th-Pb, and Pb-Pb ages are concordant at 4.54 eons for the total meteorite and for high-purity whitlockite, which indicates that Angra dos Reis is an early planetary differentiate that has not been disturbed for these systems since 4.54 eons ago. The implications of different ratios of Sr-87 and Sr-86 found in different components are discussed. Xe isotopic measurements show that Pu-244 was enriched in the whitlockite relative to the pyroxene by a factor of about 18. Chemical enrichment factors between the whitlockite and the fassaitic pyroxene in Angra dos Reis are presented
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 35; 2, Ju; June 197
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  • 222
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    On the mass of Saturn's rings (1977)
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    Publication Date: 2019-06-27
    Description: This paper presents a statistical estimate of the mass of Saturn's rings, determined to be (6.2 plus or minus 2.4) x 10 to the -6th masses of Saturn. This value was obtained by fitting a gravitational model of the Saturn system which included rings, satellites, and the planet to the observed secular apsidal and nodal rates of the inner satellites. The apsidal commensurability of particles in the rings of Titan was shown to produce no significant effect on the structure of the rings.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Royal Astronomical Society; vol. 179
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  • 223
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    Genesis of the Angra dos Reis and other achondritic meteorites (1977)
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    Publication Date: 2019-06-27
    Description: Major, minor, and trace element abundances were determined in seven Angra dos Reis samples, which included whole rocks, fassaite (clinopyroxene), olivine, and whitlockite separates, via sequential instrumental neutron activation analysis. The rare earth element abundance patterns and the trace element abundance patterns of this achondritic meteorite are discussed. A two-stage crystal-liquid fractionation model with source material containing olivine, orthopyroxene, and clinopyroxine is presented for the genesis of Angra dos Reis. Multilinear regression analysis was used to estimate possible composition and properties of the parent magmas. Angra dos Reis was compared with other achondrites, cumulate eucrites and nakhlites in particular. It is thought that the unique Angra dos Reis could not be related to those achondrites by crystal-liquid fractionation of the same parent body.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 35; 2, Ju; June 197
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  • 224
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    Measured oxygen fugacities of the Angra dos Reis achondrite as a function of temperature (1977)
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    Publication Date: 2019-06-27
    Description: Measurements of the oxygen fugacity, f(O2), as a function of temperature, T, were made on an interior bulk sample of the cumulate achondrite, Angra dos Reis. Data clustered between the f(O2)-T relationship of the iron-wustite assemblage and 1.2 log atm units above iron-wustite. Interpretation of the data indicates that, throughout most of the cooling history of the meteorite, f(O2) values were defined by equilibria involving iron-bearing species at values close to the f(O2) of the assemblage iron-wustite. Measured f(O2) data are compatible with crystallization and cooling at pressures greater than 50 bars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 35; 2, Ju; June 197
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  • 225
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    Sm-Nd-Pu timepieces in the Angra dos Reis meteorite (1977)
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    Publication Date: 2019-06-27
    Description: Isotope ratios and age estimations are presented for the ultramafic pyroxenite Angra dos Reis meteorite. A pyroxene-phosphate internal isochron age of 4.55 plus or minus 0.04 eons was obtained, in agreement with reported Pb-Pb ages. It is suggested that Sm-146 decay led to an increase in the ratio of Nd-142 to Nd-144 in pyroxene, which is greater than the ratio of the Nd isotopes in phosphates. The effect of Pu-244 on the fission xenon components in pyroxene and phosphate is examined. The ratios of Pu-244 to Nd, U-238, and Th-232 are compared for pyroxene and phosphate separates. The exposure age of the meteorite, as obtained by the Kr-81 to Kr-83 method, was found to be 55.5 plus or minus 1.2 million years.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 35; 2, Ju; June 197
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  • 226
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    Plasma electron measurements in the outer Jovian magnetosphere (1977)
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    Publication Date: 2019-06-27
    Description: The existence of the plasma electrons in the outer Jovian magnetosphere reported by Intriligator and Wolfe (1974) is consistent with (1) the additional pressure needed to supplement the magnetospheric magnetic field in the outer magnetosphere so as to balance the solar wind and interplanetary magnetic field dynamic pressure across the magnetopause, (2) the drastic change in the plasma electron spectrum as soon as Pioneer 10 crossed the magnetopause from the magnetosheath into the magnetosphere, (3) the fact that the instrument aperture was at spacecraft ground, and (4) the fact that beyond about 2 AU the continuous observations of all ambient electron fluxes (solar wind electrons, secondary electrons, photoelectrons, etc.) are below the instrument threshold.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 4; June 197
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  • 227
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    Thermal metamorphism of primitive meteorites. V - Ten trace elements in Tieschitz H3 chondrite heated at 400-1000 C (1977)
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    Publication Date: 2019-06-27
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 41; Sept
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  • 228
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    The occultation of Epsilon Geminorum by Mars - Analysis of McDonald data (1977)
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    Publication Date: 2019-06-27
    Description: An analysis of observations of the occultation of Epsilon Gem by Mars on April 8, 1976, is presented. The data were obtained by three neighboring telescopes at McDonald Observatory. Intensity fluctuations on time scales of the order of 100 ms were observed simultaneously at the three telescopes. As the observations compare well with predictions of turbulent scintillation theory, it is concluded that such fluctuations were probably largely the effect of stellar scintillations in the Martian atmosphere. The stellar diameter is included as a parameter in the theory but in a way which differs from previously published interpretations of occultations of extended sources by planetary atmospheres. Scintillations govern the experimental uncertainty in the deduction of the scale height of the high Martian atmosphere. A density scale height of 9.9 + or - 2.5 km is obtained at an altitude of 74 + or - 8 km above the mean surface. For CO 2 gas, this result corresponds to a temperature of 190 + or - 50 K.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal; vol. 214
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  • 229
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    Fluorine in meteorites (1977)
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    Publication Date: 2019-06-27
    Description: Microanalysis using a resonant nuclear reaction was used to measure F concentrations in USGS standard rocks and 21 meteorites. The F appears to be a moderately depleted element, but there were significant variations within each sample. Measurements on separated metal phases suggest that about 20% of meteoritic F is in the metal or in a phase closely associated with it. Simultaneous measurements of F, Mg, Na, Al and Si in the nonmagnetic fractions of meteorites suggest plagioclase as a F containing phase.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 41; May 1977
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  • 230
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    Distribution of the pre-solar component in Allende and other carbonaceous chondrites (1977)
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    Publication Date: 2019-06-27
    Description: Detailed analyses of separated phases of several Allende Ca-Al-rich inclusions are reported which reveal a consistent pattern of large O-16 enrichments in spinel, pyroxene, and sometimes olivine, and small O-16 enrichments in melilite, feldspathoids, and grossular. The heterogeneous distribution of the O-16 excesses, together with their enhancement in minerals believed to be early solar nebular condensates, suggests the existence of pre-solar carriers of the isotopic anomaly, probably grains or molecules with oxygen which was nearly pure O-16. Pre-solar grains of corundum or spinel, and pre-solar molecules of SiO are considered possibilities. Excess O-16, relative to terrestrial abundances, has been found in all samples of C2, C3 (the Allende is this kind), and C4 carbonaceous chondrites which have been analyzed. No direct correlation has yet been observed between the oxygen anomalies and isotope anomalies in neon, magnesium, or xenon.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 34; 2, Ma; Mar. 197
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    The clouds of Venus. II - An investigation of the influence of coagulation on the observed droplet size distribution (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: An approximate numerical technique is used to investigate the influence of coagulation, sedimentation and turbulent motions on the observed droplet size distribution in the upper layers of the Venus clouds. If the cloud mass mixing ratio is less than 0.000001 at 250 K or the eddy diffusivity throughout the cloud is greater than 1,000,000 sq cm per sec, then coagulation is unimportant. In this case, the observed droplet size distribution is the initial size distribution produced by the condensation of the droplets. It is found that all cloud models with droplet formation near the cloud top (e.g., a photochemical model) must produce the observed droplet size distribution by condensation without subsequent modification by coagulation. However, neither meteoritic or surface dust can supply sufficient nucleating particles to account for the observed droplet number density. If the cloud droplets are formed near the cloud bottom, the observed droplet size distribution can be produced solely by the interaction of coagulation and dynamics; all information about the initial size distribution is lost. If droplet formation occurs near the cloud bottom, the lower atmosphere of Venus is oxidizing rather than reducing.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 34; Feb. 197
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    A lunar density model consistent with topographic, gravitational, librational, and seismic data (1977)
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    Publication Date: 2019-06-27
    Description: A series of models of the lunar interior are derived from topographic, gravitational, librational, and seismic data. The librational parameters and low-degree gravity harmonics result primarily from surface height variations and only secondarily from lateral density variations. The moon departs from isostasy, even for the low-degree harmonics, with a maximum superisostatic stress of 200 bars under the major mascon basins. The mean crustal thicknesses under different physiographic regions are: mascons, 30-35 km; irregular maria, 50-60 km; and highlands, 90-110 km. A possible composition consistent with our model is an anorthositic crust, underlain by a predominantly forsterite upper mantle which grades into a refractory rich lower mantle surrounding a pyrrhotite core.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; Mar. 10
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  • 233
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    Evaluation of Jupiter longitudes in System III/1965/ (1977)
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    Publication Date: 2019-06-27
    Description: Commission 40 of the International Astronomical Union has adopted a new longitude system for Jupiter, labelled System III(1965), to replace the provisional System III(1957.0). The specification of the prime meridian and epoch for the new system differs slightly from that recently published. Its rotation rate implies a period of 9 hr 55 min 29.711 (plus or minus 0.04) sec, consistent with recent determinations from decimetric and decametric data. For both the new and older systems, equations are provided which are useful in the evaluation of longitudes for the analysis of Jupiter radio, particle, and field data from earth and spacecraft observations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 4; Feb. 197
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  • 234
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    Theory of motion of Jupiter's Galilean satellites (1977)
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    Publication Date: 2019-06-27
    Description: Final results are presented for a theory enabling one to calculate the positions of the Galilean satellites and their partial derivatives. Extensive use of algebraic manipulation software on a digital computer is made to generate the final expressions. The theory is, in effect, a revitalization of Sampson's (1921) theory. Algebraic and mathematical errors existing in Sampson's work are removed, some neglected effects due to solar interactions and the 3-7 commensurability are introduced, allowance is made for nonzero amplitude and phase of the free libration, and the final results are expressed as analytic functions of variations in 49 arbitrary constants of integration and physical parameters. The theory is constructed in a manner which readily allows for future revision, and analytic expressions are provided for the partial derivatives with respect to the 49 parameters.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomy and Astrophysics; 56; 3, Ap; Apr. 197
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  • 235
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    Isotopic anomalies of noble gases in meteorites and their origins. II - Separated minerals from Allende (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; Feb. 10
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  • 236
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    Turbulent viscosity and Jupiter's tidal Q (1977)
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    Publication Date: 2019-06-27
    Description: A recent estimate of tidal dissipation by turbulent viscosity in Jupiter's convective interior predicts that the current value of the planet's tidal Q is roughly 5 million. We point out a fundamental error in this calculation, and show that turbulent dissipation alone implies that at present Q is about 50 trillion. Our reduced estimate for the rate of tidal dissipation shows conclusively that tidal torques have produced only negligible modifications of the orbits of the Galilean satellites over the age of the solar system.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Feb. 197
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  • 237
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    Observations of Jupiter and Saturn at 5-8 micron (1977)
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    Publication Date: 2019-06-27
    Description: Moderate-resolution spectrophotometry (about 0.015) has shown the effects of known atmospheric constituents (NH3, CH4, C2H6) on the 5-8 micron spectrum of Jupiter. Broadband observations of Saturn at 6.5 micron are also reported.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Feb. 197
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  • 238
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    On the evolution of the lunar orbit (1977)
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    Publication Date: 2019-06-27
    Description: It is generally accepted that the earth-moon separation is at present increasing due to tidal dissipation. Values for the corresponding lunar deceleration and the related slowing of the earth's rotation are obtained from astronomical observations and studies of ancient eclipses. Extrapolation of these values leads to a close approach of the earth and moon 1-3 b.y. BP. Periodicities in the Precambrian stromatolites may yield the number of solar days in a lunar month prior to 500 m.y. BP. These data combined with dynamic constraints on the number of solar days in a lunar month indicate a close approach of the earth and moon at 2.85 plus or minus 0.25 b.y. BP. Mare volcanism on the moon and high-temperature Archean volcanism on the earth prior to this date may be due to tidal heating. Strong tidal heating during a close approach could have contributed to the formation of the first living organisms.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Feb. 197
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  • 239
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    Does application of the Rosiwal Principle to lunar soils require that concentrations of solar-wind-implanted species be grain-size independent (1977)
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    Publication Date: 2019-06-27
    Description: A reconsideration of the application of the Rosiwal Principle to lunar soils indicates a flaw in arguments put forth previously by Criswell (1975). Specifically, by introducing a boundary condition which must exist at the lunar surface, it is shown that concentrations of solar-wind-implanted species showing a dependence on grain size may be able to develop in soils at concentration levels below those required for saturation of grain surfaces. As a result, observed grain-size-dependent concentrations of solar-wind species in lunar soils do not necessarily require the exposure time scales or solar-wind fluxes deduced from the arguments of Criswell.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 34; 1, Fe; Feb. 197
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  • 240
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    Uranus occults SAO158687 (1977)
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    Publication Date: 2019-06-27
    Description: Experience gained in obtaining atmospheric parameters, oblatenesses, and diameters of Jupiter and Mars from recent stellar occultations by these planets is used to predict what can be learned from the March 1977 occultation of the star SAO158687 by Uranus. The spectra of this star and Uranus are compared to indicate the relative instrument intensities of the two objects, the four passbands where the relative intensities are most nearly equal are listed, and expected photon fluxes from the star are computed on the assumption that it has UBVRI colors appropriate for a K5 main-sequence object. It is shown that low photon noise errors can be achieved by choosing appropriate passbands for observation, and the rms error expected for the Uranus temperature profiles obtained from the occultation light curves is calculated. It is suggested that observers of this occultation should record their data digitally for optimum time resolution.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 265; Feb. 17
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  • 241
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    On the temperature dependence of possible S8 infrared bands in planetary atmospheres (1977)
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    Publication Date: 2019-06-27
    Description: The temperature dependence between 77 and 333 K of the infrared spectrum of cyclic S8 in the Jupiter atmosphere has been measured. It was found that the 23-micron Jovian feature (identified by Houck et al., 1975), if real, cannot be attributed to cyclic S8. Other features of S8, however, such as the band with a room-temperature central frequency of 835/cm may prove to be useful temperature calibrators in planetary or satellite spectra.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Jan. 197
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  • 242
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    Complex refractive index of Martian dust - Wavelength dependence and composition (1977)
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    Publication Date: 2019-06-27
    Description: The size distribution and complex refractive index of Martian dust-cloud particles observed in 1971 with the Mariner 9 UV spectrometer are determined by matching the observed single-scattering albedo and phase function with Mie-scattering calculations for size distributions of spheres. Values of phase function times single-scattering albedo are presented for 12 wavelength intervals in the range from 190 to 350 nm, and best-fit values are obtained for the absorption index. It is found that the absorption index of the dust particles increases with decreasing wavelength from 350 to about 210 nm and then drops off shortward of 210 nm, with a structural shoulder occurring in the absorption spectrum between 240 and 250 nm. A search for a candidate material that can explain the strong UV absorption yields TiO2, whose anatase polymorph has an absorption spectrum matching that of the Martian dust. The TiO2 content of the dust particles is estimated to be a few percent or less.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Jan. 197
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    Photochemistry of nitrogen in the Martian atmosphere (1977)
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    Publication Date: 2019-06-27
    Description: Models are developed for the photochemistry of a CO2-H2O-N2 atmosphere on Mars. Estimates are given for the concentrations of N, NO, NO2, NO3, N2O5, HNO2, HNO3, and N2O as a function of altitude. Nitric oxide is the most abundant form of odd nitrogen, present with a mixing ratio relative to CO2 of the order of 1 hundred-millionth. Deposition rates for nitrite and nitrate minerals could be as large as 300,000 N equivalent atoms per sq cm/sec under present conditions and may have been higher in the past.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Jan. 197
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  • 244
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    The equilibrium figures of Phobos and other small bodies (1977)
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    Publication Date: 2019-06-27
    Description: Computations of figures of hydrostatic equilibrium for isolated rotating bodies are discussed. It is shown that the theoretical figure of equilibrium for Phobos is a triaxial ellipsoid whose a and b axes differ by about 25% and that this difference is less than 2% for Deimos. A density of less than 3.9 g/cu cm is estimated for Phobos. Equilibrium figures are also examined for the inner satellites of Jupiter and Saturn as well as for small asteroids.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Jan. 197
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  • 245
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    Observations of NH3 in the atmosphere of Jupiter during 1973, 1974 (1977)
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    Publication Date: 2019-06-27
    Description: The 6450 A ammonia absorption band in the atmosphere of Jupiter was observed during the summers of 1973 and 1974. High-dispersion spectra of this band were obtained and analyzed on a line-by-line basis to derive ammonia abundances in the Jovian atmosphere. The abundances determined this way show strikingly large fluctuations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Jan. 197
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  • 246
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    The moment of inertia and isostasy of Mars (1977)
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    Publication Date: 2019-06-27
    Description: The systematic and large deviation of the gravitational equipotential surface (EPS) of Mars from a spheroid of revolution suggests a description of Mars in terms of a spheroid nearly in isostatic equilibrium with an extra mass in the Tharsis region. The displacement from Mars and the shape of the spheroid are calculated by using this description and a Mars gravity model. The EPS is represented as a contour map of its height above the spheroid. This representation provides the first clear demonstration that the Hellas depression coincides with a depression in the EPS. The disequilibrium contribution of Tharsis to the coefficient J2 of the second-degree harmonics of gravitational potential of Mars is estimated to be (126 + or - 5) times 10 to the minus 6th. The optical flattening and dynamic flattening calculated on this basis are in substantially better agreement than are those calculated in the usual way.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; Jan. 10
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  • 247
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    Chemical fractionations in meteorites. VIII - Iron meteorites and the cosmochemical history of the metal phase (1977)
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    Publication Date: 2019-06-27
    Description: The chemical composition of the metal phase of iron meteorites is traced through an idealized traditional history from condensation, oxidation, and accretion in the nebula to melting, segregation, and freezing in a parent body, considering the following fifteen elements: Au, Co, Cu, Fe, Ga, Ge, Ir, Mo, Ni, Os, Pd, Pt, Re, Rh, and Ru. Twelve iron meteorite groups resolved by Scott and Wasson (1975) are considered in the framework of cosmochemical historical analysis. The parent bodies of five of these groups seem to have had a traditional history. The others seem to have had more unusual histories. For example, the composition of the metal in group IVB matches that predicted for the metal condensate at 1270 K, implying accretion at high temperatures; and the metal in group IVA has a composition indicative of aggregates undergoing progressive stages of partial melting.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 41; Jan. 197
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  • 248
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    Axel dust on Saturn and Titan (1977)
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    Publication Date: 2019-06-27
    Description: The observed sharp drop in the geometric albedo of Titan shortward of 6000 A (also observed for Jupiter and Saturn) has been tentatively attributed to the presence of small absorbing particles referred to as Axel dust. The properties of Axel dust particles are studied, with the effect of scattering included through Mie theory, in an attempt to obtain a physically plausible set of parameters that properly characterizes the dust. Quantitative characteristics of the dust are described, scattering and absorption properties of various particle size distributions are calculated, and fits are made to observations of Titan and Saturn. It is found that: (1) a flat distribution of particle radii up to 0.1 micron and an imaginary part of the refractive index that varies as the -2.5 power of wavelength produce a good fit for Titan provided the extinction optical depth of the satellite's atmosphere is about 10 at 5000 A; (2) a clear layer of about 7 km-am hydrogen is required above the dust for a good fit to Saturn with the same dust properties; and (3) the inclusion of dust significantly increases the computed abundance of methane over the value given by reflecting-layer models.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Mar. 197
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  • 249
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    The extreme ultraviolet albedos of the planet Mercury and of the moon (1977)
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    Publication Date: 2019-06-27
    Description: The albedo of the moon in the far UV was measured by Mariner 10 at a solar phase angle of 74 deg, and the geometric albedo of Mercury was measured in same wavelength range (584-1657 A) at solar phase angles ranging from 50 to 120 deg. For both the moon and Mercury there is a general increase in albedo for wavelengths decreasing from 1657 to 584 A. The ratio of the albedos of Mercury and the moon increases from about 0.6 to 0.8 in the range 600-1600 A. This merely points to a difference in the surfaces of the moon and Mercury, there being insufficient data to make any conclusions regarding the nature of the difference.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; Feb. 10
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  • 250
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    Thermal metamorphism of primitive meteorites. III - Ten trace elements in Krymka L3 chondrite heated at 400-1000 C (1977)
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    Publication Date: 2019-06-27
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 41; Mar. 197
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    Pallasites - Metal composition, classification and relationships with iron meteorites (1977)
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    Publication Date: 2019-06-27
    Description: A comparative study was conducted of the metal composition of 34 pallasites in order to shed further light on the origin of these meteorites. Concentrations of Au, As, Co, Ga, Ge, Ir, Ni, and W in pallasitic metal were determined. Most pallasites are found to have similar compositions indicating a close genetic relationship, and are designated as main group. The Eagle Station Trio is unrelated to the main group as indicated by higher Ni, Ge, and Ir and lower As, Au, and Ga contents in the metal, and olivine richer in Fe and Sc and poorer in Mg and Mn. The trio of Springwater, Rawlinna and Phillips County have metal compositions appropriate to high-Ni main group members, but their fayalite contents suggest they are not closely related to it. Pavlodar and Glorieta Mountain appear to be unique pallasites, and Brenham an anomalous main group member. Krasnoyarsk is classified as a main group member. Main group pallasites have metal compositions which overlap those of IIIAB iron meteorites on a Ga-Ge plot, and they have similar Au, As, Cr, Ir, Ni and W contents to high-Ni IIIAB irons.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 41; Mar. 197
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    Planetary isophotes as a clue to aerosol characteristics (1977)
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    Publication Date: 2019-06-27
    Description: A study was made to see how much information could be extracted from the Mariner 9 Mars isophotes taken at phase angle roughly 60 deg. Minnaert functions and both isotropic and Rayleigh scattering could easily be ruled out, and it was essential to use forward-peaked phase functions computed from Mie theory. Isophotes similar to those observed are plotted assuming a semi-infinite dust cloud with a considerable variation in particle properties and size distribution, so long as the ratio of the multiply to singly scattered light is held within certain limits. These conditions are met by micron-sized, moderately absorbing mineral grains whose mean size should not be much larger than a micron. It was also found that a dust cloud of finite optical thickness bounded from below by a Lambert ground would fit the isophote data.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Feb. 197
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  • 253
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    de Sitter's theory flattens Jupiter (1977)
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    Publication Date: 2019-06-27
    Description: The discrepancy between values of Jupiter's dynamic oblateness as measured by space probes and via 1971 beta Sco occultations is re-examined. The indicated correction to the Io ephemeris is compared to corrections proposed by Aksnes and Franklin (1975, 1976). It is found that the latter corrections reduce the above discrepancy to a marginal level.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Feb. 197
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  • 254
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    Terrestrial analogs of the Hellespontus dunes, Mars (1977)
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    Publication Date: 2019-06-27
    Description: Geomorphic features in the Hellespontus region, Mars, were compared with dunes of the crescentic ridge type in numerous terrestrial sand seas quantitatively by dimensional analysis of dune lengths, widths, and wavelengths. Mean values for the Hellespontus dunes are close to mean values derived from measurements of all sampled terrestrial sand seas. Terrestrial analogs of form and areal distribution of the Hellespontus dunes are shown by comparison of scale ratios derived from the measurements. Dunes of similar form occur in South West Africa, in Pakistan, in the southeastern Arabian peninsula, in the Sahara, in eastern USSR and northern China, and in western North America. Terrestrial analogs closest to form and areal distribution of the Hellespontus dunes are in the Kara Kum Desert, Turkmen SSR, and in the Ala Shan (Gobi) Desert, China.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Feb. 197
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  • 255
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    Far-infrared spectral observations of Venus, Mars, and Jupiter (1977)
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    Publication Date: 2019-06-27
    Description: Spectra of Venus, Mars, and Jupiter between 45 and 115 micron have been obtained at a resolving power of about 10, observing from the NASA Lear Jet at an altitude of 13.7 km. The results are calibrated with lunar observations, and show Mars and Venus to have relatively constant brightness temperatures over this wavelength region, with Venus appearing somewhat warmer at longer wavelengths. The brightness temperature of Jupiter decreases slightly toward longer wavelengths.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 30; Feb. 197
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    Revised Pioneer 10 absolute electron intensities in the inner Jovian magnetosphere (1977)
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    Publication Date: 2019-06-27
    Description: Improved techniques for the analysis of Pioneer 10 Jupiter encounter data are used to obtain significantly more reliable values for energetic electron (Ee less than 21 MeV) intensities within the inner magnetosphere. The revised absolute intensities of electrons in the energy range 0.06-21 MeV are less than previous estimates by factors as great as 10 for L not exceeding 6. Previously published intensities at greater radial distances for Ee less than 21 MeV and at all radial distances for Ee greater than 21 MeV are not affected by the revisions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; Feb. 1
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  • 257
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    On deducing the magnetization of the lunar surface from orbital surveys (1977)
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    Publication Date: 2019-06-27
    Description: A combination of orbital photographic, selenochemical, and magnetic surveys may elucidate the mechanism by which the lunar surface became magnetized and possibly yield an estimate of the intensity of the ancient magnetizing field and its time variation. The determination of the size and shape of the magnetized regions requires the measurement of the altitude dependence of field, especially at low altitudes (less than 100 km) and with a high enough sampling rate to resolve the profile at the edges of magnetized bodies. The planned Lunar Polar Orbiter may well provide the necessary data.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Physics of the Earth and Planetary Interiors; 13; 4, Ja; Jan. 197
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  • 258
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    Can the ordinary chondrites have condensed from a gas phase (1977)
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    Publication Date: 2019-06-27
    Description: The conditions under which ordinary chondrites containing iron in three different chemical states can form in thermodynamic equilibrium with a gas phase are calculated. Hydrogen depletion factors of 100-1000 are obtained and the formation of liquid condensates from residual gases occurs at pressures (prior to hydrogen depletion) of roughly equal to or greater than 1 atm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 41; Feb. 197
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  • 259
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    Report of the Terrestrial Bodies Science Working Group. Volume 8: The comets (1977)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The determination of the nuclear and atmospheric properties of comets, and the interaction of the solar wind with the comet tail are scientific objectives for a mission to one or more comets in the next decade. Recommended priorities for direct cometary exploration are listed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-155181 , JPL-PUB-77-51-VOL-8
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    Report of the Terrestrial Bodies Science Working Group. Volume 9: Complementary research and development (1977)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Topics discussed include the need for: the conception and development of a wide spectrum of experiments, instruments, and vehicles in order to derive the proper return from an exploration program; the effective use of alternative methods of data acquisition involving ground-based, airborne and near Earth orbital techniques to supplement spacraft mission; and continued reduction and analysis of existing data including laboratory and theoretical studies in order to benefit fully from experiments and to build on the past programs toward a logical and efficient exploration of the solar system.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-155300 , JPL-PUB-77-51-VOL-9
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    Report of the Terrestrial Bodies Science Working Group. Volume 3: Venus (1977)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The science objectives of Pioneer Venus and future investigations of the planet are discussed. Concepts and payloads for proposed missions and the supporting research and technology required to obtain the desired measurements from space and Earth-based observations are examined, as well as mission priorities and schedules.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-155187 , JPL-PUB-77-51-VOL-3
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    Martian polar geological studies (1977)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Multiple arcs of rugged mountains and adjacent plains on the surface of Mars were examined. These features, located in the southern polar region were photographed by Mariner 9. Comparisons are made with characteristics of a lunar basin and mare; Mare imbrium in particular. The martian feature is interpreted to have originated in the same way as its lunar analog- by volcanic flooding of a large impact basin. Key data and methodology leading to this conclusion are cited.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-155160
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    Results of analyses performed on soil adjacent to penetrators emplaced into sediments at McCook, Nebraska, January 1976 (1977)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: During 1976 several penetrators (full and 0.58 scale) were dropped into a test site McCook, Nebraska. The McCook site was selected because it simulated penetration into wind-deposited sediments (silts and sands) on Martian plains. The physical and chemical modifications found in the sediment after the penetrators' impact are described. Laboratory analyses have shown mineralogical and elemental changes are produced in the sediment next to the penetrator. Optical microscopy studies of material next to the skin of the penetrator revealed a layer of glassy material about 75 microns thick. Elemental analysis of a 0-1-mm layer of sediment next to the penetrator revealed increased concentrations for Cr, Fe, Ni, Mo, and reduced concentrations for Mg, Al Si, P, K, and Ca. The Cr, Fe, Ni, and Mo were in fragments abraded from the penetrator. Mineralogical changes occurring in the sediment next to the penetrator included the introduction of micron-size grains of alpha iron and several hydrated iron oxide minerals. The newly formed silicate minerals include metastable phases of silica (cristobalite, lechatelierite, and opal). The glassy material was mostly opal which formed when the host minerals (mica, calcite, and clay) decomposed. In summary, contaminants introduced by the penetrator occur up to 2 mm away from the penetrator's skin. Although volatile elements do migrate and new minerals are formed during the destruction of host minerals in the sediment, no changes were observed beyond the 2-mm distance. The analyses indicate 0.58-scale penetrators do effectively simulate full-scale testing for soil modification effects.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TN-D-8500 , A-6907
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    Viking 75 project: Viking lander system primary mission performance report (1977)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Viking Lander hardware performance during launch, interplanetary cruise, Mars orbit insertion, preseparation, separation through landing, and the primary landed mission, with primary emphasis on Lander engineering and science hardware operations, the as-flown mission are described with respect to Lander system performance and anomalies during the various mission phases. The extended mission and predicted Lander performance is discussed along with a summary of Viking goals, mission plans, and description of the Lander, and its subsystem definitions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-145148 , FR-3770219
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    IPL Processing of the Viking Orbiter Images of Mars (1977)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The Viking orbiter cameras returned over 9000 images of Mars during the 6-month nominal mission. Digital image processing was required to produce products suitable for quantitative and qualitative scientific interpretation. Processing included the production of surface elevation data using computer stereophotogrammetric techniques, crater classification based on geomorphological characteristics, and the generation of color products using multiple black-and-white images recorded through spectral filters. The Image Processing Laboratory of the Jet Propulsion Laboratory was responsible for the design, development, and application of the software required to produce these 'second-order' products.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; 28; 4189-4202
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    Martian Dynamical Phenomena During June-November 1976: Viking Orbiter Imaging Results (1977)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A summary is presented of the orbital imaging observations of dynamical phenomena on Mars during the Viking primary mission. Clouds in the Tharsis/Amazonis regions are examined and the observation of an area of unusually high brightness to the southwest of Arsia Mons is considered. Attention is given to clouds and surface frost in the south polar region, the north polar cap, and aspects of dust storm activity.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; 28; 4121-4149
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    Geology of the Valles Marineris - First Analysis of Imaging from the Viking 1 Orbiter Primary Mission (1977)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The Valles Marineris on the planet Mars constitute an enormous group of steep-walled equatorial canyons extending over an area more than 4000 km long and up to 700 km wide. An overview of Valles Marineris is provided, taking into account canyon system subdivisions, imaging and topographic data, Noctis Labyrinthus, western troughs, central troughs, east central troughs, and eastern canyons. Aspects of canyon wall and canyon floor morphology are discussed, giving attention to erosional features, layered rocks in canyon walls, tectonic features, plains, landslide deposits, hilly terrain, fractured floor, and floor plateaus and ridges. Upland pits and closed depressions in the canyons are considered along with regional tectonics and regional erosional styles.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; 28; 4067-4091
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    Viking Imaging of Phobos and Deimos: An Overview of the Primary Mission (1977)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: During the Viking primary mission the cameras on the two orbiters acquired about 50 pictures of the two Martian moons. The Viking images of the satellites have a higher surface resolution than those obtained by Mariner 9. The typical surface resolution achieved was 100-200 m, although detail as small as 40 m was imaged on Phobos during a particularly close passage. Attention is given to color sequences obtained for each satellite, aspects of phase angle coverage, and pictures for ephemeris improvement.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; 28; 4203-4211
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    Viking Orbiter Observations of Atmospheric Opacity During July-November 1976 (1977)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Viking orbiter photography during the primary mission combined with lander indications of surface properties have permitted the estimation of atmospheric optical depths and phase functions. Highly variable time of day opacities ranging from 0.05 to 0.6 are seen to occur in three principle regions. A wavelength-dependent particulate component plus a time variable grey aerosol of higher density may explain these opacities versus time of day. These data should serve as a basis for extended mission comparisons.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; 28; 4151-4159
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    Viking Observations of Phobos and Deimos: Preliminary Results (1977)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The improved resolution of the Viking images has led to the discovery of a number of unusual surface features on Phobos. The features include elongated rill-like depressions associated with the crater Stickney, chains and clusters of irregular elongated craters, and linear striations or grooves. Crater counts are also considered. A total of 27 craters ranging in size from 0.3 to 1.4 km are visible on the best Deimos frame available. Craters ranging from 50 m to 4.9 km in diameter can be observed on the best of the Phobos images.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; 28; 4213-4223
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    Mars: Water Vapor Observations from the Viking Orbiters (1977)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The global distribution of the water vapor has been mapped at low resolution throughout the period from the northern summer solstice to the following equinox. During this seasonal period the water vapor underwent a gradual redistribution, the latitude of maximum column abundance moving from the northern polar area to the equatorial latitudes. The total global vapor content remained approximately constant at the equivalent of about 1.3 cu km of ice. The various data obtained indicate that the residual polar caps are composed of water ice.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; 28; 4225-4248
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    A Study of Variable Features on Mars During the Viking Primary Mission (1977)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The Viking coverage revealed numerous wind streaks on the surface of Mars. The Viking images have provided the first good examples of very distinctive mixed tone streaks which appear to consist of a tapered light streak bordered by two dark side lobes. Attention is given to a general lack of eolian activity, eolian activity on the slopes of the Tharsis volcanos, spectacular albedo changes since 1972, more subtle albedo changes, surface detail and wind flow patterns in Hellas, wind flow in the vicinity of Olympus Mons, and a comparison of the 1972 and 1976 wind streak patterns.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; 28; 4167–4188
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    Classification and time of formation of Martian channels based on Viking data (1977)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The reported evaluation of Martian channel characteristics is based on Viking photographs taken from July 1976 to February 1977. The wide variation in crater densities shown by the considered Martian channels strongly implies widely differing ages for both fluviatile and lava channels. Attention is given to age determination methodology, a description of channels and implications for channel formation, surface water under present Martian conditions, surface water under more favorable Martian conditions in the past, channel parameter estimates, and volcanic channels.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; 28; 4016-4038
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    Thermal and Albedo Mapping of Mars During the Viking Primary Mission (1977)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The behavior of Mars as observed by the Viking infrared thermal mapper (IRTM) is considered. The IRTM is a 28-channel, 4-telescope radiometer that operated in six spectral bands. The studies considered include observations from the interplanetary phase through data collection on November 7, 1976. During this interval, thermal mapping of the whole Martian surface has been possible. Attention is given to polar temperatures, global albedos, predawn temperatures, a thermal inertia contour map, geometry considerations, clouds, aspects of predawn warming, and observations of earth.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; 28; 4249-4291
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    Lunar surface chemistry - A new imaging technique (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Detailed chemical maps of the lunar surface have been constructed by applying a new weighted-filter imaging technique to Apollo 15 and Apollo 16 X-ray fluorescence data. The data quality improvement is amply demonstrated by (1) modes in the frequency distribution, representing highland and mare soil suites, which are not evident before data filtering, and (2) numerous examples of chemical variations which are correlated with small-scale (about 15 kilometer) lunar topographic features.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 197; Sept. 2
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    Azimuthal brightness variations of Saturn's rings. II - Observations at an intermediate tilt angle (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The brightness variation in Saturn's ring A with orbital phase of the ring particles increases in amplitude as the declination of earth decreases from 26 to 16 deg. The amplitude of this azimuthal effect also appears to diminish at opposition. There is an indication that the effect decreases with decreasing wavelength, and hence with decreasing particle albedo.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal; vol. 216
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    Volatile/mobile trace elements in Karoonda /C4/ chondrite (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Concentrations of ten volatile/mobile trace elements and of nonvolatile Co in the Karoonda (C4) meteorite were determined, and the atomic abundances relative to C1 are compared with values for the Murchison (C2) and Allende (C3) meteorites. Empirical Bi, In, and Tl data for Karoonda and heated Allende and Murchison are compared with theoretical curves for condensation from a gas of cosmic composition at low pressures. It is suggested that Karoonda might derive from low-temperature open-system metamorphism of pristine C3-like material.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 41; Sept
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    The structure of the planets Jupiter and Saturn (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Planetary models for Jupiter and Saturn are computed using a fourth-order theory and an equation of state for the molecular hydrogen and helium planetary envelopes taken from the Monte Carlo calculations of Slattery and Hubbard (1976). Models for Jupiter are found that have a small amount of heavy elements either mixed with hydrogen and helium throughout the interior of the planet or concentrated in a small dense core. Saturn is modeled with a solar-composition hydrogen and helium envelope and a small dense core. It is concluded that the molecular equation of state linked with suitable interior equations of state can produce Jovian models which satisfy the observational data. The planetary models show that the enrichment of heavy elements (relative to solar composition) is approximately 3 times for Jupiter and 10 times for Saturn.
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    Type: Icarus; 32; Sept
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    Venus - On the phase variation of CO2 line profiles (1977)
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    Publication Date: 2019-06-27
    Description: The shapes of Venus' CO2 profiles are found to vary with solar phase angle. High-resolution spectra of the P16 and P14 lines in the 8689- and 7820-A bands, respectively, are presented for phase angles ranging from 6 to 158 deg. The scattering mean free path at 80 mbar, approximately the effective pressure, is 1.7 km. Use of the van de Hulst (1974) similarity relations with simple parametric scattering models is inadequate to separate effects due to the scattering phase function from those due to inhomogeneities in depth when one attempts to determine the atmospheric structure by fitting a family of such models over a wide range of phase angles.
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    Type: Icarus; 32; Sept
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    Mercury's core - The effect of obliquity on the spin-orbit constraints (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Constraints were previously placed on various properties of a Mercurian liquid core for compatibility with Mercury's escape from the stable spin-orbit resonance with the spin angular velocity equal to twice the orbital mean motion (the 2n resonance), under the assumption that the planet's obliquity was nearly zero at the time of resonance passage. Capture probabilities at arbitrary nonzero obliquities for the 2n resonance are determined for the cases where the core is strongly or weakly coupled to the mantle. It is found that the capture probabilities are reduced to below unity for all core-fluid viscosities in the weak-coupling limit, but are almost unchanged in the strong-coupling limit. The reduction in capture probability is attributed to reduction of the mantle's spin angular velocity by the core-mantle interaction, which would also reduce the obliquity to negligibly small values before the 2n resonance was even reached. It is concluded that the constraints on the core may still be maintained since Mercury most likely passed through the 2n resonance with nearly zero obliquity.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; Aug. 10
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    The moon's permanent magnetic field - A cratered-shell model (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The possibility is considered that the properties of the larger-scale lunar magnetic field may depend in a rather straightforward manner on the geometrical properties of the distribution of larger craters. The relevant effects of cratering are analyzed in the framework of a model of a spherically symmetric shell magnetized to some specific intensity by a concentric dipolar magnetic field. The remanent dipole moment of the model is determined by calculating the dipole moment of the material removed to form craters and them computing the remanent dipole moment for three mutually orthogonal orientations of the magnetizing dipole. The resulting absolute values for the remanent dipole moment are found to be comparable to the upper limit of 10 to the -19th power G-cu cm estimated from Apollo subsatellite measurements. It is concluded that for a crust with an empirically reasonable mean magnetization, the craters can account for a dipole moment as great as that indicated by the estimated upper limit.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: The Moon; 16; May 1977
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    Analysis of the occultation of Epsilon Geminorum by Mars (1977)
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    Publication Date: 2019-06-27
    Description: High-time-resolution photoelectric measurements of the occultation of Epsilon Gem by Mars were obtained with the 36-in. telescope at Goddard Space Flight Center. Temperature profiles as a function of number density have been determined by inverting the immersion and emersion light curves on the assumption of a pure CO2 atmosphere. For number densities between 10 to the 13th and 10 to the 15th power per cu cm, the temperature varies in a wavelike fashion about a mean value near 150 K. These temperature profiles agree well with those derived from airborne observations by Elliot et al. (1977), indicating that the atmospheric features producing the excursions in the temperature profiles extend for at least 100 km along the Martian limb.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal; 82; July 197
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    Are striations on Phobos evidence for tidal stress (1977)
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    Publication Date: 2019-06-27
    Description: A series of striations or grooves over a great part of the surface of Phobos, the inner satellite of Mars, can be observed on Viking orbiter photographs. It is suggested that some of these features are related to a readjustment of the satellite's figure with increasing tidal stress as the orbit evolves inwards under the action of tidal friction. If the width of the grooves is in fact due to tidal readjustments of the figure of Phobos, then the older craters should be systematically deformed from their initial nearly circular shapes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 268; Aug. 4
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    Io's sodium emission profiles - Variations due to Io's phase and magnetic latitude (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: We present recent measurements of high-resolution sodium D2 emission line profiles of Io's atmosphere and cloud. The high-velocity skirts of these profiles are strongest when Io is on the magnetic equator where protons and heavy ions, which sputter atoms from Io's surface, are concentrated. The skirts are most prominent on the long-wavelength side of the line when Io is west of Jupiter, and they are most prominent on the short-wavelength side of the line when Io is east of Jupiter. Our observations also indicate that there is a shift in the emission peak with respect to Io which is correlated with Io's orbital phase angle.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal; vol. 215
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    Origin of organic matter in the early solar system. VII - The organic polymer in carbonaceous chondrites (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Degradation techniques, including pyrolysis, depolymerization, and oxidation, were used to study the insoluble polymer from the Murchison C2 chondrite. Oxidation with Cr2O7(2-) or O2/UV led to the identification of 15 aromatic ring systems. Of 11 aliphatic acids identified, three dicarboxylic acids presumably came from hydroaromatic portions of the polymer, whereas eight monocarboxylic acids probably derive from bridging groups or ring substituents. Depolymerization with CF3COO4 yielded some of the same ring systems, as well as alkanes (C1 through C8) and alkenes (C2 through C8), alkyl (C1 through C5) benzenes and naphthalenes, and methyl- or dimethyl -indene, -indane, -phenol, -pyrrole, and -pyridine. All these compounds were detected below 200 C, and are therefore probably indigenous constituents. The properties of the meteoritic polymer were compared with the properties of a synthetic polymer produced by the Fischer-Tropsch reaction. It is suggested that the meteoritic polymer was also produced by surface catalysis.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 41; Sept
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    Combined position and diameter measures for lunar craters (1977)
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    Publication Date: 2019-06-27
    Description: The note addresses the problem of simultaneously measuring positions and diameters of circular impact craters on wide-angle photographs of approximately spherical planets, such as the moon and Mercury. The method allows for situations in which the camera is not aligned on the planet's center.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 32; Sept
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    Recovery of the mean Jovian temperature structure from inversion of spectrally resolved thermal radiance data (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 32; Sept
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    Internal structure and properties of Mars (1977)
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    Publication Date: 2019-06-27
    Description: Theoretical physical models of the Martian interior are presented in the light of recent and revised data and constraints. These models include thermal evolution, densities, and seismic-wave velocities. The interior of Mars appears to be earthlike in many respects. Although thermal models indicate that Mars has passed its peak of evolution, it may still have an asthenosphere and may be moderately active tectonically. Mars has an Fe-FeS core with a radius of 1500-2000 km. The mantle is enriched in FeO with an olivine composition of about Fo75. Theoretically determined seismic-wave velocities are relatively well constrained in the mantle, with upper-mantle P-wave velocities ranging from 7.64 to 7.80 km/sec. However, there are wide variations in P-wave velocity in the core, dependent on composition. The shadow zone due to the core is larger than earth's.
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    An improved Venus cloud model (1977)
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    Publication Date: 2019-06-27
    Description: An inhomogeneous cloud model for Venus is presented in which a (transparent) sulfuric acid aerosol extends above the tropopause, but an (absorbing) sulfur aerosol consisting of much larger particles does not. It is shown that the temperature dependence of the absorption spectrum of sulfur, combined with the lapse rate in the planet's atmosphere, can explain the color of Venus. A simple 'black-white' radiative-transfer model is developed, the spectral reflectance of the cloud model is computed for the 60-km level in Marov's (1972) model atmosphere, and strong evidence is obtained that sulfur is the UV absorber on Venus. The wavelength variation of contrast in UV cloud features is analyzed, and absorption is found to increase with depth at every wavelength due to the inward increase in temperature. The black-white model is applied to CO2 absorption, variations in CO2 and UV absorption with phase angle are compared, and line profiles are calculated for pressure-broadened CO2 lines. The theoretical results are compared with Venera 9 and 10 data.
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    Soft electrons as a possible heat source for Jupiter's thermosphere (1977)
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    Publication Date: 2019-06-27
    Description: The 850 K exospheric temperature inferred for Jupiter from the radio-occultation experiments on Pioneers 10 and 11 is shown to imply a heat input of 0.25-0.5 erg/sq cm/sec. One possible source of this energy is precipitation of electrons from a warm plasma (temperature corresponding to energies of the order of 30-500 eV). A mechanism is suggested wherein the presence of this plasma can be accounted for by centrifugal acceleration and adiabatic compression of ionospheric electrons and protons. Present ideas of the source strength of ionospheric plasma, however, give heating rates that are too small by one to two orders of magnitude, although inferences from direct plasma measurements suggest that the required plasma is indeed present.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Planetary and Space Science; 25; Sept
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  • 291
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    Io's surface composition - Observational constraints and theoretical considerations (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Observations of line emission from neutral and ionic species in the Io-surrounding cloud, reflectance studies and theoretical considerations suggest Io's surface is unlike that of any other body in the solar system. The cloud has a peculiar composition which we show is probably not due to cloud/surface fractionation. Io's surface may be largely covered with an endogenically produced mixture of S and dehydrated salts, or by accretion-fractionated compounds modified by charge particle bombardment.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 4; Aug. 197
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  • 292
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    Plagioclase flotation and lunar crust formation (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Anorthitic plagioclase floats in liquids parental to the lunar highlands crust. The plagioclase enrichment that is characteristic of lunar highlands rocks can be the result of plagioclase flotation. Such rocks would form a gravitationally stable upper crust on their parental magma.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geology; 5; July 197
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  • 293
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    The composition of carbonaceous chondrite matrix (1977)
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    Publication Date: 2019-06-27
    Description: Matrix compositions of 32 of the approximately 40 known carbonaceous chondrites were analyzed using an electron probe defocussed-beam technique. Except in those chondrites that show evidence of metamorphism, matrices are compositionally similar and have correlation coefficients of +0.96 or greater. The implications of these analyses for the chemistry of individual matrix phases and for primitive solar system material are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 41; Aug. 197
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  • 294
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    Correlated O and Mg isotopic anomalies in Allende inclusions. II - Magnesium (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Large isotopic fractionation effects in magnesium were observed in three Allende inclusions. Two of the samples show a correlation between Mg and O isotopic anomalies and indicate possible nuclear effects in Mg.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 4; July 197
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  • 295
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    Computer simulations of planetary accretion dynamics - Sensitivity to initial conditions (1977)
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    Publication Date: 2019-06-27
    Description: A computer simulation program which generates mature planetary systems using only Newtonian physics and accretion with unit sticking efficiency is examined. The dependence of the simulation on a variety of radial and vertical density distribution laws, on the ratio of gas to dust in the solar nebula, on the total nebular mass, and on the orbital eccentricity of the accreting grains is explored. To approach physically realistic models, these parameters are altered according to various empirically- and theoretically-suggested criteria. The program is found to generate many recognizable planetary systems, including multiple-star systems with accompanying planets; single stars surrounded only by asteroids; and systems with large Jovian planets, planets similar to Pluto, or objects of asteroidal mass, as well as the usual terrestrial planets. Planetary spacing in the simulation obeys a relation of the Titius Bode variety; in general, the number of planets per system is inversely proportional to the orbital eccentricity. Some reservations about the simulation program are expressed; however, it does support the idea of abundant and diverse planetary systems throughout the galaxy.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 31; Aug. 197
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  • 296
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    The effects of the atmospheric point-spread 'seeing' function on spatially resolved spectra of Jupiter (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: We present the results of an analysis of the effects of atmospheric seeing and of instrumental spectral and spatial resolution on the observed variation of absorption-line profiles across the disk of Jupiter. The technique described may be applied equally well to the analysis of observations of any extended astronomical source. These results show the necessity of obtaining accurate point-spread-function information during the course of observations of this nature. We also point out that in order to avoid the uncertainties and ambiguities inherent in attempts at deconvolution of observational data, one must properly convolve the appropriate spatial and spectral resolution functions with the models being tested and then compare the results with the observational data.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal; vol. 217
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  • 297
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    Behavior of volatiles in Mars' polar areas - A model incorporating new experimental data (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A model has been developed to explain the north polar water vapor results obtained by the Viking orbiter Mars atmospheric water detector; it has also been used to compute the thickness of seasonally deposited CO2 frost, the variation of the total atmospheric pressure, and wind velocities due to mass motions associated with CO2 condensation. A north polar water ice thickness in excess of 1 m and an ice albedo a of 0.34(+0.06,-0.03) are inferred from a comparison of the model and experimental data. The model results confirm an earlier conclusion that the atmosphere over the ice is saturated. It is suggested that concentration of the atmospheric inert gases in the polar region, combined with local topography and arctic circulation patterns, could be responsible for the south remnant cap not being at the south pole
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; Sept. 10
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  • 298
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    Mass fractionation of the lunar surface by solar wind sputtering (1977)
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    Publication Date: 2019-06-27
    Description: An investigation is conducted concerning the mass-fractionation effects produced in connection with the bombardment of the moon by the solar wind. Most of the material ejected by sputtering escapes the moon's gravity, but some returning matter settles back onto the lunar surface. This material, which is somewhat richer in heavier atoms than the starting surface, is incorporated into the heavily radiation-damaged outer surfaces of grains. The investigation indicates that sputtering of the lunar surface by the solar wind will give rise to significant surface heavy atom enrichments if the grain surfaces are allowed to come into sputtering equilibrium.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; Sept. 10
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  • 299
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    A determination of the L dependence of the radial diffusion coefficient for protons in Jupiter's inner magnetosphere (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: In a previous paper (Thomsen et al., 1977), a technique was proposed for estimating the radial diffusion coefficient (n) in the inner magnetosphere of Jupiter from the observations of the sweeping effect of the inner Jovian satellites on the fluxes of the energetic charged particles. The present paper extends this technique to permit the unique identification of the parameters D sub O and n, where the diffusion coefficient is assumed to be of the form D = D sub O L to the nth. The derived value of D sub O depends directly on assumptions regarding the nature and efficiency of the loss mechanism operating on the particles, while the value of n depends only on the assumed width of the loss region. The extended technique is applied to the University of Iowa Pioneer 11 proton data, leading to values of n of about O and D(6) of about 3 x 10 to the -8th (R sub J)-squared/sec, when satellite sweepup losses are assumed to be the only loss operating on the protons. The small value of n is strong evidence that the radial diffusion is driven by ionospheric winds.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 82; Sept. 1
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    The nature of the gravity anomalies associated with large young lunar craters (1977)
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    Publication Date: 2019-06-27
    Description: The negative Bouguer anomalies (i.e., mass deficiencies) associated with four young lunar craters are analyzed. Model calculations based on generalizations made from studies of terrestrial impact structures suggest that the major contribution to the Bouguer anomaly for these lunar craters is due to a lens of brecciated material confined within the present crater rim crest and extending vertically to at least a depth of one-third the crater rim diameter. Calculations also reveal a systematic variation in the magnitude of the mass deficiencies with the cube of the crater diameter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 4; Sept
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