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  • 1
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    Happy Canyon - A new type of enstatite achondrite (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Mineralogical and chemical characteristics of the Happy Canyon meteorite, found in 1971 near Wayside, Texas, show it to be a new type of enstatite achondrite occupying the gap between the recrystallized enstatite chondrites and the igneous, crystalline, unbrecciated enstatite chondrites. Although the bulk composition of the specimen is consistent with that of an E6 enstatite chondrite, it has a crystal cumulate texture. There are minor amounts of metal and troilite which have survived extensive weathering. The Happy Canyon meteorite may represent an E6 composition which has melted and reprecipitated at a slightly higher oxidation state, possibly in the core of a small parent body.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics; 12; June 30
    Format: text
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  • 2
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    Saturn's microwave spectrum: Implications for the atmosphere and the rings (1978)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Measurements of Saturn's disk temperature are compiled to determine the planet's microwave spectrum from 1 mm to 100 cm wavelength. The data were adjusted to conform with a common flux density scale. A model of Saturn's rings is used to remove the effects of the rings from the atmospheric component at centimeter and decimeter wavelengths. Theoretical spectra for a number of convective atmospheric models were computed and compared with the observed spectrum. Radiative-convective models with approximately solar composition and with an effective temperature of approximately 89 K are in good agreement with the observations. The agreement between the observed and theoretical spectra is a strong indication that gaseous ammonia is present in Saturn's atmosphere. A good fit to the data is obtained with an ammonia mixing ratio of approximately 5 x 10,0001. A comparison of the millimeter wavelength data with the best-fitting atmospheric spectrum indicates that the thermal component of the ring brightness temperature near 1 mm wavelength is approximately 25 k.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Its The Saturn System; p 195-216
    Format: application/pdf
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  • 3
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    Distribution and significance of chromium in meteorites (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Chromium is present as a minor element in all meteorite types. Depending on the meteorite type it is lithophile (most frequent), chalcophile (less frequent), or siderophile (rare). Chromium is an indicator of physical and chemical conditions of meteorite formation, especially of the state of oxidation. The Cr contents of meteoritic chromites are related to classification and can be used to distinguish among meteorite types that contain this mineral. The distribution of Cr between coexisting pyroxenes may indicate the degree of equilibration of this mineral pair. Siderophile Cr appears to result from primitive condensation processes rather than secondary reduction processes. The lack of much experimental data on Cr in silicate systems limits the interpretation of the occurrences of Cr-silicate phases, ureyite and krinovite, in the meteorite type in which they occur.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 4
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    Silicon in carbonaceous chondrite metal - Relic of high-temperature condensation (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Electron microprobe analyses of an extraordinarily large metal grain from the Murchison type 2 carbonaceous chondrite gave 0.24 mole % silicon. Thermodynamic calculations show that this is a natural consequence of condensation of alloys from the solar nebular gas at a total pressure between 10 to the -5th and 10 to the -3rd atm, provided they failed to equilibrate with it after cooling to less than 1200 K
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 206; Oct. 26
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  • 5
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    On the origin of isolated olivine grains in type 2 carbonaceous chondrites (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Two possibilities exist for the origin of aggregates and isolated grains in C2 meteorites: (1) high-temperature phases that condensed directly from a solar nebular gas accumulated as aggregates and single grains on the parent bodies of carbonaceous chondrites and remained unaltered since, or (2) all high-temperature phases in these meteorites are now, or once were, insided chondrules and have been melted out. Petrographic evidence for these two alternative models is examined critically. Four different scenarios to account for the kinds of aggregates and isolated grains in the Murchison C2 meteorite are studied. It is concluded that the majority of isolated olivine grains in the matrix never underwent melting in a chondrule-making stage. These crystal fragments and aggregates can thus be accounted for by direct condensation from a solar nebular gas.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 41; 2, Oc; Oct. 197
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  • 6
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    Venus - Detection of variations in stratospheric carbon monoxide (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The reported observations of the J = 0-1 rotational transition (115271.2 MHz) of carbon monoxide in the Venusian atmosphere indicate that the distribution of stratospheric CO is variable. Observations were obtained with a 11-m antenna on several days in February 1977, when Venus was near maximum eastern elongation (k approximately 0.4), and in April 1977 during inferior conjunction (k approximately 0.01). Differences in the line intensities and shapes for the two data sets are described. The results are interpreted to suggest that on the nightside of Venus there is relatively more CO at higher altitudes and relatively less CO at lower altitudes than on the dayside of the planet.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: In: Symposium on Planetary Atmospheres; Aug 16, 1977 - Aug 19, 1977; Ottawa; Canada
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  • 7
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    Eleven new meteorites from Antarctica, 1976-1977 (1978)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Basic petrographic, mineralogic, and chemical descriptions are given for all eleven meteorites recovered by the U.S.-Japan team in Antarctica during the austral summer 1976-1977. The meteorites are: Mt. Baldr a (H6), Mt. Baldr b (H6), Allan Hills 1 (L6), Allan Hills 2 (coarsest octahedrite, chemical group IA), Allan Hills 3 (L6), Allan Hills 4 (LL3), Allan Hills 5 (eucrite), Allan Hills 6 (H6), Allan Hills 7 (L6), Allan Hills 8 (H6), and Allan Hills 9 (L6).
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics; 13; June 30
    Format: text
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  • 8
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    Evidence for the depletion of ammonia in the Uranus atmosphere (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The theoretical disk brightness temperature spectra for Uranus are computed and compared with the observed microwave spectrum. It is shown that the emission observed at short centimeter wavelengths originates deep below the region where ammonia would ordinarily begin to condense. We demonstrate that this result is inconsistent with a wide range of atmospheric models in which the partial pressure of NH3 is given by the vapor-pressure equation in the upper atmosphere. It is estimated that the ammonia mixing ratio must be less than 10 to the minus 6 in the 150 to 200 K temperature range. This is two orders of magnitude less than the expected mixing ratio based on solar abundances. The evidence for this depletion and a possible explanation are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 34; Apr. 197
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  • 9
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    A measurement of the brightness temperature of Saturn's rings at 8-mm wavelength (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The brightness temperature of Saturn's rings has been measured at 8-mm wavelength using a millimeter-wavelength interferometer. A ring brightness temperature of 12.7 + or -2 K is obtained with the assumption that the rings are of uniform brightness and the region of emission coincides with the visible A and B rings. This result is higher than comparable results obtained at centimeter wavelengths and may indicate a small increase in the thermal emission from the rings at 8 mm. The low brightness temperature places significant constraints on the nature of the ring particles and implies that they must be either highly metallic or of limited size and composed of a low-loss dielectric material such as water ice.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 33; Feb. 197
    Format: text
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