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  • Chemistry  (16)
  • LUNAR AND PLANETARY EXPLORATION  (14)
  • AERODYNAMICS  (5)
  • 1980-1984  (20)
  • 1975-1979  (12)
  • 1925-1929  (3)
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  • 1
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    Interstellar organic matter in meteorites (1983)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: Deuterium-enriched hydrogen is present in organic matter in such meteorites as noncarbonaceous chondrites. The majority of the unequilibrated primitive meteorites contain hydrogen whose D/H ratios are greater than 0.0003, requiring enrichment (relative to cosmic hydrogen) by isotope exchange reactions taking place below 150 K. The D/H values presented are the lower limits for the organic compounds derived from interstellar molecules, since all processes subsequent to their formation, including terrestrial contamination, decrease their D/H ratios. In contrast, the D/H ratios of hydrogen associated with hydrated silicates are relatively uniform for the meteorites analyzed. The C-13/C-12 ratios of organic matter, irrespective of D/H ratio, lie well within those observed for the earth. Present findings suggest that other interstellar material, in addition to organic matter, is preserved and is present in high D/H ratio meteorites.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 47; 2199-221
    Format: text
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  • 2
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    Saturn's rings - 3-mm observations and derived properties (1980)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Three-millimeter Saturn observations, obtained from 1965 through 1977 and with Jupiter as a reference, have been used to derive a ring brightness temperature of 18 + or - 8 K. The brightness temperature of the disk of Saturn is 156 + or - 9 K. Part of the ring brightness (approximately 6 K) may be accounted for as disk emission which is scattered from the rings; the remainder (12 + or - 8K) is attributed to ring particle thermal emission. Because this thermal component brightness temperature is so much less than the particle physical temperature, limits are placed on the mean size and composition of the ring particles. In particular, as found by others, the particles cannot be rocky, but must be either metallic or composed of extremely low-loss dielectric material such as water ice. If the particles are pure water ice, for example, then a simple slab model and a multiple-scattering model both give upper limits to the particle sizes of approximately 1 m, a value three times smaller than previously available. The multiple-scattering model gives a particle single-scattering albedo at 3 mm of 0.83 + or - 0.13.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Icarus; 41; Jan. 198
    Format: text
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  • 3
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    Millimeter-wave studies of the surfaces of Mercury and Mars and the atmosphere of Venus (1983)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: Disk average brightness temperatures of Mercury were obtained using a 4.6 m radio telescopes. The data was searched for periodicities which correlate with phase angle, hermocentric longitude and beat frequencies produced by modulations of various celestial mechanical parameters. Spectral line observations were made of Venus with the NRAO 11 m radio telescope. The total CO content and the CO vertical profile, and their variability were observed. Large scale thermophysical properties of the surface of Mars were studied.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: NASA-CR-169867 , NAS 1.26:169867
    Format: application/pdf
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  • 4
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    Carbon, hydrogen and nitrogen isotopes in solvent-extractable organic matter from carbonaceous chondrites (1982)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: CCl4 and CH3OH solvent extractions were performed on the Murray, Murchison, Orgueil and Renazzo carbonaceous chondrites. Delta-D values of +300-+500% are found in the case of the CH3OH-soluble organic matter. The combined C, H and N isotope data makes it unlikely that the CH3OH-soluble components are derivable from, or simply related to, the insoluble organic polymer found in the same meteorites. A relation between the event that formed hydrous minerals in CI1 and CM2 meteorites and the introduction of water- and methanol-soluble organic compounds is suggested. Organic matter soluble in CCl4 has no N, and delta-C-13 values are lower than for CH3OH-soluble phases. It is concluded that there either are large isotopic fractionations for carbon and hydrogen between different soluble organic phases, or the less polar components are partially of terrestrial origin.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Geochimica et Cosmochimica Acta; 46; Jan. 198
    Format: text
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  • 5
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    The concentration and isotopic composition of hydrogen, carbon and nitrogen in carbonaceous meteorites (1982)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: Stepwise pyrolysis was used to extract H2, N2 and C from powdered meteorites and from meteorite residues resulting from partial dissolution in aqueous HF or from reaction with HF-HCl solutions. Concentrations and isotopic compositions were determined for the cases of the carbonaceous chondrites Orgueil, Murray, Murchison, Renazzo and Cold Bokkeveld. Acidification of the meteorites removed the organic sources of H2, so that H2 in the HF-HCl acid residues came mostly from the insoluble organic matter making up 70-80% of the total carbon in carbonaceous meteorites. Good correlation is found between delta-D and the concentration of H2 in the acid residues, but no correlation exists between the delta-D, delta-C-13 and delta-N-15 in them. A model is proposed for both the high delta-D values and the relationship between those values and the H2 concentration.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Geochimica et Cosmochimica Acta; 46; Jan. 198
    Format: text
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  • 6
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    Relic interstellar grains in Murchison meteorite (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: It is shown that, in the Murchison meteorite, the D/H ratios of hydrogen are unusually high in several separates and in one case up to 30 times the cosmic value of 2 x 10 to the -5th. Many phases show high C-13/C-12 ratios, up to 2.5 times the terrestrial value of 0.011. These C-13-rich and D-rich components of the two chemical elements are not correlated. They are heterogeneously distributed, suggesting that different components in the meteorite originated from different astrophysical sites and at different times. The D-rich hydrogen in the meteorite is probably due to molecules formed by ion-molecule reactions in interstellar clouds while the tiny amount of C-13-rich carbon is probably due to nucleosynthesis in red giant stars as suggested by Swart et al. (1983). Both of these heavy-isotope enriched components survived homogenization in the accumulation and subsequent history of the meteorites.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Nature (ISSN 0028-0836); 311; 544-547
    Format: text
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  • 7
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    Mars - Subsurface properties from observed longitudinal variation of the 3.5-mm brightness temperature (1983)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: Extensive 3.5-mm measurements are reported which show a variation in the brightness temperature of Mars, with the Central Meridian Longitude that is generally in phase with the variation at 2.8 cm and is opposite in sign from the variations at 20 microns. It is pointed out that the phase result is not unexpected, since 3.5 mm is longer than the wavelength at which the phase behavior is expected to change. The result that the 3.5-mm rotation curve amplitude is larger than the amplitudes at both 20 microns and 2.8 cm, however, is unexpected. This result, it is noted, can be explained as a consequence of subsurface scattering from rocks smaller than 1.5 cm in radius. A correlation of subsurface scatterers with the location of the high-thermal inertial regions would be consistent with the hypothesis that rock abundance predominates in determining the thermal inertia.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Icarus (ISSN 0019-1035); 56; 465-475
    Format: text
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  • 8
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    Quantitative density visualization in a transonic compressor rotor (1977)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The flow in a 59-cm-diameter high-work transonic compressor rotor has been visualized using a fluorescent gas, 2,3, butanedione, as a tracer. The technique allows the three-dimensional flow to be imaged as a set of distinct planes. Quantitative static density maps were obtained by correcting the images for distortion and nonlinearities introduced by the illumination and imaging systems. These images and maps were used to analyze the three-dimensional nature of the blade's boundary layer and shock system.
    Schlagwort(e): AERODYNAMICS
    Format: text
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  • 9
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    Time resolved measurements in a low aspect ratio transonic compressor stage (1982)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: The time resolved flowfield in a low aspect ratio transonic compressor stage has been studied using a high frequency response sphere probe with a bandpass of D.C. to 20 kHz in a blowdown compressor facility. Averaged over the compressor annulus, the data agree well with those measured with standard pitot type probes on the same stage in a conventional test rig. Not all the spanwise distributions agree, however. These differences are explained as errors in the pitot probe readings due to fluctuations in the flow. The experimental data are compared to the results of a three-dimensional inviscid Euler calculation.
    Schlagwort(e): AERODYNAMICS
    Materialart: ASME PAPER 82-GT-201 , International Gas Turbine Conference and Exhibit; Apr 18, 1982 - Apr 22, 1982; London
    Format: text
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  • 10
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    Ca isotope fractionation on the moon (1977)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: Ca has been measured in a lunar soil in order to establish the presence of isotopically mass-fractionated components. Ca was extracted by a series of water leaches after the soils were 'activated' by brief exposures to fluorine gas. The O2 obtained by this fluorination is found to have delta (O-18) of +21 per mil and to be, therefore, significantly mass-fractionated. Ca obtained in the leaches was analyzed using the double-spike technique. Very small Ca isotope fractionation is found in the leaches of this soil of up to 1 per mil per mass unit difference. The small Ca effects are in marked contrast to the measured delta (O-18) for the same sample and to large effects observed in many soils for oxygen, silicon, sulfur, and potassium. The data on Ca provide stringent constraints on models which attempt to explain the isotope mass-fractionation effects in lunar soils.
    Schlagwort(e): LUNAR AND PLANETARY EXPLORATION
    Materialart: Lunar Science Conference; Mar 14, 1977 - Mar 18, 1977; Houston, TX
    Format: text
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