ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • LUNAR AND PLANETARY EXPLORATION  (14,409)
Collection
Keywords
Years
  • 1
    facet.materialart.
    Unknown
    Zr-Hf-Ta fractionation during lunar evolution (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Zr/Hf ratios and other elemental data in 68 samples of various mare basalts, KREEP units, and lunar glasses have been determined using instrumental neutron activation analysis coupled with coincidence-anticoincidence counting for greater precision. The data are presented in order to quantify further the amount of Zr/Hf fractionation that has occurred during primordial crystallization and cumulate remelting or by any other process. Models of Zr-Hf evolution are developed to place additional constraints on the bulk lunar composition and on the effects of minor phases that may be responsible for the observed fractionations. The Hf-Ta fractionation in lunar compositions is also reviewed in order to characterize normal Hf(4+) versus Ta(4+) behavior and to delineate possible effects due to the oxidation of Ta(4+) to Ta(5+) during late-stage ilmenite crystallization.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 90; D31-D45
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Zr-Hf fractionation in chemically defined lunar rock groups (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Zirconium and hafnium, a geochemically coherent pair of elements, are strongly fractionated in lunar rocks, as evidenced by a wide range of Zr/Hf mass ratios from 12 for the anorthosite 60015,65A to 50 for the KREEP breccia 14321. This may be explained in part by selective reduction of Zr(4+) to Zr(3+) and exclusion of the Zr(3+) from early crystallized Fe-Ti minerals.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar Science Conference; Mar 15, 1976 - Mar 19, 1976; Houston, TX
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Zr and Nb partition coefficients - Implications for the genesis of mare basalts, KREEP, and sea floor basalts (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The distribution coefficients of Zr and Nb have been found between armalcolite, ilmenite, clinopyroxene, rutile, plagioclase, and a coexisting high-Ti mare basalt melt in the 1105-1128 C temperature range. Henry's Law is not broken over the compositional range evaluated. The distribution coefficients of clinopyroxene are strongly dependent on melt and crystal compositions. The Al2O3 activity in the melt is a strong controlling parameter. It is concluded that: (1) Apollo 11 (low K) and Apollo 17 high-Ti mare basalts may have been generated by the partial melting of an ilmenite-rich cumulate, (2) Apollo 11 (high K) basalts may have been generated by a small amount of partial melting of a more fractionated ilmenite-rich cumulate, (3) KREEP magmas may have been formed as residual melts produced by fractional crystallization of the lunar magma ocean, and (4) anomalous (type II) MOR basalts may have been generated by small degrees of partial melting of a relatively undepleted mantle with clinopyroxene remaining in the residium.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Zonally symmetric response to atmospheric tidal forcing in the dusty Martian atmosphere (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The paper presents a steady state, zonally symmetric response of an atmospheric circulation to the combined effects of the very large zonal-mean diabatic heating and thermotidal forcing thought to exist in the dusty Martian atmosphere during one of its episodic global dust storms. The zonal-mean components of the tidal flux-convergences of momentum and heat are computed using an existing classical atmospheric tidal model constrained by the surface pressure observations at the two Viking Lander sites on Mars. A nearly inviscid two-dimensional model is used to compute the zonally symmetric response to the computed tidal flux-convergences and to the zonal-mean heating of the airborne dust. The results are compared with data from the Viking missions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 2469-248
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Zonally averaged thermal balance and stability models for nitrogen polar caps on Triton (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Voyager four-color imaging data of Triton are analyzed to calculate the bolometric hemispheric albedo as a function of latitude and longitude. Zonal averages of these data have been incorporated into a thermal balance model involving insolation, reradiation, and latent heat of sublimation of N2 ice for the surface. The current average bolometric albedo of Triton's polar caps is 0.8, implying an effective temperature of 34.2 K and a surface pressure of N2 of 1.6 microbar for unit emissivity. This pressure is an order of magnitude lower than the surface pressure of 18 microbar inferred from Voyager data (Broadfoot et al., 1989; Conrath et al., 1989), a discrepancy that can be reconciled if the emissivity of the N2 on Triton's surface is 0.66. The model predicts that Triton's surface north of 15 deg N latitude is experiencing deposition of N2 frosts, as are the bright portions of the south polar cap near the equator. This result explains why the south cap covers nearly the entire southern hemisphere of Triton.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 17; 1773-177
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Zonal winds near Venus' cloud top level - An analytic model of the equatorial wind speed (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: A consequence of the presently hypothesized maintenance of the equatorial wind speed near the cloud top level of Venus by a balance between the semidiurnal tide's pumping and the Hadley circulation's vertical advection (both integrated across the thermal driving region) is that the maximum equatorial zonal wind speed is proportional to the product of the buoyancy frequency and the magnitude of the driving region's thickness. The proportionality constant is characterized as a weakly increasing function of the heating rate, and a decreasing function of the product of an inverse length, expressing the mean zonal wind shear, and the driving region thickness. For the class of solutions thus treated, there is a threshold heating rate value below which no equilibrium satisfies the prescribed balance.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 69; 193-201
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Zonal winds near Venus' cloud top level - A model study of the interaction between the zonal mean circulation and the semidiurnal tide (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The Holton (1982) wave-mean flow interaction model's primitive equation is presently adapted in order to clarify the interaction between the semidiurnal tide and the thermally driven mean meridional circulation near cloud top level. The model is found to produce midlatitude jets whose structure is insensitive to vertical shear of the background angular velocity, both above and below cloud top level; a sensitivity to background angular velocity at cloud top level, however, is noted. Agreement between the model tide and either the observed one or that generated by the more detailed calculations of Pechmann and Ingersoll (1984) is found to be greatest when the background angular velocity at the jet level is of the order of 30 percent larger than that which is observed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 69; 202-220
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Zonal winds in the middle atmosphere of Venus from Pioneer Venus radio occultation data (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The present investigation is concerned with the derivation of zonal winds for the middle atmosphere (40-80 km) of Venus, using Pioneer Venus (PV) radio occultation data. The considered altitude range is of particular interest because the atmospheric circulation of Venus is uncertain above the cloud tops (65-70 km). The Pioneer Venus orbiter began circling the planet every 24 hours on December 4, 1978. Four seasons of occultation data have now been collected. It is found that the assumption of cyclostrophic balance, in conjunction with radio occultation derived temperature data, yields a zonal wind field for most of the middle atmosphere of Venus. An intense midlatitude jet at and above the cloud tops is the most notable feature of the winds.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 41; 1901-191
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Zonal winds and the angular momentum balance of Venus' atmosphere within and above the clouds (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Temperatures and pressures inferred from radio occultation data acquired by the Pioneer Venus orbiter between September 1982 and November 1983 are used to derive cyclostrophic zonal winds in the middle atmosphere of Venus (1350 to 2.1 mb, 10 deg to 70 deg latitude). The main feature of the wind field is a jet positioned just above the cloud tops at 70 km and approximately 48 deg latitude. The maximum speed of the jet is about 130 m/s. A comparison with results of similar analyses on Pioneer Venus radio occultation data obtained between December 1978 and October 1981 suggests an equatorward shift of the jet and a decrease in jet speed during this five-year time interval. It is proposed that the poleward transport of westward zonal momentum by the upper branch of the cloud level Hadley cell supplies the excess momentum of the jet and maintains it against dissipation. The location of the jet thereby provides a minimum estimate of the latitudinal extent of the Hadley cell. Cyclostrophic zonal wind velocities decrease with height above about 70-75 km. It is suggested that this deceleration of the superrotation in equatorial latitudes is due to the dissipation of vertically propagating thermal tides forced primarily at altitudes around 65 km.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 42; 1982-199
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Zonal velocity and texture in the Jovian atmosphere inferred from Voyager images (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Smith et al. (1970) have described Jupiter's changing appearance at resolutions down to 10 km over intervals as small as 1 h. Examples of small-scale convection, rapid variations of features, and complex interactions of closed vortices were given. In the present paper, these results are extended to include measurements of the latitudinal profile of zonal (eastward) velocity, from which the absolute vorticity gradient is estimated. Also, a classification scheme based on texture (i.e., the patterns of small features visible at resolutions of 100 km or better) is proposed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 280; Aug. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...