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  (668)
  • 1980-1984  (668)
  • 1925-1929
  • 1980  (668)
  • 101
    facet.materialart.
    Unknown
    Surface evolution of two-component stone/ice bodies in the Jupiter region (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Observational and theoretical data converge on the conclusion that planetesimals in Jupiter's region of the solar nebula were initially composed predominantly of a mixture of roughly 39-70% H2O ice by volume, and 30-61% dark stony material resembling carbonaceous chondrites. Recent observations emphasize a division of most asteroid and satellite surfaces in this region into two distinct groups: bright icy material and dark stony material. The present model accounts for these by two main processes: an impact-induced buildup of a dark stony regolith in the absence of surface thermal disturbance, and thermal-disturbance-induced eruption of 'water magmas' that create icy surfaces. 'Thermal disturbances' include tidal and radiative effects caused by nearness of a planet. A correlation of crater density and albedo, Ganymede's dark-ray craters, and other observed phenomena (listed in the summary) appear consistent with the model discussed here.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 102
    facet.materialart.
    Unknown
    Evolution of planetary lithospheres - Evidence from multiringed structures on Ganymede and Callisto (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The thickness and viscosity of a planetary lithosphere increase with time as the mantle cools, with a thicker lithosphere leading to the formation of one (or very few) irregular normal faults concentric to the crater. Since a gravity wave or tsunami induced by impact into a liquid mantle would result in both radial and concentric extension features, which are not observed in the case of the large impact structures on Ganymede and Callisto, an alternative mechanism is proposed in which the varying ice/silicate ratios, tectonic histories, and erosional mechanisms of the two bodies are considered to explain the subtle differences in thin lithosphere ring morphology between Ganymede and Callisto. It is concluded that the present lithosphere thickness of Ganymede is too great to permit the development of any rings.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 103
    facet.materialart.
    Unknown
    Visible spectral reflectance measurements /0.33-1.1 microns/ of the Galilean satellites at many orbital phase angles (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: One hundred eighty-seven reflectance spectra (0.33-1.10 microns) of the Galilean satellites have been obtained. Solar phase angle color correction coefficients were derived and the spectra corrected to a solar phase of 6 deg. Solar phase angle coefficients beyond 0.55 micron are presented for the first time. The spectra as a function of orbital phase angle are presented in the form of images to display hemispheric spectral variations. Io and Europa are redder on their trailing hemispheres while Callisto is redder on its leading hemisphere. Ganymede shows small longitudinal color variations despite the complex albedo structure visible in Voyager images. Comparisons of these data with previous measurements reveal that most differences can be attributed to the solar calibration. Reflectance measurements of Io at 0.73 micron observed 8.5 years apart show a 6% global reflectance decrease. However, it is difficult to unambiguously attribute this particular decrease in reflectance to a change in Io's surface composition.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 104
    facet.materialart.
    Unknown
    The surface composition of Amalthea (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: It is proposed that charged particles from the Jovian magnetosphere, contaminants such as sulfur from Io, and high-velocity micrometeoritic matter, combine to darken, redden, and alter the surface of Amalthea revealed by Voyager; whose few isolated bright spots have a distinct greenish spectrum. A major finding of this analysis is that available spectral reflectance data contain little information about the bulk composition of the satellite. The effects of contamination by sulfur and its allotropes are shown to redden a variety of bulk compositions: carbonaceous material, refractory minerals, iron and iron sulfides, and moderate temperature silicates. The bright, greenish spots probably identify locations in which atypical alteration processes occur, such as variations in the amount of contaminant sulfur in micrometeoritic glasses or in the relative abundances of certain sulfur allotropes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 105
    facet.materialart.
    Unknown
    Some possible effects of Jupiter's rings on the Jovian inner plasmasphere (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The ionospheric plasma density on magnetic field lines threading the Jovian rings which are located inside approximately 1.8 Jupiter radii on the jovigraphic equatorial plane is calculated by using a rotating ion exosphere model. It is found that the bulk of the ionospheric particles on these field lines are on ballistic trajectories. On field lines approximately symmetric with respect to the jovigraphic equator, the ring, which to a first approximation would absorb the population of trapped particles, consequently has little effect. On field lines which are made asymmetric by the higher-order multipoles of Jupiter's field and the tilt of the dipole axis, the rings may have a significant effect. It is suggested that better definition of the rings' atmospheric and ionospheric properties is required to model these localized effects. If the rings are found to be an important plasma source for the inner magnetosphere, the present exospheric model will have to be revised.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 106
    facet.materialart.
    Unknown
    Ganymede, Europa, Callisto, and Saturn's rings - Compositional analysis from reflectance spectroscopy (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The reflectance spectra of Ganymede, Europa, Callisto, and the rings of Saturn are analyzed, using laboratory reflectance studies of water, frost, ice, and mineral mixtures. It is found that the spectra of the icy Galilean satellites are characteristic of water ice, or frost on ice, rather than pure water frost; and that the decrease in reflectance at visible wavelengths is caused by other mineral grains on the surface. The spectra of Saturn's rings are more characteristic of water frost, with other mineral grains mixed in the frost but not on the surface. It is also found that impurities of all these objects are not in isolated patches, but intimately mixed with the water. A new absorption feature at 1.15 microns has been identified in Ganymede, Callisto, and possibly Europa, which cannot be seen in Saturn's rings and whose cause is unknown.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 107
    facet.materialart.
    Unknown
    Physical processes in Jupiter's ring - Clues to its origin by Jove (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: It is shown that many of the observed properties of the Jovian ring can be explained by the presence of numerious small and unseen parent bodies, or 'mooms', residing within the ring; whose radii are less than 1 km. The small visible ring grains, which are destroyed in short times by sputtering and meteoroid erosion, are derived from these parent bodies largely through meteoroid impacts, and partly from Io's dust. Substantial orbit modification results from plasma drag, and the charge carried by the grains will influence their dynamics and may modify their shapes. It is concluded that the processes discussed, though present in other planetary ring systems, may be highlighted in Jupiter's ring because of its low optical depth and the small size of some of its particles. It is suggested that hidden reservoirs similar to the Jovian 'mooms' proposed may be present in the rings of Saturn and Uranus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 108
    facet.materialart.
    Unknown
    An explanation for the alternating north-south asymmetry of Io's sodium cloud (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The hot Jovian plasma torus discovered by Voyager 1 is responsible for the periodic intensity variations of Io's sodium cloud, which are correlated with Io's magnetic latitude. The plasma torus must be a long-lived phenomenon in spite of its apparent absence at the time of the Pioneer flybys. The hot electrons (100,000 K) must be concentrated about one Jupiter radius from the magnetic equator in order to produce the observed variations. Electron impact ionization in the hot plasma torus is strong enough to form and to maintain Io's ionosphere; the hot plasma torus may be the dominant agent forming the ionosphere. Io's bound atmosphere is dense enough that the plasma torus electrons cannot cause a noticeable variation in its Na emission intensity.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 109
    facet.materialart.
    Unknown
    Joule heating of Io's ionosphere by unipolar induction currents (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Electrical induction in Io's ionosphere, due to the corotating plasma bound to the Jovian magnetosphere, is one possible source for the attainment of the high temperatures suggested by the large scale height of Io's ionosphere. Unipolar induction models are constructed to calculate ionospheric joule heating numerically, whose heating rates lie between 10 to the -9th and 10 to the -8th W/cu m. The binding and coupling of the ionosphere is due to the dense, and possibly ionized, neutral SO2 atmosphere, and there appears to be no need to postulate the existence of an intrinsic Ionian magnetic field in order to retain the observed ionnosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 110
    facet.materialart.
    Unknown
    Io's sodium emission cloud and the Voyager 1 encounter (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Monitoring of Io's neutral sodium emission cloud, monitored from two earth observatories during the period of the Voyager 1 encounter, demonstrated that the behavior of the cloud is complex; displaying a variety of changes, both systematic and secular, which can have both time and spatial dependencies while also possessing some characteristics of stability. Dynamic models of the sodium cloud employing Voyager 1 plasma data provide a reasonable fit to the encounter images of one of the observatories. The modeling assumptions of anisotropic ejection of neutral sodium atoms from the leading, inner hemisphere of Io, with a velocity distribution characteristic of sputtering, adequately explain the overall intensity distribution of the 'near cloud'.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 111
    facet.materialart.
    Unknown
    Mass-injection rate from Io into the Io plasma torus (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Theoretical arguments to the effect that both plasma and energy are supplied to the Jovian magnetosphere from primarily internal sources are presented. Two major assumptions are made: (1) that Io is the source of plasma for the Jovian magnetosphere, and that the outward flow of plasma from the torus is the means of drawing from the kinetic energy of rotation of Jupiter to drive magnetospheric phenomena; thereby obtaining a new, independent estimate of the rate of mass injection from Io into the Io plasma torus, and (2) that the solar wind supplies neither plasma nor energy to the Jovian magnetosphere in significant amounts. A lower limit to the rate of mass injection into the torus, which on the average must equal the rate of mass loss from the torus, is therefore derivable through adoption of a value for the power expended to drive the various magnetospheric phenomena.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 112
    facet.materialart.
    Unknown
    Near-surface flow of volcanic gases on Io (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Significant near-surface flow of gas several hundred kilometers from Pele (Plume 1) on Io is indicated by a series of bright, elongate albedo markings. Particles produced at small, local vents are apparently carried as much as 70 km farther 'downwind' from Pele. The gas densities and velocities necessary to suspend 0.1 to 10 micron particles at such a distance imply mass flow rates of 10 to the 7th - 10 to the 9th g/sec. Such flow rates are consistent with other estimates of mass transport by the plume. The large flow rates so far from the source allow an estimate of the rate of resurfacing of Io by lava flows and pyroclastics that is independent of estimates based on meteorite flux or on the amount of solids carried within the plumes themselves.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 113
    facet.materialart.
    Unknown
    Io - Energy constraints and plume volcanism (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Observational and theoretical considerations, including near-surface energy constraints, suggest a model of Io that features a surface layer of sulfur overlying an active silicate crust. Such a model would imply frequent contact between silicate magma intrusions and the sulfur layer. This contact could produce volcanic plumes driven by high-temperature sulfur vapor. Plumes driven by sulfur vapor meet observational constraints for a wide range of possible conditions, in contrast to the special conditions required for plume generation by SO2. Characteristics of the two models are compared, and it is suggested that high-spatial-resolution infrared radiometry could identify the driving volatile.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 114
    facet.materialart.
    Unknown
    Stability of sulfur slopes on Io (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The mechanical properties of elemental sulfur are such that the upper crust of Io cannot be primarily sulfur. For heat flows in the range 100-1000 ergs/sq cm sec sulfur becomes ductile within several hundred meters of the surface and would prevent the formation of calderas with depths greater than this. However, the one caldera for which precise depth data are available is 2 km deep, and this value may be typical. A study of the mechanical equilibrium of simple slopes shows that the depth to the zone of rapid ductile flow strongly controls the maximum heights for sulfur slopes. Sulfur scarps with heights greater than 1 km will fail for all heat flows greater than 180 ergs/sq cm sec and slope angles greater than 22.5 deg. The observed relief on Io is inconsistent with that anticipated for a predominantly sulfur crust. However, a silicate crust with several percent sulfur included satisfies both the mechanical constraints and the observed presence of sulfur on Io.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 115
    facet.materialart.
    Unknown
    Io - Observational constraints on internal energy and thermophysics of the surface (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Infrared observations of the Io eclipse of April 12, 1980, in five broad bands from 3 to 30 microns define the thermal emission spectrum both during and after eclipse. A substantial fraction of the emitted radiation during eclipse arises from hot spots; the equivalent global average heat flow is 1.5 + or - 0.3 W/sq m, corresponding to an internal source of (6 + or - 1) x 10 to the 13th W. The hot spot spectra can be matched by components with color temperatures of 200-600 K covering 1-2% of the surface. Comparison with observations over the past eight years suggests that, while the flux at the hottest temperatures may be highly variable, there is no evidence for major changes in the total heat flow, which is emitted primarily in the spectral region 10-20 microns. The heating curves of the surface were observed at 10 and 20 microns; when corrected for the hot spot contribution they indicate a typical global thermal inertia for Io of 0.0002 + or - 0.0001 cal/sq cm sec(exp 1/2) K, similar to that of the other Galilean satellites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 116
    facet.materialart.
    Unknown
    The satellites of Jupiter; Proceedings of the Fifty-seventh Colloquium, Kailua, Hawaii, May 13-16, 1980 (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Among the topics covered by the colloquium on the satellites of Jupiter are: the internal energy and thermophysics of the surface of Io, plume volcanism on Io, the photometric variability of Io, the near-surface flow of volcanic gases on Io, and the sodium emission cloud of Io and its north-south asymmetry. Also considered are: the physical processes and origins of Jupiter's ring and its possible effect on the Jovian inner plasmasphere, the composition of such moons of Jupiter as Amalthea, Ganymede, Europa and Callisto and their lithospheric and ice evolutions. Particular attention is given such topographic features as the domes and grooved terrain on Ganymede, water frost and ice, and the photometric properties of these outer satellites of Jupiter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 117
    facet.materialart.
    Unknown
    Images of Venus by three-station radar interferometry - 1977 results (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: During the 1977 inferior conjunction of Venus, radar observations were made using three receiving stations as a multiple interferometer. Maps of surface reflectivity and altimetry were prepared from these observations. The new altimetry maps show considerable improvement in relation to many of the earlier maps made using the two-station interferometer. In particular, there are consistent and explainable correlations between the altimetry and reflectivity maps that did not always exist in the past. The highest-resolution maps (about 8 km) show three isolated mountains having altitudes of approximately 2 km above their environs, a pair of ridges separated by approximately 100 km and extending 800 km, and a few anomalous reflectivity features for which little or no altitude change is observed. Other maps at slightly lower resolution show a bright irregular ringed crater, a few large low-reflectivity regions, a shallow crater 150 km in diameter, a gently sloping mountain, and a short ridge running north-south. Many of the later features have been seen in earlier radar maps and should be useful in refining the spin axis and further characterizing the regolith of certain areas of Venus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 118
    facet.materialart.
    Unknown
    Solar zenith angle dependence of ionospheric ion and electron temperatures and density on Venus (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The measurements taken during the first year of the Pioneer Venus orbiter retarding potential analyzer indicate the changes of ion and electron temperatures with solar zenith angles. The ion density decreases by an order of magnitude from dayside to nightside; median ion temperatures above 300 km are constant with the solar zenith angle below 150 deg and reach 2300 K at the ionopause. The ion temperatures below 300 km are almost constant with solar zenith angles during the dayside, but increase with the angles on the nightside. The electron temperatures suggest a constant heat flux into the electron gas at the ionopause which may be supplied by dissipation of energy by the whistler mode plasma waves at the ionopause and/or conduction of heat from the ionosheath through the mantle.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 119
    facet.materialart.
    Unknown
    Observation of the Venus mantle, the boundary region between solar wind and ionosphere (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: For three orbit paths of the Pioneer Venus orbiter the interaction between the solar wind and the Venusian ionosphere has been studied. Results of the retarding potential analyzer and the magnetometer are described for the boundary region between the solar wind and the planetary ionosphere. These are the first measurements that show that a transition region exists between the two plasmas of different origin. The observed magnetic field and current system producing it appear strong enough to stop the solar wind flow in front of the ionosphere and to separate the shocked solar wind from the ionosphere. The transition region between the ionosheath and the ionosphere is called the 'mantle'. The observed mantle electron energy spectra close to the ionopause show ionospheric character. With increasing height the number of electrons that have ionospheric energies decreases, and the number of electrons that have solar wind energies gradually increases toward the ionosheath boundary, where only solar wind energy spectra are observed. The mantle surrounds the frontside of the ionosphere and extends probably more than eight Venus radii downstream.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 120
    facet.materialart.
    Unknown
    The surface of Io - Geologic units, morphology, and tectonics (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The geologic units, morphology and tectonics evident on a preliminary geological map obtained from best-resolution Voyager 1 images and a preliminary pictorial map of the surface of Io are discussed. Nine volcanic units are identified on the surface which are composed of mountain materials, intervent, layered and eroded layered plains, and wall and floor, pit crater flow, shield crater flow, fissure flow and crater cone units associated with volcanic vents, along with seven types of structural features. The cumulative volcanic crater size distribution of 170 Ionian vents with craters greater than 14 km is similar to that of impact craters on other solar system bodies, with a surplus of small craters and a preponderance of volcanic vents in the Io equatorial zone. The observed surface morphologies provide evidence for a mixture of silicates and sulfur as the dominant surface material. Lineaments and grabens are also apparent on the surface, in a common planetary grid pattern.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 43; Sept
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 121
    facet.materialart.
    Unknown
    Photometry and polarimetry of Saturn's rings from Pioneer Saturn (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A profile of the average normal optical depth for Saturn's rings between 1.22 and 2.35 Saturn radii is examined. In the A and B rings, horizontal inhomogeneities make these values deceptive. A thinner component of the B ring with an optical depth below 0.08 covers up to 4% of its surface area. In the A ring, the more transparent component covers more than 7% of its area and has an optical depth greater than 0.10. These thinner parts of the rings would rarely be apparent from earth based observations. The particles of the C ring are larger than 15 microns and differ from those of the B and A rings. The C ring is either homogeneous with high albedo and forward scattering phase functions, or shows a gradient in albedo with distance from Saturn. Polarimetry of Saturn's ring provides only an upper limit (below 15%) which is consistent with ground-based predictions. Polarization in the outer A ring is negative.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 122
    facet.materialart.
    Unknown
    Structure of the ionosphere and atmosphere of Saturn from Pioneer 11 Saturn radio occultation (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The paper deals with radio occultation measurements of Saturn's ionosphere and upper neutral atmosphere, made by Pioneer 11 near the terminator at latitudes of 9.7 deg south and 11.6 deg south. The principal electron density peak (of about 11,400 cu cm), in the ionosphere occurred at an altitude of about 1800 km, with a sharp lower peak of about 9000 cu cm at 1200 km. The scale height above the main peak corresponds to an exosphere temperature of about 1150 K for an H(+) ionosphere. Ionization appears to extend to 30,000 km. The low density of the lower portion of the ionosphere may be explained by ring shadowing and equatorial anomaly. In the neutral atmosphere, measurements were made to a pressure level of about 180 mbar, showing a temperature inversion region with a triple minimum.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 123
    facet.materialart.
    Unknown
    Observations of extreme ultraviolet emissions from the Saturnian plasmasphere (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Emission signals from the Saturnian plasmasphere at wavelengths shortward of 800 A have been detected by the Pioneer ultraviolet photometer. The surface brightness of the emissions is about 0.3 + or - 0.2 R. These short-wavelength emissions are interpreted as arising primarily from the radiative decay of electron-excited atomic oxygen ions (O(2+)), in the region between 5 and 7 Saturn radii from Saturn. The total power radiated by the Saturnian plasma inferred from these ultraviolet measurements is about 2 x 10 to the 16th erg/sec, consistent with in situ plasma measurements. From the observed energy loss rate it is estimated that the ions are introduced into the plasma torus at a rate of 8 x 10 to the 25th ions/sec, possibly through the sputtering of water ice on the surface of Tethys and Dione by particle impact.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 124
    facet.materialart.
    Unknown
    Very energetic protons in Saturn's radiation belt (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Very energetic protons are trapped in the inner Saturnian radiation belt. The University of California at San Diego instrument on Pioneer 11 has definitely identified protons of energy greater than 80 MeV on channel M3 and has tentatively detected protons of energy greater than 600 MeV on channel C3. The spatial distribution of the protons is distinct from that of the trapped electrons, the main difference being that the protons are strongly absorbed by the innermost moons and that the electrons are not. The source strength for injecting protons by the decay of cosmic ray albedo neutrons generated in the rings of Saturn has been estimated. The required proton lifetime is approximately 20 years.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 125
    facet.materialart.
    Unknown
    The trapped radiations of Saturn and their absorption by satellites and rings (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The Pioneer 11 encounter with Saturn has revealed the existence of a fully developed magnetosphere with high-energy trapped radiation about Saturn. The present paper gives a detailed summary of the energetic charged particle measurements, including the overall characteristics of the trapped electron, proton, and helium radiation, which was found to lie inside 20 Saturn radii from the planet, and the regions extending outward to beyond the planetary bow shocks and into the interplanetary medium.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 126
    facet.materialart.
    Unknown
    The energetic charged particle absorption signature of Mimas (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: In the present paper, the average long-term effect of Saturn's satellite Mimas on the distribution of trapped radiation (macrosignature) is examined, along with a microsignature of satellite absorption, specifically, a brief dip in charged particle intensities observed on the inbound pass of Pioneer 11 as it passed through the orbital range of Mimas. It is hypothesized that it is indeed the shadow of Mimas, in the sense that the observations reveal the effect of this satellite on a distribution of particles which interacted with it in the recent past and then drifted in longitude to the observational location. The hypothesis led to a characterization of the electron energy spectrum in Saturn's inner magnetosphere and to an estimate of the radial diffusion coefficient for such electrons.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: AD-A093433 , Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 127
    facet.materialart.
    Unknown
    Plasmas in Saturn's magnetosphere (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Passage of Pioneer 11 through Saturn's magnetosphere revealed a third magnetosphere with a high plasma abundance. The dominant ion species appears to be oxygen. The plasma is located in a large torus about Saturn, including the orbits of Dione and Tethys. The plasma are rigidly corotating with the planet to distances of at least 10 Saturn radii. Bulk flows appear to move in the corotation direction, but at speeds lower than those expected from rigid corotation. The ions appear to be the ionization products of water frost on the surface of the ring material.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 128
    facet.materialart.
    Unknown
    Observations of large scale steady magnetic fields in the dayside Venus ionosphere (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Although the dayside ionosphere of Venus is often field-free except for fine-scale features, large-scale steady ionospheric magnetic fields with magnitudes sometimes exceeding 100 gammas are occasionally observed by the Pioneer Venus Orbiter magnetometer. These fields are mainly horizontal and can assume any angle in the horizontal plane. The orientation of the field may change along the spacecraft trajectory. The field magnitude in the upper ionosphere usually shows a distinct minimum near approximately 200 km altitude, but the altitude profile is otherwise arbitrary. With few exceptions, the observations of these large scale fields occur when periapsis is at solar zenith angles less than 50 deg. The occurrence of large-scale fields is often coincident with the observation of high solar wind dynamic pressures by the Pioneer Venus Orbiter plasma analyzer closely following the ionosphere encounter. However, the detection of this phenomenon even during some orbits for which the dynamic pressure is not extraordinarily high suggests that other factors, such as hysteresis effects, must also play a role in determining the occurrence frequency of large-scale magnetic fields in the dayside Venus ionosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 7; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 129
    facet.materialart.
    Unknown
    Spectrophotometry of Io - Preliminary Voyager 1 results (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Multispectral images of Io acquired with the Voyager 1 narrow-angle camera agree with earth-based spectrophotometry to better than 10%. Although the surface materials have general spectral properties similar to various allotropes of sulfur, their ultraviolet (UV) reflectances are much higher. It is likely that varying amounts of SO2 frost mixed with or absorbed on sulfur-rich materials raises the UV reflectance. The possible association with large amounts of SO2 with low temperature forms of sulfur in the white patches on Io is consistent with Io surface models in which SO2 and S exist in thermally stable stratified zones.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 7; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 130
    facet.materialart.
    Unknown
    Radar measurement of heterogeneous small-scale surface texture on Mars Chryse (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Radar measurements from Chryse Planitia in 1978 confirm earlier estimates of 4-5 deg rms slope (on meter scales) over 45-50 deg W longitude. The new measurements also confirm a skewing of the measured spectra. This has now been interpreted as a combined result of large-scale surface tilt and a side effect of the decrease in small-scale roughness as the subradar point moves from the basin floor toward the west.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 10
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 131
    facet.materialart.
    Unknown
    Heating of the moon by heterogeneous accretion (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Monte Carlo models of lunar accretion are developed by randomly sampling mass and velocity distributions of objects in the solar nebula in circumsolar and circumterrestrial orbits. The thermal effect of an impact is expressed as the volume of melt produced; the melt volumes produced by each Monte Carlo case are sorted into regions to produce percentage melt estimates as a function of radius. One-hundred cases are calculated to obtain a range of plausible thermal histories for lunar accretion. The average melt percentage estimates show substantial deep melting, but the spread of melt percentage values about the mean from the random sampling procedure is wide enough to include 0% melting for radii below 100 km and 100% melting for radii below 500 km.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 10
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 132
    facet.materialart.
    Unknown
    Stratigraphy of Oceanus Procellarum basalts - Sources and styles of emplacement (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The basaltic fill of Oceanus Procellarum has been formally subdivided into four lithostratigraphic formations: The Repsold Formation, the Telemann Formation, the Hermann Formation, and the Sharp Formation. The Repsold Formation is composed of high-Ti basalts and pyroclastic deposits with an estimated age of 3.75 + or - 0.05 b.y. and an estimated volume of about 2.1 x 10 to the 5th cu km. This is overlain by the Telemann Formation composed of very low-Ti basalts and pyroclastic deposits with an estimated age of 3.6 + or - 0.2 b.y. and a volume of 4.2 x 10 to the 5th cu km. The Hermann Formation, composed of intermediate basalts with an estimated age of 3.3 + or - 0.3 b.y., represents the next youngest unit with an estimated volume of 2.2 x 10 to the 5th cu km. The youngest materials in Procellarum are the medium-to-high-Ti basalts comprising the Sharp Formation with an estimated age of 2.7 + or - 0.7 b.y. and a volume of 1.8 x 10 to the 4th cu km.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 10
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 133
    facet.materialart.
    Unknown
    Lunar near-surface shear wave velocities at the Apollo landing sites as inferred from spectral amplitude ratios (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The horizontal-to-vertical amplitude ratios of the long-period seismograms are reexamined to determine the shear wave velocity distributions at the Apollo 12, 14, 15, and 16 lunar landing sites. Average spectral ratios, computed from a number of impact signals, were compared with spectral ratios calculated for the fundamental mode Rayleigh waves in media consisting of homogeneous, isotropic, horizontal layers. The shear velocities of the best fitting models at the different sites resemble each other and differ from the average for all sites by not more than 20% except for the bottom layer at station 14. The shear velocities increase from 40 m/s at the surface to about 400 m/s at depths between 95 and 160 m at the various sites. Within this depth range the velocity-depth functions are well represented by two piecewise linear segments, although the presence of first-order discontinuities cannot be ruled out.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 10
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 134
    facet.materialart.
    Unknown
    Isotopic anomalies of noble gases in meteorites and their origins. VII - C3V carbonaceous chondrites (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 44; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 135
    facet.materialart.
    Unknown
    Elemental abundances in chondrules from unequilibrated chondrites Evidence for chondrule origin by melting of pre-existing materials (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Bulk abundances of Na, Mg, Al, Ca, Sc, V, Cr, Ir, and Au were analyzed by neutron activation of chondrules separated from unequilibrated H, L, and LL chondrites and correlated with petrographic properties. The geometric mean composition of the whole-rock chondrule suites are almost indistinguishable from each other for many elements; chondrules are enriched in lithophile and depleted in siderophile elements in a pattern consistent with chondrule formation by melting of preexistent materials. The porphyritic chondrules are more enriched in refractory and siderophile elements as compared with the nonporphyrytic chondrules, indicating that these two chondrule groups may have formed from different precursors.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 50; 1, Oc; Oct. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 136
    facet.materialart.
    Unknown
    Sm-Nd isotopic evolution of chondrites (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The Nd-143/Nd-144 and Sm-147/Nd-144 ratios measured in 5 chondrites and the Juvinas achondrite correlated with the variation of 4.2% in Sm-147/Nd-144. Most of the spread in the range of these ratios results from small heterogeneities in the chondrites and does not reflect the large-scale volumetric averages. A new set of self-consistent reference values were selected for the 'chrondritic uniform reservoir' (CHUR); the new Sm-147/Nd-144 value is 1.6% higher than the previous value assigned to CHUR using the Juvinas data of Lugmair (1975). The new CHUR curve indicates significant changes in model ages for lunar rocks and in the interpretation of early lunar chronology.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 50; 1, Oc; Oct. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 137
    facet.materialart.
    Unknown
    Convective instability when the temperature gradient and rotation vector are oblique to gravity. II - Real fluids with effects of diffusion (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The linear stability analysis of Hathaway et al. (1979) is repeated for Boussinesq fluids with viscous and thermal diffusion. The fluid is confined between plane parallel boundaries and the rotation vector is oblique to gravity; this tilted rotation vector introduces a preference for roll-like disturbances whose axes are oriented north-south. The presence of a latitudinal temperature gradient produces a thermal wind shear which favors axisymmetric convective rolls if the gradient exceeds some critical value. The axisymmetric rolls are similar in many respects to the cloud bands on Jupiter provided they extend to a depth of about 15,000 km.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: AD-A112461 , AFGL-TR-82-0087 , Geophysical and Astrophysical Fluid Dynamics; 15; 1-2,; 1980
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 138
    facet.materialart.
    Unknown
    Anomalous region on Mars - Implications for near-surface liquid water (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An anomalous region has been identified on Mars from the 1971 and 1973 earth-based Goldstone radar data. This region is characterized by coincident very high radar reflectivities and unusual smoothness. Very few realistic surface morphologies can generate such return-signals. Liquid water within about 50-100 cm of the surface is one possibility, an interpretation strengthened by an apparent seasonal variation in surface reflectivity for the same locality.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 288; Nov. 13
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 139
    facet.materialart.
    Unknown
    Measuring metamorphic history of unequilibrated ordinary chondrites (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Measurements performed by a thermoluminescence sensitivity technique of the degree of metamorphism experienced by unequilibrated ordinary chondrites are reported. Samples of type 3 chondrites were ground and heated to 500 C to remove their natural thermoluminescence, then irradiated with either 50 krad from a Co-60 gamma ray source or 25 krad from a Sr-90 beta source. The resulting thermoluminescence measured as a function of temperature is found to differ as much among some type 3 chondrites as between type 3 and other types, leading to the proposal of scheme for subdividing type 3 ordinary chondrites based on their thermoluminescence sensitivity.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 287; Oct. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 140
    facet.materialart.
    Unknown
    Martian valleys - Morphology, distribution, age, and origin (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The article summarizes the geological and geomorphological evidence concerning the formation of the valley networks of Mars which were observed in the Mariner 9 and Viking Orbiter images. There is no clear evidence of direct fluid erosion in any Martian valley. The networks are diffuse and inefficient, with irregular tributary junction angles and large, undissected intervalley regions. The deeply entrenched canyons, with steep-walled amphitheater terminations suggest headward extension (sapping) by basal undermining and wall collapse. It is believed that valley formation has not occurred on Mars for billions of years because the size-frequency distributions of impact craters in these valleys and in the heavily cratered terrain which surrounds them are statistically insignificant.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 210; Nov. 21
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 141
    facet.materialart.
    Unknown
    Io - Longtudinal distribution of sulfur dioxide frost (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A longitudinal variation in the distribution of SO2 frost on Io is examined. Twenty spectra of Io (0.26 to 0.33 micrometer) are presented and a strong ultraviolet absorption is found shortward of 0.33 micrometer. The abundance of frost is greatest at orbital longitudes 72 to 137 degrees. Longitudes 250 to 323 degrees are least abundant in SO2. Comparisons are made with a Voyager color relief map, which suggest that SO2 frost is in greatest concentration in the white areas of Io and other sulfurous materials are in greatest concentration in the red areas.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 210; Nov. 14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 142
    facet.materialart.
    Unknown
    Recent planetary physics and chemistry (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: During the past few years considerable progress has been made in the knowledge and understanding of the origin of planets and of the structure of their interiors and atmospheres. Some of these advances, including Venera and Viking results, are reviewed for all the planets (except earth) with emphasis on those data that seem amenable to theoretical analysis. Results of the 1978-79 Mariner-Venus Orbiter, Pioneer 11, and Voyager 1 and 2 missions as well as other observations are briefly summarized.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 143
    facet.materialart.
    Unknown
    Mars sample return: Site selection and sample acquisition study (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Various vehicle and mission options were investigated for the continued exploration of Mars; the cost of a minimum sample return mission was estimated; options and concepts were synthesized into program possibilities; and recommendations for the next Mars mission were made to the Planetary Program office. Specific sites and all relevant spacecraft and ground-based data were studied in order to determine: (1) the adequacy of presently available data for identifying landing sities for a sample return mission that would assure the acquisition of material from the most important geologic provinces of Mars; (2) the degree of surface mobility required to assure sample acquisition for these sites; (3) techniques to be used in the selection and drilling of rock a samples; and (4) the degree of mobility required at the two Viking sites to acquire these samples.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-164558 , JPL-PUB-80-59
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 144
    facet.materialart.
    Unknown
    The composition of the Martian dark regions: Observations and analysis (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Near infrared telescopic spectrophotometry for dark regions is present and interpreted using laboratory studies of iron bearing mineral mixtures and terrestrial oxidized and unoxidized basalts. Upon closer inspection (by spacecraft) the telescopic dark regions were found to consist of large scale intermixtures of bright soil (aeolian dust) and dark materials. The dark materials themselves consist of an intimate physical association of very fine grained ferric oxide bearing material with relatively high near infrared reflectance and darker, relatively unoxidized rocks or rock fragments. While these two components could exist finely intermixed in a soil, a number of lines of evidence indicate that the usual occurrence is probably a thin coating of physically bound oxidized material. The coated rocks are dark and generally clinopyroxene bearing. The shallow band depths and low overall reflectances indicate that opaque minerals such as magnetite are probably abundant.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-164072
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 145
    facet.materialart.
    Unknown
    Pioneer: First to Jupiter, Saturn, and beyond. Bibliography (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The reference citatons are grouped by experiment. Experiments include: the charged particle instrument experiment; the ultraviolet photometer experiment; imaging experiments; and magnetometer experiments. The asteroid detector experiment and the plasma analyser experiment are also included.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-81233
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 146
    facet.materialart.
    Unknown
    Standing Alfven wave current system at Io: Voyager 1 observations (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The enigmatic control of the occurrence frequency of Jupiter's decametric emissions by the satellite Io is explained theoretically on the basis of its strong electrodynamic interaction with the corotating Jovian magnetosphere leading to field aligned currents connecting Io with the Jovian ionosphere. Direct measurements of the perturbation magnetic fields due to this current system were obtained by the magnetic field experiment on Voyager 1 on 5 March 1979 when it passed within 20,500 km south of Io. An interpretation in the framework of Alfven waves radiated by Io leads to current estimates of 2.8 million amps. A mass density of 7400 to 13600 proton mass units per Cu cm is derived which compares very favorably with independent observations of the torus composition characterized by 7-9 proton mass units per electron for a local electron density of 1050 to 1500 per cu cm. The power dissipated in the current system may be important for heating the Io heavy ion torus, inner magnetosphere, Jovian ionosphere, and possibly the ionosphere or even the interior of Io.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-82060
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 147
    facet.materialart.
    Unknown
    Observations of the magnetic field and plasma flow in Jupiter's magnetosheath (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Large scale (many minutes to 10 hours) magnetic field structures consisting predominantly of nearly north-south field direction were discovered in Jupiter's magnetosheath from the data of Voyagers 1 and 2 and Pioneer 10 during their outbound encounter trajectories. The Voyager 2 data, and that of Voyager 1 to a lesser extent, show evidence of a quasi-period of 10 hours (and occasionally 5 hours) for these structures. The north-south components of the field and plasma velocity were strongly correlated in the outbound magnetosheath as observed by Voyagers 1 and 2, and the components orthogonal to the north-south direction showed weak correlations. For both Voyager encounters the sense (positive and negative) of the north-south correlations were directly related to the direction of the ecliptic plane component of the interplanetary magnetic field using the field and plasma measurements of the non-encountering spacecraft.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-82035
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 148
    facet.materialart.
    Unknown
    Energetic particles in the pre-dawn magnetotail of Jupiter (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A detailed account is given of the energetic electron and proton populations as observed with Voyagers 1 and 2 during their passes through the dawn magnetotail of Jupiter. The region between 20 and 150 R sub J is dominated by a thin plasma sheet, where trapped energetic electron and proton fluxes reach their maximum. Proton spectra can be represented by an exponential in rigidity with a characteristic energy of approximately 50 keV. Proton anisotropies were consistent with corotation even at 100 R sub J. A major proton acceleration event as well as several cases of field aligned proton streaming were observed. The flux of 0.4 MeV protons decreases by three orders of magnitude between 30 and 90 R sub J and then remains relatively constant to the magnetopause. Fine structure in the data indicate longitudinal asymmetries with respect to the dipole orientation. Electron spectra in the magnetosheath and interplanetary space are modulated by the Jovian longitude relative to the subsolar point.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-81991
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 149
    facet.materialart.
    Unknown
    The formation of arcs in the dynamic spectra of Jovian decameter bursts (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A model is presented that can account for several features of the dynamic spectral arcs observed at decameter wavelengths by the planetary radio astronomy experiment on Voyagers 1 and 2. It is shown that refraction of an extraordinary mode wave initially excited nearly orthogonal to the local magnetic field is significantly influenced by the local plasma density, being greater the higher the density. It is assumed that the source of the decameter radiation lies along the L = 6 flux tube and that the highest frequencies are produced at the lowest altitudes, where both the plasma density and magnetic field gradients are largest. It is further assumed that the decameter radiation is emitted into a thin conical sheet, consistent with both observation and theory. In the model the emission cone angle of the sheet is chosen to vary with frequency so that it is relatively small at both high and low frequencies, but approximately 80 deg at intermediate frequencies. The resulting emission pattern as seen by a distant observer is shown to resemble the observed arc pattern. The model is compared and contrasted with examples of Voyager radio data.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-81987
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 150
    facet.materialart.
    Unknown
    Jupiter's magnetopause, bow shock, and 10-hour modulated magnetosheath: Voyagers 1 and 2 (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Fine scale magnetic field data from the Voyager 1 and 2 magnetopause and bow shock crossings at Jupiter were analyzed. Explicit models of the dawnside magnetopause and bow shock in Jupiter's orbital plane employ an axisymmetric parabola and hyperbola, respectively, and are determined separately for the encounters. A new phenomenon was discovered in the magnetosheath. It is manifested as (5 or) 10 hour quasi-periodic modulation of the direction of the magnetic field in the outbound magnetosheath, predominantly in the northward (N) and southward (S) directions. It was seen to occur during both encounters and appears most evident in Voyager 2 outbound observations, probably due to the extreme tailward extent of the Voyager 2 trajectory through the magnetosheath. The durations of the N to and from S transitions range from tens of minutes to approximately 3 hours. The directional variation of the field during these transitions is fairly well restricted to a plane parallel to the local model magnetopause location. These signatures may be due to magnetosheath field line draping modulated by the large scale motion of the magnetospheric plasma disk.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-82033
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 151
    facet.materialart.
    Unknown
    Implications for the structural integrity of the Venusian crust (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Comparisons of the fracture and yield stresses for the lithospheres of the Earth and Venus are derived from known empirical fracture and flow laws.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-163729
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 152
    facet.materialart.
    Unknown
    Photometry, spectrophotometry and polarimetry of comet P/Encke during fall of 1979 (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Broadband S-20, B and V magnitudes of P/Encke were obtained with the digital area photometer, using an Image Dissector Scanner (IDS) detector on the 2.7 m telescope at McDonald Observatory during August 1979. The notation V(S-20) is used for S-20 magnitudes transformed to V magnitudes. The variation in the V(S20) magnitudes (26, 5 minute integrations) on the best photometric night (21 August) was small and random indicating either a lack of rotational albedo variations or, more likely, a masking of the nucleus by the outburst activity. A spectrum covering the region from 3630 to 4900 A at a resolution of 5 A was obtained on 27 August with the IDS spectrograph. The spectrum was featureless, showing no emission at the CN or CO+ wavelengths.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-163717 , REPT-1
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 153
    facet.materialart.
    Unknown
    Dynamical and photometric investigation of comets (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The findings of dynamic and photometric investigations of comets are summarized, and include discussions of the comets Bennett 1970 II, Kohoutek 1973f, West 1976 VI, and periodic comets d'Arrest, Encke, and Swift Tuttle. The phenomena examined include striated and anomalous tails, tail composition and the dynamics of vaporizing dust particles, the evolution of dust jets, and split and dissipating comets.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-163699
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 154
    facet.materialart.
    Unknown
    Coordinates of features on the Galilean satellites (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Control nets of the four Galilean satellites, established photogrammetrically from pictures taken by the two Voyager spacecraft during their flybys of Jupiter in 1979, are discussed. Coordinates of 504 points on Io, 112 points on Europa, 1547 points on Ganymede, and 439 points on Callisto are listed. Selected points are identified on maps of the satellites. Measurements of these points were made on 234 pictures of Io, 115 pictures of Europa, 282 pictures of Ganymede, and 200 pictures of Callisto. The systems of longitude were defined by craters on Europa, Ganymede, and Callisto. Preliminary solutions are found for the directions of the axes of rotation of the Galilean satellites. Mean radii are determined as 1815 + or - 5 km for Io, 1569 + or - 10 km for Europa, 2631 + or - km for Ganymede, and 2400 + or - 10 km for Callisto.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-163724 , RAND/N-1617-JPL/NASA
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 155
    facet.materialart.
    Unknown
    Pioneer Venus radar results - Altimetry and surface properties (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A topographic map of 93% of the Venus globe was depicted by the radar altimeter of the Pioneer Venus orbiter with a resolution better than 150 km. Extremes in relief expressed as a center-of-mass-to-surface radius extend from 6049 to 6062 km; the elevated terrain is dominated by a massive equatorial area equal in size to South America. The distribution of average meter-scale surface slopes is determined for the same regions in the 1 to 10 deg range; elevated areas have higher slopes, so that most features observed in the earth-based images are also evident in the vertical-incidence spacecraft measurements.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 156
    facet.materialart.
    Unknown
    A low-order global gravity field of Venus and dynamical implications (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An estimate of sixth-degree and sixth-order harmonic coefficients of the global gravity field of Venus is obtained by processing the long periodic variations of the mean orbital elements of the Pioneer Venus orbiter. Approximately 220 days of data are included in this reduction, which provides almost complete longitudinal coverage. Oblateness is estimated to be -5.97 + or - 3.2 x 10 to the -6. It is noted that the amplitudes of other coefficients are similar to the predicted coefficients using Kaula's rule under equal stress assumption. Atmospheric density values as a function of altitude are obtained to help model drag perturbation. A radial acceleration map at 100 km above the Venus surface is generated, and correlation between gravity anomalies and major topographic features is observed. Spectral analysis of the harmonic model suggests that the interior density anomalies are like those on earth. The orientation angles of the principal axes of the moments of inertia are computed, and deviation of the maximum moment of inertia axis from the spin axis is observed to be small (less than 5 deg). It is found that the minimum moment of inertia axis passes through the Aphrodite and Beta regions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 157
    facet.materialart.
    Unknown
    Net radiation in the atmosphere of Venus - Measurements and interpretation (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Aerodynamic testing of the Pioneer Venus small probe net flux radiometer (SNFR) has led to a better understanding of transient errors in the net flux measurements immediately following deployment. Corrections to the net flux profiles in this region produce profiles that are reasonably consistent with constraints imposed by ground-based and orbiter results for fluxes above the atmosphere. The tests raised questions about possible steady state errors associated with the changing atmospheric temperature encountered as the probes descended. However, the lack of sensor-to-sensor variability of the transient error (caused by a newly discovered flow-through mechanism) suggests that any related errors discovered by future testing will be correctable and will not alter the conclusions that net fluxes in the lower atmosphere vary considerably with location and are relatively large at the north and night probe sites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 158
    facet.materialart.
    Unknown
    Ultraviolet contrasts and the absorbers near the Venus cloud tops (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The UV measurements of the Venus atmosphere absorbers constrain the location, altitude, and identity near the Venus cloud tops. The spin-scan images observed by the Pioneer Venus orbiter spectrometer (UVS) and the cloud photopolarimeter measure contrasts in the 1990-3650 A range and at phase angles between 33 and 130 deg; the planet is darkest at the location where the UVS line of sight penetrates in the direction perpendicular to the cloud tops. SO2 absorption accounts for the contrast from 2000 to 3200 A; the persistence of contrast at longer wavelengths requires another absorber at about 75-mbar altitude. The correlation between the planetary differences and polarization does not need large-scale clearing or major vertical motions of the cloud tops as the main cause of the observed variations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 159
    facet.materialart.
    Unknown
    Zonal and meridional circulation of the lower atmosphere of Venus determined by radio interferometry (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The results of the Pioneer Venus differential long-baseline interferometry experiment are presented. The velocity component of the Pioneer probes as they fell to the surface of Venus was calculated from the Doppler shift of the received signal, and the other two orthogonal components were determined by long-baseline interferometry. The ambient wind velocity was about 1 m/s or less near the surface of the planet and about 100 m/s at an altitude of about 65 km at all four probe locations. Strata of high wind shear were found at altitudes of 15, 45, and 60 km. The wind velocity was always directed within a few degrees of due west except at a few km above the surface. The dominant motion of the lower atmosphere seems to be a retrograde zonal rotation, and eddies appear to account for most of the instantaneous meridional velocity. The data suggest that, within the clouds, a thermally driven mean meridional circulation is superimposed upon the much more rapid zonal rotation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 160
    facet.materialart.
    Unknown
    Model calculations of the dayside ionosphere of Venus - Energetics (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A model of the energy balance of the dayside ionosphere of Venus is presented. Calculations of the dayside electron and ion temperature profiles are carried out and compared with data from experiments on the Pioneer Venus orbiter. The coupled heat conduction equations for electrons and ions are solved for several values of the solar zenith angle. It is shown that thermal conductivities are inhibited by the presence of a horizontal magnetic field. A realistic model of the magnetic field that includes fluctuations is employed in deriving an appropriate expression for the thermal conductivity. The contributions of photoelectrons, ion chemistry, Joule heating, and solar wind heating to the energy balance of the ionosphere are considered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 161
    facet.materialart.
    Unknown
    Solar wind flow past Venus - Theory and comparisons (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Advanced computational procedures are applied to an improved model of solar wind flow past Venus to calculate the locations of the ionopause and bow wave and the properties of the flowing ionosheath plasma in the intervening region. The theoretical method is based on a single-fluid, steady, dissipationless, magneto-hydrodynamic continuum model and is appropriate for the calculation of axisymmetric supersonic, super-Alfvenic solar wind flow past a nonmagnetic planet possessing a sufficiently dense ionosphere to stand off the flowing plasma above the subsolar point and elsewhere. Determination of time histories of plasma and magnetic field properties along an arbitrary spacecraft trajectory and provision for an arbitrary oncoming direction of the interplanetary solar wind have been incorporated in the model. An outline is provided of the underlying theory and computational procedures, and sample comparisons of the results are presented with observations from the Pioneer Venus orbiter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 162
    facet.materialart.
    Unknown
    Differentiation of crusts and cores of the terrestrial planets - Lessons for the early earth (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The extent and mechanisms of global differentiation and the early thermal and tectonic histories of the terrestrial planets are surveyed in order to provide constraints on the first billion years of earth history. Indirect and direct seismic evidence for crusts on the moon, Mars and Venus is presented, and it is pointed out that substantial portions of these crusts have been in place since the cessation of heavy bombardment of the inner solar system four billion years ago. Evidence for sizable cores on Mars and Mercury and a small core on the moon is also discussed, and the heat involved in core formation is pointed out. Examination of the volcanic and tectonic histories of planets lacking plate tectonics indicates that core formation was not closely linked to crust formation on the moon or Mars, with chemical differentiation restricted to shallow regions, and was much more extensive on Mercury. Extension of these considerations to the earth results in a model of a hot and vigorously convecting mantle with an easily deformable crust immediately following core formation, and the gradual development of a lithosphere and plates.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Precambrian Research; 10; 1980
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 163
    facet.materialart.
    Unknown
    First Voyager view of the rings of Saturn (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Voyager 1 imaging data of the Saturn rings, taken at a resolution of 1000 km/line pair between September 3 and October 13, 1980 are discussed. It is pointed out that as the spacecraft approached Saturn, finer radial structure in the rings between and within the major divisions became apparent, together with extensive azimuthal structure in the B ring. It is shown that the fine structure observed in the rings cannot, for the most part, be attributed to classical resonances with the known inner satellites. Preliminary model calculations of ring brightness based on photometry data indicate that the particles of the A and B rings are characterized by a greater degree of diffuse backscattering ability than previously suspected, behaving like Lambert spheres, while those of the C ring are either darker or more highly forward scattering than the A or B ring particles.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 288; Dec. 4
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 164
    facet.materialart.
    Unknown
    Io and its plasma environment (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The interaction of Io with its plasma torus and the Jovian magnetic field is described and examined in the context of several currently popular models. Three specific matters are addressed. First, features implied by sub-Alfvenic flow which must be common to all models are discussed. Next, the magnetic signature observed near Io by the Goddard Space Flight Center Voyager 1 magnetometer is examined and it is pointed out that the preliminary estimate of 5,000,000 A current may be an overestimate. Good fits are obtained with alternative current distributions which yield currents as small as 700,000 A through Io. The best fits are obtained for an Alfven Mach number of 0.15, but good fits are also found for Alfven Mach numbers between 0.1 and 0.25. Lastly, the crucial role of charged particle data for probing the near Io interaction is pointed out. Published data from the low energy charged particle (LECP) detector are made to suggest that Io has an intrinsic magnetic field of magnitude comparable with earlier estimates. Predictions are made which can test this picture as further data become available.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 165
    facet.materialart.
    Unknown
    Interior structure of Saturn inferred from Pioneer 11 gravity data (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The structure of Saturn is studied via a fourth-order theory for rotating planets and equations of state for the envelope which depend parametrically on the helium abundance, on the starting temperature for the adiabat, and on adopted forms of the pressure-density curve in the region of transition from molecular to metallic hydrogen. Models are constrained by the values of J2 and J4 obtained from the Pioneer-Saturn celestial mechanics experiment. Equations of state are tested by computing Jupiter models, which can now be subjected to a more stringent comparison with observed zonal harmonics. It is found that Saturn has a low-density hydrogen-helium envelope with no evidence for enhancement of H2O, CH4, or other abundant compounds. Such compounds are presumably located near the core. The helium mass abundance for Saturn's envelope appears to be in the range of approximately 0.12 to 0.19, but this result is very model-dependent. The helium abundance in the envelope of Jupiter is apparently very similar to that of Saturn.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 166
    facet.materialart.
    Unknown
    A possible magnetic wake of Titan - Pioneer 11 observations (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The paper deals with measurements of the magnetic field along the outbound leg of Pioneer's trajectory at Saturn, which suggest that the spacecraft may have passed through the magnetic wake of Titan at a distance of 145 Titan radii downstream from Titan. The data obtained over a period of several hours around the crossing of Titan's L shell exhibit a number of characteristics which are qualitatively consistent with predictions based on theories of the interaction between a supersonic magnetized plasma and a conducting or magnetized planetary body. In addition, values of the plasma mass density derived from the interaction geometry are consistent with an upper limit inferred from in situ plasma measurements obtained during the outbound leg of Pioneer's trajectory.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 167
    facet.materialart.
    Unknown
    Sources of high-energy protons in Saturn's magnetosphere (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The passage of Pioneer 11 through Saturn's magnetosphere revealed an especially intense region of high-energy particle fluxes that places unique constraints on models for sources of high-energy protons in the innermost radiation zones. Of special interest is the flux of protons with energies above 35 MeV which was measured with a fission cell in the innermost magnetosphere between the A ring and the orbit of Mimas. The negative phase space density gradients derived from the proton and electron observations in this region imply that steady-state inward diffusion from the outer magnetosphere is not an adequate source for these high-energy protons. In the present paper, the nature of the Crand source at Saturn is examined, and its significance for injection of high-energy protons into the region inside L = 4 is estimated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 168
    facet.materialart.
    Unknown
    Charged particle anisotropics in Saturn's magnetosphere (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The paper deals with observations of anisotropies and pitch angle distributions for 0.5 to 1.8 MeV protons and 7 to 17 MeV electrons in Saturn's magnetosphere. In the outer magnetosphere (L = 6), there is clear evidence for corotation of the proton flux. The pitch-angle distribution shows maximum flux perpendicular to the magnetic field ('pancake' distribution). Observed changes in the amplitude and shape of the pitch angle distributions suggest the existence of substantial temporal variations in the outer magnetosphere. From L = 6 to L = 4, the proton intensity decreased by more than two orders of magnitude, while the pitch angle distribution shifted to a 'dumbbell' form (maximum flux parallel to magnetic field).
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 169
    facet.materialart.
    Unknown
    Corotation of Saturn's magnetosphere - Evidence from energetic proton anisotropies (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The theory and technique of Northrop and Thomsen (1980) are applied to the observations of energy spectra and directional anisotropies of 0.61- to 3.41 MeV protons in Saturn's magnetosphere. The observations were made by the Goddard Space Flight Center/University of New Hampshire and University of Iowa instruments aboard Pioneer 11 during the Pioneer encounter with Saturn in August-September 1979. Fourier fits to 15-min intervals of data are combined with spectral indices to yield information about the E x B convection velocity and temporal changes in the particle population. There is a fundamental inability to distinguish unambiguously between the two, but if one can be assumed, the other then follows from these calculations. It is found that although these data do not by themselves allow an unambiguous determination of the extent of corotation in Saturn's outer magnetosphere, they are consistent with exact corotation at the nominal rotation period in the presence of significant but not unreasonable temporal variations in the energetic proton population.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: AD-A093436 , Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 170
    facet.materialart.
    Unknown
    Sources and sinks of energetic electrons and protons in Saturn's magnetosphere (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The paper deals with some results of continuing analysis and interpretation of energetic particle observations made onboard Pioneer 11 during its August-September 1979 encounter with Saturn. Source strength estimates and the radial dependence of the phase space density of protons of energies above 80 MeV indicate with some confidence that the cosmic-ray neutron albedo from the planets atmosphere and rings is the source of these particles.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: AD-A093434 , Journal of Geophysical Research; 85; Nov. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 171
    facet.materialart.
    Unknown
    Tidal dissipiation in Europa - A correction (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The possibility that tidal dissipation in a thin ice crust was sufficient to preserve liquid water on Jupiter's satellite Europa was suggested by Cassen et al. (1979). However, their calculation of the tidal heating rate for that situation is in error; for the same parameter values, the actual heating rate would be much less than given in their paper. Thus, their conclusion regarding the possibility that liquid water exists today on Europa is considerably weakened. This paper corrects the calculation of the tidal dissipation rate in a Europan ice crust, and discusses the implications for Europa's thermal history, and clarifies certain aspects of the tidal heating problem.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 7; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 172
    facet.materialart.
    Unknown
    Evidence for a secular variation in the C-13/C-12 ratio of carbon implanted in lunar soils (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A curve of delta(C-13) vs delta(N-15) for lunar soils and breccias shows that the previously recorded 30% change in delta(N-15) is associated with a change in delta(C-13). The correlation represents concurrent changes in the isotope ratios of both elements at their source, and does not result from maturation effects or nonselective sample contamination. A computation of the relative production rates of C-13 and N-15 shows that spallation reactions in the sun could produce the observed ratio of the delta(C-13) to delta (N-15) variations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 50; 1, Oc; Oct. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 173
    facet.materialart.
    Unknown
    Surface erosion caused on Mars from Viking descent engine plume (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: During the Martian landings the descent engine plumes on Viking Lander 1 (VL-1) and Viking Lander 2 (VL-2) eroded the Martian surface materials. This had been anticipated and investigated both analytically and experimentally during the design phase of the Viking spacecraft. This paper presents data on erosion obtained during the tests of the Viking descent engine and the evidence for erosion by the descent engines of VL-1 and VL-2 on Mars. From these and other results, it is concluded that there are four distinct surface materials on Mars: (1) drift materials, (2) crusty to cloddy material, (3) blocky material, and (4) rock.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Moon and the Planets; 23; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 174
    facet.materialart.
    Unknown
    Measurements of the H2 4-0 quadrupole bands of Uranus and Neptune (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: It is found that the equivalent widths of the lines of the 4-0 H2 quadrupole band on Uranus and Neptune are substantially smaller than the values found by some previous observers. An analysis of the results based on a range of atmospheric models yields H2 abundances of 240 + or - 60 km-amagats for Uranus and greater than approximately 200 km amagats for Neptune.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 43; Aug. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 175
    facet.materialart.
    Unknown
    Spatial imaging of hydrogen Lyman-alpha emission from Jupiter (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A sounding rocket measurement of the H I L-alpha emission from Jupiter made on Dec. 1, 1978 shows limb darkening and an average disk brightness of 13 kR. This brightness is significantly higher than in previous measurements, and was confirmed by an IUE observation on Dec. 10, 1978. Comparison with a plane-parallel hydrogen layer model indicates that there is enhanced emission from the equatorial regions, reaching a peak near 80 deg longitude.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal; vol. 240
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 176
    facet.materialart.
    Unknown
    Si-rich Fe-Ni grains in highly unequilibrated chondrites (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Consideration is given to the Si contents of Fe-Ni grains in highly unequilibrated chondrites, which have undergone little metamorphosis and thus best preserve the record of processes in the solar nebula. Electron microprobe determinations of silicon content in grains of the Bishunpur chondrite are presented for the six Si-bearing Fe-Ni grains for which data could be obtained, five of which were found to be embedded in olivine chondrules. In addition, all grains are found to be Cr-rich, with Cr increased in concentration towards the grain edge, and to be encased in FeS shells which evidently preserved the Si that entered the FeNi at higher temperatures. A mechanism for the production of Si-bearing metal during the condensation of the cooling solar nebula is proposed which considers the metal to have condensed heterogeneously while the mafic silicates condensed homogeneously with amounts of required undercooling in the low-pressure regions where ordinary and carbonaceous chondrites formed, resulting in Si mole fractions of 0.003 at nebular pressures less than 0.000001 atm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 287; Oct. 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 177
    facet.materialart.
    Unknown
    Statics of the nightside Jovian plasma sheet (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Data are analyzed from the low energy charged particle (LECP) and magnetic field (MAG) experiments on the Voyager 2 spacecraft that demonstrate that the configuration of the Jovian plasma sheet at distances of about .80 to about 120 Jupiter radii is determined by ions (protons and heavier nuclei) of energies greater than approximately 30 keV. The energy densities of these ions are sufficient to provide the diamagnetic depressions in the magnetic field strengths observed as the spacecraft crossed the Jovian plasma sheet. The particle bulk direction of motion is predominantly across the local magnetic field, consistent with that expected from corotation of the planetary magnetic field.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 7; Oct. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 178
    facet.materialart.
    Unknown
    The distribution of temperature maxima for micrometeorites decelerated in the earth's atmosphere without melting (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A simple model for the statistics of heating of micrometeorites decelerated in the earth's atmosphere without melting predicts that for 10 micron particles with thermal emissivity near 1, roughly half of those with density 1 g/cc are heated above 550 C, while half of those with density 3 g/cc are heated above 800 C. In the study of stratosphere collected interplanetary dust, the model can be helpful in identifying petrographic thermometers of the atmospheric entry process, and in understanding the most recent history of this new class of extraterrestrial material available in the laboratory.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 7; Oct. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 179
    facet.materialart.
    Unknown
    A model of Saturn's seasonal stratosphere at the time of the Voyager encounters (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A polar-equatorial climate model by Cess and Cladwell (1979) is extended to all latitudes of Saturn. Modifications for solar absorption within the stratosphere are made in the extension to intermediate latitudes. The latitudinally and temporally variable effects of sunlight absorption by the rings of Saturn are included in the model. Temperature-latitude profiles for several levels within the Saturn stratosphere are presented for January 1981, which should be directly comparable with Saturn Voyager observations in November 1980 and August 1981. Temperature-pressure profiles for latitudes +30 degrees and -25 degrees are provided, which correspond to the planned points at which radio equipment aboard Voyager II will produce occultation observations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 37; Aug. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 180
    facet.materialart.
    Unknown
    Detection of energetic hydrogen molecules in Jupiter's magnetosphere by Voyager 2 - Evidence for an ionospheric plasma source (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The discovery of energetic (approximately 1 MeV/nuc) H3 and H2 molecules in Jupiter's magnetosphere is reported. The data, obtained with the LECP instrument on Voyager 2, showed these molecules to be present throughout the magnetosphere and as far as 180 Jupiter radii from the planet, in the 'magnetospheric wind' region. Although the relative abundances of H3 and H2 do not show a monotonic trend with distance from Jupiter, the intervals of highest abundance were found in the outer magnetosphere. As an example, in the radial range 51-56 Jupiter radii, of the dayside magnetosphere, the abundances of H3 and H2 (0.60-0.95 MeV/nuc) were about 20 and 13-25% that of He, respectively, and the He abundance was about 1-2% that of H. Since H3(+) is expected to be an important constituent of Jupiter's ionosphere, the data provide strong evidence that, in addition to Io, the ionosphere may be an important local plasma source for the Jovian energetic particles. The measurements reported may represent the first detection in nature of molecules at energies as high as 1 MeV/nucleon.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 7; Oct. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 181
    facet.materialart.
    Unknown
    Superthermal electrons and Bernstein waves in Jupiter's inner magnetosphere (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A theoretical model for generation of banded electrostatic emissions by low density, superthermal electrons is developed for application to Jupiter's magnetosphere. The model employs a power law form for the energy dependence and a loss cone pitch angle distribution of the superthermals to drive convective instability of Bernstein modes. A direct correspondence between spectral features of the 3/2 band and resonant superthermal electrons is found. The concept of a critical flux of resonant electrons able to provide 10 e-foldings of electric field amplification yields an explicit relation in terms of the background thermal electron pressure. This result is used to construct a theoretical/empirical model of thermal electron density and temperature from 6-20 Jupiter radii in the Jovian magnetosphere which suggests that the electron temperature is less than the ion temperature which is approximately equal to 10 times the electron temperature in this region. Finally, wave ray paths are computed for propagation in the magnetic equator and in the magnetic meridional plane of a dipole magnetic field. These ray paths suggest that intense wave activity is tightly confined to a small latitudinal extent, less than + or - approximately 4 deg, about the magnetic equator.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 182
    facet.materialart.
    Unknown
    A 3.6-b.y.-old impact-melt rock fragment in the Plainview chondrite - Implications for the age of the H-group chondrite parent body regolith formation (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 51; 2, De; Dec. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 183
    facet.materialart.
    Unknown
    Protoplanetary core formation by rain-out of minerals (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Models of giant protoplanets computed by DeCampli and Cameron (1979) show that Fe and other minerals in the planet interior are in a liquid state during one of the stages of protoplanet evolution. A model of coalescence of liquid drops was developed using the 'stochastic' collection equation of Slattery (1978); the growth times to droplets was much shorter than the period during which the drops are in a liquid state. Brownian collection quickly coalesced the tiny droplets to a radius of 0.005 cm; gravitational collection was required to form droplets of radii greater than 0.005 cm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Moon and the Planets; 23; Dec. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 184
    facet.materialart.
    Unknown
    Observations from earth orbit and variability of the polar aurora on Jupiter (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Spatially resolved spectra of Jupiter taken with the International Ultraviolet Explorer satellite show enhanced emissions from the polar regions at H L-alpha (1216 A) and in the Lyman and Werner bands of H2 (1175-1650 A). Two types of variability in emission brightness have been observed in these aurorae: an increase in the observed emission as the auroral oval rotates with Jupiter's magnetic pole to face toward the earth and a general variation in brightness of more than an order of magnitude under nearly identical observing conditions. In addition, the spectral character of these aurorae (determined by the ratio of H L-alpha to H2 brightnesses) appears variable, indicating that the depth of penetration of the auroral particles is not constant.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 185
    facet.materialart.
    Unknown
    Moon and earth - Compositional differences inferred from siderophiles, volatiles, and alkalis in basalts (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A comparison of RNAA analyses of 18 trace elements in 25 low-Ti lunar and 10 terrestrial oceanic basalts indicated that the volatiles such as Ag, Bi, and Br are depleted in lunar basalts by nearly constant factors of 0.026 relative to terrestrial basalts. This constancy is not consistent with models that derive the moon's volatiles from partial recondensation of the earth's mantle or from partial degassing of a captured body; it is consistent with models which derive planetary volatiles from a thin veneer of C-chondrite material. Chalcogens (Se and Te) have almost constant and identical abundances in lunar and terrestrial basalts; siderophiles show abundant Ni in lunar basalts, while Ir, Re, Ge, and Au are depleted.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 44; Dec. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 186
    facet.materialart.
    Unknown
    Thermal metamorphism of primitive meteorites. XI - The enstatite meteorites: Origin and evolution of a parent body (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The neutron activation data for Ag, As, Bi, Cd, Co, Cs, Cu, Ga, In, Rb, Se, Te, Tl, and Zn were obtained in samples of Abee heated to 1000-1400 C at low pressures. In addition, these elements were reported in nine enstatite achondrites and in the silicate part of the Mt. Egerton stony-iron. The data show trace element losses above 1000 C by diffusion-controlled processes with apparent activation energies of 8 to 55 kcal/mol; these data together with abundances of aubrites, Mt. Egerton, and E4-6 chondrites, and isotopic results link all enstatite meteorites to a common parent body. The data also indicate that aubrites and the Mt. Egerton material reflect fractional crystallization of a magma produced from enstatite chondrite-like parent material (E6) and the late introduction of chalcophiles and mobile elements transported by an FeS-Fe eutectic from an E4-6 region undergoing open-system metamorphism.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 44; Dec. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 187
    facet.materialart.
    Unknown
    Deep-sea spherules from Pacific clay - Mass distribution and influx rate (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: From 411 kg of Pacific clay, 22 mg of stony spherules and 50 mg of iron spherules larger than 150 microns were concentrated. The extraterrestrial origin of these particles was evaluated with the aid of optical and electron microscopy and atomic absorption elemental analysis. An expression for the integral number of stony particles from this sediment in the mass range 20-300 micrograms was derived. The world-wide influx rate of stony particles in the mass range which survive atmospheric heating and ocean sediment storage is calculated to be 90 tons/yr. The relative contributions of ablation debris vs fused interplanetary dust to the influx of stony spherules is discussed, but no conclusions could be made.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 44; Dec. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 188
    facet.materialart.
    Unknown
    Lu-Hf total-rock isochron for the eucrite meteorites (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The isotope Lu-176 (2.6% of natural lutetium) decays by beta(-) to Hf-176, with a long half life. The first Lu-Hf isochron is presented. The eucrite meteorites, a suite of planetary igneous rocks of known age, 4,550 Myr, define a 10-point total-rock isochron with a slope of 0.0934 + or - 40, leading to a value of 3.53 + or - 0.14 x 10 to the 10th yr for the beta(-) decay half life of Lu-176. The isochron intercept of 0.27973 + or - 12 gives the initial Hf-176/Hf-177 for the inner solar system at the time of accretion.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 288; Dec. 11
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 189
    facet.materialart.
    Unknown
    Solitary Rossby waves in the presence of vertical shear (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The effects of vertical shear on regular neutral mode Rossby solitons driven by a horizontal shear are investigated in light of the proposition that certain features in the Jupiter atmosphere may be explained by solitary Rossby waves. Consideration is given to a two-layer quasi-geostrophic model in which the motion in each layer consists of a different zonal shear flow, with vertical shear concentrated at the interface between the layers. In the case of a strong vertical shear, it is found that only a very restricted set of flows will admit Rossby neutral model solitons. For the more realistic case of a weak vertical shear, results indicate similar, but latitudinally shifted, wave patterns in each layer. It is noted that no such slant has yet been detected in the Great Red Spot.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 37; Oct. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 190
    facet.materialart.
    Unknown
    Ionospheres of the terrestrial planets (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The theory and observations relating to the ionospheres of the terrestrial planets Venus, the earth, and Mars are reviewed. Emphasis is placed on comparing the basic differences and similarities between the planetary ionospheres. The review covers the plasma and electric-magnetic field environments that surround the planets, the theory leading to the creation and transport of ionization in the ionospheres, the relevant observations, and the most recent model calculations. The theory section includes a discussion of ambipolar diffusion in a partially ionized plasma, diffusion in a fully ionized plasma, supersonic plasma flow, photochemistry, and heating and cooling processes. The sections on observations and model calculations cover the neutral atmosphere composition, the ion composition, the electron density, and the electron, ion, and neutral temperatures.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Reviews of Geophysics and Space Physics; 18; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 191
    facet.materialart.
    Unknown
    The composition of mesosiderite olivine clasts and implications for the origin of pallasites (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The composition of olivine clasts from the mesosiderites Emery, Mincy and Pinnaroo is investigated, and implications of the results for the origin of the pallasites, which, although chemically distinct, may be related to the diogenites, eucrites, howardites and mesosiderites, are discussed. Centimeter-sized olivines were analyzed by electron microprobe, and instrumental neutron activation analysis was performed on one olivine each from Emery and Pinnaroo and an olivine separate from the Brenham pallasite. The olivine compositions are found to range from Fa8 to Fa28, with Emery samples having values from Fa18 to Fa28, and to require essentially total melting of a source composition rich enough in FeO to produce basaltic clasts. It is argued that the mesosiderite olivines were formed in the outer few kilometers of their parent body, as were those of the pallasites, which have the same compositions as the mesosiderite olivines. A model is then developed for the origin of the pallasites as a by-product of igneous differentiation in the external heating of a chondritic parent body.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 51; 1; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 192
    facet.materialart.
    Unknown
    The position angle of Jupiter's linearly polarized synchrotron emission Observations extending over 16 years (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Parkes, Owens Valley and Goldstone measurements are presented, showing the variation with central meridian longitude of the position angle of Jupiter's linearly polarized synchrotron emission at wavelengths of 21, 13, 11 and 6 cm; the observations span a total time interval greater than one Jovian orbital period. The form of the position angle versus longitude curve shows a slight dependence on wavelength and epoch. The epoch dependence appears to reflect Jupiter's changing aspect with respect to the earth. The observations yield a Jovian rotation period agreeing to within about 0.02 s with that derived from the decametric burst measurements, implying a highly stable inner magnetic field configuration.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Royal Astronomical Society; vol. 193
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 193
    facet.materialart.
    Unknown
    Io - Are vapor explosions responsible for the 5-micron outbursts (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: It is proposed that a vapor explosion of a submerged pool of liquid sulfur will remove the crust overlying an area of about 50-km diam. Thermal radiation from the exposed liquid sulfur pool with a surface temperature of 600 K is then presumed to be responsible for the 5-micron outbursts that have been observed. The explosive volcanoes are expected to leave black sulfur calderas, which are, indeed, found on the surface. The 5-micron outburst observed by Sinton (1980), on June 11, 1979 (UT), is identified with a new caldera found on Voyager 2 photographs but which had not been present on Voyager 1 pictures.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 43; July 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 194
    facet.materialart.
    Unknown
    Tidal dissipation, orbital evolution, and the nature of Saturn's inner satellites (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Estimates of tidal damping times of the orbital eccentricities of Saturn's inner satellites place constraints on some satellite rigidities and dissipation functions Q. These constraints favor rock-like rather than ice-like properties for Mimas and probably Dione. Photometric and other observational data are consistent with relatively higher densities for these two satellites, but require lower densities for Tethys, Enceladus, and Rhea. This leads to a nonmonotonic density distribution for Saturn's inner satellites, apparently determined by different mass fractions of rocky materials. In spite of the consequences of tidal dissipation for the orbital eccentricity decay and implications for satellite compositions, tidal heating is not an important contributor to the thermal history of any Saturnian satellite.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: PB81-137184 , Icarus; 43; July 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 195
    facet.materialart.
    Unknown
    I-Xe age and trapped Xe components of the Murray /C-2/ chondrite (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A neutron-irradiated bulk sample of the Murray (C-2) carbonaceous chondrite was etched with H2O2 and then divided into colloidal and non-colloidal fractions. The H2O2 treatment removed about 80% of the trapped Xe and greatly increased variations in the Xe-129/Xe-132 ratio measured in stepwise heating. The colloid showed very little excess Xe-129, but the anti-colloid gave a fairly good I-Xe correlation corresponding to formation 3.7 + or - 2.1 m.y. after Bjurbole. Variations in the trapped Xe component were also observed; most notably the 550 C anti-colloid fraction has large deficiencies relative to AVCC at the heavy isotopes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 48; 2, Ju; July 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 196
    facet.materialart.
    Unknown
    Ancient solar wind in lunar microbreccias (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Possible components of the ancient solar wind, particularly the N-15/N-14 ratio, are investigated on the basis of lunar microbreccia studies. Nitrogen contents and isotope ratios were determined for Apollo 11 and 15 microbreccia samples by means of vacuum pyrolysis techniques. The Apollo 11 soil breccias, which had been closed to the addition of recent solar wind due to their compaction, are found to contain the lowest N-15/N-14 ratios yet reported for the solar wind, extending the range of variation of the ratio to between a delta N-15 of -190% in the past to +120% at present. Nitrogen isotope analysis of the Apollo 15 drill core, which had undergone two episodes of solar wind exposure, also support the secular variation in the N-15 content of the solar wind, which is attributed to spallation reactions in the sun. The formation of the breccias at the Apollo 11 and 15 sites is discussed on the basis of the observed nitrogen systematics, and differences between N-15 and Ne-21 cosmic ray exposure ages implied are attributed to the diffusive loss of neon from lunar soils.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters; 47; 1, Ma; Mar. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 197
    facet.materialart.
    Unknown
    SO2 frost - UV-visible reflectivity and Io surface coverage (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The reflectance spectrum in the range 0.24-0.85 microns of SO2 frost is measured in light of the discovery of SO2 gas in the atmosphere of Io and the possible discovery of the frost on its surface. Frost deposits up to 1.5 mm thick were grown in vacuum at 130 K and bi-directional reflectance spectra were obtained. Typical SO2 frost is found to exhibit very low reflectivity (2-5%) at 0.30 microns, rising steeply at 0.32 microns to attain a maximum reflectivity (75-80%) at 4.0 microns and uniformly high reflectivity throughout the visible and near infrared. Comparison with the full disk spectrum of Io reveals that no more than 20% of the surface can be covered with optically thick SO2 frost. Combinations of surface materials including SO2 frost which can produce the observed spectrum are indicated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 7; Sept
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 198
    facet.materialart.
    Unknown
    Ordering of FeNi in clear taenite from meteorites (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 287; Sept. 18
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 199
    facet.materialart.
    Unknown
    Downslope movement of material on Deimos (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Viking Orbiter images have shown downslope movement of loose material to be an important surface process on Deimos. Loose surface material moves downslope from prominent ridges and accumulates in topographic lows. In some areas, up to 10 m of surface material have been removed; in others, craters up to 200 m in diameter have been filled completely by material moving downslope. Brighter material associated with, and probably derived from crater rims, also moves downslope and forms tapered streamers up to 3 km in length which appear as prominent features on the satellite. The mechanism for downslope movement is uncertain, but thermal creep, micrometeroroid bombardment and impact-related seismic shaking may be involved. Certain craters show conspicuous infilling even though their prominent rims should prevent material moving downslope from reaching their interiors. Such fill must have been emplaced ballistically - the amounts of sediment suggest that over half of all ejecta produced on Deimos are retained on the satellite. Phobos appears to retain little ejecta and shows little evidence of downslope movement of debris.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 42; May 1980
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 200
    facet.materialart.
    Unknown
    Effects of atmospheric breakup on crater field formation (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: This paper investigates the physics of meteoroid breakup in the atmosphere and its implications for the observed features of strewn fields. There are several effects which cause dispersion of the meteoroid fragments: gravity, differential lift of the fragments, bow shock interaction just after breakup, centripetal separation by a rotating meteroid, and possibly a dynamical transverse separation resulting from the crushing deceleration in the atmosphere. Of these, it is shown that gravity alone can produce the common pattern in which the largest crater occurs at the downrange end of the scatter ellipse. The average lift-to-drag ratio of the tumbling fragments must be less than about 0.001, otherwise small fragments would produce small craters downrange of the main crater, and this is not generally observed. The cross-range dispersion is probably due to the combined effects of bow shock interaction, crushing deceleration, and possibly spinning of the meteoroid. A number of terrestrial strewn fields are discussed in the light of these ideas, which are formulated quantitatively for a range of meteoroid velocities, entry angles, and crushing strengths. It is found that when the crater size exceeds about 1 km, the separation between the fragments upon landing is a fraction of their own diameter, so that the crater formed by such a fragmented meteoroid is almost indistinguishable from that formed by a solid body of the same total mass and velocity.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 42; May 1980
    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...