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  • LUNAR AND PLANETARY EXPLORATION  (3,679)
  • AERODYNAMICS  (2,110)
  • ASTRONOMY  (1,188)
  • 1975-1979  (6,977)
Collection
Keywords
Years
Year
  • 1
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    Some unique meteorites found in Antarctica and their relation to asteroids (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Two unique meteorites were identified by means of a mineralogical examination of the smaller-sized Yamato achondrites. Yamato-74130 is the most iron-rich ureilite with Na, Cr-rich augite instead of pigeonite. Yamato-74160 was extensively recrystallized, but the composition and proportion of olivine, orthopyroxene, augite, and plagioclase is consistent with LL7 chondrites. ALHA77005 is a unique achondrite with olivine, possibly three pyroxene assemblages, and maskelynite. These meteorites provide evidence that there may be other 'thermalized' asteroids than the howardite parent body. Detailed petrologic descriptions of the unique achondrites, recrystallized diogenite Yamato-74013, and the rapidly cooled eucrite Yamato-74450 with pyroxene phenocrysts are given. It is inferred from the bulk chemistry and the mineralogical reexamination of Yamato-75028 that it is composed of the H5-type clasts and chondrule-rich H(L)3-like matrix with the H5 fragments. A close relationship in the collisional evolution of some asteroids with these materials is inferred.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: National Institute of Polar Research, Memoirs (ISSN 0386-0744); 15, 1; 54-76
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  • 2
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    Meteoroid protection for the Comet Halley probe (1979)
    In:  CASI
    Details
    Publication Date: 2006-06-26
    Description: The high closing speed of 57km/s between the spacecraft and Halley poses special problems in the design of the required meteoroid protection. A double wall structure with a total thickness equal to 0.1 to 1 times the diameter of the largest meteoroid encountered is sufficient to stop that meteoroid. However, the unusually high number of meteoroid impacts on the Halley probe will cause significant erosion of the outer wall so that failure of the second wall is more likely to occur from a small meteoroid passing through a previously created hole in the outer wall and then penetrating the second wall. Calculations of the shielding required based on this failure mode, show that a double wall structure must actually have a total thickness 1.2 to 7.3 times the diameter of the largest meteoroid encountered, depending on the size distribution of the meteoroids.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: ESA Comet Halley Micrometeoroid Hazard Workshop; p 73-76
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  • 3
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    Executive summary of Aircraft Icing Specialists Workshop (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: In a period of escalating development costs for new aircraft, there is growing interest in a renewed and coordinated icing research effort to achieve an updating or modernization of each aspect of the technological issues that are involved. This includes the data base, analysis methods, test techniques, and test facilities.
    Keywords: AERODYNAMICS
    Type: Aircraft Icing; p 1-16
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  • 4
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    Absorption lines in the spectra of distant objects (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Studies that can be carried out with the Space Telescope of absorption line systems which may be expected to occur in the spectra of distant objects are discussed. The phenomenology of quasar absorption line systems is described and the principal suggested explanations are summarized. It is proposed that the numerous Ly-alpha systems are caused by 'extremely large hydrogenic halos around galaxies or clusters of galaxies. Two tests are also described for the origins of known absorption systems, the results of which will favor either the cosmological or intrinsic hypothesis. Absorption lines that are likely to be strongest are listed and a sample observing program is presented.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Sci. Res. with the Space Telescope; p 215-240
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  • 5
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    Space telescope observations of normal galaxies (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Observations of the stellar content of galaxies are discussed. Specific emphasis is placed on the following two types of observation: (1) those objects near enough to observe individual stars; and (2) those so distant that only their integrated light can be observed.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Sci. Res. with the Space Telescope; p 165-180
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  • 6
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    Population statistics of faint stellar and non-stellar objects (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A disc and halo population model is constructed to fit star counts and color data down to V approximately 23 at absolute value of b = 90 deg. This model is used to predict star counts and colors down to V approximately 30. Deviations from these extrapolated relationships provide constraints on the number of faint quasars and black dwarf stars. It is shown that extra-galactic globular clusters start contributing significantly to star counts at V approximately 25 and are more numerous than stars for V 31. Morphological studies of galaxies with approximately 0.5, were made with the space telescope. Significant constraints on theoretical models that describe the evolution of clusters of galaxies are provided.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Sci. Res. with the Space Telescope; p 151-164
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  • 7
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    The space telescope observatory (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: A guide to the expected characteristics of the space telescope (ST) observatory is presented. The general objectives of the ST observatory are summarized. The plans for the development of the observatory are described with a brief history of the scientific activities; an account of the scope of the present program; a summary of the major responsibilities of the contractors; and a list of the project milestones are included. The performance characteristics of the observatory are provided including the imaging and stray light characteristics, pointing capability, and operational access. The expected performance characteristics of all six of the first generation science instruments are summarized. The mode of operations is described which includes a discussion of program options, guide star selection, methods of acquisition, and quick look data capabilities.
    Keywords: ASTRONOMY
    Type: Sci. Res. with the Space Telescope; p 5-46
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  • 8
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    Safety hazard of aircraft icing (1979)
    In:  CASI
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    Publication Date: 2006-01-12
    Description: The problem of aircraft icing is reported as well as the type of aircraft affected, the pilots involved, and an identification of the areas where reduction in icing accidents are readily accomplished.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; p 21-27
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  • 9
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    Radio astronomers, X-ray astronomers and the space telescope (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The use of the Space Telescope and the study of objects in the radio and X-ray wavebands, particularly extragalactic objects, are discussed. The scientific objectives of a number of projects which involve observations with the Space Telescope are described.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Sci. Res. with the Space Telescope; p 241-262
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  • 10
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    Space vehicle meteoroid shielding design (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Design principles of spaced, multiwall meteoroid protection are investigated in the light of experimental data generated during the Apollo Program. The outer wall or shield is shown to be the most important element in the meteoroid-spacecraft interaction. The condition of the debris is primarily a function of the shock pressure, the melting points of the meteoroid and the shield, and the length of the meteoroid and thickness of the shield. Spacing between the walls is effective up to approximately 100 times the length of the meteoroid. The required thickness of the second wall is shown to be proportional to the meteoroid mass, velocity, and density, and to the spacing between the walls, taken with exponents dependent upon the condition of the debris. The effects of placing additional elements (insulation or honeycomb cells) between the two walls are discussed, and the efficiency of various protective configurations is presented. An analysis of the meteoroid protection proposed for the Comet Halley probe is included as an appendix.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: ESA Comet Halley Micrometeoroid Hazard Workshop; p 85-92
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  • 11
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    Planetary astronomy with the space telescope (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Experimental methods in planetary astronomy are discussed using a comparison of the advantages and disadvantages in the astronomical methods of ground based, Earth-orbit, and deep space missions. Problem areas in planetary astronomy which demonstrate the utility and power of the space telescope (ST) over other methods are delineated. These include utilizing the ST for studying the atmospheric dynamics, stratospheric and upper atmospheric processes, and circumplanetary nebulae of the planets. The capability of the ST for solar system observations is summarized with a discussion of the increases in resolution and sensitivity of the ST over other Earth-orbiting telescopes highlighted.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Sci. Res. with the Space Telescope; p 47-75
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  • 12
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    Mining and beneficiation of lunar ores (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The beneficiation of lunar plagioclase and ilmenite ores to feedstock grade permits a rapid growth of the space manufacturing economy by maximizing the production rate of metals and oxygen. A beneficiation scheme based on electrostatic and magnetic separation is preferred over conventional schemes, but such a scheme cannot be completely modeled because beneficiation processes are empirical and because some properties of lunar minerals have not been measured. To meet anticipated shipping and processing needs, the peak lunar mining rate will exceed 1000 tons/hr by the fifth year of operation. Such capabilities will be best obtained by automated mining vehicles and conveyor systems rather than trucks. It may be possible to extract about 40 kg of volatiles (60 percent H2O) by thermally processing the less than 20 micron ilmenite concentrate extracted from 130 tons of ilmenite ore. A thermodynamic analysis of an extraction process is presented.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Space Resources and Space Settlements; p 275-288
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  • 13
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    A geologic assessment of potential lunar ores (1979)
    In:  CASI
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    Publication Date: 2006-01-12
    Description: Although bulk lunar soil is not a suitable feedstock for extracting metals, certain minerals such as anorthite and ilmenite can be separated and concentrated. These minerals can be considered as potential ores of aluminum, silicon, titanium, andiron. A separation and metal extraction plant could also extract large amounts of oxygen and perhaps hydrogen from these minerals. Anorthie containing 19 percent aluminum and 20 percent silicon can be concentrated from some highland soils where it is present in amounts up to 60 percent. Ilmenite containing 32 percent titanium and 37 percent iron can be concentrated from some mare soils where it is present in amounts up to 10 percent. The ideal mining site would be located at the boundary between a high-titanium mare and a high-aluminum highlands. Such area may exist around the rims of some eastern maria, particularly Tranquilitatis. A location on Earth with raw materials as described above would be considered an economically valuable ore deposit if conventional terrestrial resources were not available.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA. Ames Res. Center Space Resources and Space Settlements; p 243-255
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  • 14
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    Civil Helicopter icing problems (1979)
    In:  CASI
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    Publication Date: 2006-01-12
    Description: The ice capabilities of rotary wing aircraft are examined. Recommendations are given to improve the inadequacies of the weather forecasts pertaining to ice, and to adopt a low maintenance anti-ice system.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; p 29-30
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  • 15
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    Overview of helicopter ice protection system developments (1979)
    In:  CASI
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    Publication Date: 2006-01-12
    Description: Helicopter ice protection design criteria was developed and technological shortcoming in meeting helicopter mission requirements is that of helicopter rotor blade ice protection. Airframe components are protected using existing technology while the rotor blade protected using the cyclic electrothermal deicing concept.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; p 39-65
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  • 16
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    A review of the icing situation from the standpoint of general aviation (1979)
    In:  CASI
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    Publication Date: 2006-01-12
    Description: An overview of the present situation in the field of aircraft icing with respect to certification and operation of nontransport category airplanes is given. Problems of definition and inconsistencies are pointed out. Problems in the forecasting and measurement of icing intensities are discussed. The present regulatory environment is examined with respect to its applicability and appropriateness to nontransport airplanes.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; p 31-38
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  • 17
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    Icing of aircraft Some remarks with an historical slant from a cloud physicist (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: Three areas of interest are commented on: cloud physics, nowcasting, and instrumentation. A comparison is made of what was done 30 years ago to what might be done in light of developments in related areas of cloud physics, weather modification and instrumentation.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; p 17-19
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  • 18
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    Sample fields of the Viking landers, physical properties, and aeolian processes (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Surface sampler activities on Mars during the Viking extended mission are considered, including excavation of deep trenches, construction of conical piles of materials, backhoe touchdown experiments, and acquisition of contiguous pictures of the surface beneath number 2 terminal descent engines using mirrors. Results of the Physical Properties Investigation that are relevant to aeolian processes are also discussed. Both pictures and surface sampler data indicate that the surface materials in the sample fields of the Viking landers may be grouped, in order of increasing strength, into drift material, crusty to cloddy material, blocky material and rocks.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 84; Dec. 30
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  • 19
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    Pitted and fluted rocks in the Western Desert of Egypt - Viking comparisons (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The Western Desert of Egypt is one of the most arid regions on earth and is probably the closest terrestrial analog to the surface of Mars. An expedition to the area in 1978 revealed an abundance of quartzite and basalt rocks that have been pitted and fluted by wind erosion and deflation of the desert surface. These pitted rocks are internally homogeneous, show no internal holes or vesicles, and are considered an important but neglected type of ventifact. They bear a striking resemblance to the pitted and fluted rocks seen by the Viking Landers, rocks that have generally been interpreted as vesicular basalts only slightly modified by wind erosion. Wind tunnel studies of the air flow over and around nonstreamlined hand specimens from the Western Desert show that windward abrasion coupled with negative flow, secondary flow, and vorticity in a unidirectional wind can explain the complex arrays of pits and flutes. These field and laboratory observations suggest that the pitted rocks at the Viking Lander sites are also ventifacts, and thus the Martian surface may be far more wind eroded than previously thought.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 84; Dec. 30
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  • 20
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    Morphology and distribution of common 'sand' dunes on Mars - Comparison with the earth (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A comparative study of Martian and terrestrial dunes was made based on Viking Orbiter pictures and aerial pictures of terrestrial deserts. The morphological similarity between the Martian dunes and terrestrial crescentic dunes implies that the dynamics of dune formation are similar on the two planets, despite Martian constraints on dune formation that include much higher velocity winds required to move 'sand' in saltation, the possible inhibition of sand movement by absorbed water vapor, the seasonal 'snow' cover in the north circumpolar erg, and a probably sparse sand supply. The absence of longitudinal dunes and the restriction of massive crescentic dunes to a few sites on Mars suggests that Mars may have a long eolian history in which much of the sand suitable for saltation has already been transported to the north polar erg and crater floor fields.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 84; Dec. 30
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  • 21
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    Direct determination of asteroid diameters from occultation observations (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Of the available earth-based techniques for determining asteroid diameters, observation of stellar occultations involving asteroids is clearly the most direct. The high degree of accuracy achievable by this method has already been demonstrated in the case of Pallas, whose mean diameter has been measured with a standard error of plus or minus 2%. In this paper the problems, results and prospects of the stellar occultation technique are reviewed. It is shown that, with the use of a network of small, portable telescopes, the method is currently applicable to a large number of asteroids. The best results can be expected for asteroids of large angular diameter and regular shape. The potential of lunar occultation observations for asteroid diameter measurements is also briefly discussed.
    Keywords: ASTRONOMY
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  • 22
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    Viking magnetic properties experiment - Extended mission results (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The backhoe magnets on Viking Lander (VL) 2 were successfully cleaned, followed by a test involving successive insertions of the cleaned backhoe into the surface. Rapid saturation of the magnets confirmed evidence from primary mission results that the magnetic mineral in the Martian surface is widely distributed, most probably in the form of composite particles of magnetic and nonmagnetic minerals. An image of the VL 2 backhoe taken via the X4 magnifying mirror demonstrates the fine-grained nature of the attracted magnetic material. The presence of maghemite and its occurrence as a pigment in, or a thin coating on, all mineral particles or as discrete, finely divided and widely distributed crystallites, are consistent with data from the inorganic analysis experiments and with laboratory simulations of results of the biology experiments on Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 84; Dec. 30
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  • 23
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    Proper elements and family memberships of the asteroids (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The proper elements tabulated are calculated according to the secular perturbation theory of Williams (1969); the free oscillations are referred to a zero value for the proper argument of perihelion. The secular theory for the planets is taken from Brouwer and van Woerkom (1950). Families with numbers smaller than 100 are reasonably close matches to families found by previous investigators. Families with numbers greater than 100 are new to this work. Guidelines for use of the table are given.
    Keywords: ASTRONOMY
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  • 24
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    Primordial heating of asteroidal parent bodies (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Most meteorites show evidence of thermal processing either because of metamorphic changes or as a result of melting and differentiation. Proposed mechanisms for supplying this energy generally rely upon short-lived radioisotopes or electrical induction, though accretion is sometimes mentioned, and more exotic models have been discussed. Interest in isotopic heating has been heightened by the discovery of Al-26 in Allende inclusions and also by the proposal that a lunar core and dynamo resulted from the radioactive decay of superheavy elements during the early solar system. Electrical induction as a heat source can be scaled to a broad range of solar system conditions, but corroborative evidence for these conditions is inconclusive. The accretion mechanism is probably not viable for the asteroidal and meteorite parent bodies, because the high kinetic energy requirement is inconsistent with the formation of the objects and their regoliths in the presence of a weak gravitational field.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 25
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    Aqueous activity on asteroids - Evidence from carbonaceous meteorites (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Carbonaceous chondrites of groups CI and CM were formed by impact brecciation and aqueous alteration of earlier generations of mineral phases within the surface regions of two or more parent bodies. Those parent bodies were probably asteroids, rather than comets, although a problem still exists in delivering such material safely to earth. Aqueous activity may have been widespread on asteroids.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 26
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    Diverse puzzling asteroids and a possible unified explanation (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Recent observations have led to unconventional models of certain asteroids, suggesting previously unsuspected forms. Some of these include binary asteroids (e.g., 532 Herculina, 18 Melpomene), very irregular asteroids (e.g., the Mars-crossing 1580 Betulia), and very elongated asteroids, unlikely to be collisional fragments (e.g., 624 Hector). A connection is suggested between this observational work and ongoing theoretical work concerning collisions of large comparable-sized asteroids. Such collisions have different consequences from the collisions usually considered. The new work suggests possible sources of elongated and binary asteroids.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 27
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    Radio observations of asteroids - Results and prospects (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Radio observations of the asteroids can provide information on the thermal and dielectric properties of the surface materials and, because the radio emission arises somewhat below the surface, the data give some indication of layering. Observational difficulty has limited the investigations to only 6 asteroids. 1 Ceres and 324 Bamberga appear to have a layer of dust covering a more compacted material; the data on 4 Vesta cannot be matched by any current models for the surface; and the results for 18 Melpomene, 31 Euphrosyne and 433 Eros are too incomplete for firm conclusions. Future possibilities include more accurate radiometry of a few selected asteroids of different taxonomic classes and actual resolution of some of the larger objects by aperture synthesis techniques.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 28
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    Optical polarimetry of asteroids and laboratory samples (1979)
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    Publication Date: 2011-08-17
    Description: Interpretations of astronomical polarization data for more than 100 minor planets are summarized with reference to laboratory data for lunar, meteoritic, and terrestrial samples. All observed asteroids, including objects only a few kilometers in diameter, have microscopically intricate surfaces. Detailed comparisons between laboratory measurements of basaltic achondrites and telescopic results for Vesta show that its surface is particulate with a broad range of particle sizes, including a component of fine (1-5 micron) dust. The surface soils have not, however, undergone marked optical alterations as is the case for the lunar fines. For albedos greater than about 0.06, the albedo and hence the diameter can be determined with some reliability from the slope of the ascending branch of the polarization-phase curve. Many minor planets have surfaces that are remarkably uniform in albedo and texture on a hemispheric scale. A notable exception is 4 Vesta, which shows about ten percent albedo variegation between hemispheres.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 29
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    The asteroids - Nature, interrelations, origin, and evolution (1979)
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    Publication Date: 2011-08-17
    Description: The paper deals with the physical and chemical nature of the asteroids and with their physical and orbital distributions and interrelationships. Existing hypotheses about the formation and evolution of asteroids are examined. A thematic synopsis of these topics is presented, and accepted interpretations are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 30
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    Review of the metallographic cooling rates of meteorites and a new model for the planetesimals in which they formed (1979)
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    Publication Date: 2011-08-17
    Description: The cooling rates of meteorites through approximately 900 -650 K, as read from their metal alloy compositions, are reviewed. Metallographic cooling rates are compared with the cooling rates that appear to be required by the K/Ar and Ar-40/Ar-39 ages of five meteorite classes, and discrepancies are found in all cases. Either (1) the metallographic cooling rates (and also Pu-244 fission cooling rates) are systematically in error, being too slow by a factor of approximately 6; or (2) the traditional thermal model for parent meteorite planets (having constant dimension and uniform physical properties) is oversimplified and the Ar closure temperatures for chondrites derived by Turner et al. (1978) are too low. An alternative parent planet model is proposed and numerically modeled, in which accretion of thermally insulating particulate matter, heat generation by Al-26 decay, melting or sintering of the particulate matter into conductive rock, and establishment of the properties of the meteorites occurred concurrently. Meteorite chronologies are somewhat easier to understand in this context, since the initially small, hot (thus sintered and conductive) bodies would have cooled rapidly to isotopic closure, but later cooling might have been much slower as a result of the continued accretion of insulating particulate matter.
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  • 31
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    Asteroid taxonomy and the distribution of the compositional types (1979)
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    Publication Date: 2011-08-17
    Description: Physical observations of minor planets documented in the TRIAD computer file are used to classify 752 objects into the broad compositional types C, S, M, E, R, and U (unclassifiable) according to the prescriptions adopted by Bowell et al. (1978). Diameters are computed from the photometric magnitude using radiometric and/or polarimetric data where available, or else from albedos characteristic of the indicated type. An analysis of the observational selection effects leads to tabulation of the actual number of asteroids, as a function of type and diameter, in each of 15 orbital element zones. For the whole main belt the population is 75% of type C, 15% of type S, and 10% of other types, with no belt-wide dependence of the mixing ratios on diameter. In some zones the logarithmic diameter-frequency relations are decidedly nonlinear. The relative frequency of S-type objects decreases smoothly outward through the main belt, with exponential scale length 0.5 AU. The rarer types show a more chaotic, but generally flatter, distribution over distance. Characteristic type distributions, contrasting with the background population, are found for the Eos, Koronis, Nysa and Themis families.
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    Phobos and Deimos - A preview of what asteroids are like (1979)
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    Publication Date: 2011-08-17
    Description: The surfaces of Phobos and Deimos are discussed, as the best available examples of what asteroid surfaces may be like. Attention is given to shape, regolith properties, crater densities, albedo markings and surface gravities. It is found that although the surfaces of these two similarly-sized asteroid-like bodies are nearly identical in terms of many disk-integrated properties, they are strikingly different in surface morphology.
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    Radar observations of asteroids (1979)
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    Publication Date: 2011-08-17
    Description: Radar observations of asteroids use simple CW waveforms, the transmissions lasting for the duration of the round-trip delay. The echo is received, spectrum-analyzed, and integrated for a similar period. Since radar coherently illuminates the target, the surface scattering properties at radio wavelengths are directly determined as a function of angle and polarization. The distance and radial velocity obtained with radar complement the angular position of the object as determined from telescope measurements. Radar cross sections, scattering law, and radius are given for radar-observed asteroids.
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    Colorimetry and magnitudes of asteroids (1979)
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    Publication Date: 2011-08-17
    Description: In the present paper, 1500 UBV observations are analyzed by a new rather general multiple scattering theory which provided clear insight into previously poorly-recognized optical nature of asteroid surfaces. Thus, phase curves are shown to consist of a surface-texture controlled component, due to singly scattered light, and a component due to multiple scattering. Phase curve shapes can be characterized by a single parameter, the multiple scattering factor, Q. As Q increases, the relative importance of the opposition effect diminishes. Asteroid surfaces are particulate and strikingly similar to texture, being moderately porous and moderately rough on a scale greater than the wavelength of light. In concequence, Q (and also the phase coefficient) correlate well with geometric albedo, and there exists a purely photometric means of determining albedos and diameters.
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    Masses and densities of asteroids (1979)
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    Publication Date: 2011-08-17
    Description: Ceres, Pallas, and Vesta allow a determination of mass from gravitational effects in the motion of another asteroid. An extended and partly corrected set of observations of 197 Arete leads to an increase of 15% in the resulting mass of Vesta that was first determined by Hertz. Other possibilities of mass determination and estimates of the total mass of asteroids are mentioned. The available diameter determinations and adopt preferred values are reviewed. The densities for Ceres, Pallas, and Vesta are respectively 2.3 plus or minus 1.1 g/cu cm, 2.6 plus or minus 0.9 g/cu cm and 3.3 plus or minus 1.5 g/cu cm.
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    On the origin of asteroids (1979)
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    Publication Date: 2011-08-17
    Description: A general scenario is described for the early history of the solar system. The primitive solar nebula is formed from the infall of gas from a collapsing interstellar cloud fragment. It becomes repeatedly unstable against collapse to form giant gaseous protoplanets. In the course of protoplanet evolution the center of the protoplanet enters a thermodynamic regime in which common rocky minerals become liquids; convection brings solids to the central region where a substantial fraction of them rain out to form a protoplanetary core. In the inner solar system protoplanetary envelopes are tidally stripped away, thus injecting into the solar nebula large equantities of chondrules and inclusions. Late in the development of the solar nebula, after most of the gas has disappeared, turbulence dies out and the small solids settle into a thin layer at midplane of the nebula. Gravitational instabilities in this layer form asteroidal and cometary bodies. Some further consequences of this scenario are discussed.
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    Geochemical evolution of the eucrite parent body - Possible nature and evolution of asteroid 4 Vesta (1979)
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    Publication Date: 2011-08-17
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    Infrared spectral reflectances of asteroid surfaces (1979)
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    Publication Date: 2011-08-17
    Description: This review compares the types of compositional information produced by three complementary techniques used in infrared observations of asteroid surfaces: broadband JHKL photometry, narrow band photometry, and multiplex spectroscopy. The high information content of these infrared observations permits definitive interpretations of asteroid surface compositions in terms of the major meteoritic minerals (olivine, pyroxene, plagioclase feldspar, hydrous silicates, and metallic Ni-Fe). These studies emphasize the individuality of asteroid surface compositions, the inadequacy of simple comparisons with spectra of meteorites, and the need to coordinate spectral measurements of all types to optimize diagnostic capabilities.
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    The nature and effects of impact cratering on small bodies (1979)
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    Description: Collisions between asteroids and other forms of solar system debris are discussed, especially relatively high-energy, non-catastrophic collisions, the resulting craters, and the effects they should have on the surfaces and interiors of target bodies. Attention is given to the nature and formation of impact craters, as well as to shock waves and the energy (kinetic, internal) imparted through them, crater scaling, stress wave-surface interactions, impact melt, and the effects of non-escaping ejecta on the surface of the target body (rock, fine-grained regolith, porous media).
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    Regolith development and evolution on asteroids and the moon (1979)
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    Description: Early descriptions of regoliths on small bodies were devised to account for observations of asteroids (Chapman 1971, 1976) and the gas-rich meteorites (Anders 1975). Lack of agreement between these approaches prompted Housen et al. (1978, 1979) to examine the problem in detail. The resulting model predicted that moderate-sized (100-300 km) asteroids should evolve regoliths up to a few kilometers deep which could be source regions of gas-rich meteorites. Smaller objects should have regoliths ranging from dust coatings to meters-thick layers depending on the strength of the object. The earlier model could not treat asteroids larger than 300 km in diameter. The model, now modified to treat larger-sized objects, predicts regolith depths, on asteroids larger than 300 km, which decrease with increasing size. A regolith depth of 7 m is predicted for the lunar maria in reasonable agreement with the observed depths of 5 m.
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    Distant asteroids and outer Jovian satellites (1979)
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    Publication Date: 2011-08-17
    Description: Sixty percent of the sampled objects in the Hilda, Trojan and outer Jovian satellite locations belong to C-type and another 30% belong to a new group called RD-type (reddish and dark), sometimes referred to simply as D-type. Objects in this group have low albedo values between 2 and 4% and steep reflection spectra between 0.7 micron and 0.9 micron. Furthermore, 944 Hidalgo belongs to this group but shows color variation over its surface. Meteoritic minerals with similar optical reflection spectra are discussed. Trojans with sizes down to 15 km in the cloud preceding Jupiter are about 3.5 times more numerous than those in the following cloud. RD-type Trojans appear more often in the preceding cloud. There is a resemblance of spectrum, albedo and phase relation among the majority of Trojans and the outer Jovian satellites.
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    Families of minor planets (1979)
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    Description: Physical studies of individual family members show that at least the Themis, Eos, Koronis, Nysa/Hertha, and Budrosa families of minor planets are the result of the breakup of discrete parent bodies. Only a few families have been studied in detail, and even in those few cases, the full force of observational techniques has not been applied. Crucial for the understanding of families and their parent bodies are detailed physical studies of family members; precise mineralogical interpretation of observational data to identify the geochemistry of the parent bodies; and studies of the collisional evolution of family members.
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    Rb-Sr age of the Shergotty achondrite and implications for metamorphic resetting of isochron ages (1979)
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    Publication Date: 2011-08-17
    Description: The age of the Shergotty achondrite is determined by Rb-Sr isotope analysis and the metamorphic resetting of isochron ages, which is presumed to have occurred during a shock event in the history of the meteorite, is discussed. The isochron best fitting the Rb-Sr evolution diagram is found to correspond to an age of 165 million years, with an initial Sr-87/Sr-86 value of 0.72260. Different apparent ages obtained by the K-Ar and Sm-Nd methods are interpreted in terms of a model which quantifies the degree of resetting of internal isochron ages by low temperature solid state diffusion. On the basis of these considerations, it is concluded that Shergotty crystallized from a melt 650 million years ago, was shock heated to 300 to 400 C after its parent body was involved in a collision 165 million years ago, and was first exposed to cosmic rays two million years ago.
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    Type: Geochimica et Cosmochimica Acta; 43; July 197
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    Minor planets and related objects. XXVIII - Asteroid magnitudes and phase relations (1979)
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    Keywords: ASTRONOMY
    Type: Astronomical Journal; 84; July 197
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    Voyager spacecraft radio observations of Jupiter - Initial cruise results (1979)
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    Publication Date: 2011-08-17
    Description: Low frequency (below 1326 kHz) observations of Jupiter obtained from November, 1977 through June, 1978 by the radio astronomy receivers carried by the two Voyager spacecraft are reported and compared with a large body of higher-frequency ground-based observations. Although the morphology of hectometric wavelength (HOM) emissions strongly resembles that of decametric (DAM) wavelength radio noise, they display opposite polarization. DAM emissions are strongly modulated by Io, whereas HOM emissions exhibit little or no influence from any satellite and appear to be modulated by the rotation phase of the planet. Several single-source models could possibly account for these results, including a model assuming emission at two well-separated frequencies above and below the local electron plasma frequency and the model proposed by Barbosa (1976) in which electrostatic waves at twice the upper hybrid frequency couple to both the ordinary and extraordinary electromagnetic modes. However, neither of these is entirely satisfactory.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 6; June 197
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  • 46
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    Space Telescope optics (1979)
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    Description: The paper reviews the optical technology that has been developed over the last decade for the Space Telescope. The optical design of the telescope, the optical performance control system, and the anticipated optical performance are all presented. Consideration is also given to the initial complement of focal plane instruments.
    Keywords: ASTRONOMY
    Type: Optical Engineering; 18; May-June
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    Numerical solution for perpendicular sonic hydrogen injection into a ducted supersonic airstream (1979)
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    Publication Date: 2011-08-17
    Description: This note discusses a computer program being developed to study the flow field near opposing perpendicular fuel injectors in scramjets. The MacCormack time-split, finite difference relaxation technique was used to solve the full two-dimensional compressible Navier-Stokes equations along with energy and species equations. By using this technique, a program was developed to consider the turbulent nonreacting flow of hydrogen and air in a rectangular duct. A damping term, proportional to the second derivative of pressure and temperature, was used to produce a stable solution behind the hydrogen jet in the neighborhood of the recompression shock. A case using actual conditions encountered in current scramjet design was analyzed, with results agreeing qualitatively with experimental observations.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; May 1979
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    Forbidden Fe X and forbidden Fe XIV emission from Puppis A and other supernova remnants (1979)
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    Description: Measurements of Fe XIV 5303-A and Fe X 6374-A forbidden emission from several supernova remnants are reported, and their relation to X-ray observations is discussed. The brightest Fe XIV forbidden-emission region in Puppis A is interpreted as being the result of the supernova shock wave's interacting with a dense cloud in the interstellar medium.
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    Type: Astrophysical Journal; vol. 228
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    Io - An intense brightening near 5 micrometers (1979)
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    Description: Spectrophotometric observations of the Jovian satellite Io on February 20 and 21, 1978, (Universal Time) were made from 1.2 to 5.4 micrometers. Io's brightness at 4.7 to 5.4 micrometers was found to be three to five times greater at an orbital phase angle of 68 deg than at orbital phase angles of 23 deg (5.5 hours before the brightening) and 240 deg (20 hours after the brightening). Since the 5-micrometer albedo of Io is near unity under ordinary conditions, the observed transient phenomenon must have been the result of an emission mechanism. Although several such mechanisms were examined, the actual choice is not clear.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 203; Feb. 16
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    Encounter with Venus (1979)
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    Description: The orbiter and multiprobe components of the Pioneer Venus mission are briefly described. The orbiter was launched on May 20, 1978 and was placed into a highly eccentric near-polar orbit around Venus on December 4, 1978, while the multiprobe was launched on August 8, 1978 and reached Venus on December 9, 1978. Parameters of the orbiter orbit are presented, and modifications of the periapsis altitude are described. The time sequences of the probe entry events are reported for the large probe, north probe, day probe, and night probe, which, along with the bus, are the components of the multiprobe. The multiprobe entry and impact locations as well as related data are reported.
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    Type: Science; 203; Feb. 23
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    Venus upper atmosphere neutral composition - Preliminary results from the Pioneer Venus orbiter (1979)
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    Publication Date: 2011-08-17
    Description: Measurements in situ of the neutral composition and temperature of the thermosphere of Venus are being made with a quadrupole mass spectrometer on the Pioneer Venus orbiter. The presence of many gases, including the major constituents CO2, CO, N2, O, and He has been confirmed. Carbon dioxide is the most abundant constituent at altitudes below about 155 kilometers in the terminator region. Above this altitude atomic oxygen is the major constituent, with O/CO2 ratios in the upper atmosphere being greater than was commonly expected. Isotope ratios of O and C are close to terrestrial values. The temperature inferred from scale heights above 180 kilometers is about 400 K on the dayside near the evening terminator at a solar zenith angle of about 69 deg. It decreases to about 230 K when the solar zenith angle is about 90 deg.
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    Type: Science; 203; Feb. 23
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    Electron temperatures and densities in the Venus ionosphere - Pioneer Venus orbiter electron temperature probe results (1979)
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    Publication Date: 2011-08-17
    Description: The Pioneer Venus orbiter electron temperature probe was used to obtain altitude profiles of electron temperature and density in the ionosphere of Venus. Elevated temperatures at times of low solar wind flux might indicate support for a certain model. According to this model, less than 5% of the solar wind energy is deposited at the ionopause and is conducted downward through an unmagnetized ionosphere to the region below 200 km where electron cooling to the neutral atmosphere proceeds rapidly. The patterns of electron temperatures and densities at higher solar wind fluxes are considered, the variability of the ionopause height in the late afternoon is noted, and the role of an induced magnetic barrier in the neighborhood of the ionopause is discussed.
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    Type: Science; 203; Feb. 23
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    Status of the Space Telescope project in the United States (1979)
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    Publication Date: 2011-08-17
    Description: A general description of the evolution of the Large Space Telescope project is given, including mirror construction, interface requirements, and the review cycle for the scientific instruments. The anticipated participation of ESA scientists through the means of the Science Institute is discussed.
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    Type: ESA Astron. Uses of the Space Telescope; p 27-31
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    The Spacelab Wide Angle Telescope (SWAT) (1979)
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    Publication Date: 2011-08-17
    Description: A fast wide angle telescope that will be capable of imaging to the darker sky limit and in the ultraviolet wavelength region available above the atmosphere is described. The telescope (SWAT) has a resolution comparable to that of the large ground-based Schmidt telescope and a field of at least five degrees. A number of astrophysically important investigations can only be accomplished with such a telescope, e.g., detection of hidden, hot objects like hot white dwarfs and subwarfs in stellar binary systems, and energetic regions in globular clusters and galaxy nuclei. It permits unique studies of the UV-morphology of extended objects and allows discovery of very faint extensions, halos, jets, and filaments in galaxies. It can contribute to the investigation of dust in the Milky Way and in other galaxies and, with an objective prism, spectra of very faint objects can be obtained. The SWAT will localize objects for further study with the narrow-field Space Telescope.
    Keywords: ASTRONOMY
    Type: ESA Astron. Uses of the Space Telescope; p 375-392
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    CO2 and CO electron vibrational cooling rates (1979)
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    Description: Electron cooling rates for electron vibrational excitation of CO2 and CO and rotational excitation of CO are calculated. Results of the calculation are expressed as closed form analytic relations that are both convenient for numerical calculations and valid over a wide range of electron and neutral temperatures. It is found that the cooling rates and their temperature dependences differ significantly from other calculations. For CO2, these differences are related mainly to the assumptions about the approach to equilibrium and not to the actual cross-section choices. For electron temperatures below 1000 K and gas temperatures near 300 K (representative of conditions in the Venus atmosphere, where collisional cooling of the electrons dominates), the CO2 cooling rate is as much as an order of magnitude larger than previously considered in ionospheric models.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 84; Nov. 1
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    The magnetosphere of Mercury (1979)
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    Publication Date: 2011-08-17
    Description: According to Mariner 10 data on Mercury's magnetosphere, the bow shock and magnetosheath signatures in the magnetic field are entirely consistent with the geometry expected for interaction between a planet-centered magnetic dipole and the solar wind. The geometrically determined distance to the magnetopause stagnation point of solar wind flow was 1.45 plus or minus 0.15 Mercury radii. Comparative scaling of the magnetosphere of Mercury to earth shows that Mercury itself occupies a much larger fraction of the magnetosphere than does the earth. While there is no evidence for the permanent existence of a trapped charged particle radiation belt, intense transient bursts of energetic electrons indicate that a local acceleration process must be active. It is reasonable to assume that this process occurs in the magnetic tail. The interior plasma features compare well with those in the earth's magnetosphere. Characteristic time scales for transient phenomena at Mercury should be reduced by a factor of about 20 in comparison with those on earth - i.e., a few minutes for substorms vs an hour at earth. The origin of the magnetic field is unclear.
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    Planetary geodesy (1979)
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    Publication Date: 2011-08-17
    Description: The results of investigations of the geodesy of the planets and their satellites conducted during the period 1975 - 1978 are surveyed. Analysis of the photographic data of Mercury taken by Mariner 10 have revealed the mass, oblateness, radius rotation period and density of the panet, and allowed the high-resolution mapping of the surface. Earth-based radar imagery has permitted the identification of large-scale topographic features on Venus. Knowledge of the gravitational field of Mars has been improved by Mariner 9 and Viking tracking data, and the global topography and geometric figure of Mars have been derived. Doppler and ranging tracking data from the Viking landers have provided data for the precise determination of Martian rotational dynamics and the topographic features and figures of Phobos and Deimos have been observed. Pioneer 10 and 11 data have yielded information on the mass, gravitational field and dynamic parameters of Jupiter. Discoveries of a satellite of Pluto and a set of rings around Uranus have been made, the rotation of Uranus and Neptune have been measured, and the geodetic properties of the rings and satellites of Saturn have been investigated. Future developments in planetary geodesy are expected from continued Viking data and the Pioneer Venus probe and Voyager probes to Jupiter and Saturn.
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    Cosmic ray ionization of the Jovian atmosphere (1979)
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    Publication Date: 2011-08-17
    Description: An approximate form of the Boltzmann equation has been used to obtain local ionization rates due to the absorption of galactic cosmic rays in the Jovian atmosphere. It is shown that the muon flux component of the cosmic-ray-induced cascade may be especially important in ionizing the atmosphere at levels where the total number density exceeds 10 to the 19th per cu cm (well below the ionospheric layers produced by solar EUV). A model containing both positive and negative ion reactions has been employed to compute electron and ion number densities. Peak electron number densities of the order of 1000 per cu cm may be expected even at relatively low magnetic latitudes. The dominant positive ions are NH4(+) and CnHm(+) cluster ions, with n at least 2; it is suggested that the absorption of galactic cosmic-ray energy at such relatively high pressures in the Jovian atmosphere (M about 10 to the 18th to 10 to the 20th per cu cm) and the subsequent chemical reactions may be instrumental in the local formation of complex hydrocarbons.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 39; Sept
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    Martian meteorology (1979)
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    Description: Viking mission results concerning the structure and dynamics of the Martian atmosphere are reviewed. The large-scale variability of pressure, temperature, and zonally averaged wind at the Lander sites is described, and small-scale phenomena involving the boundary layer and internal gravity waves are discussed. Observational evidence for the existence of transient planetary-scale waves, forced quasi-stationary waves, and thermal tides on Mars is examined. Atmospheric dynamics and properties of dust storms are considered, with emphasis on dust properties and distribution, the time evolution of planetwide dust storms, and dust-storm genesis and decay. Attention is also given to the nature of past Martian climates, the sizes and composition of volatile reservoirs, and volatile escape from the atmosphere.
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    Latitudinal beaming of Jupiter's low frequency radio emissions (1979)
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    Publication Date: 2011-08-17
    Description: Observations of Jupiter's radio emissions from Jovigraphic latitudes greater than 3.3 deg are reported. The measurements were obtained from the Voyager 2 spacecraft at declinations up to 6.5 deg, and when these results are compared with simultaneous observations from Voyager 1 near the ecliptic plane (at a Jovigraphic latitude of about 3 deg), they indicate that the latitudinal-beaming effects persist and may even become stronger with higher latitudes. The results were combined with earlier low-frequency measurements from periods with De as low as -3 deg in order to show the beaming effects the occurrence of the emission over a full 10 deg range of altitude. The results of observations at frequencies near 1 MHz are also discussed, which were obtained from Voyager 1 and 2 in 1978, Rae 1 in 1969, and Imp 6 in 1971-1972. The implications of the new results for models of Jupiter's radio-emission beam pattern are considered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 84; Sept. 1
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    The mean Jovian temperature structure derived from spectral observations from 105 to 630 cm kaysers (1979)
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    Publication Date: 2011-08-17
    Description: Far infrared observations of the thermal emission of Jupiter are used to determine the temperature at 1 bar. High-altitude observations of the whole-disk brightness temperature of Jupiter in the range of 100 to 347 kaysers were inverted to obtain a P-T profile between 1.5 and 0.06 atm, assuming as opacity sources the H2 collisionally induced continuum and the rotation inversion bands of ammonia. The P-T profile derived from the spectrum reproduces the main features of the observed spectrum, with a slightly improved fit if the effects of ammonia haze opacity or NH3 supersaturation in the saturated region are taken into account. The Jovian temperature is found to be 160 + or - 7 K at 1 bar, and 105 + or - 3 K at the inversion level at 0.15 bar. The 1-bar temperature is shown to be consistent with Jovian interior models which match the observed gravitational moment.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 40; Oct. 197
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  • 62
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    Generalized velocities in the outer region of hypersonic turbulent boundary layers (1979)
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    Publication Date: 2011-08-17
    Description: An attempt is made to show that the outer portion of the velocity profile of hypersonic turbulent boundary layers can be transformed so that the constants determined by a best fit to the law of the wake are in reasonable agreement with the wake constant for incompressible boundary layers at the same Reynolds number. Both y transformations (where y is distance from the surface) and velocity transformations produce velocity profiles which, with the proper choice of wall shear stress to give shear velocity, can be reduced to the incompressible law of the wall.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; Aug. 197
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  • 63
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    Accurate numerical evaluation of modified Struve functions occurring in unsteady aerodynamics (1979)
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    Publication Date: 2011-08-17
    Description: A method is developed for computing the modified Struve functions that occur in unsteady aerodynamics. The method uses a rational approximation supplemented by an asymptotic series for large argument. Simple recursive formulas for generating the coefficients are derived. The method is capable of generating results of arbitrary accuracy. It can also be used for complex argument and order. For greater computing speed, a method is presented that uses the rational and asymptotic approximations to generate Chebyshev coefficients.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 16; July 197
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  • 64
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    The magnetic fields of Mercury, Mars, and moon (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Mariner observations have shown a significant global magnetic field at Mercury with a dipole moment at a tilt of 14 + or - 5 deg relative to the normal of the orbit plane. A presently active dynamo is the most likely origin for the planet's magnetic field. Limited evidence for an intrinsic magnetic field on Mars was obtained by USSR spacecraft in 1971 and 1974. The Martian magnetic field, if it exists, may result from either remanent magnetism or an active dynamo. On the moon, local magnetic fields have been detected by the Apollo and Lunokhod missions, but no global correlation of the steady state values has been noted.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 65
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    Infrared photometry and spectrophotometry of G75.84+0.4 (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Photometric mapping of G75.84+0.4 at 12.6 microns is compared with previously published radio maps of the region to deduce the relative dust/gas mass ratio for the dust responsible for the 12.6-micron emission. Spectrophotometry from 2-4 microns and 8-13 microns of the highest-emission-measure region reveals the presence of the fine structure lines of forbidden Ar III at 8.99 microns, forbidden Ne II at 12.78 microns, and forbidden S IV at 10.53 microns. Estimates of the abundance of these ions are made, and the nature of the exciting source is discussed.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 74; 3, Ma; May 1979
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  • 66
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    Stability of inner planetary systems (1979)
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    Publication Date: 2011-08-17
    Description: The stability of inner planetary systems with arbitrary mass ratios is studied on the basis of the model of the plane restricted three-body problem. A quantitative stability criterion is obtained in terms of the difference between the critical value of the Jacobi constants (at which bifurcation can occur) and the critical value corresponding to a planetary orbit. An orbit is stable if it cannot leave a region that contains only the larger central body (Hill). For small values of the mass parameter, the maximum dimensionless radius of a Hill-stable orbit is 1 minus 2.4 times the cube root of the mass parameter.
    Keywords: ASTRONOMY
    Type: Zeitschrift fuer angewandte Mathematik und Physik; 30; Mar. 25
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  • 67
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    Ionosphere of Venus - First observations of the dayside ion composition near dawn and dusk (1979)
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    Publication Date: 2011-08-17
    Description: Independent Bennett radio-frequency ion mass spectrometers on the Pioneer Venus bus and orbiter spacecraft obtained in situ measurements of the composition of the ionosphere of Venus. The spectrometer on the bus explored the dawn region while the spectrometer on the orbiter explored the duskside region. Information on the ion composition in the topside, the lower ionosphere, and the upper ionosphere is presented. Below the O(+) peak near 200 km, the ions are found to exhibit scale heights consistent with a neutral gas temperature of about 180 K near the terminator. In the upper ionosphere, scale heights of all species reflect the effects of plasma transport.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 203; Feb. 23
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  • 68
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    Initial observations of the Pioneer Venus orbiter solar wind plasma experiment (1979)
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    Publication Date: 2011-08-17
    Description: The ionosphere, ionosheath, ionopause, and bow shock wave of Venus are characterized. Venus is found to have a well-defined strong standing bow shock wave. In the ionosheath, downstream from the shock, compressed and heated postshock plasma apparently interacts directly with the ionosphere. Plasma ion velocity deflections suggest that the ionopause has a blunt shape. The positions of the bow shock and ionopause are variable and appear to respond to changes in the external solar wind pressure.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 203; Feb. 23
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  • 69
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    Minor planets and related objects. XXVII - Lightcurves of 887 Alinda (1979)
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    Publication Date: 2011-08-17
    Description: Eleven light curves and UBV photometry of the Amor asteroid Alinda, a candidate for having a cometary origin, are analyzed. A probable rotation period of 73 h 58 m + or - 3 m (p.e.) is derived on the assumption of two maxima and two minima per cycle in a composite light curve. An absolute V magnitude of 14.10 + or - 0.08 and a phase coefficient of 0.042 + or - 0.003 mag/deg in V are obtained, along with a B-V color of 0.86 + or - 0.02 and a U-B color of 0.50 + or - 0.05, both extrapolated to zero phase. The rotation period is shown to be the longest yet observed for an asteroid. It is concluded that the colors of Alinda are not unusual for an asteroid, that Alinda is probably not an extinct cometary nucleus, that the slow rotation may be a consequence of one or more collisions, and that the pole of Alinda may be nearly perpendicular to the ecliptic.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal; 84; Feb. 197
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  • 70
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    Post-development image intensification by autoradiography (1979)
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    Publication Date: 2011-08-17
    Description: A method of post-development intensification of photographic images using a newly developed autoradiographic procedure is described. Radioactive Thiourea-S35 is combined with silver in the developed emulsion, which is then contact printed with a receiver emulsion. The beta decay from S35 produces an enhanced autoradiographic image. The laboratory technique is described and results of astronomical applications are presented.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 91
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  • 71
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    Discovery of a new Jupiter satellite (1979)
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    Publication Date: 2011-08-17
    Description: During detailed analysis of Voyager 2 pictures of the Jupiter ring, a starlike object was identified in the plane of the ring. The same object was subsequently found on a higher-resolution frame and proved to be a satellite of Jupiter. This satellite has a circular orbit whose radius is 1.8 Jupiter radii, a period of 7 hours and 8 minutes, and a diameter of less than 40 kilometers. It is located at the outer edge of the Jupiter ring.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 206; Nov. 23
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  • 72
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    A comparison of luminosity calibrations for MK classifications of OB stars (1979)
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    Publication Date: 2011-08-17
    Keywords: ASTRONOMY
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  • 73
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    A general algorithm for the solution of Kepler's equation for elliptic orbits (1979)
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    Publication Date: 2011-08-17
    Description: An efficient algorithm is presented for the solution of Kepler's equation f(E)=E-M-e sin E=0, where e is the eccentricity, M the mean anomaly and E the eccentric anomaly. This algorithm is based on simple initial approximations that are cubics in M, and an iterative scheme that is a slight generalization of the Newton-Raphson method. Extensive testing of this algorithm has been performed on the UNIVAC 1108 computer. Solutions for 20,000 pairs of values of e and M show that for single precision, 42.0% of the cases require one iteration, 57.8% two and 0.2% three. For double precision one additional iteration is required.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 20; Oct. 197
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  • 74
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    Airborne stellar spectrophotometry from 1.2 to 5.5 microns - Absolute calibration and spectra of stars earlier than M3 (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Airborne infrared spectrophotometry (1.2-5.5 microns, 1.5% resolution) is presented for 13 stars which have been extensively used as infrared calibration objects: alpha Lyr, alpha CMA, alpha UMi, beta Dra, and mu Her; the K giants beta Gem, alpha UMa, alpha Boo, gamma-1 And, and alpha Tau; and the M giants beta And, beta Peg, and alpha Cet. These spectra, obtained using NASA's Kuiper Airborne Observatory and Lear Jet Observatory, are virtually free of the interfering effects of terrestrial absorptions. Absolute calibration of the spectrophotometry was based on the theoretical model of alpha Lyr by Schild, Peterson, and Oke (1971), which fits photometric measurements at shorter wavelengths. The resulting flux densities are compared with previous ground-based photometry.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series; 41; Nov. 197
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  • 75
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    The magnetic field of Mercury (1979)
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    Publication Date: 2011-08-17
    Description: The paper examines the magnetic field observations and their analyses relating to the determination of the Mercury magnetic field. Methods of analyzing data included: (1) comparison of bow shock and magnetopause relative positions at Mercury to the earth, (2) direct spherical harmonic analysis, (3) magnetosphere modeling by an image dipole, and (4) scaling of a mathematical model for the terrestrial magnetosphere. Dipole moments were determined using partial quadrupole and octupole terms to improve the least-square fit of models to observations; analyses by method (2) yield a convergent series of dipole moments values considered to best represent the intrinsic planetary field. Finally, it is suggested that the origin of the magnetic field of Mercury cannot be uniquely determined, but the sources of convective energy may be radiogenic decay and heat release, gravitational settling, and differentiation of processional torques.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 76
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    Some new results on spherical dynamos (1979)
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    Publication Date: 2011-08-17
    Description: Small-scale motions in the earth's liquid core are likely to be highly anisotropic because of the effects of rotation. Guided by physical considerations, the 'alpha-effect' described by an anisotropic tensor alpha sub ik is formulated and the corresponding boundary value problem for a sphere is solved for a variety of boundary conditions. A converged solution has been obtained only in the case of the Fermi condition of an infinitely conducting exterior of the sphere. Some remarks are made on the hypothetical upper bound on magnetic field strengths in planetary cores originally proposed by Busse (1976).
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 77
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    Io's surface and environs - A magmatic-volatile model (1979)
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    Publication Date: 2011-08-17
    Description: A model is proposed to account for the observed properties of Io. The crust is probably siliceous, but the outermost visible surface is composed primarily of several allotropes of elemental sulfur, plus frosts of SO2, H2S, and S2O. The 4-micron feature in Io's IR reflectance is identified as the (nu 1 + nu 3) band of SO2 frost. A possible source of the S is dissociation of iron sulfide brought up from the core by mantle convection. The SO2 is produced in the volcanoes, and the H2S by interaction of magnetospheric protons with the surface S. Delayed luminescence from S2O could cause the posteclipse brightening. The orbital torus is sustained by evaporation from molten ejecta from the volcanoes. Several additional diagnostic absorption bands and two additional minor torus species are predicted by this model.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 6; Oct. 197
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  • 78
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    Nebular condensation of Ga, Ge and Sb and the chemical classification of iron meteorites (1979)
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    Publication Date: 2011-08-17
    Description: The quantization of the Ga and Ge contents in iron meteorites, which is used as a key parameter in the chemical classification of iron meteorites, is discussed in terms of nebular condensation. The calculation of nebular equilibrium condensation is examined, taking into account the dependence of the activity coefficient on temperature and composition, and recent calculations of the condensation temperatures of Ga, Ge, Sb, Au, As and Cu are presented, noting that Ge is the most volatile siderophile, followed by Ga and Sb. The narrow intragroup ranges of Ga and Ge are interpreted in terms of minimal fractionation during core crystallization, while the larger ranges of Sb are attributed to its significantly smaller solid/liquid distribution coefficient in IIIAB meteorites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 282; Dec
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  • 79
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    Albedo and color contrasts on asteroid surfaces (1979)
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    Publication Date: 2011-08-17
    Description: Asteroids in general display only small or negligible variations in spectrum or albedo during a rotational cycle. Color variations with rotation are described in the literature but are usually comparable to the noise in the measurements. Twenty-four asteroids have been systematically monitored for such color changes. Only 3 Juno, 4 Vesta, 6 Hebe, 71 Niobe, 349 Dembowska, and 944 Hidalgo display color variations larger than 0.03 mag. In each of these cases the asteroid appears redder near maximum brightness. Of seven asteroids monitored polarimetrically, only 4 Vesta shows a convincing variation, attributed to an albedo change with rotation. The lightcurve can be explained by albedo differences alone; Vesta apparently has a nearly spheroidal shape. Nothwithstanding the above results, the degree of uniformity of most asteroid surfaces is remarkable. If asteroids exist with large discrete domains of ferrosilicate, metallic, and/or carbonaceous material together on their surfaces, they have not yet been identified.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 40; Dec. 197
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  • 80
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    Laminar and turbulent flows over a spherically blunted cone with massive surface blowing (1979)
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    Publication Date: 2011-08-17
    Description: Numerical solutions are presented for the flow over a spherically blunted cone with massive surface blowing. Time-dependent viscous shock layer equations are used to describe the flowfield. The boundary conditions on the body surface include a prescribed blowing rate distribution. The governing equations are solved by a time-asymptotic finite-difference method. Results presented here are only for a perfect gas-type flow at zero angle of attack. Both laminar and turbulent flow solutions are obtained. It is found that the surface blowing smooths out the effect of the curvature discontinuity at the sphere-cone juncture point on the laminar flowfield and results in a negative pressure gradient over the body. The shock slope increases on the downstream portion of the body as the surface blowing rate is increased. The turbulent flow with surface blowing is found to redevelop a boundary-layer-like region near the surface. The effects of this boundary-layer-like region on the flowfield and heating rates are discussed.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; Dec. 197
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  • 81
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    Magnetic field studies at Jupiter by Voyager 2 - Preliminary results (1979)
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    Publication Date: 2011-08-17
    Description: The Voyager 2 magnetic field experiment, for which the instrumentation is identical to that on Voyager 1, operated flawlessly throughout the second Jupiter encounter. The paper presents a brief overview of the results obtained to date on the Jovian magnetosphere, the bow shock, the magnetopause, and the extended magnetic tail. The results and the magnetic field geometry confirm the earlier conclusion from Voyager 1 that Jupiter has an enormous magnetic tail, approximately 300-400 Jupiter radii in diameter, trailing behind the planet with respect to the supersonic flow of the solar wind. Additional observations of the distortion of the inner magnetosphere by a concentrated plasma show a spatial merging of the equatorial magnetodisk current with the current sheet in the magnetic tail. Disturbances near Ganymede are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 206; Nov. 23
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    Radio science with Voyager at Jupiter - Initial Voyager 2 results and a Voyager 1 measure of the Io torus (1979)
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    Publication Date: 2011-08-17
    Description: About 22 hours after its closest approach to Jupiter, Voyager 2 passed behind the planet as viewed from the earth. Although the spacecraft was geometrically occulted for nearly two hours, the radio links between it and the earth were maintained almost continuously because of the refraction of the signals in Jupiter's south polar atmosphere. A figure shows the plane-of-the-sky geometry of this grazing occultation and preliminary data on the intensity of the spacecraft radio signals as received by the tracking station at Goldstone, California. The intensity data indicate a classic atmospheric occultation profile and the effects of turbulence and ionospheric focusing and defocusing. Analysis of the dispersive ionospheric refraction data yields preliminary profiles for the topside ionosphere at 66.7 deg S (entry in the evening) and 50.1 deg S (exit in the morning) that are reversed with respect to corresponding Voyager 1 profiles in terms of plasma concentration at a fixed altitude. Preliminary reduction of the preencounter occultation of Voyager 1 by the Io torus gives an average plasma density of about 1000 e/cu cm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 206; Nov. 23
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  • 83
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    Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars (1979)
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    Publication Date: 2011-08-17
    Description: This paper discusses effective temperatures, angular diameters, distances, and linear diameters that have been determined for 160 O and B stars on the basis of published UV spectrophotometry, visible and near-IR intermediate-band photometry, and model-atmosphere fluxes. The results are compared with previous measurements and calculations for main-sequence and giant O and B stars. It is found that: (1) the flux effective temperatures of O and B supergiants are systematically lower than those of main-sequence and giant stars of the same subtype; (2) the effective temperatures and radii of Beta Cep stars are the same as those of nonvariable stars of the same spectral type; (3) Be stars that do not have two Balmer jumps have effective temperatures very similar to those of normal B stars of the same subtype; (4) O and B stars increase in size from the main sequence to supergiants; and (5) late B supergiants are approximately twice as large as O9 supergiants.
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society; vol. 189
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  • 84
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    Twenty southern peculiar emission-line stars (1979)
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    Publication Date: 2011-08-17
    Description: Observational data for 20 southern stars having emission-line spectra that suggest a significant degree of mass ejection are given in order to present an atlas of their spectra and to give a quantitative description of their appearance during the 1961-62 epoch. Most of the stars are P Cygni stars; others include nova-like, peculiar Be, and symbiotic stars, as well as stellar planetary nebulae and emission-line binaries, all of whose spectra were obtained with the Newtonian two-prism Zeiss Spectrograph and the 74-inch reflector at Mount Stromlo Observatory. It is noted that among the P Cygni stars, there is a strong correlation between the a-e expansion velocity and the strength of Balmer emission, while in both the P Cygni and the Bep stars, there is positive dependence of Fe II and negative dependence of (Fe II) emission strengths on Balmer emission strength.
    Keywords: ASTRONOMY
    Type: Vistas in Astronomy; 23; pt. 3
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  • 85
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    Residence lifetimes of 1.79- to 2.15-MeV protons in the equatorial region of the Jovian magnetosphere (1979)
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    Publication Date: 2011-08-17
    Description: The magnitude of the strong flow of 1.79-2.15 MeV protons away from the Jovian magnetic equator is used to estimate the residence lifetimes of these protons in the equatorial source region. The lifetime is approximately 1.2 x 10 to the 5th/(R - 5.8)-squared sec, where R is distance in Jovian radii from Jupiter's center to the equatorial region of interest. At Europa and Ganymede (but not at Io) this lifetime is 1-2 orders of magnitude shorter than sweepup lifetimes by the moons. The fluxes of these protons, integrated over the observed range from 6 to 40 Jovian radii, amount to 3 x 10 to the 23rd particles per second, per degree of longitude and carry away about 9 x 10 to the 17th ergs per second per degree.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 84; Oct. 1
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  • 86
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    Investigation of Luna-20 soil samples, using a mass spectrometer with a spark-discharge ion source (1979)
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    Publication Date: 2011-08-17
    Description: A method of analyzing soil samples with a mass spectrometer employing a spark-discharge ion source is described, and the effectiveness of the method is demonstrated by applying it to the determination of impurities, in amounts of less than 10 mg, in lunar samples. It is shown that four parts of the Luna-20 lunar highland sample differ in their chemical composition.
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  • 87
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    Viking radio occultation measurements of the atmosphere and topography of Mars - Data acquired during 1 Martian year of tracking (1979)
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    Publication Date: 2011-08-17
    Description: The results of one Martian year of radio occultation measurements of the atmosphere and topography of Mars obtained using the Viking Orbiters are briefly summarized. Determinations of the vertical distribution of tropospheric gas refractivity and ionospheric electron density obtained from atmospheric Doppler frequency perturbations of the S and X band radio tracking frequencies indicate large meteorological variations, with near-surface temperatures ranging from 150 to 250 K, 5-km atmospheric pressure ranging from 3.5 to 4.8 mbar, inversion layers over the polar caps and dust storms, and seasonal pressure variations. Double- and single-layered upper atmospheric electron density profiles were observed on the sunlit and dark sides of the planet, respectively. A topographic map of the Martian surface, obtained from the limb diffraction effects observed at ingress and egress, is found to agree well with the elevation contours of US Geological survey map M 25M 3 RMC, with the exception of the south polar and Alba Patera regions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 84; Dec. 30
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  • 88
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    Osculating orbital elements of the asteroids (1979)
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    Publication Date: 2011-08-17
    Description: In the present paper, osculating orbital elements are listed for 2118 numbered asteroids, of which 17 are considered lost. The columns give asteroid number; name; semimajor axis, in AU; eccentricity; longitude of the ascending mode; argument of perihelion; mean anomaly; and Julian date of epoch minus 2,400,000.
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  • 89
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    Non-equilibrium effects on the chemistry of nebular condensates - Implications for the planets and asteroids (1979)
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    Publication Date: 2011-08-17
    Description: Kinetic effects, for example nucleation constraints and slow reactions, should have been important in nebular condensation. Consideration of these effects leads to the prediction of pressure-dependent compositions and physical properties of nebular condensates which is consistent with (1) the differences between different classes of chondritic meteorites, (2) some of the differences between planets, and (3) the presence of oxidized iron on the moon and in the eucrite parent body (presumably an asteroid) despite the low abundance of volatiles. Diffusion effects appear to be important for understanding oxygen isotope anomalies in refractory inclusions in Allende. The consideration of kinetic effects leads to more information concerning nebular processes than if equilibrium is assumed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 90
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    Reflectance spectra for 277 asteroids (1979)
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    Publication Date: 2011-08-17
    Description: Visible and near-infrared reflectance spectra are presented for 277 asteroids. These represent the results of an 8-yr program and constitute all spectra available in 1979. There are approximately 80 recognizably different spectral types among the asteroids surveyed. Relatively few of these can be explained as mixtures of C- and S-type materials on individual asteroids, although Eos family members may be an exception.
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    Chronology of asteroid collisions as recorded in meteorites (1979)
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    Publication Date: 2011-08-17
    Description: Because meteorites are derived from asteroidal objects, the chronology of meteorites give age information on the histories of the asteroidal parents. With a few possible exceptions, the radiometric chronology of less than 4.4 Gyr determined in meteorites can be attributable to collisions among meteorite parent bodies. Three types of collisional chronologies which have been determined are: (1) cosmic ray exposure ages, which generally date the time of the last fragmentation of the parent object when the meteorite is reduced to meter size, and which generally fall over the wide range of 1-1000 Myr; (2) the collisional shock ages shown by many meteorites, which are believed to date the times of major collisions among parent bodies in the asteroid belt in the time interval of 30-700 Myr; and (3) the brecciation ages of several meteorites which are believed to date the times of their collisional formation from regoliths of larger parent bodies over the period of 1.4-4.4 Gyr.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 92
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    Collisional evolution of asteroids - Populations, rotations, and velocities (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The collisional evolution of various initial populations of asteroids is simulated numerically and compared with the present asteroid size-frequency distribution to find those populations which collisionally relax to the present belt. Both orbital and size distributions are treated, as well as the simultaneous evolution of two collisionally interacting populations with different physical properties. If the initial belt distribution was a power law, the initial belt population at the time when the present high-collision speed was established was probably only modestly larger than the present population. However, other distributions allow a more massive early belt. The rotational evolution due to collisions of asteroids with power-law distributions is also examined and compared with observations, leading to conclusions generally in agreement with those of size evolution. The high-collision speed in the present belt is likely due to Jupiter. Gravitational stirring by massive Jupiter-scattered planetesimals or secular resonances sweeping through the belt are the most probable mechanisms.
    Keywords: ASTRONOMY
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  • 93
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    Earth-crossing asteroids - Orbital classes, collision rates with earth, and origin (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Asteroids that can intersect the orbit of the earth are discussed, which include Aten asteroids (semimajor axis (a) less than 1 AU, aphelion greater than 0.983 AU), Apollo asteroids (a greater than 1 AU, perihelion less than 1.017 AU), and Amor asteroids (perihelion distance between 1.017 and 1.3 AU). The principal sources of earth-crossing asteroids appear to be extinct comet nuclei and collision fragments from regions in the main asteroid belt. The total population of earth-crossers is estimated at 13,000, of which approximately 8% are Atens, 50% are Apollos, and 40% are Amors,and the present collision rate of such asteroids with the earth is estimated at about 3.5 objects, to absolute magnitude 18, per million years.
    Keywords: ASTRONOMY
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  • 94
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    Radiometry of asteroids (1979)
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    Publication Date: 2011-08-17
    Description: Measurements of the thermal emission of asteroids can be used to derive albedos and diameters and to infer information on thermophysical properties of the upper layer of asteroid surfaces. Radiometric diameters and albedos, derived on the basis of standard thermal models for low-conductivity regoliths, have been determined for approximately 200 asteroids, with results in agreement with determinations by polarimetry and stellar occultations. For objects to which these standard models apply, diameters can be determined with an accuracy of plus or minus 10%. In several cases of small asteroids, however, there is evidence that the standard models do not apply, presumably due to the absence of an insulating regolith. Thus the interpretation of radiometric diameters is in question and the utility for objects with diameters less than about 30 km is diminished. In these cases the thermal observations potentially can provide information on the ability of low-gravity objects to retain regoliths.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 95
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    The asteroids - Accretion, differentiation, fragmentation, and irradiation (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Various types of meteorites have experienced processes of condensation, accretion, metamorphism, differentiation, brecciation, irradiation and fragmentation. A typical view of meteorite formation has been that the processes following accretion take place in a few asteroidal-sized (approximately 100 km) objects. Discovery of decay products of now extinct Al-26 and Pd-107 in meteorites, discovery of isotopic heterogeneity among meteorite types, re-analysis of meteorite cooling rates, and continuing study of meteoritic compositions have led some meteoriticists to conclude that meteorites obtained their chemical, isotopic, and some textural characteristics in objects initially less than 10 km in diameter. Such a scenario, which is described in this paper, raises the possibility that some of these small planetesimals may have been 'condensation nuclei' for the formation of comets as well as the precursors of asteroids.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 96
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    Voyager 1 photopolarimeter experiment and the phase curve and surface microstructure of Ganymede (1979)
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    Publication Date: 2011-08-17
    Description: Results are reported for optical-wavelength photopolarimetry of Ganymede from Voyager 1. A phase coefficient of 0.011 + or - 0.001 mag/deg and an opposition effect of 0.17 + or - 0.03 mag are derived. It is shown that Ganymede's surface is probably more porous than Callisto's and that micrometeoroids may continuously roughen the surface of Ganymede.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 280; Aug. 30
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  • 97
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    Jupiter's magnetic tail (1979)
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    Publication Date: 2011-08-17
    Description: Voyager 1 observations of the Jovian magnetosphere are discussed which are most naturally interpreted in terms of a well-developed magnetic tail on the nightside of the planet. It is shown that this tail, with a 'neutral sheet' separating the upper and lower lobes of opposite field polarity, is formed and controlled by external forces associated with the solar wind. The inner magnetosphere's current tail is found to merge with the magnetotail's neutral sheet. It is concluded that this configuration leads to a strong local-time control of the outer Jovian magnetosphere rather than planetary control.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 280; Aug. 30
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  • 98
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    Jovian cloud structure and velocity fields (1979)
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    Publication Date: 2011-08-17
    Description: A global view of Jovian small-scale morphologies and zonal velocity profiles has been discussed previously. In the present paper, a regional comparison is made of the structures and velocity fields (meridional and zonal velocities) in the Jovian atmosphere as observed by Voyager I imaging system. The cloud structures discussed are fairly independent of the visual wavelength. The analysis shows that although both Jovian hemispheres exhibit similar patterns of diminishing and alternating eastward and westward jets as one progresses polewards, there is a pronounced asymmetry in the structural appearance of the two hemispheres.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 280; Aug. 30
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  • 99
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    Zonal velocity and texture in the Jovian atmosphere inferred from Voyager images (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Smith et al. (1970) have described Jupiter's changing appearance at resolutions down to 10 km over intervals as small as 1 h. Examples of small-scale convection, rapid variations of features, and complex interactions of closed vortices were given. In the present paper, these results are extended to include measurements of the latitudinal profile of zonal (eastward) velocity, from which the absolute vorticity gradient is estimated. Also, a classification scheme based on texture (i.e., the patterns of small features visible at resolutions of 100 km or better) is proposed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 280; Aug. 30
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  • 100
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    Photometric evidence on long-term stability of albedo and colour markings on Io (1979)
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    Publication Date: 2011-08-17
    Description: Photometric measurements of the color and albedo of Io during the last 50 years are examined in order to determine the stability of the Ionian surface. Brightness measurements of Io relative to Ganymede show a slight, however inconclusive, increase with time, while light curve amplitudes and shapes are found to agree well during this period. The extent of volcanic activity observed by Voyager 1, however, is shown to be undetectable with the precision attainable by earth-based albedo determinations, and just barely detectable as color changes, which explains the observed photometric stability. Possible mechanisms for the preservation of the observed longitudinal distribution of color on Io are also discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature; 280; Aug. 30
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