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  • LUNAR AND PLANETARY EXPLORATION  (1,281)
  • EARTH RESOURCES AND REMOTE SENSING  (830)
  • Atomic, Molecular and Optical Physics
  • Physics
  • 2010-2014
  • 1990-1994  (1,070)
  • 1980-1984  (2,146)
  • 1925-1929
  • 1990  (1,070)
  • 1980  (2,146)
Collection
Keywords
Publisher
Years
  • 2010-2014
  • 1990-1994  (1,070)
  • 1980-1984  (2,146)
  • 1925-1929
Year
  • 1
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    The meaning of hydrophobicity (1990)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1990-10-12
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dill, K A -- New York, N.Y. -- Science. 1990 Oct 12;250(4978):297-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco 94143.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2218535" target="_blank"〉PubMed〈/a〉
    Keywords: Energy Transfer ; Physical Phenomena ; Physics ; *Protein Conformation ; Proteins/*chemistry ; Solutions
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Uranus - The planet, rings and satellites (1990)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The present overview of available data regarding Uranus and its planetary structures encompasses ground- and space-based observations of the planet with specific attention given to the interpretation of Voyager 2 data. A brief examination of historical observations is given which includes its discovery, position determination, and the related discoveries of Uranus' five large satellites and rings. The observational data preceding the Voyager 2 mission are reviewed in terms of the planetary interior, atmosphere, and magnetosphere. The Voyager 2 mission is given detailed treatment with descriptions of NASA's development and deployment of the spacecraft as well as detailed data from the Uranus encounter. Reference is given to structure and composition of Uranus' atmosphere, valid models of the interior, and wave-particle interactions in the magnetosphere. The structures of the rings and satellites are examined with reference to specific observational requirements from future missions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 3
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    Application of the Semivariogram Textural Classifier (STC) to SIR-B data of Borneo (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: This paper presents the results of an application of the semivariogram textural classifier to SIR-B data. Ford and Casey (1988) performed a visual interpretation of a SIR-B image of a tropical rain forest in Borneo in which they recognized and mapped three units of forest canopy (coastal lowland forest, tidal forest and swamp) and two units of open areas (clearcut and wetland). In this study the same image is classified using the STC in an attempt to emulate their interpretation.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL, Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 53-57
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  • 4
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    River and lake ice conditions as determined from AIRSAR imagery (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: Synthetic aperture radar (SAR) imagery data can provide information on types and distribution of river and lake ice needed for studying river ice processes and dynamics, monitoring ice during winter navigation, and formulating ice control strategies. Visible and IR remote sensing systems cannot provide such data and present field methods are inadequate for characterizing ice conditions over long river reaches. Our ongoing analysis of JPL's AIRSAR imagery data and concurrent ground truth of ice conditions on the Tanana River and surrounding lakes near Fairbanks, Alaska, in March 1988, has resulted in several findings: hummocked ice covers and zones of variable ice surface roughness within them can be differentiated; C- and L-band data are more sensitive than P-band to the range of surface roughnesses encountered; smooth, level ice that is clear or contains small bubbles produces little backscatter; snow-covered river ice, whether rough or smooth, is distinguishable from snow-covered river sediments on exposed river beds and unvegetated bars; and open water leads are readily distinguished.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL, Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 37-42
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  • 5
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    Preliminary results from the MAESTRO 1 Campaign over the Black Forest (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: The Joint Research Center (JRC) Ispra and the European Space Agency (ESA) have co-sponsored the deployment of the National Aeronautics and Space Agency (NASA) and Jet Propulsion Laboratory (JPL), C-, L-, and P-band polarimetric synthetic aperture radar (SAR) in Europe in mid-August 1989. This deployment represents the first opportunity for European agencies and institutes to evaluate the current state of the art of multifrequency polarimetric imaging technology over European Test Sites. Of particular interest to the Joint Research Center (JRC) Ispra is the Black Forest Test Site at Freiburg in the Federal Republic of Germany. This Test Site incorporates the Villingen region of the Black Forest to the south-west of Germany. This paper reports upon the activities undertaken in preparation for the MAESTRO 1 Campaign in the Black Forest Test Site. In particular this paper reports upon the ground data collection campaign for the Freiburg Test Site where extensive and intensive ground data measurements were undertaken. These measurements were based upon standard ground data collection protocols developed for forestry by the JRC and utilized throughout Europe for the MAESTRO 1 Campaign. The paper then goes on to present preliminary results derived from the SAR data using the JRC-developed software for polarimetric data interpretation, POLTOOL.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL, Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 43-52
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  • 6
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    Comparison of active and passive microwave signatures of Arctic sea ice (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: In March 1988, overlapping active and passive microwave instrument data were acquired over Arctic sea ice using the NASA DC-8 aircraft equipped with multifrequency, variable polarization SAR and radiometer. Flights were conducted as a series of coordinated underflights of the DMSP SSM/I satellite radiometer in order to validate ice products derived from the SSM/I radiances. Subsequent flights by an NRL P-3 aircraft enabled overlapping high-resolution, single frequency image data to be acquired over the same regions using a Ka-band scanning microwave radiometer. In this paper, techniques are discussed for the accurate coregistration of the three aircraft datasets. Precise coregistration to an accuracy of 100 m plus or minus 25 m has, for the first time, enabled the detailed comparison of temporally and spatially coincident active and passive airborne microwave datasets. Preliminary results from the intercomparisons indicate that the SAR has highly frequency- and polarization-dependent signatures, which at 5.3 GHz (C-band) show an extremely high correlation with the 37 GHz radiometric temperatures.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 29-36
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  • 7
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    Synthetic aperture radar observations of the Greenland ice sheet (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: Results of preliminary analyses of aircraft polarimetric SAR data acquired over the Greenland Ice Sheet are presented. Data were collected in August 1989 by the Jet Propulsion Laboratory (JPL) multifrequency, polarimetric SAR using the NASA DC-8 aircraft over southern Greenland. Data of this kind are the first to be acquired over an ice sheet. They are complementary to the limited coverage provided by the SEASAT satellite SAR in 1978, and more recent aircraft X-band SAR image coverage. Frequency and polarization dependencies observed in the P-, L-, and C-band image products are attributed to large-scale variations in the snow and ice surface characteristics. At this time of year, during the ablation season, ice topography exerts a strong influence upon drainage and other hydrological features on the ice sheet surface. Systematic trends in backscatter strength observed across regions of changing snow facies are suggestive of a capability to map areas of snow wetness. Trends observed at C-band indicate that algorithms could possibly be developed which have the ability to delineate areas of significant melt.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 21-28
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  • 8
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    Ground truth measurement for the analysis of airborne SAR data recorded over Oberpfaffenhofen, FRG, 1989 (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: As a preliminary investigation to the joint multiparameter SIR-C/X-SAR shuttle experiment of NASA/JPL (USA), DLR (FRG), and PSN (Italy) which is scheduled for the year 1992 an airborne SAR campaign was conducted over Oberpfaffenhofen, FRG, in August 1989. Primarily this campaign was planned to test and verify equipment and algorithms developed at the DLR to calibrate multifrequency polarimetric SAR data. Oberpfaffenhofen is designated as one of the super test sites for the SIR-C/X-SAR experiment which will be imaged under all circumstances except severe mission errors. A super test site drives radar parameters and look directions and the recorded SAR data will be calibrated. In addition ancillary data will be available for the site. During the airborne STAR campaign conducted in the week of August 14th 1989 various sensor types were used to record remote sensing data over the calibration test site and its vicinity: the polarimetric DC-8 JPL-SAR (P-, L-, C-band), the DLR airborne SAR (C-, X-band), color infrared aerial photography (DLR), and the truck-mounted scatterometer (C- and X-band) of the Institute for Navigation, University of Stuttgart (INS). Because of this variety of different sensor types used and out of the fact that sufficiently large forested and agriculturally used areas were planned to be covered by these sensors, the interest of several German research groups involved in investigations concerning SAR land applications arose. The following groups carried out different ground-truth measurements: University of Bonn, Institute for plant cultivation (plant morphology and moisture content); University of Braunschweig, Institute for Geography (soil moisture and surface roughness); University of Freiburg, Institute for Geography (dielectric soil properties, landuse); and University of Munich, Institute for Geography (landuse inventory, plant, surface, and soil parameters). This paper presents the joint ground truth activities of the Institute for Geography, University of Munich, and the German Remote Sensing Data Center of the DLR.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL, Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 8-13
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  • 9
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    Remote sensing of Italian volcanos (1990)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The results of a July 1986 remote sensing campaign of Italian volcanoes are reviewed. The equipment and techniques used to acquire the data are described and the results obtained for Campi Flegrei and Mount Etna are reviewed and evaluated for their usefulness for the study of active and recently active volcanoes.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: EOS (ISSN 0096-3941); 71; 1789-179
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  • 10
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    Mars Observer's global mapping mission (1990)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The objectives of the Mars Observer global mapping mission are to determine the global elemental and mineralogical character of the Martian surface material, define globally the topography and gravitational field of Mars, establish the nature of Mars's magnetic field, determine the time and space distribution, abundance, sources, and sinks of volatile Martian material and dust over a seasonal cycle, and explore the structure and aspects of the circulation of the Martian atmosphere. The experiments and instruments to be used in this mission are described, and the operations and data analysis are briefly considered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: EOS (ISSN 0096-3941); 71; 1099
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  • 11
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    Small-scale plasma, magnetic, and neutral density fluctuations in the nightside Venus atmosphere (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The evolution of the Venus small-scale waves as they propagate into the nightsite is examined, and the small-scale structures are compared with the waves in the three components of the magnetic field, magnetic dip angle, and neutral density. It is demonstrated that the small-scale fluctuations evolve between the transterminator and antisolar regions. It is shown that atmospheric gravity waves may also be producing some of the fluctuations observed at longer wavelengths. The electron temperature and density are shown to be approximately 180 deg out of phase and exhibiting the highest correlation of any pair of variables. Waves in the electron and neutral densities are found to be correlated moderately on most orbits, while the average electron temperature is higher when the average magnetic field is more horizontal.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 4085-410
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  • 12
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    Application of remote sensing in tropical forests (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Cloud cover in tropical humid forests can pose serious operational constraints on Landsat TM and SPOT HRV instrumentation, given their respective orbital frequencies of 16 and 26 days. SAR data intrinsically precludes such problems; the increase of data acquisition frequency to daily rates, as with the NOAA AVHRR instrument, also bears consideration. It is deemed essential that SAR data-related research be expedited, in order to ascertain inherent SAR information for tropical forests in a timely and cost-effective manner.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 13
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    A sensor fusion field experiment in forest ecosystem dynamics (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The background of the Forest Ecosystem Dynamics field campaign is presented, a progress report on the analysis of the collected data and related modeling activities is provided, and plans for future experiments at different points in the phenological cycle are outlined. The ecological overview of the study site is presented, and attention is focused on forest stands, needles, and atmospheric measurements. Sensor deployment and thermal and microwave observations are discussed, along with two examples of the optical radiation measurements obtained during the experiment in support of radiative transfer modeling. Future activities pertaining to an archival system, synthetic aperture radar, carbon acquisition modeling, and upcoming field experiments are considered.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 14
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    Experiment design and operations (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The objectives, design, and field operations of the First ISLSCP Field Experiment (FIFE) are described. The simultaneous acquisition of satellite, atmosphere, and surface data, and the understanding of the processes governing surface energy and mass exchange and how these are manifested in satellite-resolution radiometric data are identified as the specific objectives of the field-phase experiment. The central issues concerning the design of the field experiment are considered: the size of the site, the duration of the experiment, and the location of the site; it is noted that the Konza Prairie National Reserve was selected as the focus of the study. Field operations in 1987 and 1989 are discussed, and it is pointed out that a data set is available now from a single combined repository to all FIFE investigators, and that scientists can test models and algorithms on scales consistent with satellite observations and with enough supporting data on finer scales.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 15
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    Functional relation among subpixel canopy cover, ground shadow, and illuminated ground at large sampling scales (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The functional relation among subpixel canopy cover, illuminated soil, and shadowed soil, which progressively develops with increasing pixel size, is investigated for Poisson distributed plants using a geometric canopy simulation model. An analytical relation among cover components is shown to be applicable when the scale of the pixel is much larger than the scale of the plant and ground shadow. The analysis is facilitated through the use of a nondimensional solar-geometric similarity parameter, eta, equal to the ratio of the area of one plant canopy to its associated ground shadow area, as viewed from nadir. A sampling scale ratio, defined as the ratio of the area of the pixel to the mean area of a single plant shadow, is tested as a quantitative criterion to evaluate when the functional relation among subpixel components occurs. The results of a remote sensing experiment over a natural conifer landscape provide preliminary confirmation of the theoretical analysis.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 16
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    Progress in microwave remote sensing of soil moisture (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Significant progress has been made in the application of microwave remote sensing for measuring soil moisture. Both passive and active systems have demonstrated the capability for measuring soil moisture. However, several questions are still unresolved regarding the optimal instrument configuration and other target characteristics, such as roughness and vegetation. In addition, the most likely disciplines for using these data, agriculture and hydrology, do not currently possess adequate models or procedures for using these new data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Canadian Journal of Remote Sensing (ISSN 0008-2821); 16; 6-14
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  • 17
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    Comment on 'Update on terrestrial ages of Antarctic meteorites' by K. Nishiizumi, D. Elmore and P. W. Kubik (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters (ISSN 0012-821X); 99; 4, Se; 380-382;
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  • 18
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    Geochemistry and genesis of the angrites (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The major and trace elements were analyzed in samples of LEW86010, LEW87051, and Angra dos Reis angrites were analyzed using INAA and fused-bead EMP techniques. Results suggest that all three angrites originated on a volatile-depleted (Na-poor) but oxidized parent body or on several bodies. The combination of low Na and high FeO/MnO found in these samples suggests that the extreme Na depletion was caused by parent-body outgassing during differentiation, rather than by nebular processes. It was also found that the refractory-element abundances observed in LEW86010 and LEW87051 are related via olivine control; it is suggested that LEW86010 may be a residual melt from a LEW87051-like precursor or that LEW87051 formed from a LEW86010-like precursor via olivine accumulation. On the other hand, the Angra dos Reis displayed an unusual refractory element pattern suggesting that either the angrite parent body was heterogeneous or that Angra dos Reis was formed on a parent body different from that of the other two angrites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 54; 3209-321
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  • 19
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    Relationship of multispectral satellite data to land surface evaporation from the Australian continent (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Based on NOAA-9 AVHRR and Nimbus-7 SMMR satellite data, satellite indices of vegetation from the Australian continent are calculated for the period of May 1986 to April 1987. Visible (VIS) and near infrared (NIR) reflectances and the normalized difference (ND) vegetation index are calculated from the AVHRR sensor. The microwave polarization difference (PD) is also calculated as the difference between the vertically and horizontally polarized brightness temperatures at 37 GHz. ND, PD, VIS, and NIR indices were plotted against rainfall and water balance estimates of evaporation. It is concluded that direct satellite monitoring of annual evaporation across the Australian continent using PD or VIS satellite indices of vegetation biomass appears possible for areas with evaporation less than 600 mm/y and that use of the ND relationship at continental scale may underpredict monthly evaporation of forests relative to agriculture.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 11; 2069-208
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  • 20
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    Zonal motion and structure in Jupiter's upper troposphere from Voyager infrared and imaging observations (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Global digital maps of Jupiter's upper-tropospheric temperature have been generated at the 270- and 150-mb pressure levels, together with IR cloud optical depths at 5 and 45 microns and the ammonia abundance near the 680-mb pressure level, on the basis of Voyager IRIS north-south mapping sequences. Attention is given to the 270-mb and 45 micron data; global digital maps are presented for violet and orange reflectivities. The dominant upper tropospheric thermal structures move at a rate far different from that of the cloud indicators, and are noted to remain stationary relative to the planet's bulk rotation. Strong stationary features are found at a zonal wavenumber of 9 near 15 deg N latitude and of 11 near 20 deg latitude.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 88; 39-72
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  • 21
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    Tidal disruption of solid bodies (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The problem of stress, strain, and breakup in solid satellites and stray bodies subject to tidal perturbations is presently addressed in view of three novel considerations. After presenting a new analytic solution for the stress tensor in a homogeneous and compressible elastic sphere, where the inclusion of compressibility alters stresses by several percent, realistic failure criteria are noted to demonstrate the general failure of such ductile bodies as iron meteoroids by plastic shear, while brittle ice bodies fail by either tensile or shear fracture. A reexamination of crack propagation after initial failure allows the diverse breakup criteria to be reconciled.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 88; 24-38
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  • 22
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    Low-frequency scattering from cylindrical structures at oblique incidence (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Classical Rayleigh scattering theory is extended to the case of a homogeneous dielectric cylinder of arbitrary cross section whose transverse dimensions are much smaller than the wavelength. By assuming that the surface fields can be approximated by those of the infinite cylinder, the far zone scattered field is expressed in terms of polarizability tensors, whose properties are discussed. Numerical results are presented for circular, semicircular, triangular, and square cylinders. The results are applicable to the remote sensing of twigs, stalks, and vegetation needles at centimeter and millimeter wavelengths.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); 28; 879-885
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  • 23
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    Cloud-tracked winds from Pioneer Venus OCPP images (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results are presented on the analysis of the Pioneer Venus Orbiter Cloud Photopolarimeter (OCPP) UV images, covering 80-day periods from 1979 to 1985. The analysis provides a method for determining wind speeds at the cloud level, from the motions of cloud UV features. Data used for tracking the cloud feature motions are described along with the analysis method. The results identified four wave modes: a diurnal solar tide, a semidiurnal solar tide, a '4-day equatorial' wave, and a '5-day midlatitude' wave. The features of these wave modes are described.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 47; 2053-208
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  • 24
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    (Ar-39)-(Ar-40) dating of mesosiderites - Evidence for major parent body disruption less than 4 Ga ago (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The (Ar-39) (Ar-40) chronologies were determined for 14 different mesosiderites representing the full range of classification according to recrystallization, and these chronologies were compared with analogous data for other meteorite types and for lunar highland rocks. Results of Ar-Ar chronologies indicate the history of a degassing of Ar due to a major thermal event that occurred less than 3.9 Ga ago; this event is not the metal-silicate mixing event, which is known to have occurred earlier than 4.4 Ga ago. It is suggested that a major collisional disruption-reassembly event less than 3.9 Ga ago took place, leaving the metal-silicate breccias buried under tens of kilometers of rubble, where they cooled slowly through the Ar closure temperatures.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 54; 2549-256
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  • 25
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    Inter- and intra-group compositional variations in Apollo 15 pyroclastic green glass - An electron- and ion-microprobe study (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results are presented on major- and trace-element abundance analyses of Apollo 15 pyroclastic green glasses from groups A, B, C, D, and E, carried out using electron- and ion-microprobe techniques. The diagrams depicting Sr, Zr, Ba, and Nd vs Co variations indicate the presence of a high-Co trend in groups A and D and a low-Co trend in groups B and C. Group-E glasses were found to be significantly enriched in Sr, relative to the other four glass groups. Chemical data of this study were integrated with previous data to evaluate various magmatic processes that have been proposed in the past to explain chemical variations in the lunar green glass. Results of calculations using a source mixing model suggest that the Apollo 15 green glasses represent multiple eruptive events from three chemically distinct but compositionally variable source regions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 54; 2565-257
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  • 26
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    Energy sources for Triton's geyser-like plumes (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Four geyser-like plumes were discovered near Triton's south pole in areas now in permanent sunlight. Because Triton's southern hemisphere is nearing a maximum summer solstice, insolation as a driver or a trigger for Triton's geyser-like plumes is an attractive hypothesis. Trapping of solar radiation in a translucent, low-conductivity surface layer (in a solid-state greenhouse), which is subsequently released in the form of latent heat of sublimation, could provide the required energy. Both the classical solid-state greenhouse consisting of exponentially absorbed insolation in a gray, translucent layer of solid nitrogen, and the 'super' greenhouse consisting of a relatively transparent solid-nitrogen layer over an opaque, absorbing layer are plausible candidates. Geothermal heat may also play a part if assisted by the added energy input of seasonal cycles of insolation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 250; 431-435
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    Temperature and thermal emissivity of the surface of Neptune's satellite Triton (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Analysis of the preliminary results from the Voyager mission to the Neptune system has provided the scientific community with several methods by which the temperature of Neptune's satellite Triton may be determined. If the 37.5 K surface temperature reported by several Voyager investigations is correct, then the photometry reported by the imaging experiment on Voyager requires that Triton's surface have a remarkably low emissivity. Such a low emissivity is not required in order to explain the photometry from the photopolarimeter experiment on Voyager. A low emissivity would be inconsistent with Triton having a rough surface at the about 100-micron scale as might be expected given the active renewal processes which appear to dominate Triton's surface.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 250; 429-431
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    Subsurface energy storage and transport for solar-powered geysers on Triton (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The location of active geyser-like eruptions and related features close to the current subsolar latitude on Triton suggests a solar energy source for these phenomena. Solid-state greenhouse calculations have shown that sunlight can generate substantially elevated subsurface temperatures. A variety of models for the storage of solar energy in a subgreenhouse layer and for the supply of gas and energy to a geyser are examined. 'Leaky greenhouse' models with only vertical gas transport are inconsistent with the observed upper limit on geyser radius of about 1.5 km. However, lateral transport of energy by gas flow in a porous N2 layer with a block size on the order of a meter can supply the required amount of gas to a source region about 1 km in radius. The decline of gas output to steady state may occur over a period comparable with the inferred active geyser lifetime of 5 earth years. The required subsurface permeability may be maintained by thermal fracturing of the residual N2 polar cap. A lower limit on geyser source radius of about 50 to 100 m predicted by a theory of negatively buoyant jets is not readily attained.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 250; 424-429
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    Triton's geyser-like plumes - Discovery and basic characterization (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: One model for the mechanism driving the plumes of the four active geyser-like eruptions observed by Voyager 2 on Triton is a heating up of nitrogen ice in a subsurface greenhouse environment, where nitrogen gas pressurized by solar heating explosively vents to the surface carrying clouds of ice and dark particles into the atmosphere. A temperature increase of less than 4 K above the ambient surface value of 38 + or - 3 K suffices to drive the plumes to 8-km altitude. Each eruption may last a year or more, over the course of which 0.1 cu km of ice is sublimed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 250; 410-415
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    Sensitivity of the normalized difference vegetation index to subpixel canopy cover, soil albedo, and pixel scale (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An analytical framework is provided for examining the physically based behavior of the normalized difference vegetation index (NDVI) in terms of the variability in bulk subpixel landscape components and with respect to variations in pixel scales, within the context of the stochastic-geometric canopy reflectance model. Analysis focuses on regional scale variability in horizontal plant density and soil background reflectance distribution. Modeling is generalized to different plant geometries and solar angles through the use of the nondimensional solar-geometric similarity parameter. Results demonstrate that, for Poisson-distributed plants and for one deterministic distribution, NDVI increases with increasing subpixel fractional canopy amount, decreasing soil background reflectance, and increasing shadows, at least within the limitations of the geometric reflectance model. The NDVI of a pecan orchard and a juniper landscape is presented and discussed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment (ISSN 0034-4257); 32; 169-187
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    Bidirectional measurements of surface reflectance for view angle corrections of oblique imagery (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An apparatus for acquiring bidirectional reflectance-factor data was constructed and used over four surface types. Data sets were obtained over a headed wheat canopy, bare soil having several different roughness conditions, playa (dry lake bed), and gypsum sand. Results are presented in terms of relative bidirectional reflectance factors (BRFs) as a function of view angle at a number of solar zenith angles, nadir BRFs as a function of solar zenith angles, and, for wheat, vegetation indices as related to view and solar zenith angles. The wheat canopy exhibited the largest BRF changes with view angle. BRFs for the red and the NIR bands measured over wheat did not have the same relationship with view angle. NIR/Red ratios calculated from nadir BRFs changed by nearly a factor of 2 when the solar zenith angle changed from 20 to 50 degs. BRF versus view angle relationships were similar for soils having smooth and intermediate rough surfaces but were considerably different for the roughest surface. Nadir BRF versus solar-zenith angle relationships were distinctly different for the three soil roughness levels. Of the various surfaces, BRFs for gypsum sand changed the least with view angle (10 percent at 30 degs).
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment (ISSN 0034-4257); 32; 189-202
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    Light polarization by vegetation cover - Possible agricultural applications (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A review of the physical mechanisms involved in light polarization by reflecting surfaces is presented and experimental results for single leaf, bare soil, and plant canopies are analyzed. It is shown that light polarization can be employed to identify different plant canopies and to estimate their standing biomass. For bare soils, light polarization can be used to monitor the surface soil moisture and the state of the surface. Thus light polarization may be considered as a new remote sensing technique for potential agricultural application.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Canadian Journal of Remote Sensing (ISSN 0008-2821); 16; 32-41
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  • 33
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    Magellan orbits Venus (1990)
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    Publication Date: 2011-08-19
    Description: Various events surrounding Magellan's orbit of Venus are recounted. Significant events include the successful firing of a solid rocket motor while the spacecraft was behind Venus to transfer it from a solar-centered trajectory to an orbit around the planet. The spacecraft orbits Venus every 3.26 hours at a maximum altitude of 8500 km and minimum altitude of 291 km in an elliptical orbit. The successful August 16 test of the synthetic-aperture radar system is discussed, noting that it produced two strips, each about 20 km x 16,000 km, revealing details as small as 120 m. Two anomalies causing a delay in the start of mapping operations and subsequent breaks in the communication link with earth for 14.5 hours and 17.7 hours are discussed. Protective measures directed from the spacecraft's ROM during breach of contact are listed, and possible causes of the anomalies are suggested, such as solar activity or hardware or software elements, although the actual cause is not yet known.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Spaceflight (ISSN 0038-6340); 32; 334-337
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    Comparative dynamics of the ionospheres of Venus and Mars at large solar zenith angles (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Simple three-ion spectral models of the dynamics and ion chemistry in the upper ionospheres of Venus and Mars have been constructed by including two minor ions, H(+) and O2(+) for Venus and O(+) and CO2(+) for Mars, along with the major ion, O(+) for Venus and O2(+) for Mars. Horizontal flow velocities and ion densities have been calculated in each case and compared with available measured data. For Venus, the present calculations yield results in agreement with earlier finite-difference model studies and with experimental observations. Calculations for Mars are in agreement with the limited observational data obtained by the Viking landers.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Indian Journal of Radio and Space Physics (ISSN 0367-8393); 19; 88-102
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    Albedo and color maps of the Saturnian satellites (1990)
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    Publication Date: 2011-08-19
    Description: The paper discusses the production of maps of the albedos and colors of Mimas, Enceladus, Tethys, Dione, and Rhea over the full range of their imaged surfaces. Voyager images were used to prepare maps of the normal reflectances and color ratios (0.58/0.41 micron) of these satelites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 87; 339-357
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    Cosmogenic nuclides in extraterrestrial materials (1990)
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    Publication Date: 2011-08-19
    Description: Research on cosmogenic nuclides in extraterrestrial materials is summarized. Methods for determining average production rates in meteorites are considered as well as the composition dependence of production rates. Also discussed are lunar meteorites, solar-gas-rich meteorites, presolar grains, and solar cosmic rays.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Reviews of Geophysics (ISSN 8755-1209); 28; 253-275
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  • 37
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    Remote sensing of tropical forests - An overview of research and applications using non-photographic sensors (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A comprehensive overview is presented on how remote sensing technology has been applied to tropical forest monitoring over the past 20 years. Research needs for monitoring the condition and extent of tropical forests are suggested. The discussion focuses on nonphotographic sensors, especially those on orbiting satellites. Several remote sensing approaches to tropical forest monitoring are outlined, including NOAA AVHRR, Landsat MSS, the Landsat Thematic Mapper, SPOT-1, and Synthetic Aperture Radar. Suggested research needs are addressed, along with discussions on the use of Geographic Information Systems, and multistage and multisensor approaches in data analysis and acquisition. It is concluded that additional research and technique development is urgently needed to advance the utility of remotely sensed data for tropical forest monitoring. However, there is sufficient information available now to prototype a global tropical forest monitoring system that would utilize current satellite sensors complemented with airborne sensors for detailed measurements on sample locations.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing (ISSN 0099-1112); 56; 1343-135
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    Normalization of satellite imagery (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Sets of Thematic Mapper (TM) imagery taken over the Washington, DC metropolitan area during the months of November, March and May were converted into a form of ground reflectance imagery. This conversion was accomplished by adjusting the incident sunlight and view angles and by applying a pixel-by-pixel correction for atmospheric effects. Seasonal color changes of the area can be better observed when such normalization is applied to space imagery taken in time series. In normalized imagery, the grey scale depicts variations in surface reflectance and tonal signature of multi-band color imagery can be directly interpreted for quantitative information of the target.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 11; 1331-134
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  • 39
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    A model of Saturn's magnetic field based on all available data (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A model of Saturn's magnetic field, called Saturn Pioneer Voyager (SPV), is developed on the basis of an analysis of three sets of data: those from the Pioneer 11, the Voyager 1, and the Voyager 2 magnetometers. It is shown that the SPV model fits the data observed between 1.3 and 8.0 Saturn radii from the planet's center with a 1.13 percent weighted rms average of the percent differences between the observed and modeled fields, which is substantially better than the fits yielded by any of the previous models.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 15257-15
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  • 40
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    Backscattering from frost on icy satellites in the outer solar system (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two extreme models are presented of how frost and ice might be intermixed on a typical satellite surface: areal and intimate mixing. Applying such models to selected representative satellite data, it is found that the frost component of the surfaces of these outer satellites must itself be backscattering, unlike its terrestrial counterpart. The difference may arise because frost particles can have much more complex internal textures under the low-temperature and low-gravity conditions of the outer satellites than is the case on earth.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 347; 162-164
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    Ubiquitous interstellar diamond and SiC in primitive chondrites - Abundances reflect metamorphism (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is shown here that interstellar diamond and SiC were incorporated into all groups of chondrite meteorites. Abundances rapidly go to zero with increasing metamorphic grade, suggesting that metamorphic destruction is responsible for the apparent absence of these grains in most chondrites. In unmetamorphosed chondrites, abundances normalized to matrix content are similar for different classes. Diamond samples from chondrites of different classes have remarkably similar noble-gas constants and isotropic compositions, although constituent diamonds may have come from many sources. SiC seems to be more diverse, partly because grains are large enough to measure individually, but average characteristics seem to be similar from meteorite to meteorite. These observations suggest that various classes of chondritic meteorites sample the same solar system-wide reservoir of interstellar grains.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 347; 159-162
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    Regional aeolian dynamics and sand mixing in the Gran Desierto - Evidence from Landsat Thematic Mapper images (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Mesoscale mapping of spatial variations in sand composition of the Gran Desierto (Sonora, Mexico) was carried out on multispectral Landsat TM images of this region, making it possible to examine the dynamic development of sand sheets and dunes. Compositions determined from remote imagery were found to agree well with samples from selected areas. The sand populations delineated were used to describe the sediment source areas, transport paths, and deposition sites. The image analysis revealed important compositional variations aver large areas that were not readily apparent in the field data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 15463-15
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    Vertical distribution of water in the atmosphere of Venus - A simple thermochemical explanation (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Several lines of evidence concerning the vertical abundance profile of water in the atmosphere of Venus lead to strikingly unusual distributions (the water vapor abundance decreases sharply in the immediate vicinity of the surface) or to serious conflicts in the profiles (different IR bands suggest water abundances that are discrepant by a factor of 2.5 to 10). These data sets can be reconciled if (1) water molecules associate with carbon dioxide and sulfur trioxide to make gaseous carbonic acid and sulfuric acid in the lower atmosphere, and (2) the discrepant 0.94-micrometer water measurements are due to gaseous sulfuric acid, requiring it to be a somewhat stronger absorber than water vapor in this wavelength region. A mean total water abundance of 50 + or - 20 parts/million and a near-surface free water vapor abundance of 10 + or - 4 parts/million are derived.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 249; 1273-127
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    Assessment of tropical forest stand characteristics with multipolarization SAR data acquired over a mountainous region in Costa Rica (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A digital terrain elevation data set was coregistered with radar data for assessing tropical forest stand characteristics. Both raw and topographically corrected L-band polarimetric radar data acquired over the tropical forests of Costa Rica were analyzed and correlated with field-collected tree parameter data to study the stand characteristics. The results of analyses using 18 out of 81 plots for sites A and B indicated that per-plot bole volume and tree volume are related to SAR data, particularly at site A. The topographically corrected SAR data appear to produce the same findings as those of uncorrected data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Vancouver, Canada, July 10-14, 1989) IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); 752-755
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  • 45
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    Diurnal patterns of the bi-directional reflectance of fresh-water ice (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: To improve the interpretation of surface cryospheric albedo from satellite sensor data, diurnal measurements of the spectral bidirectional reflectance of a commonly found fresh water ice type were made, from which hemispherical reflectance can be derived. The purpose of this study is to document its clear-sky, bidirectional reflectance characteristics in the visible (650-670 nm) and near-infrared (810-840 nm) region, assess the diurnal nature of the reflectance, and quantify the surface anisotropy. Bidirectional reflectances of the refrozen slush ice measured show a spectral dependence and change significantly with solar zenith angle. Considerable variation occurs at each view angle and among view angles throughout the day. Although diurnal reflectance patterns were similar in both bands, magnitudes varied greatly, being highest in the visible and lowest in the near-infrared region. With the exception of peak saturated (specular) values in the forward scatter direction, bidirectional reflectance was generally highest in the morning when the surface and the illumination were most diffuse in character.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Annals of Glaciology (ISSN 0260-3055); 14; 153-157
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    Variations of Mars gravitational field and rotation due to seasonal CO2 exchange (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: About a quarter of the Martian atmospheric mass is exchanged between the atmosphere and the polar caps in the course of a Martian year: CO2 condenses to form (or add to) the polar caps in winter and sublimes into the atmosphere in summer. This paper studies the effect of this CO2 mass redistribution on Martian rotation and gravitational field. Two mechanisms are examined: (1) the waxing and waning of solid CO2 in the polar caps and (2) the geographical distribution of gaseous CO2 in the atmosphere. In particular, the net peak-to-peak changes in J2 and J3 over a Martian year are both found to be as much as about 6 x 10 to the -9th. A simulation suggests that these changes may be detected by the upcoming Mars Observer under favorable but realistic conditions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14755-14
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    Atmospheric measurements at Mars via gamma ray spectroscopy (1990)
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    Publication Date: 2011-08-19
    Description: This paper describes three methods for measuring the Martian atmosphere using gamma ray spectroscopy. One method determines atmospheric thickness based on the energy-dependent differential attenuation of gamma-ray line pairs from a common element. Another makes a direct determination based on measurements of the line flux generated in the atmosphere, requires knowledge of the concentration of the component being used. The third, which makes use of a single line emitted from the surface where its flux can be established. The effects of stratigraphy on the differential attenuation method are studied, and calculations are reported which show that the measurement of atmospheric argon will be a sensitive indicator of the atmospheric fractionation accompanying CO2 precipitation in south polar regions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14695-14
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    Infrared radiative transfer in the dust-free Martian atmosphere (1990)
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    Publication Date: 2011-08-19
    Description: Two theoretical radiative transfer methods are used here to derive synthetic spectra of dust-free Martian atmospheres. One is a versatile, accurate, line-by-line model which completely resolves individual absorption lines to produce high-resolution spectra within gas absorption bands. The other is a fast Voigt quasi-random model which produces accurate results for spectral regions as narrow as 1/cm and is fast enough for routine use in broadband transmission calculations. Synthetic transmission and radiance spectra from these models for dust-free conditions in the Martian atmosphere are used to illustrate the radiative effects of each important absorbing gas and to provide a baseline for comparisons with dust atmosphere spectra.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14577-14
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    Thermal emission spectra of Mars (5.4-10.5 microns) - Evidence for sulfates, carbonates, and hydrates (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Spectra of the Martian thermal emission in the 5.4-10.5 micron region are reported. Emission features at 7.8 and 9.7 microns are attributed to surface silicates, and an emission feature at 6.1 micron is attributed to a molecular water component of the surface material. An absorption band at 8.7 micron and a possible one at 9.8 microns is attributed to sulfate or bisulfate anions probably located at a distorted crystalline site, and an absorption band at 6.7 microns is attributed to carbonate or bicarbonate anions located in a distorted crystalline site. Spectral simulations indicate that the sulfate- and carbonate-bearing minerals are contained in the same particles of airborne dust as the dominant silicate minerals, that the dust optical depth is about 0.6 at a reference wavelength of 0.3 micron over the area of the observed spots, and that sulfates and carbonates constitute 10-15 percent and 1-3 percent by volume of the airborne dust, respectively.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14595-14
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    Origins of Marslike spectral and magnetic properties of a Hawaiian palagonitic soil (1990)
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    Publication Date: 2011-08-19
    Description: Results are presented on spectral, Moessbauer, static magnetic, petrographic, and compositional data for a Hawaiian palagonitic soil from Mauna Kea (HWMK1). It was found that reflectivity spectra of size separates smaller than 20 microns resemble spectra for Martian bright regions, while spectra of larger size separates show characteristics in common with spectra for Martian dark regions. Data on the HWMK1 soil are consistent with the partitioning of iron among the following minerals: olivine, titanomagnetite, hematite, and a superparamagnetic colored ferric oxide. These mineralogies are heterogeneously distributed within the soil with respect to both particle type and soil-particle diameter. The strongly magnetic titanomagnetite is associated with black particles and is responsible for the magnetic nature of the soil, while the colored weakly magnetic superparamagnetic ferric oxide and minor hematite are associated with orange particles.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14427-14
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    Emplacement of lava flow fields - Application of terrestrial studies to Alba Patera, Mars (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The relationships obtained by Kilburn and Lopes (1988, 1990) for their models of lava flow fields were used to calculate the duration of the emplacement, the average discharge rates, and the average velocities of lavas for the Martian volcano Alba Patera, on which two distinct planimetric types of lava flow field were identified. The validity of using terrestrial analogues for investigating the emplacement conditions of the Alba Patera flow fields is examined. It is concluded that, at least for basaltic-basaltic andesitic compositions, the essential conditions of eruption from Alba Patera may have been similar to those currently observed on earth.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14383-14
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    Fault propagation folds induced by gravitational failure and slumping of the Central Costa Rica volcanic range - Implications for large terrestrial and Martian volcanic edifices (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Maps are presented that describe the compressional tectonic structures found at the base of the Central Costa Rica volcanic range (CCRVR), which comprise thrust faults and related fault propagation folds, only partly covered by syntectonic and posttectonic volcanoclastic deposits. Evidence is presented that these structures formed by gravitational failure and lumping of the flanks of the volcanic range. It is suggested that similar structures may be found at the toe of the southern flank of Kilauea volcano, Hawaii, and along the perimeter scarp of the Olympus Mons volcano on Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14357-14
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    Flank tectonics of Martian volcanoes (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The origin of the numerous terraces on the flanks of the Olympus Mons volcano on Mars, seen on space images to be arranged in a roughly concentric pattern, is investigated. The images of the volcano show that the base of each terrace is marked by a modest but abrupt change in slope, suggesting that these terraces could be thrust faults caused by a compressional failure of the cone. The mechanism of faulting and the possible effect of the interior structure of Olympus Mons was investigated using a numerical model for elastic stresses within a Martian volcano, constructed for that purpose. Results of the analysis supports the view that the terraces on Olympus Mons, as well as on other three Martian volcanoes, including Ascraeus Mons, Arsia Mons, and Pavonis Mons are indeed thrust faults.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14345-14
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    The shallow structure of the Martian lithosphere in the vicinity of the ridged plains (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: On Mars, the most prominent assemblage of regularly spaced plain ridges occurs in the plains of the Coprates and Lunae Planum regions. In this paper, a number of tectonic models is developed and quantitatively evaluated, that relate the regular spacing of these ridges to the shallow internal structure of Mars. It is shown that models with both rigid and deformable megaregolith-basement interface conditions can provide solutions which can explain the ridge spacing within the constraint provided by the estimated thickness of the smooth plains materials. Implications of the models for the structure and state of stress in the Tharsis region at the time of ridge formation are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14215-14
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    Speculations on the origin and evolution of the Utopia-Elysium lowlands of Mars (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper proposes a qualitative model for the origin of the Utopia-Elysium northern lowlands on eastern Mars in terms of the long-term evolution of two large overlapping impact basins. The model, which is consistent with both the observed geologic constraints and more quantitative results obtained by numerical modeling of smaller (Orientale-size) impact basins, is shown to qualitatively account for the major topographic variation seen in the Utopia-Elysium region, including the overall 'lowness' of the area and localized depressions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14203-14
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    Discontinuities in the shallow Martian crust at Lunae, Syria, and Sinai Plana (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Detailed photoclinometric data are presented for a variety of surface features (pits, troughs, wall valleys, and grabens) within three study areas in the western equatorial regions of Mars (Lunae, Syria, and Sinai Plana) that provide evidence for mechanical discontinuities within the shallow Martian crust in these regions. The data's relation to some of the previously proposed mechanical discontinuities within the Martian crust is discussed, and the geologic significance of these features is speculated upon.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14231-14
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    A new survey of multiring impact basins on Mars (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Literature data on Martian multiring impact basins with diameters greater than 500 km are summarized, and evidence is found for eight new such basins. The pattern of changes of basin morphology with increasing basin size suggests three subclasses of multiring basins: (1) multiring basins with diameters up to about 1850 km, which are characterized by the Orientale type concentric structure and cumulative frequency power law slope of -0.75; (2) the Argyre-type basins (with diameters between 1850 and 3600 km, defined by rugged concentric annnuli and a power law slope of nearly -2.0; and (3) the Chryse-type basins (with diameters greater than 3600 km), which exhibit multiple concentric rings and very shallow topographic profiles. Multiring basins are found in all parts of Mars, including the northern lowlands, Tharsis, and surrounding highlands, and are associated with much of the subsequent resurfacing of cratered terrain.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14175-14
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    Mars gravity field error analysis from simulated radio tracking of Mars Observer (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results are presented on the analysis of the recovery of the Martian gravity field from tracking data in the presence of unmodeled error effects associated with different orbit orientations. The analysis was based on the mission plan for the Mars Observer (MO) radio tracking data from the Deep Space Network. From the analysis, a conservative estimate of the gravitational accuracy for the entire mission could be obtained. The results suggest that, because the atmospheric drag is the dominant error source, the spacecraft orbit could possibly be raised in altitude without a significant loss of gravitational signal. A change in altitude will also alleviate the large effects seen in the spectrum the satellite resonant orders.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14155-14
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    Martian impact craters - Correlations of ejecta and interior morphologies with diameter, latitude, and terrain (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An effort is made to establish the ability of a correlation between crater morphology and latitude, diameter, and terrain, to discriminate among the effects of impact energy, atmosphere, and subsurface volatiles in 3819 larger-than-8 km diameter craters distributed over the Martian surface. It is noted that changes in ejecta and interior morphology correlate with increases in crater diameter, and that while many of the interior structures exhibit distributions interpretable as terrain-dependent, central peak and peak ring interior morphologies exhibit minimal relationships with planetary properties.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 87; 156-179
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    A goal and strategy for human exploration of the moon and Mars (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Eventual settlement of the solar system, beginning with the moon and Mars, is proposed, and a strategy for the exploration of and initial settlement of the moon and Mars, based on the model of European settlement of the Americas, is discussed. Strategies suggest an allocation of functions between humans and telerobots to conduct the exploration and initial settlement.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Space Policy (ISSN 0265-9646); 6; 195-208
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    Large-scale patterns of eolian sediment transport on Venus - Predictions for Magellan (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The atmosphere of Venus is likely to exert a major influence on the surface. Arecibo and Venera 15/16 observations of the population of impact craters with bright halos give direct evidence of surface modification, on the scale of centimeters, to smooth the surface on time scales of 50 - 250 my. Both chemical and mechanical modifications probably occur. Diurnal winds in the planetary boundary layer can transport particles. Using boundary layer theory, including the effects of topography, surface stresses and resulting transport and deposition of sand-size particles are calculated. Regional slopes are sites of largest surface stresses. Sand will be generally transported downhill, although there is a preferential net transport from east to west, in the same direction as the atmospheric superrotation. It is predicted here that streaks may be seen in the Magellan radar images which will indicate directions of net eolian transport on the surface of Venus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 17; 1365-136
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    Small domes on Venus - Probable analogs of Icelandic lava shields (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: On the basis of observed shapes and volumetric estimates, small, dome-like features on radar images of Venus are interpreted to be analogs of Icelandic lava-shield volcanoes. Morphometric data for Venusian domes in Aubele and Slyuta as well as measurements of representative dome volumes and areas from Tethus Regio are used to demonstrate that the characteristic aspect ratios and flank slopes of these features are consistent with a subclass of low Icelandic lava-shield volcanoes (LILS).
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 17; 1381-138
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    Geologic evidence of hotspot activity of Venus - Predictions for Magellan (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A number of distinctive types of geologic features have been identified on Venus that are interpreted to be related to thermal plumes including domal rises, coronae, and major composite shield volcanoes. The basic characteristics of these features as well as their distribution are documented. The three types of features have related morphologies and are interpreted to represent a continuum of features formed by mantle plumes at scales from 100s to over 1000 km. The Artemis structure, located in Aphrodite Terra, is proposed to be a large corona. If crustal spreading processes are operating on Venus, hotspot features should form chains on the surface as seen in terrestrial ocean basins. On the basis of current data on hotspot-related feature distribution on Venus, no clear evidence exists for hotspot chains. The complete distribution of hotspot features in Magellan data will be used to understand better the relationship between interior processes and surface features, as well as to provide a test for the crustal spreading hypothesis.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 17; 1377-138
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    Radar characteristics of the equatorial plains of Venus from Goldstone observations - Implications for interpretation of Magellan data (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Based on analyses of recent high resolution observations of the approximately 1000 km diameter Heng-O ring structure by the Goldstone Solar System Radar, it is predicted that the structure is a large corona. Calibrated values of radar backscatter coefficient indicate lateral variations of a factor of 4 in Fresnel reflectivity in the vicinity of Heng-O, as well as in other areas of the plains, at scales of tens of km. It is predicted that areas with very low reflectivity values, which occur in a variety of geological settings, are soil-dominated, with bulk densities as low as 1.5 g/cu cm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 17; 1357-136
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    Titan and other icy satellites - Dielectric properties of constituent materials and implications for radar sounding (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Radar sounding observations of Titan and the other outer solar system icy satellites have been conducted in order to ascertain the materials present, their dielectric properties, and the degree of radar signal penetration. Deep penetration is possible at long wavelengths, while strong reflections may occur due to pockets or layers of H2O-NH3 solution. Attention is given to the case of Titan, using models to calculate radar reflection S/N ratios; the models involve H2O ice covered by a 100-m thick layer of organic sediments that are overlain by an ocean of liquid CH4-C2H6-N2. At 13.6-cm wavelength, a greater-than-10 dB S/N is computed from the ocean-sediment and sediment-ice interfaces, suggesting that the geology of Titan may be investigated by such a sounding mode despite deep ocean coverage of the satellite.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 86; 336-354
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    The deep atmosphere of Venus revealed by high-resolution nightside spectra (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The first high-resolution spectroscopic observations of the night side of Venus obtained in two narrow spectral windows centered at 1.74 and 2.3 microns, where the nightside is anomalously bright, are reported. Absorption features from CO2, CO, H2O, HDO, HCl, HF, and COS are detected, and there are a number of unidentified features. A preliminary analysis indicates that the observed radiation is thermal emission from atmospheric layers in the eight-bar pressure region for the 2.3 micron window and even deeper at 1.7 micron. The derived CO and H2O abundances agree with in situ Pioneer measurements in the deep troposphere and are consistent with the high deuterium enrichment inferred from Pioneer data. The first measurements of HCl and HF below the clouds are reported along with the first firm detection of COS.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 345; 508-511
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    Mars ionopause during solar minimum - A lesson from Venus (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The ion densities measured by the Viking landers (Hanson et al., 1977) do not show an abrupt falloff with height, giving the false impression that Mars has no ionopause. On the basis of knowledge gained from the solar wind interaction at Venus during solar minimum, it is demonstrated that the observed O2 profile above about 160 km on Mars is a distributed photodynamical ionosphere and can produce an ionopause at around 325 km, similar to that observed on Venus during solar minimum. It is concluded that the solar wind interacts directly with the Mars ionosphere, suggesting that the planet does not have an intrinsic magnetic field of any consequence.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 8265-826
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    A method for estimating eruption rates of planetary lava flows (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The eruption rates of single-lobed planetary lava flows are presently accounted for by a model for radiative losses from a partially crusted hotter core, assuming thermal characteristics similar to terrestrial flows. Eruption rates are within this framework expressible as functions of (1) exposed core area fraction, (2) initial core temperature, (3) core temperature upon cessation of flow, (3) crust thickness, and (4) the lava's density and heat capacity.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 85; 512-515
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    CH4 nonlocal thermodynamic equilibrium in the atmospheres of the giant planets (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The present consideration of methane's vibrational relaxation in the Giant Planets' upper stratospheres employs a model for the thermalization of solar energy absorbed under non-LTE conditions, at the 1.7, 2.3. and 3.3 micron-centered CH4 band groups. On this basis, a range of model atmospheres was produced, reflecting current uncertainties concerning CH4 collisional excitation rates. At 0.1 mbar, all of the non-LTE models are within 2 K of the LTE reference models; the extreme non-LTE models steadily depart from reference LTE ones, however, and reach about + or - 20 K at 0,1 mbar.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 85; 355-379
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    Titan's stratospheric temperatures - A case for dynamical inertia? (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Voyager IRIS spectral radiances in the nu4-band of CH4 for the Titan atmosphere exhibit a hemispheric asymmetry. While asymmetry in the meridional distribution of opacity about the equator cannot be discounted, attention is given to the need for angular momentum transport concurrent with seasonally varying temperatures in the Titan stratosphere, which would maintain the cyclostrophic thermal wind relation between zonal winds and temperatures. The adiabatic heating and cooling associated with these motions can produce the observed temperature asymmetry.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 85; 346-354
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    The extraordinary radar echoes from Europa, Ganymede, and Callisto - A geological perspective (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Electromagnetic echo-scattering models, empirical and theoretical considerations on regolith formation, and ice physics, are presently invoked in a geologic treatment of the anomalous radar properties of the icy Galilean satellites. These are held to arise because of the electrical differences between ice and silicates, and the absence of icy regoliths' ice-density structures in silicate regoliths. Icy regoliths may uniquely smooth out discontinuities between solid ejecta fragments and more porous surroundings, forming refraction-scattering 'lenses'; high-order multiple scatterings will thereby become more likely responsible for the echoes than low-order scattering.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 85; 335-345
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    On the effect of X rays on the color of elemental sulfur - Implications for Jupiter's satellite Io (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Absorption features arose at 0.42 and 0.52 microns when spectral reflectance measurements were conducted for elemental sulfur allotrope mixtures produced by the exposure of the cyclooctal S(8) allotrope of sulfur to X-rays; while these features due to the presence of short-chain molecules are stable at low temperatures, they fade upon warming of the sample. The hypothesis that X-rays in the Jovian environment would cause other allotropic forms of sulfur to revert to S(8) is contradicted by the fact that these features are not present in S(8) at the same temperature that had not been exposed to X-rays.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 85; 326-334
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    Internal structure of Io and the global distribution of its topography (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A global topography is presently calculated for two multilayer Io models in which dissipation occurs in a viscous asthenosphere and a solid mantle: (1) a 'thermal swell' model, in which topography and heat flow are positively correlated, and (2) a 'differentiated lithosphere' model, in which topography and heat flow are negatively correlated. Both the polar topography and the hypsometric distribution of elevations in the differentiated lithosphere model are better matched with observations than the thermal swell model. The shift of the equatorial basin-swell pattern indicates a recent zonal rotation of about 25 deg for Io's lithosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 85; 309-325
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    TV observations of Phobos - First results (1990)
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    Publication Date: 2011-08-19
    Description: From February to March, 1989, Phobos-2 acquired 37 TV images of Phobos at distances from 200 to 1100 km. These images will be used to update the figure model and topographic and geological maps of Phobos, its spectral characteristics and scattering law, the surface composition and texture, and the parameters of the orbital motion and forced libration.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Pis'ma v Astronomicheskii Zhurnal (ISSN 0320-0108); 16; 378-388
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    Faults in the Mojave Desert, California, as revealed on enhanced Landsat images (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Landsat TM images, subjected to four-component processing through which lithologies can be discriminated by their contrasting absorption and reflection at IR wavelengths, have revealed previously unsuspected strike-slip and normal faults in the central and eastern Mojave Desert. These discriminations, which extend to ferric and ferrous iron and to hydroxyl content without compromise of landform depiction, represent a novel type of geophysical display for geologic mapping in regions of well-exposed bedrock; the faults thus discovered form part of an extensive regional network of right shear which connects Death Valley region faults with those in the San Andreas system.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Science (ISSN 0036-8075); 248; 1000-100
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    Charge-coupled device spectra of asteroids. I - Near-earth and 3:1 resonance asteroids (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Main-belt asteroids and cometary nuclei are both frequently suggested sources of the relatively short-lived near-earth asteroids (NEAs). The asteroidal origin hypothesis is studied by obtaining new high-quality reflectivity spectra of 19 NEAs and 23 asteroids near the 3:1 resonance, and by performing a systematic comparison of these two groups of spectra. Nonparametric statistical tests are used to check for consistency between the color distributions of the two populations. The tests indicate that the difference between the two distributions is generally not significant at the 3 sigma level. However, this conclusion is dependent on the (unknown) size distribution of the NEAs. The observations are compatible with the hypothesis that the NEAs are derived from the 3:1 resonance region, but do not imply that this is the only possible source region.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal (ISSN 0004-6256); 99; 1985-201
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    Mars - Change in axial tilt due to climate? (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The average tilt of Mars' equator with respect to its orbital plane may have increased significantly over the age of the solar system. Obliquity oscillations might have induced changes in the climate, which altered the mass distribution and hence the solar torque on the planet. Viscous deformation attributable to loading by the large polar caps expected at low obliquity may have induced secular changes in the axial tilt. Earth-like effective viscosities can account for virtually the entire present obliquity of 24.4 degrees. Thus the present average tilt of Mars may not be primordial.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 248; 720
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    Degradation of the lunar vacuum by a moon base (1990)
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    Publication Date: 2011-08-19
    Description: Several industrial processes requiring high and ultra-high vacuum similar to the lunar vacuum are outlined. The effects of a 20-person lunar base and a 250-person industrial facility on this vacuum are discussed. It is shown that exhaust from transport spacecraft and leakage from the habitat will be comparable to the daytime gas pressure for the 20-person base, and will degrade the vacuum to the range of 2 x 10 to the -9th torr for the use of 250-person facility. This will result in replacing the mostly nonreactive gases hydrogen, helium, and neon with more reactive gases containing carbon and oxygen. This vacuum is still good enough to perform many important vacuum processes such as plasma-deposition of amorphous silicon for solar cells, but processes such as molecular beam epitaxy or locating an intersecting beam accelerator on the moon will require additional vacuum pumping.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Acta Astronautica (ISSN 0094-5765); 21; 183-187
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    The dynamics of the ionosphere of Mars at large solar zenith angles (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A model of the ion chemistry and dynamics of the ionosphere of Mars at large solar zenith angles has been constructed using techniques previously developed for Venus. It is found that a substantial nighttime ionosphere should occur even when the ionopause height is as low as 250 km. At low altitudes the interaction of the plasma flow with the neutral atmosphere appears to result in considerable 'noise' in the flow patterns. Transterminator plasma velocities are smaller than for Venus, although they may exceed the local sonic speed. The effect of a nocturnal source of suprathermal electrons is also discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 6263-626
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    Petrogenesis of mesosiderites. I - Origin of mafic lithologies and comparison with basaltic achondrites (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: New petrologic and trace element data on basaltic and gabbroic clasts in mesosiderites and basaltic achondrites, combined with existing petrologic and trace element data, have served as a basis for interpretation of the petrogenesis of mesosiderite clasts. Compared with the basaltic achondrites, the mesosiderite basaltic and gabbroic clasts contain more abundant modal tridymite and merrilite, and more commonly contain augite as a late magmatic phase. Their pyroxenes tend to be more MgO-rich, and have lower Fe/Mn ratios which are positively correlated with the Fe/Mg ratio. Some of the mesosiderite basaltic and gabbroic clasts contain xenocrystic plagioclase. The basaltic clasts commonly show superchondritic Eu/Sm ratios and slight LREE depletions. The cumulate gabbro clasts are extremely depleted in LIL, have very high Eu/Sm ratios and high Lu/Sm ratios. All of these features can be explained by a model in which the mafic lithologies of mesosiderites were formed by remelting of a mixed basalt-cumulate gabbro-metal source region near the parent body surface.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 54; 1165-117
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    Matrix effects for reflectivity spectra of dispersed nanophase (superparamagnetic) hematite with application to Martian spectral data (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effect of the matrix on the reflectivity spectra of nanophase (superparamagnetic) hematite (np-Hm) dispersed within the matrix was investigated in four series of powder samples containing np-Hm dispersed within discrete powder particles (of two size ranges) of silica gel and activated alumina. The spectral data show that matrix effects are large. Samples with the same Fe2O3 content can have np-Hm absorption edges characterized by very different positions and curvature and slope indices, while samples with equivalent absorption edges can have very different Fe2O3 concentrations. Thus, quantitative relationships between the positions of ferric absorption edges and Fe2O3 concentrations are unreliable without knowledge of matrix properties of the system. It is shown that it was possible to match the Fe2O3 concentration, magnetic properties, and spectral data for Martian surface material with a laboratory mixture whose only ferric-bearing phase was hematite.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 5101-510
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    The unpolarized component in polarimetric radar observations of forested areas (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A polarimetric radar measures the complete scattering matrix of a target. For the forest and other natural targets, the average return is, in general, partially polarized. Conditions on the second-order statistics of the scattering matrix under which the return is fully polarized are derived, and it is shown that these conditions are connected with the eigenvalues of the covariance matrix. The result of this analysis is a set of three quantities which indicate the ability of a scatterer to generate an unpolarized component. These quantities for forested areas are shown.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); 28; 268-271
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  • 83
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    Data compression in digitized lines (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The problem of data compression is very important in digital photogrammetry, computer assisted cartography, and GIS/LIS. In addition, it is also applicable in many other fields such as computer vision, image processing, pattern recognition, and artificial intelligence. Consequently, there are many algorithms available to solve this problem but none of them are considered to be satisfactory. In this paper, a new method of finding critical points in a digitized curve is explained. This technique, based on the normalized symmetric scattered matrix, is good for both critical points detection and data compression. In addition, the critical points detected by this algorithm are compared with those by zero-crossings.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing (ISSN 0099-1112); 56; 517
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  • 84
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    Artificial neural network classification using a minimal training set - Comparison to conventional supervised classification (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent research has shown an artificial neural network (ANN) to be capable of pattern recognition and the classification of image data. This paper examines the potential for the application of neural network computing to satellite image processing. A second objective is to provide a preliminary comparison and ANN classification. An artificial neural network can be trained to do land-cover classification of satellite imagery using selected sites representative of each class in a manner similar to conventional supervised classification. One of the major problems associated with recognition and classifications of pattern from remotely sensed data is the time and cost of developing a set of training sites. This reseach compares the use of an ANN back propagation classification procedure with a conventional supervised maximum likelihood classification procedure using a minimal training set. When using a minimal training set, the neural network is able to provide a land-cover classification superior to the classification derived from the conventional classification procedure. This research is the foundation for developing application parameters for further prototyping of software and hardware implementations for artificial neural networks in satellite image and geographic information processing.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing (ISSN 0099-1112); 56; 469-473
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  • 85
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    Influence of the solar wind/interplanetary medium on Saturnian kilometric radiation (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Previous studies on the periodicities of the Saturnian kilometric radiation (SKR) suggested a considerable solar wind influence on the occurrence of SKR, so it was obvious to investigate the relationship between parameters of the solar wind/interplanetary medium and this Saturnian radio component. Voyager 2 data from the Plasma Science experiment, the Magnetometer experiment and the Planetary Radio Astronomy experiment were used to analyze the external control of SKR. Out of the examined quantities known to be important in controlling magnetospheric processes this investigation yielded a dominance of the solar wind momentum, ram pressure and kinetic energy flux, in stimulating SKR and controlling its activity and emitted energy, and confirmed the results of the Voyager 1 analysis.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geomagnetism and Geoelectricity (ISSN 0022-1392); 42; 12, 1
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  • 86
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    Evaluating hydrologic modelling components of the Florida Everglades with AVHRR and ancillary data (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 87
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    Tropical forest tree stands characterization with L-band polarimetric radar (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effectiveness of using L-band polarimetric data to determine tropical tree-stand parameters is discussed with specific attention given to the correction of the radar data. Tree-parameter data from ground studies is compared to L-band polarimetric data (in both uncorrected and topographically corrected forms) for two test areas. The test sites are at two different elevations but both include 81 test plots with topographic data and tree-characteristic data given. Synthetic-aperture radar (SAR) data are found to be related to bole volume and tree volume, and the topographically corrected data show results similar to the uncorrected data. Similar r-values are given for both data sets because the data with incidence-angle values below 35 and above 55 are removed. Topographical correction is important when local incidence angles exceed the limits.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 88
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    Thermospheric gravity waves - Observations and interpretation using the transfer function model (TFM) (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper presents some numerical experiments performed with the TFM to study the various wave components excited in the auroral regions that propagate through the thermosphere and lower atmosphere, and to demonstrate the properties of realistic source geometries. The model is applied to the interpretation of satellite measurements, and gravity waves seen in the thermosphere of Venus are discussed. Gravity waves are prominent in the terrestrial thermosphere polar region and can be excited by perturbations in Joule heating and Lorentz force due to magnetospheric processes. Observations from the Dynamics Explorer-2 satellite are used to illustrate the complexity of the phenomenon and to review the TFM that is utilized.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Space Science Reviews (ISSN 0038-6308); 54; 297-375
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  • 89
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    A comparative study of Venus and Mars - Upper atmospheres, ionospheres and solar wind interactions (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The neutral atmospheres of Mars and Venus are discussed. A comparative study is presented of the upper atmospheres, ionospheres, and solar wind interactions of these two planets. The review is mainly concerned with the region about 100 km above the surface of the planets.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Indian Journal of Radio and Space Physics (ISSN 0367-8393); 19; 444-465
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  • 90
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    The global budget of impact-derived sediments on Venus (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The sedimentary cycle of Venus is examined, with specific attention to the contribution from impact events. The observed record of impact craters on the surface of Venus can be used to calculate the contribution of fine materials generated by impact processes to the global sedimentary cycle. Ejecta volume calculations carried out on the basis of various crater population scenarios suggest that the maximum global ejecta layer thickness over the past 1 Gyr is about 1-2 mm. This would translate to a global accumulation rate of only 0.002 to 0.01 micron per year. Moreover, most of this material could never have been available for global transport; it is projected that over 90 percent of the ejecta would be deposited within 1-3 radii of the crater rim, and only 0.02-0.05 percent could be available as fine dust for global sedimentary cycle. Therefore, the global layer thickness of transportable impact-derived dust can be no more than a few mm over the past 1 Gyr.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth, Moon, and Planets (ISSN 0167-9295); 50-51; 175-190
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  • 91
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    Spectral reflectance characterization (0.4 to 2.5 and 8.0 to 12.0 microns) of phanerozoic strata, Wind River basin and southern Bighorn basin areas, Wyoming (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Sedimentary Petrology (ISSN 0022-4472); 60; 504-524
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  • 92
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    Selection of Landsat TM band and band-ratio combinations to maximize lithologic information in color composite displays (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Correlation analyses of Landsat TM data for arid areas and laboratory spectral data for various combinations of minerals indicate that band combination 1-4-7 maximally differentiates lithologic materials in most scenes, but that band combination 1-5-7 is preferable for scenes in which hydroxyl-rich minerals are prominent or of specific interest. Among band ratio combinations, 3/1 - 5/4 - 5/7 ranks high for optimal information display.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 93
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    Geologic lithologic mapping in NW Ontario - Remote sensing approaches and caveats (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A previously noted higher proportion of coniferous vegetation over metavolcanic formations than over metasedimentary ones, in which deciduous vegetation predominates, has been quantified and extended to encompass granites, migmatites, and ultramafic bodies typical of the NW Ontario shield area. Preliminary analyses of TM data suggests that there are spectral differences associated with these vegetation parameters; more importantly, a species assemblage pattern associated with ultramafic units was found at five different locations.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 94
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    Revealing topographic lineaments through IHS enhancement of DEM data (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Intensity-hue-saturation (IHS) processing of slope (dip), aspect (dip direction), and elevation to reveal subtle topographic lineaments which may not be obvious in the unprocessed data are used to enhance digital elevation model (DEM) data from northwestern Nevada. This IHS method of lineament identification was applied to a mosiac of 12 square degrees using a Cray Y-MP8/864. Square arrays from 3 x 3 to 31 x 31 points were tested as well as several different slope enhancements. When relatively few points are used to fit the plane, lineaments of various lengths are observed and a mechanism for lineament classification is described. An area encompassing the gold deposits of the Carlin trend and including the Rain in the southeast to Midas in the northwest is investigated in greater detail. The orientation and density of lineaments may be determined on the gently sloping pediment surface as well as in the more steeply sloping ranges.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 95
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    Quantitative lithologic mapping in spectral ratio feature space - Volcanic, sedimentary and metamorphic terrains (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The nature of spectral lithologic mapping is studied utilizing ratios centered around the wavelength means of TM imagery. Laboratory-derived spectra are analyzed to determine the two-dimensional relationships and distributions visible in spectral ratio feature space. The spectral distributions of various rocks and minerals in ratio feature space are found to be controlled by several spectrally dominant molecules. Three study areas were examined: Rawhide Mining District, Nevada; Manzano Mountains, New Mexico; and the Sevilleta Long Term Ecological Research site in New Mexico. It is shown that, in the comparison of two ratio plots of laboratory reflectance spectra, i.e., 0.66/0.485 micron versus 1.65/2.22 microns with those derived from TM data, several molecules spectrally dominate the reflectance characteristic of surface lithologic units. Utilizing the above ratio combination, two areas are successfully mapped based on their distribution in spectral ratio feature space.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 96
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    Mapping alteration in the Goldfield Mining District, Nevada, with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Analysis of the data acquired by the Airborne Visible/IR Imaging Spectrometer over the Goldfield Mining District, Nevada, demonstrates the unique capabilities of high resolution imaging spectrometers for alteration mapping and identification of mineralogy. The study focuses on the 2-2.45 micron window, as alteration minerals of interest have their distinctive spectral reflectance features in this region. An attempt was made to map the spatial distribution of the individual minerals and produce a mixture maps showing their relative abundance on a pixel-by-pixel basis, focussing on selected subareas. Software and SNR performances limited success in detailed mapping.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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    Thematic Conference on Remote Sensing for Exploration Geology - Methods, Integration, Solutions, 7th, Calgary, Canada, Oct. 2-6, 1989, Proceedings. Volumes 1 & 2 (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent advances in airborne and satellite remote-sensing technology for application to geological exploration are discussed in reviews and reports. Sections are devoted to basement tectonics and their surface expressions, spectral geology, hydrocarbon exploration applications, radar applications and future systems, engineering and environment issues, geobotanical remote sensing, advanced image processing, data integration and mapping, and mineral exploration. Extensive diagrams, graphs, and sample images are provided.
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  • 98
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    In situ measurement of interstellar silicon carbide in two CM chondrite meteorites (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The first in situ observations of isotopically anomalous SiC are reported. The grains were found by X-ray mapping of polished sections of two chondritic meteorites, Cold Bokkeveld and Murchison. Ion microprobe measurements showed C-13 enrichments, delta C-13, from 199 to 2800 per mil, proving that the grains are indigenous. SiC grains are revealed only as isolated matrix particles, ruling out the possibility that SiC grains were brought into the solar system as inclusions in larger grains, which protected them from destruction in the solar nebula. Several of the SiC grains are cracked, suggesting that the etching treatment may result in size distributions biased toward smaller grains.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 348; 715-717
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  • 99
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    Discovery of hotspots on Io using disk-resolved infrared imaging (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: First results are presented using two new techniques for ground-based observation of Io's hotspots. An IR array camera was used to obtain direct IR images of Io with resolution better than 0.5 arcsec, so that more than one hotspot is seen on Io in Jupiter eclipse. The camera was also used to make the first observations of the Jupiter occultation of the hotspots. These new techniques have revealed and located at least three hotspots and will now permit routine ground-based monitoring of the locations, temperatures, and sizes of multiple hotspots on Io.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 348; 618-621
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  • 100
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    Yield estimation of sugarcane based on agrometeorological-spectral models (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This work has the objective to assess the performance of a yield estimation model for sugarcane (Succharum officinarum). The model uses orbital gathered spectral data along with yield estimated from an agrometeorological model. The test site includes the sugarcane plantations of the Barra Grande Plant located in Lencois Paulista municipality in Sao Paulo State. Production data of four crop years were analyzed. Yield data observed in the first crop year (1983/84) were regressed against spectral and agrometeorological data of that same year. This provided the model to predict the yield for the following crop year i.e., 1984/85. The model to predict the yield of subsequent years (up to 1987/88) were developed similarly, incorporating all previous years data. The yield estimations obtained from these models explained 69, 54, and 50 percent of the yield variation in the 1984/85, 1985/86, and 1986/87 crop years, respectively. The accuracy of yield estimations based on spectral data only (vegetation index model) and on agrometeorological data only (agrometeorological model) were also investigated.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment (ISSN 0034-4257); 33; 183-192
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