ALBERT

Beschreibung: Emittance measuring apparatus for temperatures up to 4000-deg f

Beschreibung: Total normal emittance measurement technique for opaque solid materials over 1000- to 3000-deg f range

Beschreibung: Pitfalls in thermal emission studies - terminology, experimental procedure, and physical standards

Beschreibung: Rotating-specimen furnace for use in determining spectral & total emittance of materials from measurement of radiant flux from specimen surface

Beschreibung: Temperature dependence of hemispherical emittance of metal and alloy strips in 100- to 1200-deg c range using blackbody vacuum chamber

Beschreibung: Spectral normal emittance of materials under simulated space environment

Beschreibung: Heated cavity reflectometer for thermal reflectance measurements of opaque surface

Beschreibung: Apparatus for measuring emittance and absorptivity of satellite temperature control surfaces

Beschreibung: Apparatus for measuring hemispherical emittance of solids in ambient & liquid nitrogen temperature range, with copper & aluminum foil data

Beschreibung: Thermocouple and radiation thermometry above 900 deg k

Beschreibung: Hemispherical emittance of structural materials & coatings under simulated spacecraft conditions over wide temperature range

Beschreibung: Measurement of total normal emittance of nuclear reactor materials - carbon steel, boron steel, & borated graphite

Beschreibung: Solar absorptance, emittance, & transmittance of thermal control coating for spacecraft

Beschreibung: Spectral emittance of opaque and transparent materials from 40- to 200-deg c

Beschreibung: Hemispheric spectral reflectance of opaque solids

Beschreibung: Calorimetric device for determination of solar absorption & infrared emittance ratio of materials at room temperature

Beschreibung: Thermal radiation properties of solids at cryogenic temperatures

Beschreibung: International practical temperature scale for temperature measurements below 1000-deg k using platinum resistance thermometers

Beschreibung: The discovery of concentrations of meteorites in Antarctica by Japanese field parties in 1969, and subsequently by joint U.S.-Japanese and U.S. field parties since 1976 has provided a significant new resource for understanding the origin and evolution of the solar system. The number of meteorites as well as the variety of meteorites has increased dramatically, and substantial amounts of data derived from their study has begun to appear in the scientific literature. The U.S. program of investigation has drawn on curatorial experience derived from the lunar program to: (1) develop specific collection and preliminary examination protocols; (2) provide documented samples for scientific investigations in response to specific requests; and (3) coordinate research by scientific consortia. The productivity of scientific research is significantly enhanced by these management approaches. Some of the results of the curatorial program for Antarctic meteorites carried out over the past three years are described.

Beschreibung: This paper presents the results of a series of total and spectral solar irradiance measurements made at ground surface (Table Mountain Facility, Calif., altitude 2.18 km). The spectral irradiance data are presented for the 0.3-3.0-micron spectral region for air mass 1.5.

Beschreibung: Voyager 1 images show 14 volcanic centers wholly or partly within the Kane Patera quadrangle of Io, which are divided into four major classes: (1) shield with parallel flows; (2) shield with early radial fan shapd flows; (3) shield with radial fan shaped flows, surfaces of flows textured with longitudinal ridges; and (4) depression surrounded by plateau-forming scarp-bounded, untextured deposits. The interpretation attempted here hinges largely on the ability to distinguish lava flows from pyroclastic flows by remote sensing.

Beschreibung: Opinions conflict over the role of surface gravity in shaping impact craters on Mercury. One view holds that the effects of g are evident in measurable aspects of crater form; other investigators find little or no evidence for g's geomorphic importance. Ambiguity in the role of g and other variables in cratering on Mercury stems largely from uncertainty in identifying major geomorphic contrasts and the crater sizes at which they occur. One of these, depth/diameter (d/D), undergoes a major change at the transition from simple (bowl shaped) to complex (peaks and terraces) crater interiors. Four least-squares d/D fits for fresh craters on Mercury were attemped. The results are inconsistent. The d/D data that should resolve previous shortcomings is presented. The revised d/D distributions for simple and complex craters, which intersect at a diameter of about 5 km, support the initial thesis that g substantially influences the form of Mercury's craters.

Beschreibung: Acoustic heating of polar night mesosphere

Beschreibung: Tesseral harmonics of gravitational field and geodetic datum shifts derived from Baker-Nunn camera observations of satellites

Beschreibung: Calculation of earths gravitational potential from sixth through twelfth zonal harmonic

Beschreibung: Rocket sounding measurements of upper stratosphere and mesosphere

Beschreibung: Gravity anomalies and use of reference ellipsoid in determining distribution of stress differences

Beschreibung: Theoretical interpretations of geomagnetic and ionospheric satellite measurements

Beschreibung: Gravitational theoretical implications of geodetic satellite field measurements

Beschreibung: Electron density and temperature, ion composition and density, and effects of solar corpuscular radiation in ionosphere - satellite drag measurements

Beschreibung: Earth atmospheric density from satellite measurements

Beschreibung: Cross sectional shapes of cylindrical or two-dimensional cavities with uniform diffuse radiation characteristics of heat transfer

Beschreibung: Measuring ionospheric electron density in F- 2 layer - diurnal variation

Beschreibung: Rubidium, strontium, and strontium isotopic compositions in tektites from various locations

Beschreibung: Analyses of major elements in tektite by rapid silicate procedures and X-ray fluorescence techniques

Beschreibung: Auroral dissociation of molecular oxygen in polar mesosphere

Beschreibung: Mass spectrometric investigations of upper atmosphere to measure diffusive separation of argon and nitrogen

Beschreibung: Electron temperature and ion density data compared to theories on thermal equilibrium in daytime ionosphere

Beschreibung: Turbulent forced convection heat transfer computations for air, helium, argon, hydrogen, and carbon dioxide

Beschreibung: A proposal for a multi-institutional investigation of the processes involved in the growth and maintenance of high level extended clouds is presented. Mapping of variability of the cloud and of its radiative characteristics in terms of the meteorological environment of the cloud; performance of case studies involving observation of the cloud microphysics and radiation characteristics; and investigation of the processes responsible for the generation, maintenance, and dissipation of the cloud system are recommended. Both modeling and monitoring activities are considered. The specific research projects which the author proposes to carry out are described. Suggestions for the administrative organization of the total effort are presented.

Beschreibung: The interplay of the various physical processes involved in the formation, maintenance, and decay of middle and upper tropospheric stratiform clouds is discussed. Ice phase fair weather cloud forms are considered. Simulations of cirriform clouds which attempt to incorporate the physical processes in an interactive manner were performed. A two dimensional time dependent Eulerian numerical model, which incorporates all of the important physical processes in a simplified way, is employed to investigate the role of these processes in the evolution of a cloud in an isolated atmospheric layer. Physical parameters considered are the eddy viscosity and the thermal, water vapor, and ice water eddy diffusivities.

Beschreibung: Craters within the Ganymede Jg-7 quadrangle were divided into seven mappable units. The units represent: (1) irregular or elongate craters, (2) craters with dark ejecta, (3) palimpsests, (4) secondary craters, (5) and craters of young, mature, and old age. Symbols used for crater floors include: (1) flat floors, (2) floors with pits, (3) floora with a central dome or peak, (4) and floors with a central dome and pit. Grooved terrains were divided into five mappable units. Three units of light grooved material represent small, medium, and large grooves, which are arbitrarily divided. The other two units of grooved terrain represent dark grooved materials, and reticulate grooves. Two units of ungrooved dark terrain and two units of ungrooved light terrain were defined. In Galileo Regio, two units were defined repesenting large furrowed grooves, and smaller grooves which are orthogonal to the furrowed grooves.

Beschreibung: The relative time of emplacement of some major rock units on Mars was recognized to some degree from geologic mapping using Mariner Images. Correlation charts showing the map units and their position in sequence, however, displayed little discrimination in their vertical range of occurrence. A more detailed time-stratigraphy is currently being developed as Viking geologic mapping of the planet progresses.

Beschreibung: Although many radar profiles and images of the area within 20 deg of Mercury's equator had been obtained from 1971 to 1981, at both Goldstone and Arecibo radar facilities, surprisingly little geological analysis had been done with these data until recently. Topographic profiles and radar roughness reflectivity images which can be derived from these data will be crucial in completing the geological mapping of Mercury now underway at the U.S. Geological Survey. Processing of available radar data must be completed to establish any systematic relationship between radar reflectivities and roughness, density, dielectric constant, and other related geological parameters. Specific tasks accomplished for these purposes include the following. Documentation was located and searched to establish the type and quantity of Goldstone 12.5 cm radar observations which were available for Mercury. Data has been collected during approximately 50 observation periods from 1971 to 1981. About half of the data, collected during 1972 and 1973, have been processed, but without adequate documentation. A standardized, well-documented procedure for processing and analysis for all Goldstone Earth-based observations of Mercury was established.

Beschreibung: The origin of Mars surface units and the extent of subsequent cratering play key roles in determining surface texture. At scale sizes of 0.1-10 meters, however, there is a growing body of evidence that wind is the dominant force. The direct and indirect evidence which implies that meter-scale surface texture on Mars is controlled by the wind is presented. Since radar is uniquely sensitive to structure on these scales, radio wave scattering data can provide insight on aeolian activity available from no other source.

Beschreibung: Structural and tectonic interpretations of planetary surfaces rely strongly on visual determination of regional structural grain. This grain can be very complex and confusing, and sorting out of discrete trends in time and space is of utmost importance. This study is a test of these techniques applied to a well known area having several discrete structural grains. In the Bighorn Basin region of Wyoming, a largely overlooked N10E structural grain has been verified with detailed structural analysis and indicates a significant change in stress orientation at the end of the Laramide orogeny.

Beschreibung: Two old volcano-tectonic collapse structures are exposed north and northeast of the huge shield volcano, Olympus Mons. They are semicircular and were probably low shield volcanoes similar to Alba Patera, but whose central portions have subsided or collapsed. They form the basement upon which younger volcanic materials of Alba Patera Olympus Mons have been emplaced. The oldest structure, Acheron Fossae is over 700 km across and is north of Olympus Mons. It has a surface of considerable relief broken by graben and extensive en echelon and parallel fractures and faults with varied displacements. Acheron Fossae is the most densely cratered in the Olympus Mons region. The structure must have formed very early in martian time. The second is Halex Fossae, northeast of Olympus Mons. Where exposed, it is cut by a series of arcuate grabens that become closer spaced toward its center. The radii of the fractures indicate that the structure may be at least 250 km across and centered beneath the Olympus Plains. Lava flows appear to have issued from some of the arcuate fractures and to have flowed radially away from the center of Halex Fossae. North of Halex Fossae, material of the same age as Halex Fossae overlaps Acheron Fossae.

Beschreibung: High spatial resolution data from the Viking infrared thermal mapper (IRTM) are used to examine the Tharsis volcanoes which are situated within a vast area of low thermal inertia material very fine particle size or very high porosity, with the volcanoes having the lowest thermal inertias. Thermal infrared images of the 1823 flow on Kilauea's southwest rift zone show lower thermal inertias near the vent area where shelly pahoehoe is common while individual channelized aa flows with abundant broken pahoehoe slabs are higher thermal inertia. The increase in aa flows to the southeast leads to a general trend of increasing thermal inertias from near vent to distal areas. Martian shield volcanoes have thermal inertias equal to or higher than their surrounding plans when atmospheric effects are removed from the data. The general increase in thermal inertias away from the summit calderas is consistent with the trend of the Hawaiian 1823 flow and may be related to changing lava properties away from the summit.

Beschreibung: A photometrically and geometrically reduced data base is being produced for the Galilean Satellites using Voyager Imaging data. The basic data set used is essentially all the useful satellite images returned by Voyager. Each frame was radiometrically calibrated and many are projected into cartographic formats. Mosaics of low, medium and high resolution frames being made for each satellite consist of registered digital images with intensity values scaled through a traceable calibration procedure to normal albedo values. Many of the mosaics are being made in two versions. One version is an albedo version and the second is a maximum discrimination version in which large variations in brightness across the picture are suppressed.

Beschreibung: One unique feature on Mars is the presence of ring furrows which are apparently produced by inversion of topography at the rims of partially buried craters. Ring furrows are flat-floored trenches, circular in plan view, forming rings 7 to 50 km in diameter. The moat is on the order of 0.5 km deep and 2 to 10 km wide, and it surrounds a flat topped circular mesa or plateau that is 5 to 40 km across. The central plateau is at the same elevation or lower than the surrounding plain outside the ring. The circular nature and size range of ring furrows tend to suggest that these features are related to craters partially buried by younger lava flows. The rings have been formed by preferential removal of the exposed crater rims. Ground ice decay, sapping, or fluvial erosion removed the less resistant, porous material of crater rims while leaving the more resistant volcanic flow material. Differential erosion has thus led to a reversal of topography in which the original positive relief of the rim is reduced to a negative relief feature.

Beschreibung: The morphology of channels, valleys, chaotic and fretted terrains and many smaller features on Mars is consistent with the hypothesis that localized deterioration of thick layers of ice-rich permafrost was a dominant geologic process on the Martian surface. Such ground ice deterioration gave rise to large-scale mass movement, including sliding, slumping and sediment gravity flowage, perhaps also catastropic floods. In contrast to Earth, such mass movement processes on Mars lack effective competition from erosion by surface runoff. Therefore, Martian features due to mass movement grew to reach immense size without being greatly modified by secondary erosional processes. The Viking Mission to Mars in 1976 provided adequate measurements of the relevant physical parameters to constrain models for Martian permafrost.

Beschreibung: High-resolution pictures of talus slopes on Mars show small, dark streaks that characteristically widen downward. These streaks are different from the thin and even streaks of various albedos that stream from cliffs on talus slopes, but gradations between the two streak types occur and not all streaks can be classified with confidence. In order to study the nature and origin of the small, widening, dark streaks, all Viking pictures with a resolution of less than 100 m/pixel were surveyed. To date several hundred streaks were located, but only few are of high enough resolution to be confidently identified as widening downwards. The approximate dimensions of the streaks were measured and their shapes, numbers, position, and spacing on slopes were noted. They were plotted on a topographic map, and their relation to topography, geologic units, and regions of distinct thermal inertia and albedo were studied. Also noted was the season at which images containing streaks were acquired and the direction of illumination. Albedo measurements are in progress. Several streaks can be seen stereoscopically, but none are observed on color images. The observation of small dark streaks on talus slopes on Mars is compatible with an interpretation of their origin as eruptions of small masses of wet debris in places where steep walls intersect aquifers or where seasonal equatorial warming permits the local melting of ground ice.

Beschreibung: The valley networks of Mars are widely believed to have formed at a time when climatic conditions on the planet were significantly different from those that currently prevail. This view arises from the following observations: (1) the valleys form integrated branching networks which suggests fluid drainage, and water is the most plausible fluid, (2) the present atmosphere contains only minute amounts of water, (3) the networks appear to be more akin to terrestrial valleys that are eroded by streams of modest discharges than features that form by catastrophic floods, and (4) small streams of water will rapidly freeze under present climatic conditions. Climatic conditions at the time of formation of the valleys are studied based on the assumption that they were cut by running water.

Beschreibung: Images of the surface of Venus obtained by the Soviet Venera 9, 10, 13 and 14 landers are analyzed to provide a basis for understanding the nature of geologic processes operating there. Bedrock is exposed at the Venera 10, 13 and 14 sites and is characterized by semi-continuous, flat polygonal to subrounded patches up to several meters in width. The bedrock surface is often dominated by sub horizontal to horizontal layered plates with thicknesses of several cm and abundant linear and polygonal vertical fractures. Soils (particles 1 cm) are abundant at the Venera 9, 10 and 13 sites, but are uncommon at Venera 14. Features indicative of a strong aeolian influence (moats, dunes, wind tails) are not observed. Several hypotheses are considered for the origin of the bedrock surfaces, and it is concluded that bedrock originated from surface lava flows. The relative freshness of features observed by the Veneras suggests that erosion rates are very low or that some bedrock surfaces are geologically young.

Beschreibung: A tectonic orgin for Venus banded terrain is consistent with band spacing. Both compressional (folding) and extensional models for band formation can fit present observations. Band spacing cannot distinguish among scenarios for global heat loss and for the origin of highland terrain. Tectonic models for band formation indicate that the surface brittle layer in the venus highlands is no more than a few kilometers thick.

Beschreibung: A study to determine the feasibility of conducting experiments to simulate the aeolian environment on Venus as related to wind abrasion was completed. Ideally, such experiments should involve complete investigation of weathering, in which mechanical, thermal, and chemical parameters are taken into account. This is particularly important for Venus, where atmospheric temperatures and pressures at the surface produce an environment which is equivalent to low or medium grade metamorphic conditions on Earth. Details that describe the Venus Aeolian Abrasion Device (VAAD) are included. The VAAD device would enable experiments to be conducted with the same chemistry, temperature, pressure, and other physical properties of the Venus atmosphere near the surface. The proposed device enables the important aeolian parameters to be controlled and monitored, including particle size, velocity, impact-angle and flux, atmospheric pressure, temperature, and gas composition.

Beschreibung: Tectoism in the Valles Marineris appears to have been accompanied by volcanism. The proposed volcanic features, though probably contemporaneous with the gigantic ones in the Tharsis area, are composed of small, mafic and, possibly, somewhat larger felsic flows. The size of these features is similar to that of volcanic flows on the Earth.

Beschreibung: Experiments were carried out in a steel pressure device using controlled amounts of water and thermite melt to examine the mechanical energy released on explosive mixing following the initial contact of the two materials. An experimental design was used to allow the direct calculation of the mechanical energy by the dynamic lift of the device as recorded both optically and physically. A large number of experiments were run to accurately determine the optimum mixture of water and melt for the conversion of thermal to mechanical energy. The maximum efficiency observed was about 12% at a water/thermite mass ratio of 0.50. These experiments are the basis for the development of models of hydroexplosions and melt fragmentation. Particles collected from the experimental products are similar in size and shape to pyroclasts produced by much larger hydrovolcanic explosions. Melt rupture at optimum ratios produces very fine particles whereas rupture at high or low water/melt ratios produces large melt fragments. Grain surface textures in the experimental products are also related to the water/melt ratio and the mechanism of explosive mixing. It is thus possible to have qualitative information about the nature of the explosion from the sizes and shapes of the fragments produced.

Beschreibung: Why the lowlands of Mars are concentrated in the Northern Hemisphere and the highlands in the Southern Hemisphere is probably the most fundamental unsolved problem in martian geology. No explanation that accounts both for this asymmetric distribution and for the isostatic equilibrium across the scarp or sloping transition zone dividing the two provinces has been generally accepted; thinning of the lithosphere in the northern hemisphere by internal processes has been suggested. Because other lowland-highland distributions on Mars, Moon, and Mercury are controlled by impact basins, it is proposed that a giant basin formed early in Mars' history has caused the martian hemispheric dichotomy as well.

Beschreibung: A number of researchers have concluded that saturation equilibrium cratering exists nowhere in the solar system, and therefore that diameter distributions in even the most heavily cratered provinces reveal initial production functions related to impacting bodies. Based on this premise, different populations of impactors are identified in different epochs and regions of the solar system. These hypotheses are clearly crucial to interpreting planetary history and need further independent examination. The production function in the outer solar system may differ from that in the inner solar system, but it is also possible that viscous relaxation of ice craters or immediate flooding of craters that penetrate through an ice lithosphere into watery substrate may explain the greater deficiency of large craters on icy moons. This problem is controversial and needs more study.

Beschreibung: Properties of the planetary surface and subsurface can affect the morphology of impact craters. A mechanism was proposed to explain pedestal craters and domed floors within fresh craters on Ganymede. Voyager 1 and 2 images with resolutions = to or 3.2 km/lp were examined and 523 fresh craters were identified. For each crater, the rim and ejecta diameters were measured, and the crater was characterized by ejecta class(es), interior features, floor morphology and target terrain. Of the craters examined, 97 show moderate to prominent doming of the crater floor; 340 craters have continuous ejecta which terminates in a scarp pedestal craters, of which 86 (25%) have a high albedo diffuse deposit beyond the pedestal.

Beschreibung: A systematic survey of the entire Mariner 10 coverage of Mercury was performed to determine the number, distribution and dimensions of additional ancient basins on the planet. Ancient multi-ringed basins on Mercury can be recognized by the following criteria: (1) arcs of massif chains and isolated massifs that protrude through younger units, (2) arcuate segments of lobate ridges (rupes) that align with massifs in circular patterns, (3) arcuate scarps that are aligned with ridges and massif, and (4) isolated regions of anomalously high topography within the intercrater regions of heavily cratered terrain. All of the newly identified basins predate the mercurian intercrater plains, previously held to be the oldest geologic unit on the planet. Subsequent structural evolution of various regions was influenced by the presence of these basins. Smooth plains units appear to be more extensive than mapped by Mariner 10 and more than 90 percent of them appear to be basin contained or basin related. The concentration of extensive smooth plains material within and associated with basin structural and depositional environments suggests a volcanic origin for most of this unit, analogous to the lunar maria. Basins appear to provide the basic structural pattern of early terrestrial planetary crusts.

Beschreibung: An improved version of the Pionner-Venus orbital data was used for a statistical analysis of global radar roughness and (alpha(0)) (rho) reflectivity. Classification maps of the venusian surface are produced in a supervised manner on the basis of statistical and empirical studies of the individual data sets. The primary objective is to assess the degree of homogeneity of surface radar properties within topographic provinces in order to map possible geologic boundaries. Maps were produced by correlating two data sets at a time. Classification of specific regions, such as Ishtar, has demonstrated that distinct geological units can be identified.

Beschreibung: Interest on Venus has centered on three regions; (1) Aphrodite Terra, especially east of the main uplant portion, (2) Ishtar Terra, especially Lakshmi Planum and its bounding scarp and massifs, and (3) Beta Regio-Phoebe Regio. The last region is topographically similar to the East African rift system, and has been inferred to have a similar tectonic origin. The Aphrodite region is part of a 21,000 km long tectonic zone that seems best explained as due to extension, and that may represent hot spots clustered along an incipient divergent plate boundary. The most interesting and complex portion of this tectonic zone is that part of eastern Aphrodite between Thetis Regio and Atla Regio. In contrast, the Lakshmi Planum region has many topographic characteristics suggesting that it is a true continent, and thus indicative of convergence and a thick crust. Detailed topographic contour maps of eastern Aphrodite Terra and of Lakshmi Planum are included.

Beschreibung: The results of analyses of near infrared reflectance spectra are inconsistent with numerous previous interpretations of the Reiner Gamma Formation. These include: (1) nue ardente or volcanic ash deposits, (2) volcanically derived sublimates, (3) high albedo volcanic deposits, and (4) highlands debris emplaced as impact ejecta. These results, strongly suggest that the selective preservation of high albedo features (formed by secondaries) by a local magnetic field enhancement is not a viable hypothesis. The results are generally consistent with, but place constraints on, the cometary impact hypothesis of Schultz and co-workers. While the presence of a magnetized component was not detected in either the bright or dark portions of the Reiner Gamma Formation, this material may be present in amounts under the current detection limits.

Beschreibung: On the basis of the icy conglomerate model of cometary nuclei, various observations demonstrate the spotted nature of many or most nuclei, i.e., regions of unusual activity, either high or low. Rotation periods, spin axes and even precession of the axes are determined. The observational evidence for variations in activity over the surfaces of cometary nuclei are listed and discussed. On June 11 the comet IRAS-ARAKI-ALCOCK approached the Earth to a distance of 0.031 AU, the nearest since C/Lexell, 1770 I, providing a unique opportunity for near-nucleus observations. Preliminary analysis of these images establishes the spin axis of the nucleus, with an oblioquity to the orbit plane of approximately 50 deg, and a lag angle of sublimation approximately 35 deg from the solar meridian on the nucleus. Asymmetries of the inner coma suggests a crazy-quilt distribution of ices with differing volatility over the surface of the nucleus. The observations of Comet P/Homes 1892 III, exhibiting two 8-10 magnitude bursts, are carefully analyzed. The grazing encounter produced, besides the first great burst, an active area on the nucleus, which was rotating retrograde with a period of 16.3hr and inclination nearly 180 deg. After the first burst the total magnitude fell less than two magnitudes from November 7 to November 30 (barely naked eye) while the nuclear region remained diffuse or complex, rarely if ever showing a stellar appearance. The fading was much more rapid after the second burst. The grazing encounter distributed a volume of large chunks in the neighborhood of the nucleus, maintaining activity for weeks.

Beschreibung: Dione is one of the most geologically complex of the Saturnian satellites. Crater counts and surface morphology indicates the geologic units observed are of variable age and origin. In an attempt to understand the processes which have affected Dione, a geologic map was prepared. Several geologic units were identified; ancient heavily cratered terrain, two plains units: cratered plains and lightly cratered plains, lobate deposits, crater rim deposits and bright wispy materials.

Beschreibung: For large parts of the surfaces of the Galilean satellites there is no stereoscopic high resolution imagery, and so for shadow-free regions far from the terminator, the only method of obtaining topograpic information is photoclinometry, the technique of converting brightness variations into local surface tilts and hence into topographic profiles and contour maps. The conversion from brightness changes to slopes require knowledge of the angular photometric function for the type of planetary surface terrain being analyzed, i.e., the relationship describing the brightness of the surface as a function of the angles of incidence (I) and emergence (E) of light at a surface element. In order to investigate the effects of these changes on the shapes of topographic profiles deduced from the functions, an area of grooved terrain (lines 500-505, samples 550-650 on frame 20640.27 0060J2) using wide ranges of values of all the adjustable parameters in Hapke's new photometric function were analyzed.

Beschreibung: Exploratory work on the structure of the Ionian lithosphere is reported. The approach is to examine temperature profiles within the lithosphere that result from different distributions of sulfur and silicates and different conductive heat fluxes, then compare such profiles with observations in the expectation that only a limited set of the profiles are possible. In this preliminary work some rather simplistic assumptions were taken and the report should be viewed more as a demonstration of a method rather than a presentation of results.

Beschreibung: Improvements to the design of the Mariner spacecraft resulted in the Viking spacecraft. The Viking spacecraft would consist of two major systems - an orbiter and a lander, while the lander would provide the means for safely delivering the scientific instruments to the surface, house, and provide the necessary power source and communication links for those experiments, the orbiter would transport the lander to Mars, rovide a platform for the Viking imaging system so that proposed landing sites could be surveyed and certified, relay lander science information back to Earth, and conduct scientific observations in its own right.

Beschreibung: Anorthosite massifs developed approximately 1.4 to 1.5 billion years ago along an arch which developed parallel to a zone of continental separation as a block which included North America, Europe, and probably Asia separated from a block which included parts of South America, Africa, India, and Australia. Anorthosite massifs also developed at the same time along a belt which runs through the continents which comprise Gondwanaland (South America), Africa, India, Australia, and Antarctica. This was a zone of continental separation which subsequently became a zone of continental collision about 1.2 billion years ago. The northern anorthosite belt also parallels an orogenic belt which was active between 1.8 and 1.7 billion years ago. Heat generated during this mountain building period helped in the formation of the anorthosites.

Beschreibung: Stratospheric limb radiance profiles versus altitude of closest approach of the line of sight to the Earth's surface have been measured before and after the Mount St. Helens eruptions by means of photographs taken from a Sun-oriented balloon gondola floating above 35 km altitude over France. Preliminary data were reported for flights in October 1979 and in May and June 1980. The radiance integrated along the line of sight as in-situ radiance (R) can be derived taking into account absorption by ozone and air. The onion peeling inversion method was used to derive the vertical radiance (R) profiles respectively. The values of R were determined in the solar azimuth. The solar elevation angles are chosen larger for the backscattering observation than for the forward scattering observation to deal with as similar illumination conditions as possible despite the Earth's sphericity.

Beschreibung: Microscopical investigation of volcanic ash collected from ground stations during Mount St. Helens eruptions reveal a distinctive bimodel size distribution with high concentrations of particle ranges at (1) 200-100 microns and (2) 20-0.1 microns. Close examination of individual particles shows that most larger ones are solidified magma particles of porous pumice with numerous gas bubbles in the interior and the smaller ones are all glassy fragments without any detectable gas bubbles. Elemental analysis demonstrates that the fine fragments all have a composition similar to that of the larger pumice particles. Laboratory experiments suggest that the formation of the fine fragments is by bursting of glassy bubbles from a partially solidified surface of a crystallizing molten magma particle. The production of gas bubbles is due to the release of absorbed gases in molten magma particles when solubility decreases during phase transition. Diffusion cloud chamber experiments strongly indicate that sub-micron volcanic fragments are highly hygroscopic and extremely active as cloud condensation nuclei. Ice crystals also are evidently formed on those fragments in a supercooled (-20 C) cloud chamber. It has been reported that charge generation from ocean volcanic eruptions is due to contact of molten lava with sea water. This seems to be insufficient to explain the observed rapid and intense lightning activities over Mount St. Helens eruptions. Therefore, a hypothesis is presented here that highly electrically charged fine solid fragments are ejected by bursting of gas bubbles from the surface of a crystallizing molten magma particles.

Beschreibung: The direct solar radiation transmission record at Mauna Loa, dating from 1958 to the present, revealed with remarkable precision the presence of stratospheric aerosol from volcanic activity. This record can be used to quantify the intensity of the stratospheric volcanic aerosol perturbation following a significant eruption in reference to the Agung event in 1963. The Mount St. Helens' stratospheric cloud was first detected by lidar at 18 km over Mauna Loa on 17 July. The atmospheric transmission was seen to decrease slightly after that time, but only a few tenths of 1 percent. Although it is still fairly early to draw a definite conclusion on the ultimate magnitude of the Mount St. Helens stratospheric aerosol from the Mauna Loa results, it can be stated that the stratospheric aerosol optical depth presently observed is comparable with that observed from Fuego which erupted in 1974. At Boulder, Colorado, the atmospheric debris from Mount St. Helens was observed by lidar on a number of occasions. Also, observations of the diffuse, total and direct transmission of solar radiation were made on June 3 and 4. The latter set of observations is useful for deriving information on the scattering properties of the volcanic cloud. The lidar and solar radiation data are presented and some of their special features are discussed.

Beschreibung: Samples of stratospheric aerosols collected with U-2 aircraft for several months following the first three major eruptions of Mount St. Helens were analyzed for ash and liquid acid content. Ash grain sizes and compositions vary depending on collection altitude, location within the drifting cloud, and days following their injection. s computers Size distributions of ash particles vary with altitude. Generally small particles are depleted more rapidly at low altitudes (12 km) than at higher altitudes (17-18 km). Although samples collected 1 day after the first eruption of May 18, 1980, were dry, flow marks on the aircraft indicated parts of the cloud contained heavy acid concentrations. Indeed, all other samples obtained within 1 to 4 days after later eruptions (May 25 and June 12, 1980) were covered with copious amounts of liquid acid. Proportions of liquid to ash varied considerably depending on sampling location and cloud age. Because the acid-coated ash globules were large, they rapidly fell from the stratosphere until, by late June 1980, only a residue of acid droplets remained. Size distributions and concentrations of these droplets varied considerably.

Beschreibung: An instrument capable of observing the natural electron flux in the energy range from 0.1 to 12.0 kiloelectron volts is discussed for use in an experiment intended as a forerunner of a method that will utilize artificially accelerated electrons as tracer particles for electron fields parallel to the magnetic field. Effects that are of importance either as means of detecting the echo beam or as causes of beam perturbations (e.g., spacecraft charging effects and electron background) are to be studied. The use of electron accelerators as a tool to probe magnetospheric processes rather than to modify them is planned.

Beschreibung: A dual-channel video system mounted on a stabilized two-axis gimbal system (mounted on the pallet) with associated optics and data handling electronics described the low light flux observations are required for: (1) investigating ionospheric transport processes by observing Mg+ ions; (2) supporting magnetospheric electron bounce experiments; (3) measuring electron cross sections for selected atmospheric species; (4) detecting small particle contamination; and (5) studying natural auroras.

Beschreibung: A magnetometer experiment was designed to determine the local magnetic field by measuring the total of the Earth's magnetic field and that of an unknown spacecraft. The measured field vector components are available to all onboard experiments via the Spacelab command and data management system. The experiment consists of two parts, an electronic box and the magnetic field sensor. The sensor includes three independent measuring flux-gate magnetometers, each measuring one component. The physical background is the nonlinearity of the B-H curve of a ferrite material. Two coils wound around a ferrite rod are necessary. One of them, a tank coil, pumps the ferrite rod at approximately 20 kilohertz. As a consequence of the nonlinearity, many harmonics can be produced. The second coil (i.e., the detection coil) resonates to the first harmonic. If an unknown dc or low-frequency magnetic field exists, the amplitude of the first harmonic is a measure for the unknown magnetic field. The voltages detected by the sensors are to be digitized and transferred to the command and data management system.

Beschreibung: Study of sources of Lyman-alpha emission in the atmosphere, in the interplanetary medium, and perhaps in the galactic medium is planned. Sources of Lyman-alpha emission are described and a schematic of the instrument presented.

Beschreibung: The purpose of space experiments with particle accelerators (SEPAC) is to carry out active and interactive experiments on and in the Earth's ionosphere and magnetosphere. It is also intended to make an initial performance test for an overall program of Spacelab/SEPAC experiments. The instruments to be used are an electron beam accelerator, magnetoplasma dynamic arcjet, and associated diagnostic equipment. The accelerators are installed on the pallet, with monitoring and diagnostic observations being made by the gas plume release, beam-monitor TV, and particle-wave measuring instruments also mounted on the pallet. Command and display systems are installed in the module. Three major classes of investigations to be performed are vehicle charge neutralization, beam plasma physics, and beam atmosphere interactions. The first two are mainly onboard plasma physics experiments to measure the effect of phenomena in the vicinity of Spacelab. The last one is concerned with atmospheric modification and is supported by other Spacelab 1 investigations as well as by ground-based, remote sensing observations.

Beschreibung: The Tharsis ridge system appears to form a great circle around the major volcanoes. The roughly circumferential orientation of these ridges could be interpreted as the formation of a ridge system in response to a single stress field with a center near Pavonis Mons. Wise, et al. (1979) plotted the perpendiculars to strikes of ridges on the eastern flanks of Tharsis as great circles on the upper hemisphere of an equal area net. In order to further test for circular symmetry and possible other influences on ridge orientations, normals to vector means of ridge orientations were calculated using over 1850 digitized ridge segments sampled in 10 degree boxes. Orientations of individual ridge segments were weighted by their lengths, and the magnitudes of normals to vectors means were weighted by cummulative length of the ridge segments. Normals to vector means with magnitudes less than 100 km are not shown. Assuming a single fold origin for ridges, the resulting plot shows compressive stress trajectories for the ridges in the Tharsis region. The averaged compressive stress orientation around Tharsis confirm the suggestion by Wise, et al. that the ridge system is not concentric to any single point.

Beschreibung: In this paper the tectonic features of the Elysium region are identified and characterized. Identification of features was made using USGS controlled photomosaics (Elysium quadrangle, and portions of Amenthes and Cebrenia quadrangles); Viking Orbiter photographic data were used in individual cases to assist in identification. The positions and orientations of tectonic features can then be used, in conjunction with estimates of the mass of the volcanic load obtained from gravity modelling, to constrain the thickness of the elastic lithosphere in the region.

Beschreibung: Several 3.8 cm radar frames were calibrated empirically by histogram fitting, because no instrument background data is available. Then data were corrected for geometric distortion by: (1) redetermining position of individual frames using most accurate recent lunar ephemerides; (2) reprojecting frames into simple cylindrical map projection; (3) using most recent catalog of lunar craters to determine the exact positions of features identifiable on radar frames; and (4) correcting for apparent distortion (misplacement of features in frames) by resampling using a different bilinear interpolation derived for each of the parallelopideds of the set defined for each frame. A hardcopy set of corrected frames was produced. Attempts to produce a mosaic of such corrected frames continue. The resulting mosaic can be used to show the systematic relationship between photographic thermal IR and radar data at different wavelengths in a region dominated by both mare and highland terrain.

Beschreibung: Studies of the stratigraphy of southwest Coprates have led to further constraints on both the geographic extent and the relative age of the major compressional ridge forming events in the Tharsis region of Mars. Southwestern Coprates is characterized by curvilinear ridges that are regularly spaced, suggestive of harmonic folding. The western edge of the ridged plains unit of Coprates is marked by volcanic flow fronts. In an enhanced Viking-Orbiter image, a ridge can be seen completely surrounded by a flow with only a small portion of the ridge crest still exposed. Comparison of partially buried ridges on the western edge of the ridged plains to those in central Coprates suggests that flooding of the inter-ridge plains does not exceed a few hundred meters. The morphological relationship between the flow units to the west and the ridged plains indicates that the deformational events in this region predates the emplacement of the younger units.

Beschreibung: Layered deposits within Valles Marineris and its associated system of canyons have been considered to consist of two different rock types: (1) thick, competent, cliff-forming, light and dark bedded material in canyon walls, and (2) relatively thin, alternating series of light and dark layered material, both horizontal and inclined, that form rounded hills and large flat-topped mesas rising above the canyon floors. The dissimilarity in appearance between canyon wall and floor materials, as well as their contrasting patterns of erosion, have been considered strong evidence that their modes of origin were different.

Beschreibung: Significant new geologic information has been revealed by comparing 1:5 million scale geologic maps of the equatorial zone quadrangles of Mercury (H-6, H-7 and H-8) to Earth-based elevation profiles and surface reflectivity maps of Mercury obtained in the early 1970's at the Arecibo (PR) and Goldstone (CA) radar facilities. These data consist of 23 Goldstone images and profiles of polarized return data at 12.5-cm wavelength and one Arecibo profile. Radar data with 150-m vertical accuracy and 10- to 20-km horizontal resolution are available for areas between latitudes 13 N. and 11 S. In general, these data sets show excellent correlation between: (1) relative elevation and roughness differences that are reflected by mapped geologic contacts; (2) mapped ridges and scarps that display distinctive radar signatures; and (3) position and morphology of crater-and-basin topographic elements. Inferences can also be drawn about topographic and geologic terrain beyond the area imaged by Mariner 10 cameras.

Beschreibung: The scarps along the margins of the Vales Marineris display a complex assemblage of forms that have been related to a variety of mass wasting and sapping processes. These scarp segments display variations in the degree of development of spur and gully topography, the number and density of apparent sapping features and the frequency of large scale landslides which reflect the age, geology and processes of slope development throughout the Valles Marineris. This regional analysis should provide more information on the geologic evolution of the Valles Marineris as well as new insight into the relative importance of different processes in the development of the scarp forms. In order to evaluate the regional variation in scarp form and the influence of time and structure on scarp development geomorphic mapping and morphometric analysis of geologically distinct regions of Valles Marineris is being undertaken.

Beschreibung: Parallel studies of Martian geomorphic features and their analogs on Earth continue to be fruitful in deciphering the geologic history of Mars. In the context of rock weathering, the Earth-analog approach is admirably served by the study of meteorites recovered from ice sheets in Antarctica. The weathering environment of Victoria Land possesses several Mars-like attributes. Four of the five Antarctic meteorites being studied contain rust and EETA79005 further possesses a conspicuous, dark, weathering rind on one side. Secondary minerals (rust and salts) occur both on the surfaces and interiors of some of the samples and textural evidence indicates that such secondary mineralization contributed to physical weathering (by salt riving) of the rocks. Several different rust morphologies occur and emphasis is being placed on identifying the phase compositions of the various rust occurrances. A thorough understanding of terrestrial weathering features of the meteorites is a prerequisite for identifying possible Martian weathering features (if such features exist) that might be postulated to occur in some meteorites.

Beschreibung: On Mars, the association of gullied escarpments and chaotic terrain is evidence for failure and scarp retreat of poorly consolidated materials. Some martian gullies have no surface outlets and may have drained through subterranean channels. Similar features, though on a much smaller scale, can be seen in alluvium along terrestrial river banks in semiarid regions, such as the Rio Puerco Valley of central New Mexico. Many of the escarpments along the Rio Puerco are developing through formation of collapse gullies, which drain through soil pipes. Gully development can be monitored on aerial photographs taken in 1935, 1962, and 1980. A regression model was developed to quantify gully evolution over a known time span. Soil pipes and their associated collapse gullies make recognizable signatures on the air photos. The areal extent of this signature can be normalized to the scarp length of each pipe-gully system, which makes comparisons between systems possible.

Beschreibung: Geomorphic studies of impact structures in central Australia are being used to understand the complexities of fluvial dissection in the heavily cratered terrains of Mars. At Henbury, Northern Territory, approximately 12 small meteorite craters have interacted with a semiarid drainage system. The detailed mapping of the geologic and structural features at Henbury allowed this study to concentrate on degradational landforms. The breaching of crater rims by gullies was facilitated by the northward movement of sheetwash along an extensive pediment surface extending from the Bacon Range. South-facing crater rims have been preferentially breached because gullies on those sides were able to tap the largest amounts of runoff. At crater 6 a probable rim-gully system has captured the headward reaches of a pre-impact stream channel. The interactive history of impacts and drainage development is critical to understanding the relationships in the heavily cratered uplands of Mars. Whereas Henbury craters are younger than 4700 yrs. B.P., the Gosses Bluff structure formed about 130 million years ago. The bluff is essentially an etched central peak composed of resistant sandstone units. Fluvial erosion of this structure is also discussed.

Beschreibung: Photometric studies of crater related bright and dark streaks have strongly supported the hypothesis that the bright streaks are excess dust deposits and dark streaks are erosional windows in a partial dust cover. Red-blue (and red-violet) plots show that bright streaks are consistent with mosaics of bright red dust and background material. Here the plains are also consistent with a partial dust cover; the dark streak is the least covered area. Bright and dark streaks both reverse contrast relative to surrounding plains at phase angles over 100 deg in violet filter images. The similar phase behavior of both bright and dark streaks supports the idea that they are both changes in the amount of dust cover. Red-violet plots of bright streaks are most easily explained by mosaics of optically thick dust and plains material. Lengths of bright streaks are independent of their contrasts. This suggests the streak deposition, if in the mosaic patterns indicated above, is a function of available sites of deposition, rather than atmospheric dust loading. Contrasts of dark streaks with plains indicate the plains have fractional dust covers nealy as great as the maximum additional cover in bright streaks. The bright streaks thus store little of the global supply of dust.

Beschreibung: Viking Lander 1 observations on Mars were punctuated by a strong local dust storm after two martian years of mild wind conditions. Tens of micrometers of dust settled to the surface during global dust storms of the first two falls and winters; some of this dust was locally removed during the second year. A late winter local dust storm of the first year caused little or no erosion of the surface materials despite wind speeds of 25 to 30 m/s. The strong local dust storm occurred during late winter of the third martian year. Winds of this storm altered and demolished small conical piles of surface materials constructed at the onset the first winter, removed 4 to 5 mm size fragments, displaced centimeter size fragments, destroyed clouds in areas disrupted by the sampler and footpad, eroded impact pits, and darkened the sky. Movement of erosional products and tiny wind tails indicate easterly to northeasterly winds. If the 4 to 5 mm size fragments were entrained and removd by the wind, threshold friction speeds near 3 to 5 m/s would have been required for the atmospheric temperatures and pressures that prevailed during the late winter of the third year.

Beschreibung: Eastern Acidalia Planitia contains a wide variety of terrain types on which are thousands of subkilometer volcanoes. Apparent morphometric variations were previously reported as a function of terrain type for the cones in the Cydonia area and extended to the rest of Acidalia for which high resolution Viking imagery exist. Crater counts are included for the six types of plains identified, density distributions of subkilometer cones found on each type of terrain, and orphometric data by morphological subclass as a function of terrain for more than 1400 cones.

Beschreibung: There are classes of landforms whose presence on Mars is strongly suggestive, if not confirmatory, of the participation of volatiles, presumably water, in its geomorphic development: (1) valley networks, (2) outflow channels, (3) landslides, and (4) flow-ejecta blankets. The first two may represent landforms generated by the movement of volatiles from sources, while the latter two probably represent the dissipation of energy generated by forcing inputs (e.g., kinetic energy and gravity) modulated by volatiles. In many areas on Mars, all four processes have acted on the same lithologic materials and were influenced by the composition of those units, and possibility by the climatic regime at the time of their formation. One of the approaches discussed to this specific problem of landform genesis, and to the general problem of the present and past states of martian volatiles, is to attempt to constrain the distribution, amount, and history of available volatiles by using possible evidence of volatile participation expressed in the morphology of other related landforms (e.g., flow-ejecta blankets and landslides) coupled with physical models for landform genesis.

Beschreibung: Preliminary mapping shows East Butte to be a single, large cumulo-dome composed dominantly of rhyolite which can be classified into three main groups based on color and structure. The rhyolite of East Butte is aphanitic with phenocrysts of sanidine and quartz which vary from 1 to 5 mm in length. Vesicular reddish black inclusions of basalt up to 10 cm in length, found in all varieties of the East Butte rhyolites are believed to have originated from fragmentation of the basalt walls of the conduit by rhyolitic magma as it was emplaced. Most of the inclusions contain plagioclase phenocrysts. These phenocrysts measure up to 1 to 2 cm in length and have a typical euhedral, tabular habit. A 250-m diameter depression which has the appearance of a crater is located at the top of East Butte. Evidence supporting the fact that the depression is a crater is displayed by three small (3 to 5 m in height) mounds of massive rhyolite which border the depression.

Beschreibung: Some of the geological relationships observed in the Mauna Loa sulfur flow may apply in considering volcanic processes on Io. Given the presence of sulfur/sulfur compounds in the eruption plumes and on the surface of Io, it is likely that extensive secondary deposits of sulfur exist, some of which may be of fumarolic origin and analogous to the Mauna Loa deposit. Given the likelihood of silicate volcanism of Io based on the inferred material properties of some flows, and the attendant high temperatures for silicate volcanism, it is likely that the secondary surface deposits of sulfur would have been mobilized without being heated to the high viscosity stage. Mobilized sulfur flows on Io may flow long distances as a result of: (1) low viscosities in the melting range; (2) sustained effusion resulting from continued heating source area; (3) continued remobilization within the flow as a consequence of surges from the source; and (4) extension via lava tubes, or similar conduits through which there is little heat loss. Sulfur flows may form a relatively thin veneer over silicate flows and other surface units, given their fluidity and low mobilization temperature. Active splashing and splattering may spread sulfur over a wider area contributing the bright blooms observed in association with some Ionian flows.