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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Geologic mapping of Harmakhis and Reull Valles region, Mars: Evidence for multiple resurfacing and drainage events

Numerous mesas and irregular, channel-cut escarpments south of Harmakhis and Reull Valles suggesting at least two resurfacing events with subsequent periods of erosion are revealed from detailed geologic mapping of three adjacent 1:500,000-scale quadrangles (MTM-40262, -40267, -40272). Also, two distinct episodes of surface water runoff, each from different styles of water release, are evident. Geologic mapping is based on 1:500,000-scale photomosaics of the Harmakhis vallis region, and is an outgrowth of preliminary regional geologic mapping on a 1:2,000,000-scale on the east rim of Hellas Basin.

Price, Katherine H.↗
NASA NTRS1995

Comparison of 7.5-minute and 1-degree digital elevation models

We compared two digital elevation models (DEM's) for the Echo Mountain SE quadrangle in the Cascade Mountains of Oregon. Comparisons were made between 7.5-minute (1:24,000-scale) and 1-degree (1:250,000-scale) images using the variables of elevation, slope aspect, and slope gradient. Both visual and statistical differences are presented.

Isaacson, Dennis L.↗
NASA NTRS1993

Higher order statistics of planetary gravities and topographies

The statistical properties of Earth, Venus, Mars, Moon, and a 3-D mantle convection model are compared. The higher order properties are expressed by third and fourth moments: i.e., as mean products over equilateral triangles (defined as coskewance) and equilateral quadrangles (defined as coexance). For point values, all the fields of real planets have positive skewness, ranging from slightly above zero for Lunar gravity to 2.6 sigma(exp 3) for Martian gravity (sigma is rms magnitude). Six of the eight excesses are greater than Gaussian (3 sigma(exp 4)), ranging from 2.0 sigma(exp 4) for Earth topography to 18.6 sigma(exp 4), for Martian topography. The coskewances and coexances drop off to zero within 20 deg arc in most cases. The mantle convective model has zero skewness and excess slightly less than Gaussian, probably arising from viscosity variations being only radial.

Kaula, William M.↗
NASA NTRS1995

Evidence for Regional Basin Formation in Early Post-Tessera Venus History: Geology of the Lavinia Planitia Area (V55)

On Venus, global topography shows the presence of highs and lows including regional highly deformed plateaus (tesserae), broad rifted volcanic rises, linear lows flanking uplands, and more equidimensional lowlands (e.g. Lavinia and Atalanta planitiae) Each of these terrain types on Venus has relatively distinctive characteristics, but origins are uncertain in terms of mode of formation, time of formation, and potential evolutionary links. There is a high level of uncertainty about the formation and evolution of lowlands on Venus. We have undertaken the mapping of a specific lowlands region of Venus to address several of these major questions. Using geologic mapping we have tried to establish: What is the sequence of events in the formation and evolution of large-scale equidimensional basins on Venus? When do the compressional features typical of basin interiors occur? What is the total volume of lava that occurs in the basins and is this similar to other non-basin areas? How much subsidence and downwarping has occurred after the last major plains units? WE have undertaken an analysis of the geology of the V55 Lavinia Planitia quadrangle in order to address many of these issues and we report on the results here.

Head, J. W.↗
NASA NTRS1999

Windblown Features on Venus and Geological Mapping

The objectives of this study were to: 1) develop a global data base of aeolian features by searching Magellan coverage for possible time-variable wind streaks, 2) analyze the data base to characterize aeolian features and processes on Venus, 3) apply the analysis to assessments of wind patterns near the surface and for comparisons with atmospheric circulation models, 4) analyze shuttle radar data acquired for aeolian features on Earth to determine their radar characteristics, and 5) conduct geological mapping of two quadrangles. Wind, or aeolian, features are observed on Venus and aeolian processes play a role in modifying its surface. Analysis of features resulting from aeolian processes provides insight into characteristics of both the atmosphere and the surface. Wind related features identified on Venus include erosional landforms (yardangs), depositional dune fields, and features resulting from the interaction of the atmosphere and crater ejecta at the time of impact. The most abundant aeolian features are various wind streaks. Their discovery on Venus afforded the opportunity to learn about the interaction of the atmosphere and surface, both for the identification of sediments and in mapping near-surface winds.

Greeley, Ronald↗
NASA NTRS1999

Evolution of Lacustrine Environments on Mars and Their Significance: The Case for the Brazos Lakes and East Terra Meridiani Basins as Landing Sites for Surveyor 2001

Ancient Martian lacustrine environments must be considered as primary targets to explore on Mars. Terrestrial studies show that lakes are exceptional sites to keep the record of the evolution of climate, geology, water and life. Finding this record is also the principal objective of the Mars Surveyor Program. This record encompasses changes at local, regional and global scales. Lacustrine sediments provide critical information about all events occurring in the lake catchment area. They are also a locus of complex chemical processes, concentration for life and favorable sites for fossilization processes to take place. We proposed two candidate-sites in the Schiaparelli Crater region responding to this high-priority scientific objective at the June 1999 meeting in Buffalo, NY. The two sites are located in the Sinus Sabeus quadrangle, are well documented by MOC images, and are among the best evidence yet of a Martian past lacustrine activity. We develop their case as high-priority sites for the 01' mission.

Cabrol, N. A.↗
NASA NTRS1996

Imaging Radar Applications in the Death Valley Region

Death Valley has had a long history as a testbed for remote sensing techniques (Gillespie, this conference). Along with visible-near infrared and thermal IR sensors, imaging radars have flown and orbited over the valley since the 1970's, yielding new insights into the geologic applications of that technology. More recently, radar interferometry has been used to derive digital topographic maps of the area, supplementing the USGS 7.5' digital quadrangles currently available for nearly the entire area. As for their shorter-wavelength brethren, imaging radars were tested early in their civilian history in Death Valley because it has a variety of surface types in a small area without the confounding effects of vegetation. In one of the classic references of these early radar studies, in a semi-quantitative way the response of an imaging radar to surface roughness near the radar wavelength, which typically ranges from about 1 cm to 1 m was explained. This laid the groundwork for applications of airborne and spaceborne radars to geologic problems in and regions. Radar's main advantages over other sensors stems from its active nature- supplying its own illumination makes it independent of solar illumination and it can also control the imaging geometry more accurately. Finally, its long wavelength allows it to peer through clouds, eliminating some of the problems of optical sensors, especially in perennially cloudy and polar areas.

Farr, Tom G.↗
NASA NTRS1999

Candidate-Landing Sites and Backups for the Mars Surveyor Program in the Schiaparelli. Crater Region

Our Survey area comprises the Sinus Sabeus NW quadrangle that includes most of the Schiaparelli crater and part of the Arabia SW region (3 N to 15 S Lat.) and (0 to 337.5 W long.) and covers all regions that show a potential hydrogeological link with the Schiaparelli impact structure. This area is hereafter defined as the Schiaparelli Crater Region. The Schiaparelli crater region is one of the most documented MOC targets. Up to now, MGS MOC camera took two dozen images at an average of 5m/pxl resolution that not only provide an exceptional insight on the local geology and morphology, but give also key-elements to assess landing safety criteria. In addition, the MOLA topographic profile No. 23 passes through part of the crater basin allowing the adjustment of the elevation as previously known from the Viking mission (USGS I-2125, 1991). Beyond the Mars Polar Lander mission that will land next December, the future missions (2001 APEX, 2003, and 2005) are led by a series of science objectives and engineering constraints that must be considered in order to select landing sites that will fulfill the Surveyor Program's objectives. The search for a sound and safe candidate-site (without ending up with the usual "safe but boring" or "fascinating but too risky" site) is usually limited by the data available to the investigator, by the data accuracy (e.g. poor image resolution, poor altimetry), and the lack of crucial information for science and safety that can be derived from them. The Schiaparelli region provides an exception to this recurrent pattern. We listed the preliminary constraints for landing site selection identified for the Surveyor '01 mission, in terms of safety requirements and data needed and compared them against the existing information and/or data already available for the Schiaparelli region. The engineering constraints of '03 and '05 are not designated yet but, since they are also related to atmospheric density and Lander designs, we will assume that these points will be comparable to '01. The main difference will reside in the rover design, the Rocky-7 class rover being bigger than Marie Curie ('01) will be able to overcome bigger obstacles. We listed then the main objectives of the Surveyor Program and compared them with the potential offered by the Schiaparelli Crater Region to document them. Within the survey area, the Schiaparelli impact crater is 2.5 S/343.3 W (USGS 1-1376, MC-20 NW, 1981) and occupies a significant surface area. The crater has been proposed as a potential candidate-site in the past years. The purpose of this study is to show that, not only the Schiaparelli Crater would be a high-priority target, but that the region where it is located offer several very-high potential back-up sites, all within science and engineering constraints, that make this region probably the most promising candidate area so far.

Cabrol, Nathalie A.↗
NASA NTRS2001

Imaging Radar in the Mojave Desert-Death Valley Region

The Mojave Desert-Death Valley region has had a long history as a test bed for remote sensing techniques. Along with visible-near infrared and thermal IR sensors, imaging radars have flown and orbited over the area since the 1970's, yielding new insights into the geologic applications of these technologies. More recently, radar interferometry has been used to derive digital topographic maps of the area, supplementing the USGS 7.5' digital quadrangles currently available for nearly the entire area. As for their shorter-wavelength brethren, imaging radars were tested early in their civilian history in the Mojave Desert-Death Valley region because it contains a variety of surface types in a small area without the confounding effects of vegetation. The earliest imaging radars to be flown over the region included military tests of short-wavelength (3 cm) X-band sensors. Later, the Jet Propulsion Laboratory began its development of imaging radars with an airborne sensor, followed by the Seasat orbital radar in 1978. These systems were L-band (25 cm). Following Seasat, JPL embarked upon a series of Space Shuttle Imaging Radars: SIRA (1981), SIR-B (1984), and SIR-C (1994). The most recent in the series was the most capable radar sensor flown in space and acquired large numbers of data swaths in a variety of test areas around the world. The Mojave Desert-Death Valley region was one of those test areas, and was covered very well with 3 wavelengths, multiple polarizations, and at multiple angles. At the same time, the JPL aircraft radar program continued improving and collecting data over the Mojave Desert Death Valley region. Now called AIRSAR, the system includes 3 bands (P-band, 67 cm; L-band, 25 cm; C-band, 5 cm). Each band can collect all possible polarizations in a mode called polarimetry. In addition, AIRSAR can be operated in the TOPSAR mode wherein 2 antennas collect data interferometrically, yielding a digital elevation model (DEM). Both L-band and C-band can be operated in this way, with horizontal resolution of about 5 m and vertical errors less than 2 m. The findings and developments of these earlier investigations are discussed.

Farr, Tom G.↗
NASA NTRS2003

Constraints on the Evolution of the Dichotomy Boundary at 50-90E

The global dichotomy is a fundamental feature of Mars. It marks the boundary between the highly cratered, older southern highlands, and the northern plains. Recent analysis of buried craters in the northern lowlands confirms the long held suspicion that they are comparable in age to the southern highlands, but with surficial deposits of younger material. A variety of exogenic and endogenic models have been proposed for the origin of the dichotomy, including multiple impacts, plate tectonics, and degree one convection produced by core formation, a plume under the lowlands, or a plume under the highlands. New gravity and topography data from the Mars Global Surveyor (MGS) Mission favor endogenic processes. In this study we examine MGS topography, gravity and magnetic field data to constrain the tectonic history the dichotomy in the region 30-60N and 50-90E, which encompasses portions of the Ismenius Lacus quadrangle. The dichotomy formed very early the history of Mars and has undergone extensive modification by impact cratering, erosion, and faulting. This history must be carefully interpreted in order to reconstruct the original nature of the dichotomy boundary and ultimately discriminate between models of origin. In the study area boundary-parallel faults are well preserved, and may be the result of gravitational relaxation. The geologic history has been examined in detail, including estimates of volumes of material eroded. Further, it is one of the few regions where there is a correlation between the free air gravity, magnetic anomalies, and the geology. This allows to constrain subsurface faulting beneath the lowlands fill material. In addition to being an excellent location to unravel the complex history of the dichotomy, this area preserves the transition from a highly magnetized highlands crust to an unmagnetized or slightly magnetized lowlands crust.

S E Smrekar↗
NASA NTRS2003

Magma Reservoirs Feeding Giant Radiating Dike Swarms: Insights from Venus

Evidence of lateral dike propagation from shallow magma reservoirs is quite common on the terrestrial planets, and examination of the giant radiating dike swarm population on Venus continues to provide new insight into the way these complex magmatic systems form and evolve. For example, it is becoming clear that many swarms are an amalgamation of multiple discrete phases of dike intrusion. This is not surprising in and of itself, as on Earth there is clear evidence that formation of both magma reservoirs and individual giant radiating dikes often involves periodic magma injection. Similarly, giant radiating swarms on Earth can contain temporally discrete subswarms defined on the basis of geometry, crosscutting relationships, and geochemical or paleomagnetic signatures. The Venus data are important, however, because erosion, sedimentation, plate tectonic disruption, etc. on Earth have destroyed most giant radiating dike swarm's source regions, and thus we remain uncertain about the geometry and temporal evolution of the magma sources from which the dikes are fed. Are the reservoirs which feed the dikes large or small, and what are the implications for how the dikes themselves form? Does each subswarm originate from a single, periodically reactivated reservoir, or do subswarms emerge from multiple discrete geographic foci? If the latter, are these discrete foci located at the margins of a single large magma body, or do multiple smaller reservoirs define the character of the magmatic center as a whole? Similarly, does the locus of magmatic activity change with time, or are all the foci active simultaneously? Careful study of giant radiating dike swarms on Venus is yielding the data necessary to address these questions and constrain future modeling efforts. Here, using giant radiating dike swarms from the Nemesis Tessera (V14) and Carson (V43) quadrangles as examples, we illustrate some of the dike swarm focal region diversity observed on Venus and briefly explore some key implications for the questions framed above.

Grosfils, E. B.↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Mars: Hydrology, Drainage, and Valley Systems

The titles in this section include: 1) Analysis of Orientation Dependence of Martian Gullies; 2) A Preliminary Relationship between the Depth of Martian Gullies and the Abundance of Hydrogen on Near-Surface Mars; 3) Water Indicators in Sirenum Terra and around the Argyre Impact Basin, Mars; 4) The Distribution of Gullies and Tounge-shaped Ridges and Their Role in the Degradation of Martian Craters; 5) A Critical Evaluation of Crater Lake Systems in Memnonia Quadrangle, Mars; 6) Impact-generated Hydrothermal Activity at Gusev Crater: Implications for the Spirit Mission; 7) Characterization of the Distributary Fan in Holden NE Crater using Stereo Analysis; 8) Computational Analysis of Drainage Basins on Mars: Appraising the Drainage Density; 9) Hypsometric Analyses of Martian Basins: A Comparison to Terrestrial, Lunar, and Venusian Hypsometry; 10) Morphologic Development of Harmakhis Vallis, Mars; 11) Mangala Valles, Mars: Investigations of the source of Flood Water and Early Stages of Flooding; 12) The Formation of Aromatum Chaos and the Water Discharge Rate at Ravi Vallis; 13) Inferring Hydraulics from Geomorphology for Athabasca Valles, Mars; 14) The Origin and Evolution of Dao Vallis: Formation and Modification of Martian Channels by Structural Collapse and Glaciation; 15) Snowmelt and the Formation of Valley Networks on Martian Volcanoes; 16) Extent of Floating Ice in an Ancient Echus Chasma/Kasei Valley System, Mars.

Source record↗
NASA NTRS2004

Searching for Terrain Softening near Mercury's North Pole

In 1999, following the initial discovery of radar bright craters near both poles of Mercury measured the depth-todiameter (d/D) ratios of 170 impact craters in Mariner 10 images covering four different regions on Mercury s surface. Rapid softening of crater structure, indicated by lower d/D ratios, could indicate the possibility of subsurface water ice in Mercury's terrain originating from an internal source in the planet. Their study included 3 specific radar bright craters suggested to contain ice. They concluded that no terrain softening was apparent, and a rapidly emplaced exogenic water source was the most likely source for the proposed ice in these craters. Recent radar observations of the Mercurian North pole have pinpointed many additional radar bright areas with a resolution 10x better than previous radar measurements, and which correlate with craters imaged by Mariner 10. These craters are correlated with regions that are permanently shaded from direct sunlight, and are consistent with observations of clean water ice. We have expanded the initial study by Barlow et al. to include d/D measurements of 12 craters newly identified as radar bright at latitudes poleward of +80o. The radar reflectivity resemblances to Mars south polar cap and echoes from three icy Galilean satellites suggest that these craters too may have polar ice on Mercury. The effect of subsurface H20 on impact craters is a decrease in its d/D ratio, and softening of crater rims over a period of time. The study of Barlow et al., focused on determining the d/D ratios of 170 impact craters in the Borealis (north polar), Tolstoj (equatorial), Kuiper (equatorial), and Bach (south polar) quadrangles. This work focuses on the newly discovered radar bright craters, investigating their d/D ratios as an expansion of the earlier work..We compare our results to the statistical results from Barlow et al. here. With the upcoming Messenger spacecraft mission to Mercury, this is an especially timely study whose result could potentially help the Messenger team as they develop a mission strategy.

Cobian, P. S.↗
NASA NTRS2005

Quantitative Analysis of Venus Radar Backscatter Data in ArcGIS

Ongoing mapping of the Ganiki Planitia (V14) quadrangle of Venus and definition of material units has involved an integrated but qualitative analysis of Magellan radar backscatter images and topography using standard geomorphological mapping techniques. However, such analyses do not take full advantage of the quantitative information contained within the images. Analysis of the backscatter coefficient allows a much more rigorous statistical comparison between mapped units, permitting first order selfsimilarity tests of geographically separated materials assigned identical geomorphological labels. Such analyses cannot be performed directly on pixel (DN) values from Magellan backscatter images, because the pixels are scaled to the Muhleman law for radar echoes on Venus and are not corrected for latitudinal variations in incidence angle. Therefore, DN values must be converted based on pixel latitude back to their backscatter coefficient values before accurate statistical analysis can occur. Here we present a method for performing the conversions and analysis of Magellan backscatter data using commonly available ArcGIS software and illustrate the advantages of the process for geological mapping.

Long, S. M.↗
NASA NTRS2005

Prospecting for Martian Ice

During high Martian obliquity, ice is stable to lower latitudes than predicted by models of present conditions and observed by the Gamma Ray Spectrometer (approx. 60 deg N). An ice-rich layer deposited at mid-latitudes could persist to the present day; ablation of the top 1 m of ice leaving a thin insulating cover could account for lack of its detection by GRS. The presence of an ice-layer in the mid-latitudes is suggested by a network of polygons, interpreted as ice-wedge cracks. This study focuses on an exceptional concentration of polygons in Western Utopia (section of Casius quadrangle, roughly 40 deg - 50 deg N, 255 deg - 300 deg W). We attempt to determine the thickness and age of this ice layer through crater-polygons relations.

McBride, S. A.↗
NASA NTRS2005

Lunar and Planetary Science XXXVI, Part 20

The topics include: 1) Virtual Reality Technology as a Tool to Enhance Collaboration Between Space Exploration and Public Outreach: The Case Using the Mars Exploration Rover Images; 2) Atmospheric Electron-induced X-Ray Spectrometer (AEXS) Instrument Development; 3) Impact of Low Thermal Conductivity Layers on the Bulk Conductivity of a Martian Crustal Column; 4) Impacting Classroom Teachers Through Long-Term Professional Development; 5) Oxygen, Ca, and Ti Isotopic Compositions of Hibonite-bearing Inclusions; 6) Phenomenological Excitation Functions of Xe Isotopes with Protons on Nuclei of Cs, La and Ce; 7) Double-Diffusive Convection and Other Modes of Salinity-modulated Heat and Material Transport in Europa s Ocean; 8) Slope Morphologies of the Hellas Mensae Constructs, Eastern Hellas Planitia, Mars; 9) Development of Polygonal Thermal Contraction Patterns in a South Polar Trough, Mars 3 Years of Observations; 10) Martian Relevance of Dehydration and Rehydration in the Mg-Sulfate System; 11) Formation of Martian Volcanic Provinces by Lower Mantle Flushing? 12) Can Glasses Help Us to Unravel the Origin of Barred Olivine Chondrules? 13) Loki Patera: A Magma Sea Story; 14) Compositions of Partly Altered Olivine and Replacement Serpentine in the CM2 Chondrite QUE93005; 15) Model of Light Scattering by Lunar Regolith at Moderate Phase Angles: New Results; 16) Radiation Resistance of a Silicone Polymer Grease Based Regolith Collector for the HERA Near-Earth Asteroid Sample Return Mission; 17) Analysis of the Tectonic Lineaments in the Ganiki Planitia (V14) Quadrangle, Venus; 18) Nanometer-sized Diamonds from AGB Stars; 19) Quantifying Exact Motions Along Lineaments on Europa; 20) Geometry of Thrust Faults Beneath Amenthes Rupes, Mars; 21) Mapping of the Physical Characteristics and Mineral Composition of a Superficial Layer of the Moon or Mars and Ultra-Violet Polarimetry from the Orbital Station; 22) Negative Searches for Evidence of Aqueous Alteration on Asteroid Surfaces; 23) What Processes Have Shaped Basalt Boulders on Earth and Mars? Studies of Feature Persistence Using Facet Mapping and Fractal Analysis; 24) The Popigai Fluidizites: Dense Water Inclusions in Lechatelierite; Evidence for Shock-generated Carbonate and Hydrous Silicate Melts; 25) Missing Xenon Problem and Climate of the Early Earth; and 26) More on Magnetic Spectra from Correlated Crustal Sources on Mars

Source record↗
NASA NTRS2005

Terrestrial Planet Evolution

The goals of this proposal involved constructing 1:5M scale geologic maps of V-23 (Niobe Planitia) and V-24 (Greenaway) quadrangles, and ancillary materials to be submitted to USGS as part of the VMAP project. Complete geologic maps and packages of ancillary materials for V-23 and V-24 have been submitted to USGS and are currently under review. In addition to these products, we have published or submitted various manuscript and/abstracts detailing the results of our research that has grown out of the proposed work. We presented our maps in various stages of construction at NASA Planetary Geology and Geophysics Mappers' meeting each year. We have also presented talks or posters summarizing our work at various conferences including: he Lunar and Planetary Science Conference, and the National Geological Society of America meeting. The work resulted in exciting developments of Venus lowland resurfacing. The products and publications resulting from this work are listed below.

Hansen, Vicki L.↗