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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Titan's Surface from Cassini RADAR SAR and High Resolution Radiometry Data of the First Five Flybys

The first five Titan flybys with Cassini's Synthetic Aperture RADAR (SAR) and radiometer are examined with emphasis on the calibration and interpretation of the high-resolution radiometry data acquired during the SAR mode (SAR-radiometry). Maps of the 2-cm wavelength brightness temperature are obtained coincident with the SAR swath imaging, with spatial resolution approaching 6 km. A preliminary calibration shows that brightness temperature in these maps varies from 64 to 89 K. Surface features and physical properties derived from the SAR-radiometry maps and SAR imaging are strongly correlated; in general, we find that surface features with high radar reflectivity are associated with radiometrically cold regions, while surface features with low radar reflectivity correlate with radiometrically warm regions. We examined scatterplots of the normalized radar cross-section sigma(exp o) versus brightness temperature, finding differing signatures that characterize various terrains and surface features. Implications for the physical and compositional properties of these features are discussed. The results indicate that volume scattering is important in many areas of Titan's surface, particularly Xanadu, while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties.

Titan↗
NASA NTRS2010

Crater Identification Algorithm for the Lost in Low Lunar Orbit Scenario

Recent emphasis by NASA on returning astronauts to the Moon has placed attention on the subject of lunar surface feature tracking. Although many algorithms have been proposed for lunar surface feature tracking navigation, much less attention has been paid to the issue of navigational state initialization from lunar craters in a lost in low lunar orbit (LLO) scenario. That is, a scenario in which lunar surface feature tracking must begin, but current navigation state knowledge is either unavailable or too poor to initiate a tracking algorithm. The situation is analogous to the lost in space scenario for star trackers. A new crater identification algorithm is developed herein that allows for navigation state initialization from as few as one image of the lunar surface with no a priori state knowledge. The algorithm takes as inputs the locations and diameters of craters that have been detected in an image, and uses the information to match the craters to entries in the USGS lunar crater catalog via non-dimensional crater triangle parameters. Due to the large number of uncataloged craters that exist on the lunar surface, a probability-based check was developed to reject false identifications. The algorithm was tested on craters detected in four revolutions of Apollo 16 LLO images, and shown to perform well.

Hanak, Chad↗
NASA NTRS1974

Land use and mapping

This summary is divided into two basic sections-one dealing with land use classification and delineation, and the other dealing with mapping. The term land use classification is used in respect to the actual use of land rather than land capability, land suitability, or the potential use of land. The classification of actual use of the land, as defined by man's activities that are related to the land, may be only inferred, rather than directly interpreted, in the case of the identification and classification of some surface features or vegetation cover types. Also, in the case of some surface features or vegetational cover types, the specific activity involving man's use of the land may not be designated in a four-level classification system until level 3 or level 4 is reached. Most investigations employed or implied a hierarchial land use classification scheme with more than two levels, but mainly addressed themselves to classifying and delineating surface features (land use) that would fall in the first two levels of a three- or four-level hierarchial scheme. Although not all investigators used a hierarchial classification scheme or concurred with the idea (computer-implemented classifications with digital data are not conducive to a hierarchial classification approach), the classification system proposed by the U.S. Department of the Interior is used as reference.

Joyce, A. T.↗
NASA NTRS2012

Terra MODIS Band 27 Electronic Crosstalk Effect and Its Removal

The MODerate-resolution Imaging Spectroradiometer (MODIS) is one of the primary instruments in the NASA Earth Observing System (EOS). The first MODIS instrument was launched in December, 1999 on-board the Terra spacecraft. MODIS has 36 bands, covering a wavelength range from 0.4 micron to 14.4 micron. MODIS band 27 (6.72 micron) is a water vapor band, which is designed to be insensitive to Earth surface features. In recent Earth View (EV) images of Terra band 27, surface feature contamination is clearly seen and striping has become very pronounced. In this paper, it is shown that band 27 is impacted by electronic crosstalk from bands 28-30. An algorithm using a linear approximation is developed to correct the crosstalk effect. The crosstalk coefficients are derived from Terra MODIS lunar observations. They show that the crosstalk is strongly detector dependent and the crosstalk pattern has changed dramatically since launch. The crosstalk contributions are positive to the instrument response of band 27 early in the mission but became negative and much larger in magnitude at later stages of the mission for most detectors of the band. The algorithm is applied to both Black Body (BB) calibration and MODIS L1B products. With the crosstalk effect removed, the calibration coefficients of Terra MODIS band 27 derived from the BB show that the detector differences become smaller. With the algorithm applied to MODIS L1B products, the Earth surface features are significantly removed and the striping is substantially reduced in the images of the band. The approach developed in this report for removal of the electronic crosstalk effect can be applied to other MODIS bands if similar crosstalk behaviors occur.

Sun, Junqiang↗
NASA NTRS1989

Multipolarization P-, L-, and C-band radar for coastal zone mapping - The Louisiana example

Multipolarization P-, L-, and C-band airborne SAR data sets were acquired over a coastal zone and a forested wetland of southern Louisiana. The data sets were used with field-collected surface-parameter data in order to determine the value of SAR systems in assessing and mapping coastal-zone surface features. The coastal-zone surface features in this study are sediments, sediment distribution, and the formation of new isles and banks. Results of the data analysis indicate that the P-band radar with 68-cm wavelength is capable of detecting the submerged sediment if the area is very shallow (i.e., a water depth of less than one meter). The penetration capability of P-band radar is also demonstrated in the forested wetland area. The composition and condition of the ground surface can be detected, as well as the standing water beneath dense tree leaves.

Wu, Shih-Tseng↗
NASA NTRS2000

Separation of Atmospheric and Surface Spectral Features in Mars Global Surveyor Thermal Emission Spectrometer (TES) Spectra

We present two algorithms for the separation of spectral features caused by atmospheric and surface components in Thermal Emission Spectrometer (TES) data. One algorithm uses radiative transfer and successive least squares fitting to find spectral shapes first for atmospheric dust, then for water-ice aerosols, and then, finally, for surface emissivity. A second independent algorithm uses a combination of factor analysis, target transformation, and deconvolution to simultaneously find dust, water ice, and surface emissivity spectral shapes. Both algorithms have been applied to TES spectra, and both find very similar atmospheric and surface spectral shapes. For TES spectra taken during aerobraking and science phasing periods in nadir-geometry these two algorithms give meaningful and usable surface emissivity spectra that can be used for mineralogical identification.

Smith, Michael D.↗
NASA NTRS1979

Plant cover, soil temperature, freeze, water stress, and evapotranspiration conditions

The author has identified the following significant results. Procedures to edit cloud-contaminated pixels from those pixels representing Earth surface features were investigated. Because clouds are more reflective than Earth features and are colder than Earth surface features most of the year at 26 N latitude, either a raw digital count ratio or a ratio of reflectance percentage for the VIS band to the temperature works well. For this procedure, the two bands of data need to be registered to the ground scene.

Wiegand, C. L.↗
NASA NTRS1980

Characterization of Martian surface materials from earth-based radar - The Memnonia Fossae region

The 1971 and 1973 Goldstone radar data on the Memnonia Fossae region of Mars is used as a test case for the characterization of surface materials. In addition to the discovery of greater relief in the radar-derived topographic measurements of this area than had been inferred from Mariner 9 estimates, and although a tendency for the radar measurements to break down over very rugged terrain has been observed, good correlation is found between radar topography and surface features. Photogeological mapping has identified six surface units which have distinctive radar properties that correlate well with surface features observed in the Viking Orbiter's 10 m/pixel resolution images

Mouginis-Mark, P. J.↗
NASA NTRS1984

Scene segmentation through region growing

A computer algorithm to segment Landsat Thematic Mapper (TM) images into areas representing surface features is described. The algorithm is based on a region growing approach and uses edge elements and edge element orientation to define the limits of the surface features. Adjacent regions which are not separated by edges are linked to form larger regions. Some of the advantages of scene segmentation over conventional TM image extraction algorithms are discussed, including surface feature analysis on a pixel-by-pixel basis, and faster identification of the pixels in each region. A detailed flow diagram of region growing algorithm is provided.

Latty, R. S.↗
DOE OSTI2024

Characterization of spent nuclear fuel canister surface roughness using surface replicating molds

In this study we present a replication method to determine surface roughness and to identify surface features when a sample cannot be directly analyzed by conventional techniques. As a demonstration, this method was applied to an unused spent nuclear fuel dry storage canister to determine variation across different surface features. In this study, an initial material down-selection was performed to determine the best molding agent and determined that non-modified Polytek PlatSil23-75 provided the most accurate representation of the surface while providing good usability. Other materials that were considered include Polygel Brush-On 35 polyurethane rubber (with and without Pol-ease 2300 release agent), Polytek PlatSil73-25 silicone rubber (with and without PlatThix thickening agent and Pol-ease 2300 release agent), and Express STD vinylpolysiloxane impression putty. The ability of PlatSil73-25 to create an accurate surface replica was evaluated by creating surface molds of several locations on surface roughness standards representing ISO grade surfaces N 3 , N 5 , N 7 , and N 8 . Overall, the molds were able to accurately reproduce the expected roughness average (R a ) values, but systematically over-estimated the peak-valley maximum roughness (R z ) values. Using a 3D printed sample cell, several locations across the stainless steel spent nuclear fuel canister were sampled to determine the surface roughness. These measurements provided information regarding variability in normal surface roughness across the canister as well as a detailed evaluation on specific surface features (e.g., welds, grind marks, etc.). The results of these measurements can support development of dry storage canister ageing management programs, as surface roughness is an important factor for surface dust deposition and accumulation. This method can be applied more broadly to different surfaces beyond stainless steel to provide rapid, accurate surface replications for analytical evaluation by profilometry.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1986

Nucleus morphology of Comet Halley

Images obtained by the Halley multicolor camera were used to determine the projected size and shape of the nucleus. The location of the terminator and numerous surface features were determined. There is good correlation between the brightest surface features and the dust jets; however, many bright features are seen which are not associated with jets. Most of the observed features are circular and appear to be related to surface elevation. The angularity of the terminator gives an indication of the three-dimensional structure of the face which was observed.

Reitsema, H. J.↗
NASA NTRS1981

Use of thermal inertia determined by HCMM to predict nocturnal cold prone areas in Florida

Transparencies, prints, and computer compatible tapes of temperature differential and thermal inertia for the winter of 1978 to 1979 were obtained. Thermal inertial differences in the South Florida depicted include: drained organic soils of the Everglades agricultural area, undrained organic soils of the managed water conservation areas of the South Florida water management district, the urbanized area around Miami, Lake Okeechobee, and the mineral soil west of the Everglades agricultural area. The range of wetlands and uplands conditions within the Suwanee River basin was also identified. It is shown that the combination of wetlands uplands surface features of Florida yield a wide range of surface temperatures related to wetness of the surface features.

Allen, L. H., Jr.↗
NASA NTRS1984

Ridges on basalt flows

Pressure ridges are surface features on basaltic lava flows and, as with other surface features, they may be related to the emplacement of a flow and the rheological properties of the lava. Since many ridges are of sufficient size to be detected on high resolution orbital images, an understanding of pressure ridges could provide a means for interpreting volcanic flows on other terrestrial planets. Some proposed formation mechanisms are reviewed and three different types of pressure ridges are identified on the basis of morphology. Type 1 ridges are the most common and are associated with multiple flow unit pahoehoe in which the ridges are embayed by secondary toe fed lava. They tend to be restricted to wider sections or margins of the flow and to be oriented longitudinal to flow direction; however, oblique or transverse orientation is not uncommon. Bulbous squeeze ups are common within cracks and may reflect relative timing of crack formation. The interior structure of type 1 ridges consists of an upper slab section which generally contains columnar joints and a lower massive section with an irregular surface. This basic distinction may mark the thickness of the surface crust when ridge formation was initiated. Type 2 ridges occur in association with type 1 and are very similar with the exception of the secondary squeeze out material. Instead of only filling cracks, the secondary material on these ridges originated from underneath a thin crust and flowed as toes or channels from the top and sides of the ridge. Type 3 ridges have much steeper sides (almost vertical at the top) than the other types. Medial cracks are very wide and the crack walls are convex upward. No squeeze ups are present. The main difference between type 3 and the others may be reflection of viscosity.

Theilig, E.↗
NASA NTRS2004

Modeling the Salar de Uyuni, Bolivia as an Equipotential Surface of Earth's Gravity Field

The salar de Uyuni is a massive dry salt lake that lies at the lowest point of an internal/drainage basin in the Bolivian Altiplano. Its topography is remarkable for its extraordinary flatness over almost a full degree of latitude and longitude. We surveyed a 54 x 45 km region of the salar with kinematic GPS in September, 2002 and found a topographic range of only 80 cm over the entire surveyed area. Furthermore, the survey revealed distinct surface features with several dominant wavelengths and orientations. Some of these appear to be aligned with orographic features that intersect the salar, leading us to conjecture that they are the surface expression of high-density mountains that have been buried by low-density basin sediments. Over the oceans, a similar correspondence between basin bathymetry and surface topography is exploited to map the seafloor using sea-surface satellite altimetry measurements, with the sea surface following geoid undulations due to the underwater mass distribution. On the salar, annual flooding creates a shallow lake whose surface also lies on a equipotential surface shaped by the distribution of underlying mass. The link to the actual salar surface is via the dissolution and redeposition of salt by the lake waters, which appears to push the system to an equilibrium of constant water depth and the coincidence of the shapes of the lake surface and bottom. To test our hypothesis about the origin of the surface features on the salar, we compare our GPS survey elevations with the equipotential surface generated from local gravity measurements in conjunction with gravity and potential values from the EGM96 global geopotential model. 50% of the variance of the GPS elevations can be explained by equipotential surface undulations from the EGM96 model alone, and an additional 40% is explained by the shorter-wavelength equipotential surface derived from local gravity. We examine the unexplained 10% of elevation variance from the standpoint of errors in the equipotential surface calculation and possible unmodelled surface processes.

Borsa, Adrian↗
DOE OSTI2025

Measuring 3D Profilometry of SAVY-4000 Nuclear Material Storage Containers: Novacam TubeInspect Capabilities Report

The SAVY-4000 container series is a general-purpose interim storage container for nuclear materials, developed and maintained by Los Alamos National Laboratory (LANL). It is the first vented, general-use nuclear material container to be demonstrated as meeting the requirements outlined in DOE M 441.1-1, the Nuclear Material Packaging Manual. Due to the challenging radiation, thermal, and corrosive storage conditions that the SAVY containers must endure, continuous surveillance techniques are employed to ensure the containers meet all safety standards and specifications. These inspections are typically performed by human operators, who check for issues such as corrosion, O-ring deterioration, corrosion, filter integrity, and potential manufacturing defects. However, human inspections alone are not sufficient, and automated inspection technologies, such as the ATIS system, as well as other automated systems are also utilized. The MicroCam TubeInspect, developed by Novacam Technologies Inc., is designed to address the challenges of understanding how manufacturing variations in the SAVY-4000 container series may affect performance. It is a 3D profilometry measurement system that enables detailed analysis of surface features, including defects, surface roughness, and manufacturing variations. This advanced tool significantly enhances rapid surveillance techniques for both pristine and used containers. In this study, container properties such as surface roughness, thickness, and geometric attributes like circularity are measured for SAVY-4000 containers. Artificially corroded or dented containers are examined to demonstrate the MicroCam's ability to quantify defects. A sensitivity analysis is also conducted, comparing the MicroCam results to those obtained using more precise instruments such as confocal microscopy. This comparison aims to provide valuable insights into container quality, durability, and potential improvements in manufacturing processes.

42 ENGINEERING↗
NASA NTRS1987

Active region influences upon the solar constant

The influence that active regions have upon the solar constant is discussed. Sunspots appear to lower the solar constant for the few days in which they are located near central meridian. This raises the possibility that an 11-year, solar-cycle-related depression in the solar constant may occur. Recent findings concerning the physics of active regions suggest that sunspots and faculae are largely surface features. Within that surface faculae reradiate, within a few weeks, the 'missing energy' associated with sunspots. This is consistent with the observations showing that the solar constant does not have an 11-year cycle-related depression that some authors predicted. However, there is a secular variation in the solar constant, whose explanation is not completely understood.

Schatten, Kenneth H.↗
NASA NTRS1988

Circumpolar hoods and clouds and their relation to the Martian H2O cycle

Water exists in both vapor and solid phases in the Martian atmosphere. The polar hoods are shrouds of condensate clouds which obscure both polar regions at times during their respective fall and winter seasons. The hemispheric asymmetries in the polar hood clouds are reviewed and their significance to the seasonal water cycle is discussed. Comparisons of images acquired using short wavelength filters, which provide maximum cloud contrast, and long wavelength filters, which are sensitive to surface features including the surface cap, provide correlations between cloud formation and large scale planetary dynamics.

James, Philip B.↗