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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 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Some strategies for quantitative scanning Auger electron microscopy

The general applicability of power law forms of the background in electron spectra is pointed out and exploited for background removal from under Auger peaks. This form of B(E) is found to be extremely sensitive to instrumental alignment and to fault-free construction - an observation which can be used to set up analyser configurations in an accurate way. Also, differences between N(E) and B(E) can be used to derive a spectrometer transmission function T(E). The questions of information density in an energy-analysing spatially-resolving instrument are addressed after reliable instrumental characterization has been established. Strategies involving ratio histograms, showing the population distribution of the ratio of a pair of Auger peak heights, composition scatter diagrams and windowed imaging are discussed and illustrated.

Browning, R.↗
NASA NTRS1990

Five stellar occultations by Neptune - Further observations of ring arcs

Diffraction model fits to the light curves obtained during April 18, 1984 and August 20, 1985 stellar occultations that revealed incomplete rings, or 'arcs' around Neptune, are found to indicate arc radial widths of 8-26 km, and normal optical depths of 0.07-0.14. On the basis of the Neptune pole direction ascertained from Voyager navigation analyses, it is confirmed that the arc observed on August 20, 1985, together with the Hubbard et al. (1986) and Covault et al. (1986) arcs, seem to match the radius of the outermost ring found in Voyager images analyzed by Smith et al. (1989).

Nicholson, Philip D.↗
NASA NTRS1993

Science & Technology Laboratory Applications Software (ELAS)

Digital image analysis system processes Landsat multispectral data, aircraft-acquired scanner data, digitized topographical data, and such ancillary data as soil types and rainfall information. Over 230 modules aid user in performing wide range of land cover analyses and manipulations.

Junkin, B. G.↗
NASA NTRS2011

Thermal Structure and Dynamics of Saturn's Northern Springtime Disturbance

This article combined several infrared datasets to study the vertical properties of Saturn's northern springtime storm. Spectroscopic observations of Saturn's northern hemisphere at 0.5 and 2.5 / cm spectral resolution were provided by the Cassini Composite Infrared Spectrometer (CIRS, 17). These were supplemented with narrow-band filtered imaging from the ESO Very Large Telescope VISIR instrument (16) to provide a global spatial context for the Cassini spectroscopy. Finally, nightside imaging from the Cassini Visual and Infrared Mapping Spectrometer (VIMS, 22) provided a glimpse of the undulating cloud activity in the eastern branch of the disturbance. Each of these datasets, and the methods used to reduce and analyse them, will be described in detail below. Spatial maps of atmospheric temperatures, aerosol opacity and gaseous distributions are derived from infrared spectroscopy using a suite of radiative transfer and optimal estimation retrieval tools developed at the University of Oxford, known collectively as Nemesis (23). Synthetic spectra created from a reference atmospheric model for Saturn and appropriate sources of spectroscopic line data (6, 24) are convolved with the instrument function for each dataset. Atmospheric properties are then iteratively adjusted until the measurements are accurately reproduced with physically-realistic temperatures, compositions and cloud opacities.

Fletcher, Leigh N.↗
NASA NTRS2019

Origin and Speciation of Sulfur Compounds in the Murray Formation, Gale Crater, Mars

The Mars Curiosity rover has traversed nearly 20 km and gained over 350 meters in elevation since landing in Gale crater in August 2012. Through 2250 sols of surface operations, Curiosity has spent approximately 60% of its time investigating the Murray formation, a unit of layered sediments. The occurrence of sulfur compounds in the Murray formation has been established by imaging of light-toned veins by MastCam and MAHLI, chemical compositions measured by the Alpha Particle X-ray Spectrometer (APXS) and ChemCam, crystalline phase identifications by the CheMin X-ray diffractometer, and evolved gas analyses from the Sample Analysis at Mars (SAM) instrument.

Yen, A. S.↗
DOE OSTI2021

Seeing through nuclear fuel: Three-dimensional, nondestructive X-ray microscopy and volumetric analyses of neutron-irradiated TRISO-coated fuel kernels

The three-dimensional (3D) characterization of nuclear fuel with X-ray microscopy has historically proven difficult, due to uranium’s high attenuation of easily accessible X-rays, both in a laboratory setting and at a synchrotron user facility. However, this imaging modality provides nondestructive information that can be used to investigate morphological changes arising from external stimuli (e.g., neutron irradiation, high-temperature testing). Using an appropriate X-ray energy spectrum and an adequate X-ray filter, suitable transmissions through properly sized nuclear fuel specimens can be achieved. Here, in this study, we present the methods and results of using a commercially available, laboratory-based X-ray microscope (XRM) to examine the extent of 3D morphological changes of tristructural isotropic (TRISO)-coated fuel particles, specifically uranium oxide/uranium carbide fuel kernels, after high-temperature neutron irradiation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1995

Using dark current data to estimate AVIRIS noise covariance and improve spectral analyses

Starting in 1994, all AVIRIS data distributions include a new product useful for quantification and modeling of the noise in the reported radiance data. The 'postcal' file contains approximately 100 lines of dark current data collected at the end of each data acquisition run. In essence this is a regular spectral-image cube, with 614 samples, 100 lines and 224 channels, collected with a closed shutter. Since there is no incident radiance signal, the recorded DN measure only the DC signal level and the noise in the system. Similar dark current measurements, made at the end of each line are used, with a 100 line moving average, to remove the DC signal offset. Therefore, the pixel-by-pixel fluctuations about the mean of this dark current image provide an excellent model for the additive noise that is present in AVIRIS reported radiance data. The 61,400 dark current spectra can be used to calculate the noise levels in each channel and the noise covariance matrix. Both of these noise parameters should be used to improve spectral processing techniques. Some processing techniques, such as spectral curve fitting, will benefit from a robust estimate of the channel-dependent noise levels. Other techniques, such as automated unmixing and classification, will be improved by the stable and scene-independence noise covariance estimate. Future imaging spectrometry systems should have a similar ability to record dark current data, permitting this noise characterization and modeling.

Boardman, Joseph W.↗
NASA NTRS2013

Public Health Applications of Remotely-sensed Environmental Datasets for the Conterminous United States

NASA Marshall Space Flight Center is collaborating with the University of Alabama at Birmingham (UAB) School of Public Health and the Centers for Disease Control and Prevention (CDC) National Center for Public Health Informatics to address issues of environmental health and enhance public health decision-making using NASA remotely-sensed data and products. The objectives of this study are to develop high-quality spatial data sets of environmental variables, link these with public health data from a national cohort study, and deliver the linked data sets and associated analyses to local, state and federal end-user groups. Three daily environmental data sets were developed for the conterminous U.S. on different spatial resolutions for the period 2003-2008: (1) spatial surfaces of estimated fine particulate matter (PM2.5) exposures on a 10-km grid using the US Environmental Protection Agency (EPA) ground observations and NASA's MODerate-resolution Imaging Spectroradiometer (MODIS) data; (2) a 1-km grid of Land Surface Temperature (LST) using MODIS data; and (3) a 12-km grid of daily Incoming Solar Radiation (Insolation) and heat-related products using the North American Land Data Assimilation System (NLDAS) forcing data. These environmental data sets were linked with public health data from the UAB REasons for Geographic And Racial Differences in Stroke (REGARDS) national cohort study to determine whether exposures to these environmental risk factors are related to cognitive decline, stroke and other health outcomes. These environmental datasets and the results of the public health linkage analyses will be disseminated to end-users for decision-making through the CDC Wide-ranging Online Data for Epidemiologic Research (WONDER) system and through peer-reviewed publications respectively. The linkage of these data with the CDC WONDER system substantially expands public access to NASA data, making their use by a wide range of decision makers feasible. By successful completion of this research, decision-making activities, including policy-making and clinical decision-making, can be positively affected through utilization of the data products and analyses provided on the CDC WONDER system.

Al-Hamdan, Mohammad↗
NASA NTRS1999

Leonid's Particle Analyses from Stratospheric Balloon Collection on Xerogel Surfaces

Recovered from a stratospheric balloon above 20 km on 17-18 November 1998, at least eight candidate microparticles were collected and analyzed from low-density silica xerogel collection plates. Capture time at Leonids' storm peak was validated locally along the balloon trajectory by direct video imaging of meteor fluence up to 24/hr above 98% of the Earth's atmosphere. At least one 30 micron particle agrees morphologically to a smooth, unmelted spherule and compares most closely in non-volatile elemental ratios (Mg/Si, Al/Si, and Fe/Si) to compositional data in surface/ocean meteorite collections. A Euclidean tree diagram based on composition makes a most probable identification as a non-porous stratospherically collected particle and a least probable identification as terrestrial matter or an ordinary chondrite. If of extraterrestrial origin, the mineralogical class would be consistent with a stony (S) type of silicate, olivine [(Mg,Fe)2SiO4] and pyroxene [(Mg, Fe)Si!O3)--or oxides, herecynite [(Fe,Mg) Al2O4].

Noever, David↗
NASA NTRS2014

High-Resolution Imaged-Based 3D Reconstruction Combined with X-Ray CT Data Enables Comprehensive Non-Destructive Documentation and Targeted Research of Astromaterials

Providing web-based data of complex and sensitive astromaterials (including meteorites and lunar samples) in novel formats enhances existing preliminary examination data on these samples and supports targeted sample requests and analyses. We have developed and tested a rigorous protocol for collecting highly detailed imagery of meteorites and complex lunar samples in non-contaminating environments. These data are reduced to create interactive 3D models of the samples. We intend to provide these data as they are acquired on NASA's Astromaterials Acquisition and Curation website at http://curator.jsc.nasa.gov/.

Blumenfeld, E. H.↗
DOE OSTI2024

Tau accumulation and atrophy predict amyloid independent cognitive decline in aging

INTRODUCTION: Amyloid beta (Aβ) and tau pathology are cross-sectionally associated with atrophy and cognitive decline in aging and Alzheimer's disease (AD). METHODS: We investigated relationships between concurrent longitudinal measures of Aβ (Pittsburgh compound B [PiB] positron emission tomography [PET]), tau (flortaucipir [FTP] PET), atrophy (structural magnetic resonance imaging), episodic memory (EM), and non-memory (NM) in 78 cognitively healthy older adults (OA). RESULTS: Entorhinal FTP change was correlated with EM decline regardless of Aβ, but meta-temporal FTP and global PiB change were only associated with EM and NM decline in Aβ+ OA. Voxel-wise analyses revealed significant associations between temporal lobe FTP change and EM decline in all groups. PiB and FTP change were not associated with structural change, suggesting a functional or microstructural mechanism linking these measures to cognitive decline. DISCUSSION: Our results show that longitudinal Aβ is linked to cognitive decline only in the presence of elevated Aβ, but longitudinal temporal lobe tau is associated with memory decline regardless of Aβ status.

60 APPLIED LIFE SCIENCES↗
NASA NTRS2014

Sao Paulo Lightning Mapping Array (SP-LMA): Network Assessment and Analyses for Intercomparison Studies and GOES-R Proxy Activities

A 12 station Lightning Mapping Array (LMA) network was deployed during October 2011 in the vicinity of Sao Paulo, Brazil (SP-LMA) to contribute total lightning measurements to an international field campaign [CHUVA - Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement)]. The SP-LMA was operational from November 2011 through March 2012 during the Vale do Paraiba campaign. Sensor spacing was on the order of 15-30 km, with a network diameter on the order of 40-50km. The SP-LMA provides good 3-D lightning mapping out to 150 km from the network center, with 2-D coverage considerably farther. In addition to supporting CHUVA science/mission objectives, the SP-LMA is supporting the generation of unique proxy data for the Geostationary Lightning Mapper (GLM) and Advanced Baseline Imager (ABI), on NOAA's Geostationary Operational Environmental Satellite-R (GOES-R: scheduled for a 2015 launch). These proxy data will be used to develop and validate operational algorithms so that they will be ready to use on "day1" following the GOES-R launch. As the CHUVA Vale do Paraiba campaign opportunity was formulated, a broad community-based interest developed for a comprehensive Lightning Location System (LLS) intercomparison and assessment study, leading to the participation and/or deployment of eight other ground-based networks and the space-based Lightning Imaging Sensor (LIS). The SP-LMA data is being intercompared with lightning observations from other deployed lightning networks to advance our understanding of the capabilities/contributions of each of these networks toward GLM proxy and validation activities. This paper addresses the network assessment including noise reduction criteria, detection efficiency estimates, and statistical and climatological (both temporal and spatially) analyses for intercomparison studies and GOES-R proxy activities.

Bailey, J. C.↗
NASA NTRS1973

Apollo lunar sounder experiment

The four basic data products from the ALSE are sounding, profiling, imaging, and noise measurements. Attention was concentrated on the first three products, and both theory and preliminary results are presented. Background information is presented on the experiment and on the data products. Preliminary examples of the types of analyses that can be performed and the conclusions to which they can lead are included. Preliminary analysis of the data for subsurface features was successful in indicating with a high probability the capability of the ALSE to achieve its fundamental goal of substrate sounding. The imagery and profiling data are useful immediately for geologic interpretation, as demonstrated.

Phillips, R. J.↗
NASA NTRS1976

OAST Space Theme Workshop. Volume 3: Working group summary. 3: Sensors (E-3). A. Statement. B. Technology needs (form 1). C. Priority assessment (form 2). D. Additional assessment

Developments required to support the space power, SETI, solar system exploration and global services programs are identified. Instrumentation and calibration sensors (rather than scientific) are needed for the space power system. Highly sophisticated receivers for narrowband detection of microwave sensors and sensors for automated stellar cataloging to provide a mapping data base for SETI are needed. Various phases of solar system exploration require large area solid state imaging arrays from UV to IR; a long focal plane telescope; high energy particle detectors; advanced spectrometers; a gravitometer; and atmospheric distanalyzer; sensors for penetrometers; in-situ sensors for surface chemical analysis, life detection, spectroscopic and microscopic analyses of surface soils, and for meteorological measurements. Active and passive multiapplication sensors, advanced multispectral scanners with improved resolution in the UV and IR ranges, and laser techniques for advanced probing and oceanographic characterization will enhance for global services.

Source record↗
NASA NTRS1990

Mariner 9 observations of the south polar cap of Mars - Evidence for residual CO2 frost

The first spacecraft observations of the south residual polar cap of Mars were obtained by the Mariner 9 orbiter during the Martian southern summer season, 1971-1972. Analyses of Viking orbiter observations obtained 3 Mars years later have shown that residual carbon dioxide frost was present at the south polar cap in 1977. In this study, Mariner 9 infrared interferometer spectrometer spectra and television camera images are used in conjuction with multispectral thermal emission models to constrain the temperatures of dark bare ground and bright frost regions within the south residual cap. The results provide strong evidence that carbon dioxide frost was present throughout the summer season despite the fact that the residual frost deposits observed by Mariner 9 were less extensive than those observed by Viking.

Paige, D. A.↗
NASA NTRS2002

Understanding the Global Water and Energy Cycle Through Assimilation of Precipitation-Related Observations: Lessons from TRMM and Prospects for GPM

Understanding the Earth's climate and how it responds to climate perturbations relies on what we know about how atmospheric moisture, clouds, latent heating, and the large-scale circulation vary with changing climatic conditions. The physical process that links these key climate elements is precipitation. Improving the fidelity of precipitation-related fields in global analyses is essential for gaining a better understanding of the global water and energy cycle. In recent years, research and operational use of precipitation observations derived from microwave sensors such as the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager and Special Sensor Microwave/Imager (SSM/I) have shown the tremendous potential of using these data to improve global modeling, data assimilation, and numerical weather prediction. We will give an overview of the benefits of assimilating TRMM and SSM/I rain rates and discuss developmental strategies for using space-based rainfall and rainfall-related observations to improve forecast models and climate datasets in preparation for the proposed multi-national Global Precipitation Mission (GPM).

Hou, Arthur↗
NASA NTRS2015

An Overview of WFIRST-AFTA Coronagraph Modelling

The WFIRST/AFTA 2.4 m space telescope currently under study includes a stellar coronagraph for the imaging and spectral characterization of extrasolar planets. Based largely on performance predictions from end-to-end optical propagation modeling, promising coronagraphic methods were selected in late 2013 for further consideration for use on AFTA. Since those downselect analyses further modeling work has been done on evaluating refined coronagraph designs, wavefront sensing and control, detector representation, and time-dependent effects. Thermal, structural, ray trace, and diffraction propagation models are used in these studies. Presented here is the progress to date and plans for future analyses.

Krist, John↗
NASA NTRS2017

The Mars Science Laboratory Curiosity Rover Mastcam Instruments: Preflight and In-Flight Calibration, Validation, and Data Archiving

The NASA Curiosity rover Mast Camera (Mastcam) system is a pair of fixed-focal length, multispectral, color CCD imagers mounted approximately 2 m above the surface on the rover's remote sensing mast, along with associated electronics and an onboard calibration target. The left Mastcam (M-34) has a 34 mm focal length, an instantaneous field of view (IFOV) of 0.22 mrad, and a FOV of 20 deg × 15 deg over the full 1648 × 1200 pixel span of its Kodak KAI-2020 CCD. The right Mastcam (M-100) has a 100 mm focal length, an IFOV of 0.074 mrad, and a FOV of 6.8 deg × 5.1 deg using the same detector. The cameras are separated by 24.2 cm on the mast, allowing stereo images to be obtained at the resolution of the M-34 camera. Each camera has an eight-position filter wheel, enabling it to take Bayer pattern red, green, and blue (RGB) 'true color' images, multispectral images in nine additional bands spanning approximately 400-1100 nm, and images of the Sun in two colors through neutral density-coated filters. An associated Digital Electronics Assembly provides command and data interfaces to the rover, 8 Gb of image storage per camera, 11 bit to 8 bit companding, JPEG compression, and acquisition of high-definition video. Here we describe the preflight and in-flight calibration of Mastcam images, the ways that they are being archived in the NASA Planetary Data System, and the ways that calibration refinements are being developed as the investigation progresses on Mars. We also provide some examples of data sets and analyses that help to validate the accuracy and precision of the calibration.

MSL Mastcam; quantitative multispectral↗