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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Groundbased near-IR observations of the surface of Venus

We present images of the nightside of Venus taken in the near-infrared windows at 1.0, 1.1, 1.18, 1.28, 1.31, and 2.3 microns with the new infrared camera/spectrometer IRIS on the Anglo-Australian Telescope. These data were taken in spectral-mapping mode. This technique involves scanning the telescope perpendicular to the slit, while collecting spectra at successive slit positions across the planet. We produce data cubes with one spectral and two spatial dimensions. Images can be extracted over any wavelength regions. Each image has square pixels of 0.8 inch resolution. We reduced the scattered light from the sunlit crescent in images extracted from each window by subtracting images taken on either side of the window, where the Venus atmosphere is opaque. Unlike the short wavelength windows, which reveal thermal contrasts that originate primarily from the surface and deep atmosphere, the emission in the 2.3 microns window is produced at much higher altitudes (30-40 km). Emission contrasts seen near 2.3 microns are associated with horizontal variations in the cloud optical depths, and have rotation periods of about six days. We detect large contrasts in infrared emission (20-40 percent) across the disc of Venus in the 1.0-, 1.1-, 1.18-, 1.28-, and 1.31-micron images. Contrasts at these wavelengths may be due to a combination of variations in the optical depths of the overlying sulfuric acid clouds and differences in surface emission. Comparison with the 2.3-micron images show that the patterns seen in the 1.28- and 1.31-micron windows are consistent with cloud optical depth variations alone and require no contribution from the surface. However, images at 1.0, 1.1, and 1.8 microns from July 1991 show a dark feature having a contrast that increases with decreasing wavelength. This behavior is contrary to that expected of cloud absorption. Images taken on three successive days in October show another dark feature that is stationary with respect to the surface. These regions of lower emission correspond closely to the high-altitude surface regions of Beta Regio and Aphrodite Terra. The images can potentially reveal the near-infrared emissiveity of the surface of Venus, thereby complementing Magellan radar reflectivity and ground based radio emissivity measurements. The contrast ratio between highlands and plains is much smaller than would be expected for blackbody radiation from the surface along. Unlike at radio wavelengths, where the atmosphere is essentially transparent, at near-infrared wavelengths the atmosphere emits, absorbs, and scatters radiation, and can modify the observed topographically induced contrasts. The additional radiation from the atmosphere reduces the contrast, and further modification would be expected if terrain at different altitudes has different emissivities. A fit to our data therefore requires, and may constrain, a model of the lowest scale height of the atmosphere.

Meadows, V. S.↗
NASA NTRS1973

ERTS evaluation for land use inventory

The author has identified the following significant results. The feasibility of accomplishing a general inventory of any given region based on spectral categories from satellite data has been demonstrated in a pilot study for an area of 6300 square kilometers in central New York State. This was accomplished by developing special processing techniques to improve and balance contrast and density for each spectral band of an image scene to compare with a standard range of density and contrast found to be acceptable for interpretation of the scene. Diazo film transparencies were made from enlarged black and white transparencies of each spectral band. Color composites were constructed from these diazo films in combinations of hue and spectral bands to enhance different spectral features in the scene. Interpretation and data takeoff was accomplished manually by translating interpreted areas onto an overlay to construct a spectral map. The minimum area interpreted was 25 hectares. The minimum area geographically referenced was one square kilometer. The interpretation and referencing of data from ERTS-1 was found to be about 88% accurate for eight primary spectral categories.

Hardy, E. E.↗
NASA NTRS1995

The abundances of major elements in Cas A and Tycho supernova remnants

The objective of this program was to map the abundances of major elements such as O, Si, S, and Fe in the supernova remnants, Tycho and Cas A. The approach was based upon using archival cosmic X-ray data from several space missions, notably, the Einstein Observatory, EXOSAT, ROSAT, BBSRT, and ASCA. Two of the missions, Einstein and ROSAT, had high resolution telescopes that provided excellent images, but no spectral information. Two missions with much poorer resolution telescopes, BBXRT and ASCA, gave good spectral information through pulse height of signals in their cooled solid state detector, but rather crude spatial information. Our goal was to extract spectral information from the combined analysis of the Einstein and ROSAT images of Cas A and Tycho and to verify or refine the spectral map by checking its agreement with the BBSRT or ASCA spectra results for larger regions. In particular, we note that the Einstein and ROSAT telescopes have different spectral responses. The Einstein bandwidth includes the 2-4 keV region which is absent from ROSAT. Hence, by forming linear combinations of the Einstein and ROSAT images, we are able to resolve the contributions of the 0.5-2 keV band from the 2-4 keV band. The former contains lines of O and Fe while the latter is dominated by Si and S. We correct for the expansion that has taken place in the remnants during the ten-year interval between the Einstein and ROSAT measurements, but we must assume that no significant spectral changes have occurred during that time. The analysis of the Tycho SNR was completed and the results have been published. A copy of the paper is included. The analysis of Cas A has proved to be more complicated. It is continuing with support from another program. Part of the problem may be due to difficulties in the aspect information which is needed to precisely register the ROSAT and Einstein images.

Gorenstein, P.↗
NASA NTRS2001

Labview Interface Concepts Used in NASA Scientific Investigations and Virtual Instruments

This article provides an overview of several software control applications developed for NASA using LabVIEW. The applications covered here include (1) an Ultrasonic Measurement System for nondestructive evaluation of advanced structural materials, an Xray Spectral Mapping System for characterizing the quality and uniformity of developing photon detector materials, (2) a Life Testing System for these same materials, (3) and the instrument panel for an aircraft mounted Cloud Absorption Radiometer that measures the light scattered by clouds in multiple spectral bands. Many of the software interface concepts employed are explained. Panel layout and block diagram (code) strategies for each application are described. In particular, some of the more unique features of the applications' interfaces and source code are highlighted. This article assumes that the reader has a beginner-to-intermediate understanding of LabVIEW methods.

Roth, Don J.↗
NASA NTRS1987

Spectral reflectance of SNC meteorites: Relationships to Martian surface composition

The spectral signatures of each of the Shergottite-Nakhlite-Chassignite (SNC) meteorite types measured to date are unique among extraterrestrial materials. Reflectance spectra of dark regions of Mars show evidence of basaltic composition. Analytic analysis of absorption band positions and widths in reflectance spectra of SNC meteorites will permit comparisons with spectra from approximately 600 km sized regions for which high-quality, near-IR spectra are available. Multi-spectral mapping data from orbital spacecraft is expected to provide the necessary spectra to determine basaltic compositions of smaller regions on Mars provided fresh, unaltered basalts can be observed or the effects of Martian weathering can be understood and removed from the spectra. With modeling of spectral weathering and mixing of SNC meteoritic assemblages it should be possible with the Mars Observer data to test for the presence of SNC analogs on the Martian surface. Before the relationship between the basaltic composition of units on Mars and the SNC meteorites can be addressed, it is necessary to analyze the absorption band parameters of the SNC reflectance spectra and to acquire high resolution spectral data on smaller regions of the Martian surface.

Mcfadden, L. A.↗
NASA NTRS1988

Multisensor classification of sedimentary rocks

A comparison is made between linear discriminant analysis and supervised classification results based on signatures from the Landsat TM, the Thermal Infrared Multispectral Scanner (TIMS), and airborne SAR, alone and combined into extended spectral signatures for seven sedimentary rock units exposed on the margin of the Wind River Basin, Wyoming. Results from a linear discriminant analysis showed that training-area classification accuracies based on the multisensor data were improved an average of 15 percent over TM alone, 24 percent over TIMS alone, and 46 percent over SAR alone, with similar improvement resulting when supervised multisensor classification maps were compared to supervised, individual sensor classification maps. When training area signatures were used to map spectrally similar materials in an adjacent area, the average classification accuracy improved 19 percent using the multisensor data over TM alone, 2 percent over TIMS alone, and 11 percent over SAR alone. It is concluded that certain sedimentary lithologies may be accurately mapped using a single sensor, but classification of a variety of rock types can be improved using multisensor data sets that are sensitive to different characteristics such as mineralogy and surface roughness.

Evans, Diane↗
NASA NTRSDate not supplied

Organic-rich fluids in Pluto’s interior—A source of cryovolcanic activity

The highly variegated surface of Pluto revealed by the New Horizons spacecraft is composed of both volatile ices (N2, CH4, CO) and H2O ice, all of which are intrinsically colorless. The colors on Pluto reveal a non-ice component generally acknowledged to be a refractory complex organic material (tholins) produced by photolysis in the planet’s atmosphere [1], and by photolysis and radiolysis of the surface ices [2-4]. These processes have produced a range of colors from pale yellow to red to brown, and result in a variation of a factor of 10in albedo across the surface. Tholins are disordered polymer-like materials made of repeating chains of linked subunits and complex combinations of functional groups containing carbon. Nitrogen, oxygen, and other elements can be substituted in both the aliphatic and aromatic subunits. The detection of the spectral absorption of an ammoniated compound associated with surface exposures of red-colored H2O ice (herein, RAW) in the LEISA spectral mapping data from New Horizons suggests that a third source of a colored material is ejected from Pluto’s interior as a water-rich fluid(cryomagma) that rapidly freezes at the low temperature (~40K) of the surface [5,6]. The ammoniated compound is thought to be an ammonia hydrate or an ammoniated salt; the spectral data cover a limited wavelength range, resulting in ambiguity in the identification of the form of the ammonia. The distribution of RAW in the vicinity of tectonically stressed and deformed geological structures, particularly graben (fossae), is seen as the result of both fluid effusion and fountaining ejection of cryoclastic materials in Pluto’s Virgil Fossae region [5,6]. RAW is seen elsewhere on Pluto, both in association with graben complexes and on broad expanses of old surface, but primarily in zones of tectonic stress. The nature of the putative subsurface fluid is unknown, but it must have existed at relatively shallow depths such that the graben faulting could reach it. Geochemical modeling of fluids in the interiors of small planetary bodies in the outer Solar System[7] shows that ammonia-bearing H2O in contact with rock and metal components produce a rich chemical soup, including gases that can, in principle, help propel the fluid from shallow reservoirs through crustal fractures to reach the surface. An organic component of the fluid cryomagma is predicted to originate from thermal processing of the components [ref] and may be an example of one-pot synthesis of such complexes as amino acid precursors [ref].

Dale P Cruikshank↗
NASA NTRS1988

A Near-Infrared Mapping Spectrometer for investigation of Jupiter and its satellites

The Near-Infrared-Mapping Spectrometer (NIMS) is one of the science instruments in the Galileo mission, which will explore Jupiter and its satellites in the mid-1990's. The NIMS experiment will map geological units on the surfaces of the Jovian satellites and characterize their mineral content; and, for the atmosphere of Jupiter, investigate cloud properties and the spatial and temporal variability of molecular abundances. The optics are gold-coated reflective and consist of a telescope and a grating spectrometer. The balance of the instrument includes a 17-detector (silicon and indium antimonide) focal plane array, a tuning fork chopper, microprocessor-controlled electronics, and a passive radiative cooler. A wobbling secondary mirror in the telescope provides 20 pixels in one dimension of spatial scanning in a pushbroom mode with 0.5 mr x 0.5 mr instantaneous field of view. The spectral range is 0.7-5.2 microns; resolution is 0.025 micron. NIMS is the first infrared experiment to combine both spatial and spectral mapping capability in one instrument.

Aptaker, Irving M.↗
NASA NTRS2008

The First Detection of [O IV] from an Ultraluminous X-ray Source with Spitzer: Evidence of High Unbeamed Luminosity in Holmberg II ULX

We present the first Spitzer Infrared Spectrograph (IRS) observations of the [O IV] 25.89 micron emission line detected from the ultraluminous X-ray source (ULX) in Holmberg II. This line is a well established signature of high excitation, usually associated with AGN. Its detection suggests that the ULX has a strong impact on the surrounding gas. A Spitzer high resolution spectral map shows that the [O IV] is coincident with the X-ray position of the Holmberg II ULX. We find that the luminosity and the morphology of the line emission is consistent with photoionization by the soft X-ray and far ultraviolet (FUV) radiation from the accretion disk of the binary system and inconsistent with narrow beaming. We show that the emission nebula is radiation bounded both in the line of sight direction and to the west, and probably matter bounded to the east. Evidence for a massive black hole (BH) in this ULX is mounting. Detailed photoionization models favor an intermediate mass black hole of at least 85 Solar Mass as the ionization source for the [OIV] emission. We find that the spectral type of the companion star strongly affects the expected strength of the [O IV] emission. This finding could explain the origin of [O IV] in some starburst galaxies containing black hole binaries.

Berghea, C. T.↗
NASA NTRS2020

Visible - Near Infrared Spectral Indices for Mapping Mineralogy and Chemistry with OSIRIS-REx

The primary objective of the Origins, Spectral Interpretation, Resource Identification, SecurityRegolith Explorer (OSIRIS-REx) mission is to return to Earth a pristine sample of carbonaceous material from the primitive asteroid (101955) Bennu. To support compositional mapping as part of sample site selection and characterization, we tested 95 spectral parameters on visible to near infrared laboratory reflectance data of minerals and carbonaceous meteorites to find which of these parameters reliably identified spectral features of interest. Most spectral parameters had high positive detection rates when used on spectra of pure, single component materials. The meteorite spectra have fewer and weaker absorption features and, as a result, fewer detections with the spectral parameters. Parameters targeting absorptions at 0.7 and 2.7 – 3 µm, which arise due to hydrated minerals, were most successful for the meteorites. Based on these results, we have identified a set of 17 parameters that are most likely to be useful at Bennu and spectral analogs. These parameters detect olivines, pyroxenes, carbonates, water/OH-bearing minerals, serpentines, ferric minerals, and organics. Particle size and albedo are known to affect band depth but had a negligible impact on parameter accuracy. The effect of instrument-like noise added to the laboratory spectra can result in more false positive detections, but these exhibit large errors. Our study has determined the prioritization of spectral parameters used for OSIRISREx spectral analysis and mapping and informs the reliability of all parameter-derived data products.

Hannah H Kaplan↗
DOE OSTI2026

Disentangling multiple gas kinematic drivers in the Perseus galaxy cluster

Galaxy clusters, the Universe’s largest halo structures, are filled with an X-ray-emitting gas with a temperature between 10 million and 100 million degrees. Their evolution is shaped by energetic processes such as feedback from supermassive black holes (SMBHs) and mergers with other cosmic structures. The imprints of these processes on gas kinematics remain largely unknown, restricting our understanding of energy conversion within clusters4. High-resolution spectral mapping with the X-Ray Imaging and Spectroscopy Mission (XRISM) observatory offers a way forward. Here we present XRISM kinematic measurements of the Perseus cluster, radially covering the extent of its cool core. We find direct evidence for at least two dominant drivers of gas motions operating on distinct physical scales: a small-scale driver in the inner approximately 60 kpc, probably associated with the SMBH feedback; and a large-scale driver in the outer core, powered by mergers. This finding suggests that, during the active phase, SMBH feedback drives gas motions, which, if fully dissipated into heat, could have a substantial role in offsetting radiative cooling losses in the Perseus core. Furthermore, our study underscores the necessity of kinematic mapping observations of extended sources to robustly characterize the velocity fields and their role in the evolution of massive halos. It further offers a kinematic diagnostic for SMBH feedback models.

Astronomy and AstroPhysics↗
DOE OSTI2026

The Emission and Suppression of Line Features in Luminous Transients

Featureless optical and ultraviolet (UV) spectra are a puzzling signature to emerge from recent observations of luminous fast blue optical transients (LFBOTs) and some tidal disruption events (TDEs). We describe the landscape of source and gas properties that are expected to form H, He I , and He II emission lines, and map spectral types to the parameter space of luminosity and system radius. Using one-dimensional radiative transfer calculations, we show that high source luminosities (L > 10 44 erg s −1 ) and compact ejecta radii (r < 10 14 cm) produce featureless spectra, due to the high temperature and ionization state of the emitting medium. Intermediate luminosities and moderately compact systems can generate He II -dominated spectra, while lower luminosities and more extended atmospheres result in conspicuous H and He I emission. Large expansion velocities (v ≥ 0.1c) can further broaden lines such that they blend into the continuum. Featureless UV spectra may require even more extreme ionization environments or velocities in order to suppress the many intrinsically strong metal lines at those wavelengths. Applying this framework to understand the absence of features observed in LFBOTs and featureless TDEs, we find that, under the optically thick, quasi-thermal conditions considered here, nonhomologous, compact outflows are likely necessary for featurelessness to persist in optical and UV spectra.

Aspegren, Olivia [University of California, Berkel↗
NASA NTRS1972

Differentiating elements of the soil-vegetation complex

The application of remote sensing to study soil-vegetation systems requires quantification and precise location of ground observation data such that they can be correlated with multispectral aerial acquired data. Griddling and sampling of an area for exact identification in a known address on magnetic tape containing multispectral scanner data produces quantitative physico-chemical parameters and the energy which is radiating from within the soil-vegetation complex of an area. Example classifications and spectral mappings of soils made from multispectral scanner data are included.

Baumgardner, M. F.↗
NASA NTRS1987

A search for spectral alteration effects in chondritic gas-rich breccias

Several samples of gas-rich breccias were selected, including slabs of the Kapoeta howardite, the ordinary chondrites Dubrovnik, Cangas de Onis, and Dimmit. Numerous 0.8 to 2.5 micron reflection spectra of selected areas on sawed or broken surfaces were measured with the Planetary Geosciences Division spectrogoniometer. While these spectra are not directly comparable to those of powered samples, comparisons within the data set should reveal any spectral differences due to weathering. These results indicate that unknown regolith processes do not confer the ordinary-chondrite parent bodies with an altered layer exhibiting S-class spectral properties. This is consistent with recent interpretations of the new Q-class of asteroids as the ordinary-chondrite parent bodies. However, significant spectral effects do occur in asteroid regoliths: darkening and suppression of absorption bands in highly shocked material, as seen previously in the so-called black chondrites; and segregation of metal in large impact melt pools on chondritic asteroids, which may have achondritic spectra. Neither of these effects is likely to be significant in interpreting current integral-disk spectra, but should be searched for in spectral maps returned by future spacecraft.

Bell, J. F.↗
NASA NTRS1986

An interstellar line coincident with the P(2,1) transition of hydronium (H3O+)

Double-sideband observations of the Orion KL nebular region with the NRAO 12 m radiotelescope in March 1986 detected a weak emission spectral line that coincided with the P(2,1) rotation-inversion transition of H3O+. Spectral maps are provided for the observed line at 307,192 MHz with 2 and 1 MHz resolution. The line parameters, along with a calculated transition dipole moment of 1.44 D, are used to estimate column densities of 7.7 and 8.7 x 10 to the 13/sq cm for excitation temperatures of 50 and 90 K, respectively. A minimum H2 density of 1 million/cu cm is estimated for the region if the thermalization of the transition to the excitation temperatures is to occur. Finally, fractional abundances of H2O in the Orion cloud are projected to be 1/100,000 and 1/1 million for the nonthermal and thermal transition cases, respectively.

Hollis, J. M.↗
NASA NTRS1987

Studies of isolated neutron stars, pulsars and pulsar-driven nebulae with the advanced X-ray astrophysics facility (AXAF)

The AXAF will signal a revolution in the understanding of neutron stars, pulsars, and Crab Nebula-type supernova remnants. The mission will provide vital and detailed observational data relevant to the physics of superdense matter inside neutron stars, to the acceleration and radiation of nonthermal particles in their magnetospheres, and to the processes whereby these relativistic particles and magnetic fields fuel the surrounding synchrotron nebulosities on scales of parsecs. Highlights of the results should include (1) detection of thermal surface emission from neutron stars, (2) greatly enlarged samples of pulsars that emit magnetospheric (nonthermal) X-rays, and (3) high resolution (spatial and spectral) maps of the nebulae powered by slowing pulsars. The AXAF will extend these studies to external galaxies, being capable of detection of young pulsars and remnants in normal galaxies like M31, in starburst systems like M82, and probably even in galaxies as distant as the Virgo cluster.

Wilson, A. S.↗
NASA NTRS1991

Transformations For Atmospheric-Radiation Calculations

Atmospheric radiation calculations essential part of climate models and inversion techniques for analyzing remote sensing observations. Two spectral mapping transformation methods developed to reduce computing time and storage requirements greatly while preserving accuracy achievable with rigorous methods. Evolved from "correlated-k" (c-k) method.

West, Robert A.↗
NASA NTRS1991

A hybrid numerical method for three-dimensional spatially-developing free-shear flows

The present novel algorithm for 3D incompressible Navier-Stokes equations treats a domain which is (1) infinite in the vertical direction, using a mapped spectral method; (2) finite in the streamwise direction, using a classical Fourier method; and (3) homogeneous in the spanwise direction, using high-order compact finite differencing. A projection method is employed which ensures the exact conservation of mass, as well as the satisfaction of the boundary conditions at infinity. The novel aspects of these methods are noted, and the code they constitute is validated in light of several test cases. Results are presented for two- and three-dimensional mixing layers.

Buell, Jeffrey C.↗