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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 937 records · Page 52
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Broadband Direct Detection Submillimeter Spectrometer with Multiplexed Superconducting Transition Edge Thermometer Bolometers

We present performance results based on the first astronomical use of multiplexed superconducting bolometers as direct detectors (i.e., with cold electrons) for spectroscopy. The Fabry-Perot Interferometer Bolometer Research Experiment (FIBRE) is a broadband submillimeter spectrometer for the Caltech Submillimeter Observatory (CSO). FIBRE's detectors are superconducting transition edge sensor (TES) bolometers read out by a SQUID multiplexer. The Fabry-Perot uses a low resolution grating to order sort the incoming light. A linear bolometer array consisting of 16 elements detects this dispersed light, capturing 5 orders simultaneously from one position on the sky. With tuning of the Fabry-Perot over one free spectral range, a spectrum covering Delta lambda/lambda = 1/7 at a resolution of delta lambda/lambda = 1/1200 can be acquired. This spectral resolution is sufficient to resolve Doppler-broadened line emission from external galaxies. FIBRE has been operated in the 350 Am (850 GHz) band. These bands cover line emission from the important star formation tracers neutral carbon [CI] and carbon monoxide (CO).

Benford, D. J.↗
NASA NTRS1986

X-Ray Imaging System

The FluoroScan Imaging System is a high resolution, low radiation device for viewing stationary or moving objects. It resulted from NASA technology developed for x-ray astronomy and Goddard application to a low intensity x-ray imaging scope. FlouroScan Imaging Systems, Inc, (formerly HealthMate, Inc.), a NASA licensee, further refined the FluoroScan System. It is used for examining fractures, placement of catheters, and in veterinary medicine. Its major components include an x-ray generator, scintillator, visible light image intensifier and video display. It is small, light and maneuverable.

Source record↗
NASA NTRS2002

Discontinuous Galerkin Methods for Turbulence Simulation

A discontinuous Galerkin (DG) method is formulated, implemented, and tested for simulation of compressible turbulent flows. The method is applied to turbulent channel flow at low Reynolds number, where it is found to successfully predict low-order statistics with fewer degrees of freedom than traditional numerical methods. This reduction is achieved by utilizing local hp-refinement such that the computational grid is refined simultaneously in all three spatial coordinates with decreasing distance from the wall. Another advantage of DG is that Dirichlet boundary conditions can be enforced weakly through integrals of the numerical fluxes. Both for a model advection-diffusion problem and for turbulent channel flow, weak enforcement of wall boundaries is found to improve results at low resolution. Such weak boundary conditions may play a pivotal role in wall modeling for large-eddy simulation.

Collis, S. Scott↗
NASA NTRS2003

Future Applications of Remote Sensing to Archeological Research

Archeology was one of the first disciplines to use aerial photography in its investigations at the turn of the 20th century. However, the low resolution of satellite technology that became available in the 1970 s limited their application to regional studies. That has recently changed. The arrival of the high resolution, multi-spectral capabilities of the IKONOS and QUICKBIRD satellites and the scheduled launch of new satellites in the next few years provides an unlimited horizon for future archeological research. In addition, affordable aerial and ground-based remote sensing instrumentation are providing archeologists with information that is not available through traditional methodologies. Although many archeologists are not yet comfortable with remote sensing technology a new generation has embraced it and is accumulating a wealth of new evidence. They have discovered that through the use of remote sensing it is possible to gather information without disturbing the site and that those cultural resources can be monitored and protected for the future.

Sever, Thomas L.↗
NASA NTRS2000

Stennis Space Center Environmental Geographic Information System

As NASA's lead center for rocket propulsion testing, the John C. Stennis Space Center (SSC) monitors and assesses the off-site impacts of such testing through its Environmental Office (SSC-EO) using acoustical models and ancillary data. The SSC-EO has developed a geographical database, called the SSC Environmental Geographic Information System (SSC-EGIS), that covers an eight-county area bordering the NASA facility. Through the SSC-EGIS, the Enivronmental Office inventories, assesses, and manages the nearly 139,000 acres that comprise Stennis Space Center and its surrounding acoustical buffer zone. The SSC-EGIS contains in-house data as well as a wide range of data obtained from outside sources, including private agencies and local, county, state, and U.S. government agencies. The database comprises cadastral/geodetic, hydrology, infrastructure, geo-political, physical geography, and socio-economic vector and raster layers. The imagery contained in the database is varied, including low-resolution imagery, such as Landsat TM and SPOT; high-resolution imagery, such as IKONOS and AVIRIS; and aerial photographs. The SSC-EGIS has been an integral part of several major projects and the model upon which similar EGIS's will be developed for other NASA facilities. The Corps of Engineers utilized the SSC-EGIS in a plan to establish wetland mitigation sites within the SSC buffer zone. Mississippi State University employed the SSC-EGIS in a preliminary study to evaluate public access points within the buffer zone. The SSC-EO has also expressly used the SSC-EGIS to assess noise pollution modeling, land management/wetland mitigation assessment, environmental hazards mapping, and protected areas mapping for archaeological sites and for threatened and endangered species habitats. The SSC-EO has several active and planned projects that will also make use of the SSC-EGIS during this and the coming fiscal year.

Lovely, Janette↗
NASA NTRS2003

Evaluation of the Space Shuttle Transatlantic Abort Landing Atmospheric Sounding System

A study was conducted to determine the quality of thermodynamic and wind data measured by or derived from the Transatlantic Abort Landing (TAL) Atmospheric Sounding System (TASS). The system has Global Positioning System (GPS) tracking capability and includes a helium-filled latex balloon that carries an instrument package (sonde) and various ground equipment that receives and processes the data from the sonde. TASS is used to provide vertical profiles of thermodynamic and low-resolution wind data in support of Shuttle abort landing operations at TAL sites. TASS uses GPS to determine height, wind speed, and wind direction. The TASS sonde has sensors that directly measure air temperature and relative humidity. These are then used to derive air pressure and density. Test flights were conducted where a TASS sonde and a reference sonde were attached to the same balloon and the two profiles were compared. The objective of the testing was to determine if TASS thermodynamic and wind data met Space Shuttle Program (SSP) accuracy requirements outlined in the Space Shuttle Launch and Landing Program Requirements Document (PRD).

Leahy, Frank B.↗
NASA NTRS2004

Evaluation of the Space Shuttle Transatlantic Abort Landing Atmospheric Sounding System

This paper describes a study that was conducted to determine the quality of thermodynamic and wind data measured by the Space Shuttle Transatlantic Abort Landing (TAL) Atmospheric Sounding System (TASS). The system has Global Positioning System (GPS) tracking capability and provides profiles of atmospheric parameters such as temperature, relative humidity, and wind in support of potential emergency Space Shuttle landings at TAL sites. Ten comparison flights between the Low-Resolution Flight Element (LRFE) of the Automated Meteorological Profiling System (AMPS) and TASS were conducted at the Eastern Test Range (ETR) in early 2002. Initial results indicated that wind, temperature, and relative humidity compared well. However, incorrect GPS settings in the TASS software were resulting in altitude differences of about 60 to 70 m (approximately 200 to 230 ft) and air pressure differences of approximately 4 hectoPascals (hPa). TASS software updates to correct altitude data were completed in early 2003. Subsequent testing showed that altitude and air pressure differences were generally less than 5 m and 1 hPa, respectively.

Leahy, Frank B.↗
NASA NTRS1987

Geometrical analysis of Cys-Cys bridges in proteins and their prediction from incomplete structural information

Analysis of C-alpha atom positions from cysteines involved in disulphide bridges in protein crystals shows that their geometric characteristics are unique with respect to other Cys-Cys, non-bridging pairs. They may be used for predicting disulphide connections in incompletely determined protein structures, such as low resolution crystallography or theoretical folding experiments. The basic unit for analysis and prediction is the 3 x 3 distance matrix for Cx positions of residues (i - 1), Cys(i), (i +1) with (j - 1), Cys(j), (j + 1). In each of its columns, row and diagonal vector--outer distances are larger than the central distance. This analysis is compared with some analytical models.

NASA Discipline Exobiology↗
NASA NTRS1999

Classification of ion mobility spectra by functional groups using neural networks

Neural networks were trained using whole ion mobility spectra from a standardized database of 3137 spectra for 204 chemicals at various concentrations. Performance of the network was measured by the success of classification into ten chemical classes. Eleven stages for evaluation of spectra and of spectral pre-processing were employed and minimums established for response thresholds and spectral purity. After optimization of the database, network, and pre-processing routines, the fraction of successful classifications by functional group was 0.91 throughout a range of concentrations. Network classification relied on a combination of features, including drift times, number of peaks, relative intensities, and other factors apparently including peak shape. The network was opportunistic, exploiting different features within different chemical classes. Application of neural networks in a two-tier design where chemicals were first identified by class and then individually eliminated all but one false positive out of 161 test spectra. These findings establish that ion mobility spectra, even with low resolution instrumentation, contain sufficient detail to permit the development of automated identification systems.

Non-NASA Center↗
NASA NTRS1986

Multistep modeling of protein structure: application to bungarotoxin

Modelling of bungarotoxin in atomic details is presented in this article. The model-building procedure utilizes the low-resolution crystal coordinates of the c-alpha atoms of bungarotoxin, sequence homology within the neurotoxin family, as well as high-resolution x-ray diffraction data of cobratoxin and erabutoxin. Our model-building procedure involves: (a) principles of comparative modelling, (b) embedding procedures of distance geometry, and (c) use of molecular mechanics for optimizing packing. The model is not only consistent with the c-alpha coordinates of crystal structure, but also agrees with solution conformational features of the triple-stranded beta sheet as observed by NOE measurements.

NASA Discipline Exobiology↗
NASA NTRS1993

Ten years in the library: new data confirm paleontological patterns

A comparison is made between compilations of times of origination and extinction of fossil marine animal families published in 1982 and 1992. As a result of ten years of library research, half of the information in the compendia has changed: families have been added and deleted, low-resolution stratigraphic data been improved, and intervals of origination and extinction have been altered. Despite these changes, apparent macroevolutionary patterns for the entire marine fauna have remained constant. Diversity curves compiled from the two data bases are very similar, with a goodness-of-fit of 99%; the principal difference is that the 1992 curve averages 13% higher than the older curve. Both numbers and percentages of origination and extinction also match well, with fits ranging from 83% to 95%. All major events of radiation and extinction are identical. Therefore, errors in large paleontological data bases and arbitrariness of included taxa are not necessarily impediments to the analysis of pattern in the fossil record, so long as the data are sufficiently numerous.

NASA Discipline Number 52-40↗
NASA NTRS2005

Miniaturized system of a gas chromatograph coupled with a Paul ion trap mass spectrometer

Miniature gas chromatography (GC) and miniature mass spectrometry (MS) instrumentation has been developed to identify and quantify the chemical compounds present in complex mixtures of gases. The design approach utilizes micro-GC components coupled with a Paul quadrupole ion trap (QIT) mass spectrometer. Inherent to the system are high sensitivity, good dynamic range, good QIT resolution, low GC flow-rates to minimize vacuum requirements and the need for consumables; and the use of a modular approach to adapt to volatile organic compounds dissolved in water or present in sediment. Measurements are reported on system response to gaseous species at concentrations varying over four orders of magnitude. The ability of the system to deal with complicated mixtures is demonstrated, and future improvements are discussed. The GC/QIT system described herein has a mass, volume and power that are, conservatively, one-twentieth of those of commercial off-the-shelf systems. Potential applications are to spacecraft cabin-air monitoring, robotic planetary exploration and trace-species detection for residual gas analysis and environmental monitoring.

Miniaturization/instrumentation/methods↗
NASA NTRS2005

The First Six Months of Iapetus Observations by the Cassini ISS Camera

Since Saturn arrival in June 2004, Iapetus has been studied intensively by the Cassini ISS camera [1] at various ranges. The first of two relatively close flybys in the primary mission occurred on Dec 31, 2004 at an altitude of approx.123,400 km over the northern leading hemisphere, resulting in images with a minimum pixel scale of 740 m. Detailed results of this flyby are given in [2], while this abstract covers the observations obtained earlier. Among the most important discoveries are: (a) Four giant impact basins with diameters between 390 and 550 km were detected, three of them are located in the dark terrain [3]. (b) Data revealed a >1300 km long ridge that marks exactly Iapetus' equator within the dark terrain. Individual mountains within the western part of the ridge reach heights of approx.20 km over surrounding terrain [3]. (c) Impact craters were confirmed to be the main geological feature within the dark terrain and at high southern latitudes. (d) There are numerous craters with dark walls roughly facing towards the central parts of the dark hemisphere [3]. (e) Almost all parts of Iapetus have been imaged at least at low resolution (< 60 km/pxl).

Denk, T.↗
NASA NTRS2005

Ultraviolet Views of Enceladus, Tethys, and Dione

The Cassini Ultraviolet Imaging Spectrograph (UVIS) has collected ultraviolet observations of many of Saturn's icy moons since Cassini's insertion into orbit around Saturn. We will report on results from Enceladus, Tethys and Dione, orbiting in the Saturn system at distances of 3.95, 4.88 and 6.26 Saturn radii, respectively. Icy satellite science objectives of the UVIS include investigations of surface age and evolution, surface composition and chemistry, and tenuous exospheres. We address these objectives by producing albedo maps, and reflection and emission spectra, and observing stellar occultations. UVIS has four channels: EUV: Extreme Ultraviolet (55 nm to 110 nm), FUV: Far Ultraviolet (110 to 190 nm), HSP: High Speed Photometer, and HDAC: Hydrogen-Deuterium Absorption Cell. The EUV and FUV spectrographs image onto a 2-dimensional detector, with 64 spatial rows by 1024 spectral columns. To-date we have focused primarily on the far ultraviolet data acquired with the low resolution slit width (4.8 angstrom spectral resolution). Additional information is included in the original extended abstract.

Hansen, C. J.↗
NASA NTRS2004

Novel Image Processing Interface to Relate DSB Spatial Distribution from Immunofluorescence Foci Experiments to the State-of-the-Art Models of DNA Breakage

A recently developed software (NASARadiationTrackImage) allows a quick and automatic segmentation of foci that indicate spatial localization of specific proteins that are visualized by immunofluorescence. Of interest are the spatial and temporal distribution of foci such as gammaH2AX, a signal of the phosphorylation of a variant of the histone H2A that has been shown to correspond to DSBs, or proteins involved in DSB processing, such as ATM, Rad51, and p53, following exposures of human cells to high charge and energy (HZE) ion irradiation. Experimental data are recorded as sets of two-dimensional images in color with cells and foci of gammaH2AX, ATM, Rad51 or others shown. Different cells, levels of radiation and timing after radiation were recorded. The software allows us to calculate the number of foci per cell, overall intensity of light in foci and their spatial organization. A simple statistical model allows for testing of foci overlap (eclipse). A more complex statistical model previously known as DNAbreak simulates track structure and random chromosome geometry. It has one adjustable parameter corresponding to an average intensity of DSB creation in cubic micrometers of DNA volume per particle track or unit dose. Its limitation is the low-resolution limit both in physical space and DSB's along DNA. It works adequately on the scale of a cell and provides further insights on how the geometry of tracks and DNA affects genomic damage of the cell and subsequent repair. Future developments of the model for the description of the time evolution of DNA damage response proteins, and more robust track structure models will be discussed.

Ponomarev, A. L.↗
NASA NTRS2005

Optical and X-ray studies of chromospherically active stars: FR Cancri, HD 95559 and LO Pegasi

We present a multiwavelength study of three chromospherically active stars, namely FR Cnc (= BD +16 degrees 1753), HD 95559 and LO Peg (=BD +22 degrees 4409), including newly obtained optical photometry, (for FR Cnc) low-resolution optical spectroscopy, as well as archival IR and X-ray observations. The BVR photometry carried out during the years 2001 - 2004 has found significant photometric variability to be present in all three stars. For FR Cnc, a photometric period 0.826685 +/- 0.000034 d has been established. The strong variation in the phase and amplitude of the FR Cnc light curves when folded on this period implies the presence of evolving and migrating spots or spot groups on its surface. Two independent spots with migration periods of 0.97 and 0.93 years respectively are inferred. The photometry of HD 95559 suggests the formation of a spot (group) during the interval of our observations. We infer the existence of two independent spots or groups in the photosphere of LO Peg, one of which has a migration period of 1.12 years. The optical spectroscopy of FR Cnc carried out during 2002-2003, reveals the presence of strong and variable Ca I1 H and K, H(sub beta) and H(sub alpha) emission features indicative of high level of chromospheric activity. The value of 5.3 for the ratio of the excess emission in H(sub alpha) to H(sub beta), EH(sub alpha)/EH(sub beta), suggests that the chromospheric emission may arise from an extended off-limb region. We have searched for the presence of color excesses in the near-IR JHK bands of these stars using 2MASS data, but none of them appear to have any significant color excess. We have also analyzed archival X-ray observations of HD 95559 and LO Peg carried out by with the ROSAT observatory. The best fit models to their X-ray spectra imply the presence of two coronal plasma components of differing temperatures and with sub-solar metal abundances. The inferred emission measures and temperatures of these systems are similar to those found for other active dwarf stars. The kinematics of FR Cnc suggest that it is a very young (35 - 55 Myrs) main-sequence star and a possible member of the IC 2391 supercluster. LO Peg also has young disk-type kinematics and has been previously suggested to be a member of the 100 Mys old Local Association (Pleiades Moving Group). The kinematics of HD 95559 indicate it is a possible member of the 600 Myrs old Hyades supercluster.

Pandey, J. C.↗
NASA NTRS2005

Satellite Calibration With LED Detectors at Mud Lake

Earth-monitoring instruments in orbit must be routinely calibrated in order to accurately analyze the data obtained. By comparing radiometric measurements taken on the ground in conjunction with a satellite overpass, calibration curves are derived for an orbiting instrument. A permanent, automated facility is planned for Mud Lake, Nevada (a large, homogeneous, dry lakebed) for this purpose. Because some orbiting instruments have low resolution (250 meters per pixel), inexpensive radiometers using LEDs as sensors are being developed to array widely over the lakebed. LEDs are ideal because they are inexpensive, reliable, and sense over a narrow bandwidth. By obtaining and averaging widespread data, errors are reduced and long-term surface changes can be more accurately observed.

Hiller, Jonathan D.↗