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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 NTRS1993

(abstract) Monitoring Seasonal State and Mapping Species in Alaskan Taiga Using Imaging Radar as Input to CO(sub 2) Flux Models

Changes in the seasonal CO(sub 2) flux of the boreal forests may result from increased atmospheric CO(sub 2) concentrations and associated atmospheric warming. To monitor this potential change, a combination of remote sensing information and ecophysiological models are required. In this paper we address the use of synthetic aperture radar (SAR) data to provide some of the input to the ecophysiological models: forest type, freeze/thaw state which limits the growing season for conifers, and leaf on/off state which limits the growing season for deciduous species. AIRSAR data collected in March 1988 during an early thaw event and May 1991 during spring breakup are used to generate species maps and to determine the sensitivity of SAR to canopy freeze/thaw transitions. These data are also used to validate a microwave scattering model which is then used to determine the sensitivity of SAR to leaf on/off and soil freeze/thaw transitions. Finally, a CO(sub 2) flux algorithm which utilizes SAR data and an ecophysiological model to estimate CO(sub 2) flux is presented. CO(sub 2) flux maps are generated from which areal estimates of CO(sub 2) flux are derived.

leaf cover boreal forests radar backscatter↗
NASA NTRS1973

Radar studies of arctic ice and development of a real-time Arctic ice type identification system

Studies were conducted to develop a real-time Arctic ice type identification system. Data obtained by NASA Mission 126, conducted at Pt. Barrow, Alaska (Site 93) in April 1970 was analyzed in detail to more clearly define the major mechanisms at work affecting the radar energy illuminating a terrain cell of sea ice. General techniques for reduction of the scatterometer data to a form suitable for application of ice type decision criteria were investigated, and the electronic circuit requirements for implementation of these techniques were determined. Also, consideration of circuit requirements are extended to include the electronics necessary for analog programming of ice type decision algorithms. After completing the basic circuit designs a laboratory model was constructed and a preliminary evaluation performed. Several system modifications for improved performance are suggested. (Modified author abstract)

Rouse, J. W., Jr.↗
NASA NTRS2003

Spectroscopy and Photometry of the Earth Grazer 2002 NY40

The near Earth asteroid 2002 NY40 was discovered on July 14, 2002 by the LINEAR survey. The object was predicted to make a close pass by the Earth on August 18, which led to observations at a large range of wavelengths, including radar. The combination of visible and near infrared spectroscopy/spectrophotometry gives some indication of the composition. Thermal emission in the 3 micron spectral region gives constraints on the albedo, which is consistent with the spectral type and with the available size from the radar measurements. The lightcurve was well measured by a large number of observers, which helps to determine the rotation phase of the observations at the various wavelengths. The favorable observing conditions and rapid dissemination of the astrometry have led to a good physical characterization of this object, which is relatively rare for a newly discovered near Earth asteroid. The data sets reported in this abstract are shown.

Rivkin, A. S.↗
NASA NTRS1989

An interactive, discipline-independent data visualization system

The data visualization techniques used by National Space Science Data Center Graphics System are discussed. The system includes a self-describing data abstraction for the storage and manipulation of multidimensional data for discipline-independent scientific applications. The system's data format and graphics display are described. Consideration is given to techniques developed for the rapid display and manipulation of large, complex data sets and for manipulating algorithms with portable implementations which can operate on any data object or geometry. The processes of operating the system are given and examples are presented from applying the system to various types of data, including TOMS data, data from the International Satellite Cloud Climatology Project, and IRAS data.

Treinish, Lloyd A.↗
NASA NTRS1998

X-Ray Spectrum of a Narrow-Line QSO

During the reporting period, seven papers using ASCA data, supported in whole or in part by this grant, were published or submitted to refereed journals. Their abstracts are given in this report, and the complete bibliographic references are listed in the Appendix. Titles include (1) A Broad-Band X-ray Study of the Geminga Pulsar; (2) ASCA Observations of PSR 1920+10 and PSR 0950+08; (3) X-ray and Optical Spectroscopy of IRAS 20181-2244: Not a Type 2 QSO, but a I Zw I Object; (4) Models for X-ray Emission from Isolated Pulsars; (5) Optical and X-ray Spectroscopy of 1E 0449.4-1823: Demise of the Original Type 2 QSO; (6) The ASCA Spectrum of the Broad-Line Radio Galaxy Pictor A: A Simple Power Law with No Fe Ka Line; and (7) ASCA Spectra of NGC 4388 and ESO 103-G35: Absorption, Reflection, and Variability in Intermediate Type Seyfert Galaxies.

Halpern, Jules P.↗
NASA NTRS1999

MOLA-derived Roughness Data Used to Predict Surface Scattering for Mars Subsurface Radar Sounding

The Mars Express orbiter, to be launched by the European Space Agency in 2003, will carry a low-frequency radar sounding instrument, MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding). The primary goal of MARSIS is to map the distribution of water, both solid and (if present) liquid, in the upper several km of the martian crust. Detecting discontinuities in the crust, such as an ice-water transition, presents many challenges for a Mars orbital radar sounder. One challenge that must be overcome is the presence of radar scattering (echoes) from the surface of Mars, expected to be detected by the sounder antennas at the same time as any echoes aris-ing from subsurface interfaces. As the transmitted spherical wavefront spreads within the crust of Mars,. it also interacts with surface topography at off-nadir positions, creating a "clutter" signal that can mask the subsurface echoes. The MARSIS instrument will utilize Doppler filtering to limit the off-nadir clutter in the along-track direction, and a nadir-null secondary antenna to identify strong off-nadir clutter from the cross-track direction. To evaluate the effects of off-nadir surface clutter and the capability of these schemes to reduce the clutter, it is necessary to predict the range of scattering behavior that may be expected from martian surface topography. In this paper, we utilize Mars Orbital Laser Altimeter (MOLA) data from the current Mars Global Surveyor mission to characterize the topographic roughness of a variety of martian terrain types, at scales relevant to the MARSIS clutter problem. Segments of MOLA altimetry profiles are reduced to the topographic parameters rms slope and fractal dimension, which then are used as inputs to a near-nadir radar scattering model to predict the strength of the clutter signal. Additional information is contained in the original extended abstract.

Plaut, J. J.↗
NASA NTRS1973

Review of current sonic boom studies.

Several aspects of the sonic boom phenomena are currently under investigation at The Boeing Co. This work, supported by the NASA and the FAA, includes an in-depth analysis of sonic boom measurements recorded at the BREN tower, a summary and evaluation of sonic boom investigations done in the last decade and a half, and configuration studies to determine practical lower bound sonic boom limits. The BREN tower test program yielded unique and valuable data because it was the first time that vertical profile measurements were made through caustics produced by maneuvers and atmospheric refraction. The objective of the second effort is to compile in a single reference an annotated abstract, including significant results, for each published sonic boom study and to provide a comprehensive review of the current state of the art to aid future researchers. The configuration work is devoted toward determining the feasibility of supersonic transport type airplanes with a primary design goal of acceptable sonic boom characteristics. Each of these investigations is briefly reviewed and significant results are discussed.

Kane, E. J.↗
NASA NTRS2012

Relationship Between Iron Valence States of Serpentine in CM Chondrites and Their Aqueous Alteration Degrees

The 0.6-0.7 micron absorption band observed for C-type asteroids is caused by the presence of Fe(3+) in phyllosilicates . Because Fe-bearing phyllosilicates, especially serpentine, are the most dominant product of aqueous alteration in the most abundant carbonaceous chondrites, CM chondrites, it is important to understand the crystal chemistry of serpentine in CM chondrites to better understand spectral features of C-type asteroids. CM chondrites show variable degrees of aqueous alteration, which should be related to iron valences in serpentine. It is predicted that the Fe(3+)/Sum of (Fe) ratios of serpentine in CM chondrites decrease as alteration proceeds by Si and Fe(3+) substitutions from end-member cronstedtite to serpentine, which should be apparent in the absorption intensity of the 0.6-0.7 micron band from C-type asteroids. In fact, the JAXA Hayabusa 2 target (C-type asteroid: 1993 JU3) exhibits heterogeneous spectral features (0.7 micron absorption band disappears by rotation). From these points of view, we have analyzed iron valences of matrix serpentine in several CM chondrites which span the entire observed range of aqueous alteration using Synchrotron Radiation X-ray Absorption Near-Edge Structure (SR-XANES). In this abstract we discuss the relationship between obtained Fe(3+)/Sum of (Fe) ratios and alteration degrees by adding new data to our previous studies

Mikouchi, T.↗
NASA NTRS2004

Gender and Decompression Sickness: A Critical Review and Analysis

The author addressed the following questions: are women at greater risk of decompression sickness and venous gas emboli at certain times in their reproductive cycle, is risk modified by the use of birth control pills (BCP), and is there a difference in overall risk between men and women under the same decompression dose? The summary considers information from the few abstracts and reports that were available. Except for the observation of more Type II DCS in women, particularly in women who fly after diving, there was no compelling evidence of a difference in DCS risk between men and women SCUBA divers. Many women that presented with DCS symptoms seemed to be in or near menses, with statistically fewer cases reported as time increased from menses. There was no compelling evidence that the use of BCP in SCUBA divers increases the risk of DCS. There were insufficient data about VGE from SCUBA diving to make any conclusion about the incidence of VGE and gender. In contrast, there were ample data about VGE from research in altitude chambers. Women produced less VGE and less Grade IV VGE compared to men under the same decompression dose, certainly when resting oxygen prebreathe (PB) was performed prior to ascent to altitude. Dual-cycle ergometry exercise during PB tends to reduce the differences in VGE between men and women. There was no compelling evidence that the risk of altitude DCS was different between men and women. However, a large number of DCS cases were associated with menses, and the use of BCP did seem to put women at a slightly greater risk than those that did not use BCP. There were substantial observations that women comprised a larger number of difficult cases that required complicated medical management.

Source record↗
NASA NTRS2018

SpaceWire as a Cube-Sat Instrument Interface

SpaceWire is used in the control and data interface for an instrument on a pair of small satellites, one of which was launched in summer 2017. The instrument SpaceWire interface is implemented in a Field Programmable Gate Array as an instantiated core controlled by a LEON3FT CPU, which is also implemented as an instantiated core. The UT699 processor in the flight computer provides the spacecraft side’s SpaceWire interface. A simple message based protocol consisting of four message types was defined, based on existing SpaceWire standards. One was for passing commands to and responses from the instrument in the form of text strings similar to those from a system console where each line of text is passed in a SpaceWire message. Another was for passing spacecraft time to the instrument. The third was for transferring files using a subset of the Remote Memory Access Protocol (RMAP). The fourth was for retrieving science data from the instrument. A set of user application programming interface (API) routines provided an abstracted interface to both the serial console (used during debug) and the SpaceWire device interface. Early instrument development and testing was done with a set of utilities that controlled a Star-Dundee USB-SpaceWire brick providing a user interface similar to a serial console terminal emulator with the addition of file and data transfers. Later in the integration and test process, these utilities were integrated with the COSMOS ground systems software used for spacecraft control, providing a seamless transition from standalone instrument tests to benchtop flat-sat test and full spacecraft level tests.

Lux, James P.↗
NASA NTRS2006

X-Windows PVT Widget Class

The X-Windows Process Validation Table (PVT) Widget Class ( Class is used here in the object-oriented-programming sense of the word) was devised to simplify the task of implementing network registration services for Information Sharing Protocol (ISP) graphical-user-interface (GUI) computer programs. Heretofore, ISP PVT programming tasks have required many method calls to identify, query, and interpret the connections and messages exchanged between a client and a PVT server. Normally, programmers have utilized direct access to UNIX socket libraries to implement the PVT protocol queries, necessitating the use of many lines of source code to perform frequent tasks. Now, the X-Windows PVT Widget Class encapsulates ISP client server network registration management tasks within the framework of an X Windows widget. Use of the widget framework enables an X Windows GUI program to interact with PVT services in an abstract way and in the same manner as that of other graphical widgets, making it easier to program PVT clients. Wrapping the PVT services inside the widget framework enables a programmer to treat a PVT server interface as though it were a GUI. Moreover, an alternate subclass could implement another service in a widget of the same type. This program was written by Matthew R. Barry of United Space Alliance for Johnson Space Center. For further information, contact the Johnson Technology Transfer Office at (281) 483-3809. MSC-23582 Shuttle Data Center File- Processing Tool in Java A Java-language computer program has been written to facilitate mining of data in files in the Shuttle Data Center (SDC) archives. This program can be executed on a variety of workstations or via Web-browser programs. This program is partly similar to prior C-language programs used for the same purpose, while differing from those programs in that it exploits the platform-neutrality of Java in implementing several features that are important for analysis of large sets of time-series data. The program supports regular expression queries of SDC archive files, reads the files, interleaves the time-stamped samples according to a chosen output, then transforms the results into that format. A user can choose among a variety of output file formats that are useful for diverse purposes, including plotting, Markov modeling, multivariate density estimation, and wavelet multiresolution analysis, as well as for playback of data in support of simulation and testing.

Barry, Matthew R.↗
NASA NTRS2005

An XML Representation for Crew Procedures

NASA ensures safe operation of complex systems through the use of formally-documented procedures, which encode the operational knowledge of the system as derived from system experts. Crew members use procedure documentation on the ground for training purposes and on-board space shuttle and space station to guide their activities. Investigators at JSC are developing a new representation for procedures that is content-based (as opposed to display-based). Instead of specifying how a procedure should look on the printed page, the content-based representation will identify the components of a procedure and (more importantly) how the components are related (e.g., how the activities within a procedure are sequenced; what resources need to be available for each activity). This approach will allow different sets of rules to be created for displaying procedures on a computer screen, on a hand-held personal digital assistant (PDA), verbally, or on a printed page, and will also allow intelligent reasoning processes to automatically interpret and use procedure definitions. During his NASA fellowship, Dr. Simpson examined how various industries represent procedures (also called business processes or workflows), in areas such as manufacturing, accounting, shipping, or customer service. A useful method for designing and evaluating workflow representation languages is by determining their ability to encode various workflow patterns, which depict abstract relationships between the components of a procedure removed from the context of a specific procedure or industry. Investigators have used this type of analysis to evaluate how well-suited existing workflow representation languages are for various industries based on the workflow patterns that commonly arise across industry-specific procedures. Based on this type of analysis, it is already clear that existing workflow representations capture discrete flow of control (i.e., when one activity should start and stop based on when other activities start and stop), but do not capture the flow of data, materials, resources or priorities. Existing workflow representation languages are also limited to representing sequences of discrete activities, and cannot encode procedures involving continuous flow of information or materials between activities.

Simpson, Richard C.↗
NASA NTRS1972

Thermal characteristics of the moon.

The papers describe earth-based and in situ surface measurements of the thermal characteristics of lunar-type materials. A geophysical interpretation of the thermal history of the moon is given. Microwave emission from the moon and radar mapping of lunar surface roughness are studied. Lunar thermal aspects from Surveyor data, lunar surface temperatures from Apollo 11 data, the development of an in situ thermal conductivity measurement for the lunar heat flow experiment, and the Apollo 15 lunar heat flow measurement are reviewed. Thermal properties of granulated materials, thermal property measurements on lunar material returned by Apollo 11 and 12 missions, and thermal characteristics of lunar surface roughness are discussed. Individual items are abstracted in this issue.

Lucas, J. W.↗
NASA NTRS1982

Modelling of photodegradation in solar cell modules of substrate and superstrate design made with ethylene-vinyl acetate as pottant material

A computer model which simulates, in principle, the chemical changes in the photooxidation of hydrocarbons using as input data a set of elementary reactions, corresponding kinetic rate data and appropriate initial conditions was developed. The Model was refined and exploited to examine more closely the photooxidation and photostabilization of a hydrocarbon polymer. The results lead to the following observations. (1) The time to failure, tau sub f (chosen as the level of 5% C-H bond oxidation which is within the range anticipated for marked change in mechanical properties) varies as the inverse square root of the light intensity. However, tau sub f is almost unaffected by both the photoinitiator type and concentration. (2) The time to failure decreases with the rate of abstraction of C-H by peroxy radicals but increases with the rate of bimolecular radical termination controlled by diffusion. (3) Of the various stabilization mechanisms considered, the trapping of peroxy radicals is distinctly the most effective, although the concommitant decomposition of hydroperoxide is also desirable.

Somersall, A. C.↗
NASA NTRS1994

Comparative transduction mechanisms of hair cells in the bullfrog utriculus. II. Sensitivity and response dynamics to hair bundle displacement

1. Hair cells in whole-mount in vitro preparations of the utricular macula of the bullfrog (Rana catesbeiana) were selected according to their macular location and hair bundle morphology. The sensitivity and response dynamics of selected hair cells to natural stimulation were examined by recording their voltage responses to step and sinusoidal hair bundle displacements applied to their longest stereocilia. 2. The voltage responses of 31 hair cells to sinusoidal hair bundle displacements were characterized by their gains and phases, taken with respect to peak hair bundle displacement. The gains of Type B and Type C cells at both 0.5 and 5.0 Hz were markedly lower than those of Type F and Type E cells. Phases, with the exception of Type C cells, lagged hair bundle displacement at 0.5 Hz. Type C cells had phase leads of 25-40 degrees. At 5.0 Hz, response phases in all cells were phase lagged with respect to those at 0.5 Hz. Type C cells had larger gains and smaller phase leads at 5.0 Hz than at 0.5 Hz, suggesting the presence of low-frequency adaptation. 3. Displacement-response curves, derived from the voltage responses to 5.0-Hz sinusoids, were sigmoidal in shape and asymmetrical, with the depolarizing response having a greater magnitude and saturating less abruptly than the hyperpolarizing response. When normalized to their largest displacement the linear ranges of these curves varied from < 0.5 to 1.25 microns and were largest in Type B and smallest in Type F and Type E cells. Sensitivity, defined as the slope of the normalized displacement-response curve, was inversely correlated with linear range. 4. The contribution of geometric factors associated with the hair bundle to linear range and sensitivity were predicted from realistic models of utricular hair bundles created using morphological data obtained from light and electron microscopy. Three factors, including 1) the inverse ratio of the lengths of the kinocilium and longest stereocilia, representing the lever arm between kinociliary and stereociliary displacement; 2) tip link extension/linear displacement, largely a function of stereociliary height and separation; and 3) stereociliary number, an estimate of the number of transduction channels, were considered in this analysis. The first of these factors was quantitatively more important than the latter two factors and their total contribution was largest in Type B and Type C cells. Theoretical models were also used to calculate the relation between rotary and linear displacement.(ABSTRACT TRUNCATED AT 400 WORDS).

Non-NASA Center↗
NASA NTRS1990

Management and display of four-dimensional environmental data sets using McIDAS

Over the past four years, great strides have been made in the areas of data management and display of 4-D meteorological data sets. A survey was conducted of available and planned 4-D meteorological data sources. The data types were evaluated for their impact on the data management and display system. The requirements were analyzed for data base management generated by the 4-D data display system. The suitability of the existing data base management procedures and file structure were evaluated in light of the new requirements. Where needed, new data base management tools and file procedures were designed and implemented. The quality of the basic 4-D data sets was assured. The interpolation and extrapolation techniques of the 4-D data were investigated. The 4-D data from various sources were combined to make a uniform and consistent data set for display purposes. Data display software was designed to create abstract line graphic 3-D displays. Realistic shaded 3-D displays were created. Animation routines for these displays were developed in order to produce a dynamic 4-D presentation. A prototype dynamic color stereo workstation was implemented. A computer functional design specification was produced based on interactive studies and user feedback.

Hibbard, William L.↗
NASA NTRS1999

Spectral Behavior of Hematite at Visible/Near Infrared and Midinfrared Wavelengths

The oxide mineral hematite alpha-Fe2O3) is present on Mars as evidenced by spectroscopy using visible/near infrared (VNIR) and midinfrared (MIR) wavelengths. The physical nature of this surficial hematite varies from fine-grained, crystalline red hematite (red-Hm) in certain martian bright regions, to coarser-grained, crystalline gray hematite (gray-Hm) in the Sinus Meridiani equatorial site discovered in the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) data. The VNIR spectra require that the red hematite is present in amounts subordinate to a second ferric pigment, which accounts for the general shape and position of the martian ferric absorption edge. By analogy with palagonitic tephra and synthetic samples, the pigment is a nanophase ferric oxide, possibly nanophase hematite (np-Hm). The purpose of this abstract is to document the physicospectral properties of hematite in the VNIR (0.35 to 2.2 microns) and MIR (5 to 25 microns) with respect to the terms "nanophase" and "crystalline", "red" and "gray", and "fine-grained" and "coarse-grained". We will show that different "types" of hematite (no-, red-, and gray-Hm) have different spectral responses in the VNIR and MIR regions and that these differences are important for inferring the types of hematite and their relative proportions from remotely sensed spectra of Mars. Because hematite is an alteration product that forms through many different geologic processes, determination of the type of hematite provides important clues about the style and diversity of martian weathering processes.

Lane, Melissa D.↗
NASA NTRS1999

Spectral Behavior of Hematite at Visible/Near Infrared and Midinfrared Wavelengths

The oxide mineral hematite alpha-Fe2O3) is present on Mars as evidenced by spectroscopy using visible/near infrared (VNIR) and midinfrared (MIR) wavelengths. The physical nature of this surficial hematite varies from fine-grained, crystalline red hematite (red-Hm) in certain martian bright regions, to coarser-grained, crystalline gray hematite (gray-Hm) in the Sinus Meridiani equatorial site discovered in the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) data. The VNIR spectra require that the red hematite is present in amounts subordinate to a second ferric pigment, which accounts for the general shape and position of the martian ferric absorption edge. By analogy with palagonitic tephra and synthetic samples, the pigment is a nanophase ferric oxide, possibly nanophase hematite (np-Hm). The purpose of this abstract is to document the physicospectral properties of hematite in the VNIR (0.35 to 2.2 mm) and MIR (5 to 25 mm) with respect to the terms "nanophase" and "crystalline", "red" and "gray", and "fine-grained" and "coarse-grained". We will show that different "types" of hematite (np-, red-, and gray-Hm) have different spectral responses in the VNIR and MIR regions and that these differences are important for inferring the types of hematite and their relative proportions from remotely sensed spectra of Mars. Because hematite is an alteration product that forms through many different geologic processes, determination of the type of hematite provides important clues about the style and diversity of martian weathering processes. Additional information is contained in the original extended abstract.

Lane, M. D.↗