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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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NASA NTRS1983

Implications of information from LANDSAT-4 for private industry

The broader spectral coverage and higher resolution of LANDSAT-4 Thematic Mapper (TM) data open the door for identification from space of spectral phenomena associated with mineralization and microseepage of hydrocarbon. Digitally enhanced image products generated from TM data allow the mapping of many major and minor structural features that mark or influence emplacement of mineralization and accumulation of hydrocarbons. These improvements in capabilities over multispectral scanner data should accelerate the acceptance and integration of satellite data as a routinely used exploration tool that allows rapid examination of large areas in considerable detail. Imagery of Southern Ontario, Canada as well as of Cement, Oklahoma and Death Valley, California is discussed.

Everett, J. R.↗

NASA NTRS1982

Development of LANDSAT Derived Forest Cover Information for Integration into Adirondack Park GIS

Based upon observed changes in timber harvest practices partially attributable to forest biomass removable for energy supply purposes, the Adirondack Park Agency began in 1979 a multi-year project to implement a digital geographic information system (GIS). An initial developmental task was an inventory of forest cover information and analysis of forest resource change and availability. While developing the GIS, a pilot project was undertaken to evaluate the usefulness of LANDSAT derived land cover information for this purpose, and to explore the integration of LANDSAT data into the GIS. The prototype LANDSAT analysis project involved: (1) the use of both recent and historic data to derive land cover information for two dates; and (2) comparison of land cover over time to determine quantitative and geographic changes. The "recent data," 1978 full foliage data over portions of four LANDSAT scenes, was classified, using ground truth derived training samples in various forested and non-forested categories. Forested categories include the following: northern hardwoods, pine, spruce-fir, and pine plantation, while nonforested categories include wet-conifer, pasture, grassland, urban, exposed soil, agriculture, and water.

Curran, R. P.↗

NASA NTRS1981

AgRISTARS - Plans and first-year achievements

The results of the agriculture and resources inventory surveys through aerospace remote sensing (AgRISTARS) program managed by the USDA for exploring the use of satellite data for domestic and global commodity information needs are discussed. The program was intended to gather early warning of changes affecting production and quality of commodities and renewable resources, for predicting commodity production, land use classification and quantification, for inventories and assessments of renewable resources, land productivity measurements, assessment of conservation practices, and for pollution detection and impact evaluation. Up to 20 crop/region combinations in 7 countries were covered by the experiments, which comprised NOAA 6 and Landsat data analyses. Attempts to reduce variances through improved machine classification techniques are reported, together with soil moisture profiling, and the use of airborne sensors for providing comparative data.

Hall, F. G.↗

NASA NTRS1982

Voyager to Saturn, plans for Uranus, and the future

The next two major data acquisition events in planetary exploration are outlined. They are the encounter with Uranus in January 1986 and with Neptune and its large moon Triton in 1989. A discussion of the Galileo mission and the suspended VOIR mission to Venus is given. Cost considerations and future plans are presented.

Briggs, G. A.↗

NASA NTRS1984

Ultraviolet spectral morphology of the O stars - The remarkable luminosity dependence of the Si IV stellar wind effect

An extensive survey of ultraviolet O type spectra, by means of high-resolution data from the International Ultraviolet Explorer archives, shows a strong correlation between both the photospheric and stellar wind features, and the optical spectral types. In particular, the stellar wind effect in the Si IV resonance doublet displays a strong luminosity dependence which has not been completely described before: there is no effect anywhere on the main sequence, but it develops gradually through the intermediate luminosity classes into a full P Cygni profile in the supergiants. This behavior is in sharp contrast to that of the C IV and N V, which have strong P Cygni profiles throughout most of the O type domain, including the main sequence. The Si IV effect simultaneously provides a sensitive classification criterion and poses an outstanding problem for detailed astrophysical interpretation. In addition, a new emission feature at 1574 A, possibly due to N III or to N IV forbidden line, is reported.

Walborn, N. R.↗

NASA NTRS1984

Thermospheric superrotation revisited

The characteristics of thermospheric superrotation and accompanying latitudinal variations in temperature and composition are examined theoretically. Superrotation was measured by the Dynamics Explorer 2 satellite, which provided data for the atmospheric rotational velocity with respect to that of the planet for all seasons for 300-350 km altitudes. Zonally averaged circulation is described with momentum equations. A spectral model covers the superrotation, and account is taken of symmetric radiative and auroral components, asymmetric ion drag, an asymmetric pressure gradient and a viscous component. The horizontal wind field of the diurnal tide and diurnal variations in ion density which produce a momentum source are the largest contributors to superrotation at low and midlatitudes.

Mayr, H. G.↗

NASA NTRS1985

Rotational modulation of chromospheric emission in cool giants and 'hybrid' stars

Archival data from the International Ultraviolet Explorer have been used to study temporal variations of the Mg II h and k emission lines in eight late-type giants. Evidence is presented that the variations are periodic in nature. It is argued that the periodicities can be interpreted in terms of rotation. It is found that the four fastest rotators in the sample are 'hybrid' stars.

Brosius, J. W.↗

NASA NTRS1985

Magnetic storm of September 4, 1984 - A synthesis of ring current spectra and energy densities measured with AMPTE/CCE

Compositional studies of the equatorial distributions of ring current ions during the September 4, 1984 magnetic storm have been made possible by comprehensive energy, charge state, and mass coverage data from the Charge Composition Explorer satellite. An examination of ion spectra at an L value of about 4 on September 5, in the local evening sector, shows that energy density was dominated by protons, with O ions contributing about 27 percent at the peak of about 150 keV, while He ions contributed less than about 2 percent. September 6 ion spectra, taken during the recovery phase of the storm, indicate that ion densities at more than 20 keV had decreased markedly, and that the ring current energy density was primarily provided by protons.

Krimigis, S. M.↗

NASA NTRS1985

Thermospheric hydrogen - The long-term solar influence

Atmospheric Explorer C and E satellite data are employed for a long-term analysis of the behavior of thermospheric hydrogen with respect to the 11 yr solar cycle. The data covered the period 1974-79 (increasing solar activity) and comprised in situ ionospheric (F region) and neutral atmospheric data. The data were analyzed statistically to characterize low latitude hydrogen behavior, e.g., the diurnal variation and mean concentration over the 5 yr data sampling period. Both the mean and daily maximum/minimum ratio (DMMR) varied with the solar F index. The escaping flux of H ions became a contant around 1000 K. Increasing thermospheric temperatures lowered the DMMR value. However, the DMMR values calculated were consistently large enough to require inclusion of neutral winds and/or diurnal variations in charge exchange fluxes moving in and out of the plasmasphere in any model for thermospheric hydrogen behavior.

Breig, E. L.↗

NASA NTRS1985

Seasonal, diurnal, and solar cyclical variations of the limiting H(+) flux in the earth's topside ionosphere

Seasonal and solar cyclical variations in the limiting H(+) flux are compared over the solar minimum-to-maximum interval 1974-80. The comparisons are made on the bases of values derived with the MSIS-83 and -77 models, which in turn are based on Atmospheric Explorer-E O(+) and H(+) data from the ionosphere. The H(+) flux is obtained by integration of the H(+) continuity equation along magnetic flux tubes. The seasonal and cyclical variations are dominated by the neutral hydrogen density, although the O(+) boundary density, scale height and O(+)-H reaction somewhat ameliorate the changes caused by the density variations. Finally, the plasmasphere experienced an order of magnitude decrease in H(+) in going from solar minimum to maximum, which could have been caused by longer limiting flux escapes through more, longer-lived, shorter flux tubes.

Richards, P. G.↗

NASA NTRS1984

Command and telemetry in autonomous spacecraft design

Some major steps are summarized in the evolution of autonomous design features for planetary exploration spacecraft. The control and data architectures for the Viking, Voyager, and Galileo spacecraft are considered. Telemetry and command capabilities are fundamental features of spacecraft design that have been successfully used for autonomous control. Also discussed is the Autonomous Redundancy and Maintenance Management Subsystem (ARMMS) concept. The software approach to autonomous control provides for modifications to the control process or the addition of new operating features during flight operations.

Turner, P. R.↗

NASA NTRS1985

Interstellar extinction variations in the Large Magellanic Cloud

The properties of ultraviolet extinction in the LMC are reexamined using some of the existing LMC data from the International Ultraviolet Explorer (IUE) satellite and a large number of new observations obtained during the IUE Sixth Episode. The main goal is to determine if the LMC extinction properties are regionally modulated and, if so, to examine the type and range of the variations. Among the new IUE observations presented is a large grid of unreddened LMC flux standards, which will eliminate spectral mismatch effects as complications in the extinction analysis. Eight new reddened stars were observed. The properties of the program stars are summarized; the method for producing the extinction curves (including the criteria for pairing reddened and unreddened stars) is discussed; and the curves themselves are presented and discussed.

Fitzpatrick, E. L.↗

NASA NTRS1986

Plasma fluctuations and large-scale mixing near Comet Giacobini-Zinner

The relationship among plasma densities, flow speeds and directions, and temperatures, at distances within about 100,000 km of Comet Giacobini-Zinner's nucleus, are presently examined in view of lowpass-filtered data from the International Cometary Explorer's electron spectrometer. While the largest amplitude density spikes often have more significant flow changes associated with them, a consistent pattern is not found. Power spectral analyses in and near the sheath/transition regions show that density fluctuation levels are enhanced at all detectable frequencies, consistent with strong density fluctuations on all time scales. Such mechanisms as the amplification of convected ion pickup waves and cometary rays for producing the large plasma variations are discussed. It is suggested that the Rayleigh-Taylor effect-driven mixing mechanism at a mass-loading boundary abut 100,000 km from the nucleus may be operative.

Baker, D. N.↗

NASA NTRS1986

Plasma and field observations of a Pc 5 wave event

The particle detector and electric field data collected by the Dynamo Explorer 1 on the Pc 5 wave event encounter on July 14, 1982 are presented, yielding a nearly complete picture of the event. The overall structure of the Pc 5 seems to order the event into two distinct halves, suggesting a temporal or spatial variation of the micropulsation. Thermal plasma measurements showed that the dominant ion throughout both lobes was H(+). Significant quantities of He(+), O(+), N(+), and O(2+) were also observed to be present and rotating together in a plane normal to the magnetic field direction, due to the Pc5 E x B drift. The plasma parameters determined for the two lobes were used in theoretical calculations to predict the period of the observed resonance.

Waite, J. H.↗

NASA NTRS1989

Development of an intelligent interface for adding spatial objects to a knowledge-based geographic information system

Earth Scientists lack adequate tools for quantifying complex relationships between existing data layers and studying and modeling the dynamic interactions of these data layers. There is a need for an earth systems tool to manipulate multi-layered, heterogeneous data sets that are spatially indexed, such as sensor imagery and maps, easily and intelligently in a single system. The system can access and manipulate data from multiple sensor sources, maps, and from a learned object hierarchy using an advanced knowledge-based geographical information system. A prototype Knowledge-Based Geographic Information System (KBGIS) was recently constructed. Many of the system internals are well developed, but the system lacks an adequate user interface. A methodology is described for developing an intelligent user interface and extending KBGIS to interconnect with existing NASA systems, such as imagery from the Land Analysis System (LAS), atmospheric data in Common Data Format (CDF), and visualization of complex data with the National Space Science Data Center Graphics System. This would allow NASA to quickly explore the utility of such a system, given the ability to transfer data in and out of KBGIS easily. The use and maintenance of the object hierarchies as polymorphic data types brings, to data management, a while new set of problems and issues, few of which have been explored above the prototype level.

Campbell, William J.↗

NASA NTRS1989

An intelligent user interface for browsing satellite data catalogs

A large scale domain-independent spatial data management expert system that serves as a front-end to databases containing spatial data is described. This system is unique for two reasons. First, it uses spatial search techniques to generate a list of all the primary keys that fall within a user's spatial constraints prior to invoking the database management system, thus substantially decreasing the amount of time required to answer a user's query. Second, a domain-independent query expert system uses a domain-specific rule base to preprocess the user's English query, effectively mapping a broad class of queries into a smaller subset that can be handled by a commercial natural language processing system. The methods used by the spatial search module and the query expert system are explained, and the system architecture for the spatial data management expert system is described. The system is applied to data from the International Ultraviolet Explorer (IUE) satellite, and results are given.

Cromp, Robert F.↗

NASA NTRS1989

An intelligent user interface for browsing satellite data catalogs

Cromp, Robert F.↗

NASA NTRS1990

Spatial relationships between region 2 field-aligned currents and electron and ion precipitation in the evening sector

The equatorward cutoff of ion and electron precipitation in relation to the evening region 2 field-aligned current during isolated substorms has been investigated using the magnetic field and plasma data obtained from the Dynamics Explorer 2 satellite. The equatorward boundaries of the region 2 currents relative to those of central plasma sheet (CPS) electron precipitation are determined predominantly by magnetic local time and subsequently change with substorm phases. With approaching midnight, the equatorward boundary of CPS electron precipitation extends toward and eventually equatorward of that of the region 2 current. On the other hand, the equatorward boundary of the region 2 current coincides well with that of 10-20 keV ion precipitation during the whole course of substorms. It is proposed that these ions originate in the so-called Alfven layer and that the location of this inner boundary determines the lower latitude boundary of the region 2 current.

Fujii, R.↗