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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 271 records · Page 15
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NASA NTRS1982

Tropical cyclone track and genesis forecasting using satellite microwave sounder data

Although many dynamical and statistical prediction schemes are available to forecasters, tropical cyclone track errors are still large. One primary difficulty is that tropical cyclones exist over the data-sparse tropical oceans. Satellite sounders, however, routinely provide numerous data over these areas. Mean layer temperatures from the Scanning Microwave Spectrometer on board the Nimbus 6 satellite are decomposed using empirical orthogonal functions, and the expansion coefficients are related to deviations from the persistence forecast location, to speed change, to direction change and to intensity change. The significance of the regression equations is tested by a null hypothesis of zero correlation coefficient. It appears that significant information about tropical cyclone motion exists in the satellite-estimated mean layer temperatures, especially at upper levels. A physical interpretation of the statistical results is offered, and a one-storm-out independent test is used to test the stability of the equations. Finally, some further work is suggested.

Kidder, S. Q.↗
NASA NTRS1982

Noctilucent clouds - Simulation studies of their genesis, properties and global influences

A numerical model is presented for testing theories of the physical mechanisms of noctiluminescent clouds. The time-dependent, one-dimensional model describes the formation, evolution, and properties of the clouds as interactive ice crystals, meteoric dust, water vapor, and ionized air. Mesopause temperatures below 140 K are found to be necessary for the formation of the clouds, conditions existing only at high latitudes in the summer. No predominant nucleation particle could be identified for the formation of the clouds, although a time period of up to a day was determined as necessary for materialization, which lasts several days. Several atmospheric and environmental conditions were characterized which enhance the appearance of the noctiluminescent clouds. One conclusion reached is that the numerous launches necessary to build a solar power satellite system would not significantly exacerbate noctiluminescent cloud formation.

Turco, R. P.↗
NASA NTRS1983

The Archean crust in the Wawa-Chapleau-Timmins region. A field guidebook prepared for the 1983 Archean Geochemistry-Early Crustal Genesis Field Conference

This guidebook describes the characteristics and interrelationships of Archean greenstone-granite and high-grade gneiss terrains of the Superior Province. A 300-km long west to east transect between Wawa and Timmins, Ontario will be used to illustrate regional-scale relationships. The major geological features of the Superior Province are described.

Percival, J. A.↗
NASA NTRS1983

Genesis stories for the millisecond pulsar

Theoretical models proposed to explain the origin of the millisecond pulsar (MP) PSR 1937+214 are reviewed, examining their ability to explain its low surface dipole magnetic field (B), its low birth temperature (less than 10 to the 8th K), the absence of a companion or remnant, and its low velocity perpendicular to the Galactic plane. The models discussed are a single isolated explosion forming a rapidly spinning neutron star, spin-up of a dead pulsar by accretion from a companion, collapse of an accreting spinning white dwarf, and fusion of a tight binary composed of two old neutron stars. Although all of the models have difficulties in explaining one or more of the MP characteristics, the second model is found to be most probable in the light of present knowledge. The lack of a companion is explained by its tidal disruption after it had fed the accreting pre-pulsar for 1 Gyr or more and its mass had decreased to about 0.01 solar mass. Neutron stars accreting in this way have been observed in Galactic-bulge X-ray sources.

Ruderman, M. A.↗
NASA NTRS1983

Genesis of tornadoes associated with hurricanes

The climatological history of hurricane-tornadoes is brought up to date through 1982. Most of the tornadoes either form near the center of the hurricane, from the outer edge of the eyewall outward, or in an area between north and east-southeast of the hurricane center. The blackbody temperatures of the cloud tops which were analyzed for several hurricane-tornadoes that formed in the years 1974, 1975, and 1979, did not furnish strong precursor signals of tornado formation, but followed one of two patterns: either the temperatures were very low, or the tornado formed in areas of strong temperature gradients. Tornadoes with tropical cyclones most frequently occur at 1200-1800 LST, and although most are relatively weak, they can reach the F3 intensity level. Most form in association with the outer rainbands of the hurricane.

Gentry, R. C.↗
NASA NTRS1984

On the geodynamic setting of kimberlite genesis

The emplacement of kimberlites in the North American and African continents since the early Palaeozoic appears to have occurred during periods of relatively slow motion of these continents. The distribution of kimberlites in time may reflect the global pattern of convection, which forces individual plates to move faster or slower at different times. Two-dimensional numerical experiments on a convecting layer with a moving upper boundary show two different regimes: in the first, when the upper boundary velocity is high, heat is transferred by the large-scale circulation and in the second, when the upper boundary velocity is lower, heat is predominantly transferred by thermal plumes rising from the lower boundary layer. For a reasonable mantle solidus, this second regime can give rise to partial melting beneath the moving plate, far from the plate boundaries. The transition between these modes takes place over a small range of plate velocities; for a Rayleigh number of 1,000,000 it occurs around 20 mm/yr. It is suggested that the generation of kimberlite magmas may result from thermal plumes incident on the base of a slowly moving plate.

England, P.↗
NASA NTRS1984

Trace element abundances in megacrysts and their host basalts - Constraints on partition coefficients and megacryst genesis

Rare earth and other trace element abundances are determined in megacrysts of clinopyroxene, orthopyroxene, amphibole, mica, anorthoclase, apatite and zircon, as well as their host basalts, in an effort to gather data on mineral/melt trace element partitioning during the high pressure petrogenesis of basic rocks. Phase equilibria, major element partitioning and isotopic ratio considerations indicate that while most of the pyroxene and amphibole megacrysts may have been in equilibrium with their host magmas at high pressures, mica, anorthoclase, apatite, and zircon megacrysts are unlikely to have formed in equilibrium with their host basalts. It is instead concluded that they were precipitated from more evolved magmas, and have been mixed into their present hosts.

Irving, A. J.↗
NASA NTRS1984

Volatile elements in and on lunar volcanic glasses: What do they tell us about lunar genesis?

There are good reasons to believe that lunar volcanic glasses originated from a deep interior source. The presence of a thin layer of surface correlated elements on these glasses may indicate that the Moon has some reservoirs that are enriched in volatiles. Since the glasses themselves do not show similar enrichment, the source should be of limited extent. Three scenarios are advanced for the origin of these elements. The mechanism for lunar volcanism differs from the mechanism for volcanism on Earth since the former produces bubbling and the latter explosive fountaining. From the condensation behavior of the volatile compounds, which leads to heterogeneous condensation, it is concluded that comparing element ratios of surface correlated elements gives little sense. It seems as if the volatile reservoirs are of rather limited extent and that they do not enlarge the volatile content of the bulk Moon significantly.

Koeberl, C.↗
NASA NTRS1984

Pristine rocks (8th Foray) - 'Plagiophile' element ratios, crustal genesis, and the bulk composition of the moon

Eu/Al, Sr/Al, Eu/Sr, and similar ratios among pristine lunar nonmare lithologies with implications for nonmare petrogenesis and for the bulk composition of the moon are examined. On a plot of Eu/Al versus mg, ferroan anorthosites are separated from all other pristine nonmare rocks by a considerable gap. A nonrandom process must be invoked to account for the gap in the spectrum of ratios. A single magma probably cannot account for even the Mg-rich pristine rocks subset, based on diversity of plagiophile ratios among samples with similar mg ratios. Plagiophile ratios also constrain the bulk composition of the moon. Plagiophile ratios among ferroan anorthosites exactly match those expected under a model in which ferroan anorthosites formed by flotation of plagioclase cumulates over a primordial 'magmasphere'. Ratios among nonvolatile elements confirm that the moon formed out of materials akin to chondritic meteorites.

Warren, P. H.↗
NASA NTRS1986

Komatiite genesis in the Archaean mantle, with implications for the tectonics of Archaean greenstone belts

The presence of ultramafic lavas (komatiites) associated with Archean greenstone belts has been suggested to indicate very high increments (50-80%) of partial melting of the Archean mantle. Such extensive melting of the Earth's mantle during the Archean might have profound effects on the early tectonic and chemical evolution of the planet, although problems associated with keeping the komatiite liquid in equilibrium with the residual mantle at such high increments of melting has cast doubt upon aspects of extensive melting. Two important aspects of the origin of komatiites are discussed below.

Elthon, D.↗
NASA NTRS1986

Workshop on Early Crustal Genesis: The World's Oldest Rocks

Topics addressed include: a general review of Precambrain crustal evolution; geology and geochemistry of the Archean Craton in Greenland and Labrador; Precambrian crustal evolution in North and South America; and the field excursion to the Ameralik Fjord.

Ashwal, L. D.↗
NASA NTRS1985

Ability of a regional-scale model to predict the genesis of intense mesoscale convective systems

The mesoscale part of a two-part evaluation of 30 forecasts by a mesoscale numerical weather prediction model (MASS 2.0) is presented. Unfiltered fields are combined into convective predictor fields, the loci of which are then related at two-hour intervals to the loci of strong mesoscale convective systems identifiable in national radar summary plots and GOES satellite imagery. Examples of model 'forecasts' of intense convective storm clusters, a severe squall line triggered along a dryline, orographically induced hailstorms, and sea breeze thunderstorms are provided.

Koch, S. E.↗
NASA NTRS1988

Genesis of archean granitoids in the Pilbara block and implications for crustal growth

The origin of the Mount Edgar Batholith of the Pilbara Block in Western Australia is discussed, along with other Archean granitoids that show relatively primitive isotopic characteristics but more evolved bulk geochemistry. Geochemical evidence is presented in support of a multistage process of crustal ripening, involving partial melting of a thick basaltic crust to produce the tonalitic and dacitic sources of the more evolved granitoids. These events must produce stable continental crust in less than 200 Ma and are different geologically and geochemically from those which produced Phanerozoic granitoids in Andean margin settings.

Collins, W. J.↗
NASA NTRS1988

The genesis of the ring galaxy Arp 144 (NGC 7828/29)

Multicolor near-infrared images have been obtained for the 'folded ring' galaxy Arp 144 (NGC 7828/29). About 10 to the 10th solar mass stellar nuclei associated with both NGC 7828 and NGC 7829 are found, indicating that this system is the result of an interaction between two similarly massive galaxies. The galaxy/intergalactic H I cloud collision model proposed by Freeman and de Vaucouleurs (1974) appears to be untenable, since it unequivocally predicts the existence of a single evolved stellar nucleus.

Joy, Marshall↗
NASA NTRS1990

Genesis lunar outpost criteria and design

This design study--the third in the space architecture series--focused on the requirements of an early stage lunar outpost. The driving assumptions of the scenario was that the base would serve as a research facility and technology testbed for future Mars missions, a habitat supporting 12 persons for durations of up to 20 months, and would sustain the following five experimental facilities: Lunar surface mining and production analysis facility, construction technology and materials testbed, closed environmental life support system (CELSS) test facility, lunar farside observatory, and human factors and environment-behavior research facility. Based upon the criteria set forth in a previous programming document, three preliminary lunar base designs were developed. Each of the three schemes studied a different construction method and configuration. The designs were then evaluated in terms of environmental response, human habitability, transportability, constructability, construction dependability and resilience, and their suitability in carrying out the desired scientific research. The positive points of each scheme were then further developed by the entire project team, resulting in one integrated lunar outpost design.

Hansmann, Timothy↗
NASA NTRS1990

Genesis lunar outpost: An evolutionary lunar habitat

Students at the University of Wisconsin-Milwaukee Department of Agriculture undertook a series of studies of lunar habitats during the 1989 to 1990 academic year. Undergraduate students from architecture and mechanical and structural engineering with backgrounds in interior design, biology and construction technology were involved in a seminar in the fall semester followed by a design studio in the spring. The studies resulted in three design alternatives for lunar habitation and an integrated design for an early stage lunar outpost.

Moore, Gary T.↗
NASA NTRS1990

Geochemistry and genesis of the angrites

The major and trace elements were analyzed in samples of LEW86010, LEW87051, and Angra dos Reis angrites were analyzed using INAA and fused-bead EMP techniques. Results suggest that all three angrites originated on a volatile-depleted (Na-poor) but oxidized parent body or on several bodies. The combination of low Na and high FeO/MnO found in these samples suggests that the extreme Na depletion was caused by parent-body outgassing during differentiation, rather than by nebular processes. It was also found that the refractory-element abundances observed in LEW86010 and LEW87051 are related via olivine control; it is suggested that LEW86010 may be a residual melt from a LEW87051-like precursor or that LEW87051 formed from a LEW86010-like precursor via olivine accumulation. On the other hand, the Angra dos Reis displayed an unusual refractory element pattern suggesting that either the angrite parent body was heterogeneous or that Angra dos Reis was formed on a parent body different from that of the other two angrites.

Mittlefehldt, David W.↗