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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Archean metamorphic sequence and surfaces, Kangerdlugssuaq Fjord, East Greenland

The characteristics of Archean metamorphic surfaces and fabrics of a mapped sequence of rocks older than about 3000 Ma provide information basic to an understanding of the structural evolution and metamorphic history in Kangerdlugssuaq Fjord, east Greenland. This information and the additional results of petrologic and geochemical studies have culminated in an extended chronology of Archean plutonic, metamorphic, and tectonic events. The basis for the chronology is considered, especially the nature of the metamorphic fabrics and surfaces in the Archean sequence. The surfaces, which are planar mineral parageneses, may prove to be mappable outside Kangerdlugssuaq Fjord, and if so, will be helpful in extending the events that they represent to other Archean sequences in east Greenland. The surfaces will become especially important reference planes if the absolute ages of their metamorphic assemblages can be determined in at least one location where strain was low subsequent to their recrystallization. Once an isochron is obtained, the dynamothermal age of the regionally identifiable metamorphic surface is determined everywhere it can be mapped.

Kays, M. A.↗
NASA NTRS1990

Convective dynamics

In addressing meteorological processes, including convection, it is convenient to separate these processes into their kinematic, dynamic, and microphysical components. Dynamic processes deal with the forces that initiate and sustain or alter motion, while kinematic processes describe the motion field. Microphysical processes address the distribution of water substance. This review of convective dynamics is organized along the following lines. First is an assessment of radar capability, particularly the use of one or more Doppler radars, to portray the wind field. Then various types of precipitating moist convection are reviewed. Each type or mode of convection results from a distinct environment. The principal interest of dynamics here is its role in the convection's evolution, structure, and movement. Thus, the important processes of storm rotation, splitting and propagation, including tornadogenesis, are examined.

Ray, Peter S.↗
NASA NTRS1990

Volume loss and defluidization history of Barbados

A history of pore volume loss and defluidization of accreted sediments of the basal complex of Barbados island is presented. The structural evolution of the basal complex and evidence for past and present volumetric changes are addressed by examining varied phenomena, with emphasis on porosity-depth data. The empirical findings are used to consider questions such as the position-age profile of pore volume loss relative to other deformation components in the growing prism and the type of loading that principally caused pore volume loss.

Speed, R.↗
NASA NTRS1990

Space Station Freedom commercial infrastructure

Several approaches to initiating the provision of the Space Station Freedom (SSF) commercial infrastructure are discussed, including proposals from the private sector, the commercial development of infrastructure, and the commercial operation of infrastructure. Specific options for SSF commercial infrastructure which are currently being studied by NASA are described. One candidate for commercial service is the supplemental power for SSF beyond the Assembly Complete phase. The methods which a company could use in providing supplemental power are discussed, with special attention given to the use of solar dynamic power elements attached ot the SSF evolution structure. Another option under evaluation is commercial provision of SSF logistics services using ELVs.

Barquinero, Kevin↗
NASA NTRS1992

Flame deformation and entrainment associated with an isothermal transverse fuel jet

This paper describes an analytical model of an incompressible, isothermal reacting jet in crossflow. The model represents the flow in the jet cross-section by a counter rotating vortex pair, a flow structure that has been observed to dominate the jet behavior. The reaction surface surrounding the fuel jet is represented as a composite of strained diffusion flames that are stretched and deformed by the vortex pair flow. The results shed new light on the interaction between the vortex pair circulation and flame structure evolution and their relation to the concept of entrainment.

Jenkins, D. W.↗
NASA NTRS1990

The sun at the VLA's metric and decimetric wavelengths

Preliminary results of solar observations at 0.333 and 1.5 GHz made with the VLA during the September 11-17, 1988 period are presented. Generally, there are few structural changes in the active region sources from one day to the next, suggesting that structural evolution is relatively slow. Contour maps at 1.5 GHz are presented for each of the four days. Two noise storms were present at 0.33 GHz all week and were highly polarized.

White, S. M.↗
NASA NTRS1994

Toward estimation of H(sub 0) from VLBI observations of the gravitational lens system 0957+561

We have analyzed two epochs of 6 cm very long base interferometry (VLBI) observations of the two brightest images, A and B, of the gravitationally lensed quasar 0957+561 in a search for correlated structural evolution from which to estimate delta tau(sub BA), the difference in propagation time for light traveling between the quasar and Earth along the paths corresponding to these two images. However, we detected only marginal increases in the separation between the core and the innermost jet component in each image over the 2 year interval 1987-1989. Because monitoring image brightness variations has since led to apparently reliable estimates of delta tau(sub BA), we intend to use spatial variations in the relative magnification field across the extent of the images to constrain further the mass distribution of the lens, which is now the principal contributor to the uncertainty in estimates of H(sub 0) from this lens system.

Campbell, R. M.↗
NASA NTRS1995

High angular resolution far-infrared and submillimeter mapping survey of the dust cores associated with ultracompact H II regions

The primary objective of the research funded under this grant has been to perform a high angular resolution mapping survey of the far-infrared and submillimeter continuum emission from the dust cocoons surrounding young, deeply embedded massive stars and the ultracompact H II regions they create. The high infrared, submillimeter, and radio luminosity makes the ultracompact H II regions ideal tracers of current high-mass star formation. Detailed investigations of their structure, evolution, and interaction with their parent molecular clouds are thus important for understanding the early evolutionary phases of massive main sequence stars, the nature of the dense molecular cores in which they form, and the relationship to coeval low-mass star formation.

Phillips, T. G.↗
NASA NTRS1998

Tropical Oceanic Precipitation Processes over Warm Pool: 2D and 3D Cloud Resolving Model Simulations

Rainfall is a key link in the hydrologic cycle as well as the primary heat source for the atmosphere, The vertical distribution of convective latent-heat release modulates the large-scale circulations of the tropics, Furthermore, changes in the moisture distribution at middle and upper levels of the troposphere can affect cloud distributions and cloud liquid water and ice contents. How the incoming solar and outgoing longwave radiation respond to these changes in clouds is a major factor in assessing climate change. Present large-scale weather and climate models simulate cloud processes only crudely, reducing confidence in their predictions on both global and regional scales. One of the most promising methods to test physical parameterizations used in General Circulation Models (GCMS) and climate models is to use field observations together with Cloud Resolving Models (CRMs). The CRMs use more sophisticated and physically realistic parameterizations of cloud microphysical processes, and allow for their complex interactions with solar and infrared radiative transfer processes. The CRMs can reasonably well resolve the evolution, structure, and life cycles of individual clouds and cloud systems, The major objective of this paper is to investigate the latent heating, moisture and momenti,im budgets associated with several convective systems developed during the TOGA COARE IFA - westerly wind burst event (late December, 1992). The tool for this study is the Goddard Cumulus Ensemble (CCE) model which includes a 3-class ice-phase microphysical scheme, The model domain contains 256 x 256 grid points (using 2 km resolution) in the horizontal and 38 grid points (to a depth of 22 km depth) in the vertical, The 2D domain has 1024 grid points. The simulations are performed over a 7 day time period. We will examine (1) the precipitation processes (i.e., condensation/evaporation) and their interaction with warm pool; (2) the heating and moisture budgets in the convective and stratiform regions; (3) the cloud (upward-downward) mass fluxes in convective and stratiform regions; (4) characteristics of clouds (such as cloud size, updraft intensity and cloud lifetime) and the comparison of clouds with Radar observations. Differences and similarities in organization of convection between simulated 2D and 3D cloud systems. Preliminary results indicated that there is major differences between 2D and 3D simulated stratiform rainfall amount and convective updraft and downdraft mass fluxes.

Tao, W.- K.↗
NASA NTRS2001

Tropical Oceanic Precipitation Processes Over Warm Pool: 2D and 3D Cloud Resolving Model Simulations

Rainfall is a key link in the hydrologic cycle as well as the primary heat source for the atmosphere. The vertical distribution of convective latent-heat release modulates the large-scale circulations of the topics. Furthermore, changes in the moisture distribution at middle and upper levels of the troposphere can affect cloud distributions and cloud liquid water and ice contents. How the incoming solar and outgoing longwave radiation respond to these changes in clouds is a major factor in assessing climate change. Present large-scale weather and climate model simulate processes only crudely, reducing confidence in their predictions on both global and regional scales. One of the most promising methods to test physical parameterizations used in General Circulation Models (GCMs) and climate models is to use field observations together with Cloud Resolving Models (CRMs). The CRMs use more sophisticated and physically realistic parameterizations of cloud microphysical processes, and allow for their complex interactions with solar and infrared radiative transfer processes. The CRMs can reasonably well resolve the evolution, structure, and life cycles of individual clouds and clouds systems. The major objective of this paper is to investigate the latent heating, moisture and momentum budgets associated with several convective systems developed during the TOGA COARE IFA - westerly wind burst event (late December, 1992). The tool for this study is the Goddard Cumulus Ensemble (GCE) model which includes a 3-class ice-phase microphysics scheme.

Tao, W.-K.↗
NASA NTRS2002

The Propagation and Formation of Electron Holes

One of the striking findings of the International Solar Terrestrial Physics (ISTP) program is the detection of electron holes by several satellites in different regions of the magnetosphere, near the bow shock, and in the solar wind. These measurements have come from FAST (Fast Auroral Snapshot Explorer), Polar, Geotail, and Wind satellites. Using a 2-D (two dimensional) PIC (particle in cell) code we investigate the parameters of one and two electron beams on the evolution, structure, and stability of electron phase-space holes.

Coffey, Victoria↗
NASA NTRS2002

ALTUS Cumulus Electrification Study (ACES)

The ALTUS Cumulus Electrification Study (ACES) is an uninhabited aerial vehicle (UAV)-based project that will investigate thunderstorms in the vicinity of the Florida Everglades in August 2002. ACES is being conducted to both investigate storm electrical activity and its relationship to storm morphology, and validate Tropical Rainfall Measurement Mission (TRMM) satellite measurements. In addition, as part of NASA's UAV-based science demonstration program, this project will provide a scientifically useful demonstration of the utility and promise of UAV platforms for Earth science and applications observations. Part of the demonstration involves getting approvals from the Federal Aviation Administration and the NASA airworthiness flight safety review board. ACES will employ the ALTUS II aircraft, built by General Atomics - Aeronautical Systems, Inc. Key science objectives simultaneously addressed by ACES are to: (1) investigate lightning-storm relationships, (2) study storm electrical budgets, and (3) provide Lightning Imaging Sensor validation. The ACES payload, already developed and flown on ALTUS, includes electrical, magnetic, and optical sensors to remotely characterize the lightning activity and the electrical environment within and around thunderstorms. ACES will contribute important electrical and optical measurements not available from other sources. Also, the high altitude vantage point of the UAV observing platform (up to 55,000 feet) offers a useful 'cloud-top' perspective. By taking advantage of its slow flight speed (70 to 100 knots), long endurance, and high altitude flight, the ALTUS will be flown near, and when possible, above (but never into) thunderstorms for long periods of time, allowing investigations to be conducted over entire storm life cycles. In addition, concurrent ground-based observations will enable the UAV measurements to be more completely interpreted and evaluated in the context of the thunderstorm structure, evolution, and environment.

Kim, Tony↗
NASA NTRS2002

Microphysics, Radiation and Surface Processes in the Goddard Cumulus Ensemble (GCE) Model

One of the most promising methods to test the representation of cloud processes used in climate models is to use observations together with Cloud Resolving Models (CRMs). The CRMs use more sophisticated and realistic representations of cloud microphysical processes, and they can reasonably well resolve the time evolution, structure, and life cycles of clouds and cloud systems (size about 2-200 km). The CRMs also allow explicit interaction between out-going longwave (cooling) and in-coming solar (heating) radiation with clouds. Observations can provide the initial conditions and validation for CRM results. The Goddard Cumulus Ensemble (GCE) Model, a CRM, has been developed and improved at NASA/Goddard Space Flight Center over the past two decades. The GCE model has been used to understand the following: 1) water and energy cycles and their roles in the tropical climate system; 2) the vertical redistribution of ozone and trace constituents by individual clouds and well organized convective systems over various spatial scales; 3) the relationship between the vertical distribution of latent heating (phase change of water) and the large-scale (pre-storm) environment; 4) the validity of assumptions used in the representation of cloud processes in climate and global circulation models; and 5) the representation of cloud microphysical processes and their interaction with radiative forcing over tropical and midlatitude regions. Four-dimensional cloud and latent heating fields simulated from the GCE model have been provided to the TRMM Science Data and Information System (TSDIS) to develop and improve algorithms for retrieving rainfall and latent heating rates for TRMM and the NASA Earth Observing System (EOS). More than 90 referred papers using the GCE model have been published in the last two decades. Also, more than 10 national and international universities are currently using the GCE model for research and teaching. In this talk, five specific major GCE improvements: (1) ice microphysics, (2) longwave and shortwave radiative transfer processes, (3) land surface processes, (4) ocean surface fluxes and (5) ocean mixed layer processes are presented. The performance of these new GCE improvements will be examined. Observations are used for model validation.

Tao, Wei-Kuo↗
NASA NTRS2003

The Altus Cumulus Electrification Study (ACES): A UAV-Based Science Demonstration

The Altus Cumulus Electrification Study (ACES) is an unmanned aerial vehicle (UAV)- based project that investigated thunderstorms in the vicinity of the Florida Everglades in August 2002. ACES was conducted to investigate storm electrical activity and its relationship to storm morphology, and to validate satellite-based lightning measurements. In addition, as part of the NASA sponsored UAV-based science demonstration program, this project provided a scientifically useful demonstration of the utility and promise of UAV platforms for Earth science and applications observations. ACES employed the Altus II aircraft, built by General Atomics - Aeronautical Systems, Inc. Key science objectives simultaneously addressed by ACES are to: (1) investigate lightning-storm relationships, (2) study storm electrical budgets, and provide Lightning Imaging Sensor validation. The ACES payload included electrical, magnetic, and optical sensors to remotely characterize the lightning activity and the electrical environment within and around thunderstorms. ACES contributed important electrical and optical measurements not available from other sources. Also, the high altitude vantage point of the UAV observing platform (up to 55,000 feet) provided cloud-top perspective. By taking advantage of its slow flight speed (70 to 100 knots), long endurance, and high altitude flight, the Altus was flown near, and when possible, over (but never into) thunderstorms for long periods of time that allowed investigations to be conducted over entire storm life cycles. An innovative real time weather system was used to identify and vector the aircraft to selected thunderstorms and safely fly around these storms, while, at the same time monitor the weather near our base of operations. In addition, concurrent ground-based observations that included radar (Miami and Key West WSRBD, NASA NPOL), satellite imagery, and lightning (NALDN and Los Alamos EDOT) enable the UAV measurements to be more completely interpreted and evaluated in the context of the thunderstorm structure, evolution, and environment.

Blakeslee, R. J.↗
NASA NTRS2003

Callisto: A World in Its Own Right

This paper presents a discussion on the planetary structure, evolution and composition of the Gallilean Satellite, Callisto. The Jupiter Icy Moons Orbiter (JIMO) mission is currently planned to first orbit Callisto then its two icy sisters Ganymede and Europa to investigate Callisto's actual configuration. The JIMO mission consists of three globally complete mapping sets of Callisto along with spectrographic measurements to answer remaining outstanding questions about the geomorphology of Callisto.

Moore, Jeffrey M.↗
NASA NTRS2002

Goddard Cumulus Ensemble (GCE) Model: Application for Understanding Precipitation Processes

One of the most promising methods to test the representation of cloud processes used in climate models is to use observations together with Cloud Resolving Models (CRMs). The CRMs use more sophisticated and realistic representations of cloud microphysical processes, and they can reasonably well resolve the time evolution, structure, and life cycles of clouds and cloud systems (size about 2-200 km). The CRMs also allow explicit interaction between out-going longwave (cooling) and incoming solar (heating) radiation with clouds. Observations can provide the initial conditions and validation for CRM results. The Goddard Cumulus Ensemble (GCE) Model, a cloud-resolving model, has been developed and improved at NASA/Goddard Space Flight Center over the past two decades. Dr. Joanne Simpson played a central role in GCE modeling developments and applications. She was the lead author or co-author on more than forty GCE modeling papers. In this paper, a brief discussion and review of the application of the GCE model to (1) cloud interactions and mergers, (2) convective and stratiform interaction, (3) mechanisms of cloud-radiation interaction, (4) latent heating profiles and TRMM, and (5) responses of cloud systems to large-scale processes are provided. Comparisons between the GCE model's results, other cloud-resolving model results and observations are also examined.

Tao, Wei-Kuo↗
NASA NTRS2005

NASA's Challenges in Optics for Future Space-Based Science Missions

NASA's mission is: "To understand and project our home planet, To explore the universe and search for life, To inspire the next generation of explorers ... as only NASA can." These mission concepts are further defined in our recently published"Strategic Objectives for 2005 and Beyond" , which include conducting advanced telescope searches for Earth-like planets and habitable environments around the stars, as well as exploring the universe to understand its origin, structure, evolution, and destiny. This presentation will summarize several future space-based missions currently in formulation to meet these objectives, and will outline some of the principal challenges in the field of optics to their success.

Stahl, H. Phil↗