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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

A QSO in a rich, distant cluster of galaxies

The detection of a 'classical' QSO in a previously studied, distant rich cluster of visible galaxies is reported. The blue and red/IR spectra of the QSO are shown. The QSO occurs at a redshift essentially identical to that of the cluster 0016+16, colocated on the 0.01 of the plate which contains the cluster. The simplest explanation of this association is that the QSO is a member of the cluster. The consequences of the finding are discussed. The QSO-cluster association is further confirmation of the cosmological nature of QSO-cluster association is further confirmation of the cosmological nature of QSOs, and it suggests that QSOs do not necessarily avoid the environment of rich clusters. The fact that this QSO is not well centered adds credence to the suggestion that 3C345 and QSO 1641+3998 constitute an additional case of QSOs in high redshift cluster. The location of this QSO could make it a unique probe to study the physical state of the intracluster gas that is common in rich clusters.

Margon, B.↗
NASA NTRS1982

Crop identification using Landsat temporal-spectral profiles

The temporal-spectral profile is a detailed indicator of the physical state of a field through time. Characteristic profiles have been observed for a variety of crops and other cover classes from Landsat data in the United States Corn Belt. These profiles contain information to support crop identification at various levels.

Odenweller, J. B.↗
NASA NTRS1984

Mean excitation energies for stopping powers in various materials composed of elements hydrogen through argon

The local plasma model is used to study the effects of the chemical and physical state of a medium on its stopping power. The relationship between that model and a more exact quantum treatment of bound systems is elucidated by examining related quantities in both theories for the case of one and two-electron systems. Atomic mean excitation energies and straggling parameters in the local plasma model are compared with the accurate calculations of Inokuti et al. (1975, 1978, 1981). The use of the Gordon-Kim electron gas model of molecular bonding is used to determine the effects of covalent chemical bond shifts on the mean excitation energies for elements of the first two rows. Calculations of mean excitation energies of ionic bonded substances are presented, and the mean excitation energies of metals are discussed.

Wilson, J. W.↗
NASA NTRS1984

Active regions

The following efforts were completed in support of the Solar Maximum Mission (SMM): (1) the evolution of solar vector photospheric magnetic fields in a flare-producing active region was studied; (2) an algorithm was developed to generate maps of force-free magnetic field strengths at varying heights in the solar atmosphere; and (3) the study of the physical state of the material confined along entire magnetic loops was advanced with the use of magnetic field extrapolation.

Wu, S. T.↗
NASA NTRS1984

Observations of Absorption Lines from Highly Ionized Atoms

In the ultraviolet spectra of hot stars, absorption lines can be seen from highly ionized species in the interstellar medium. Observations of these features which have been very influential in revising the perception of the medium's various physical states, are discussed. The pervasiveness of O 6 absorption lines, coupled with complementary observations of a diffuse background in soft X-rays and EUV radiation, shows that there is an extensive network of low density gas (n approx. fewX 0.001/cucm) existing at coronal temperatures, 5.3 or = log T or = 6.3. Shocks created by supernova explosions or mass loss from early-type stars can propagate freely through space and eventually transfer a large amount of energy to the medium. To create the coronal temperatures, the shocks must have velocities in excess of 150 km/sec; shocks at somewhat lower velocity 9v or = 100 km/sec) can be directly observed in the lines of Si3. Observations of other lines in the ultraviolet, such as Si 4V and C 5, may highlight the widespread presence of energetic uv radiation from very hot, dward stars. More advanced techniques in visible and X-ray astronomical spectroscopy may open up for inspection selected lines from atoms in much higher stages of ionization.

Jenkins, E. B.↗
NASA NTRS1985

Departures from LTE Populations Versus Anomalous Abundances: the Effects of Heating

The deposit of nonradiative heat and momentum in the mantle of a hot star affects the interpretation of the stellar spectrum in two ways. First, a superheated and moving plasma should be considered when doing the analysis, and second, a model atom which is appropriate for the physical state of the line forming regions. Some examples are presented for H and He showing how the changes in the electron temperature affect the solution of the equations of statistical equilibrium. The observed spectra of the Wolf-Raynet stars HD 191765, HD 192103, and HD 192163 are compatible with a normal H/He abundance ratio.

Underhill, A. B.↗
NASA NTRS1981

Solar Corona Explorer: A mission for the physical diagnosis of the solar corona

Mission objectives and spacecraft requirements for the Solar Corona Explorer (SCE), a proposed free flying, unmanned solar research craft to be tenatively launched in 1987, were defined. The SCE's purpose is to investigate structure, dynamics and evolution of the corona, globally and in the required physical detail, to study the close coupling between the inner corona and the heliosphere. Investigative objectives are: (1) to understand the corona as the source of varying interplanetary plasma and of varying solar X-ray and extreme ultraviolet fluxes; (2) to develop the capabilities to model the corona with sufficient precision to forecast the Earth's variable environment in space, on the scales from weeks to years; (3) to develop an understanding of the physical processes that determine the dynamics and physical state of the coronal plasma, particularly acceleration processes; and (4) to develop insight and test theory on the Sun applicable to stellar coronae and winds, and in particular, to understand why cool stars put such a large fraction of their energy into X-rays. Considered related factors are: (1) duration of the mission; (2) onboard measuring instrumentation; (3) ground support equipment and procedures; and (4) programs of interpretation and modeling.

Source record↗
NASA NTRS1985

Asteroid Collisional Evolution Studies

Understanding asteroid collisional evolution is important for characterizing the physical state of asteroids today and for learning about the processes that acted in this region of the solar system early in its history. The collisional outcome algorithm in the numerical simulation of asteroid evolution was revised to reflect pressure-strengthening. Asteroid collisions are now treated as a distribution of oblique impacts rather than as only head-on collisions. The initial and evolved size distribution of a plausible asteroid population is compared with the observed size distribution. Asteroid accretion times and reconstruction of the primordial solar nebula suggest that there was significantly more mass in this part of the solar system when the asteroids were accreting.

Davis, D. R.↗
NASA NTRS1984

Waves in planetary rings

The Voyager spacecraft revealed the rings of Saturn to have an unexpected richness of structure. Many of the observed features have now been identified as collective effects arising from the self-gravity of the ring material. These effects include spiral density waves and spiral bending waves, the main topics of this review. Both kinds of waves were first discussed in the astronomical literature in connection with the dynamics and structure of spiral galaxies, and the present discussion contrasts the similarities and differences between the disks of galaxies and planetary rings. After developing the theory of free and forced waves of both types, the way in which the observed waves can be used as diagnostics to obtain crucial parameters that characterize the physical state of the rings is discussed.

Shu, F. H.↗
NASA NTRS1985

O VIII resonant absorption in PKS 2155 - 304 - A hot wind

The broad X-ray absorption feature in PKS 2155 - 304 could be due to O VIII Ly-alpha resonant absorption in a wind with outflow speeds up to about 30,000 km/s. The properties of such a wind are calculated. A homogeneous, spherically symmetric wind would involve a mass flux of about a 1000 solar masses/year, but this estimate could be greatly reduced if the outflow were beamed, and/or the absorbing gas were clumped into small clouds. In the latter case, the O VIII absorption offers clues to the physical state of thermal material closer to the central energy source than the clouds which produce optical emission lines in quasars.

Krolik, J. H.↗
NASA NTRS1986

Effect of an oxygen plasma on the physical and chemical properties of several fluids for the liquid droplet radiator

The Liquid Droplet Radiator is one of several radiator systems currently under investigation by NASA Lewis Research Center. It involves the direct exposure of the radiator working fluid to the space environment. An area of concern is the potential harmful effects of the low-Earth-orbit atomic oxygen environment on the radiator working fluid. To address this issue, seven candidate fluids were exposed to an oxygen plasma environment in a laboratory plasma asher. The fluids studied included Dow Corning 705 Diffusion Pump Fluid, polymethylphenylsiloxane and polydimethlsiloxane, both of which are experimental fluids made by Dow Corning, Fomblin Z25, made by Montedison, and three fluids from the Krytox family of fluids, Krytox 143AB, 1502, and 16256, which are made by DuPont. The fluids were characterized by noting changes in visual appearance, physical state, mass, and infrared spectra. Of the fluids tested, the Fomblin and the three Krytoxes were the least affected by the oxygen plasma. The only effect noted was a change in mass, which was most likely due to an oxygen-catalyzed deploymerization of the fluid molecule.

Gulino, D. A.↗
NASA NTRS1985

Buoyant station mission comcepts for titan exploration

An advanced mission to this unique satellite of Saturn appropriate to the turn-of-the-century time period is described. The mission concept evolves about one or more buoyant stations (balloons and/or airship) operating at varying altitudes in Titan's atmosphere. An orbiter of Titan provides communications link support and accomplishes remote sensing science objectives. Use of buoyant stations are favored over a fixed site lander for two reasons: (1) adaptable to several possible surface physical states and topographies; and (2) capable of exploring both the atmosphere and surface with regional and possibly global mobility. Auxiliary payload concepts investigated include tethered packages and sounding rockets deployed from the buoyant station, and haze probes and surface penetrators deployed from the orbiter. The paper describes science objectives and payloads, propulsion system/mass delivery trades, balloon design requirements and deployment/motion characteristics, and communications link geometry and data characteristics.

Friedlander, A. L.↗
NASA NTRS1985

Computer-aided design of polymers and composites

This book on computer-aided design of polymers and composites introduces and discusses the subject from the viewpoint of atomic and molecular models. Thus, the origins of stiffness, strength, extensibility, and fracture toughness in composite materials can be analyzed directly in terms of chemical composition and molecular structure. Aspects of polymer composite reliability are considered along with characterization techniques for composite reliability, relations between atomic and molecular properties, computer aided design and manufacture, polymer CAD/CAM models, and composite CAD/CAM models. Attention is given to multiphase structural adhesives, fibrous composite reliability, metal joint reliability, polymer physical states and transitions, chemical quality assurance, processability testing, cure monitoring and management, nondestructive evaluation (NDE), surface NDE, elementary properties, ionic-covalent bonding, molecular analysis, acid-base interactions, the manufacturing science, and peel mechanics.

Kaelble, D. H.↗
NASA NTRS1986

A brief description of the simple biosphere model (SiB)

A biosphere model for calculating the transfer of energy, mass, and momentum between the atmosphere and the vegetated surface of the Earth was designed for atmospheric general circulation models. An upper vegetation layer represents the perennial canopy of trees or shrubs, a lower layer represents the annual ground cover of grasses and other herbacious species. The local coverage of each vegetation layer may be fractional or complete but as the individual vegetation elements are considered to be evenly spaced, their root systems are assumed to extend uniformly throughout the entire grid-area. The biosphere has seven prognostic physical-state variables: two temperatures (one for the canopy and one for the ground cover and soil surface); two interception water stores (one for the canopy and one for the ground cover); and three soil moisture stores (two of which can be reached by the vegetation root systems and one underlying recharge layer into and out of which moisture is transferred only by hydraulic diffusion).

Sellers, P. J.↗
NASA NTRS1987

Effect of an oxygen plasma on the physical and chemical properties of several fluids for the Liquid Droplet Radiator

The Liquid Droplet Radiator is one of several radiator systems currently under investigation by NASA Lewis Research Center. It involves the direct exposure of the radiator working fluid to the space environment. An area of concern is the potential harmful effects of the low-Earth-orbit atomic oxygen environment on the radiator working fluid. To address this issue, seven candidate fluids were exposed to an oxygen plasma environment in a laboratory plasma asher. The fluids studied included Dow Corning 705 Diffusion Pump Fluid, polymethylphenylsiloxane and polydimethylsiloxane, both of which are experimental fluids made by Dow Corning, Fomblin Z25, made by Montedison, and three fluids from the Krytox family of fluids, Krytox 143AB, 1502, and 16256, which are made by DuPont. The fluids were characterized by noting changes in visual appearance, physical state, mass, and infrared spectra. Of the fluids tested, the Fomblin and the three Krytoxes were the least affected by the oxygen plasma. The only effect noted was a change in mass, which was most likely due to an oxygen-catalyzed depolymerization of the fluid molecule.

Gulino, Daniel A.↗
NASA NTRS1987

Laser remote sensing of the atmosphere

Laser beams can be used as long-range spectroscopic probes of the chemical composition and physical state of the atmosphere. The spectroscopic, optical, and laser requirements for atmosphheric laser remote sensing are reviewed, and the sensitivity and limitations of the technique are described. A sampling of recent measurements includes the detection of urban air pollution and toxic chemicals in the atmosphere, the measurement of global circulation of volcanic ash in the upper atmosphere, and the observation of wind shear near airports.

Killinger, Dennis K.↗
NASA NTRS1987

Observations of absorption lines from highly ionized atoms

In the ultraviolet spectra of hot stars, absorption lines can be seen from highly ionized species in the interstellar medium. Observations of these features which have been very influential in revising the perception of the medium's various physical states, are discussed. The pervasiveness of O 6 absorption lines, coupled with complementary observations of a diffuse background in soft X-rays and EUV radiation, shows that there is an extensive network of low density gas (n approx. few x 0.001/cu cm) existing at coronal temperatures log T = 5.3 or 6.3. Shocks created by supernova explosions or mass loss from early-type stars can propagate freely through space and eventually transfer a large amount of energy to the medium. To create the coronal temperatures, the shocks must have velocities in excess of 150 km/sec; shocks at somewhat lower velocity (v = 100 km/sec) can be directly observed in the lines of Si3. Observations of other lines in the ultraviolet, such as Si 4V and C 5, may highlight the widespread presence of energetic UV radiation from very hot, dwarf stars. More advanced techniques in visible and X-ray astronomical spectroscopy may open up for inspection selected lines from atoms in much higher stages of ionization.

Jenkins, Edward B.↗
NASA NTRS1988

A four-layer model for the heat budget of homogeneous land surfaces

The present model envisions the heat balance of a homogeneous land surface in terms of available energy, a set of driving potentials, and parameters for the physical state of the soil and vegetation. Two unique features of the model are: (1) the expression of the interaction of evaporation from the soil and from foliage by changes in the value of the saturation vapor pressure deficit of air in the canopy (the conclusions of this interaction being consistent with field observations); and (2) the treatment of sensible and latent heat exchange between the atmosphere and a soil consisting of two discrete layers.

Choudhury, B. J.↗