291
291
Jun 18, 2010
06/10
by
Chuan, R. L.; Rogers, K. W.; Wainwright, J. B.; Wallace, D. A
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Design of direct air density measuring device for use aboard orbiting spacecraft
Topics: CRYOPUMPING, SPACECRAFT ELECTRONIC EQUIPMENT, DENSIMETERS, DENSITY MEASUREMENT, MEASURING...
183
183
May 27, 2011
05/11
by
Stowell, Elbridge Z
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In this theory, a metal consisting of two phases, each with its own elasticity and viscosity, will exhibit transient creep after application of a constant stress. A comparison of the transient creep curves resulting from this theory with experimental data on four different metals shows that the entire family of creep curves for any one metal are given by the theory using a single set of constants appropriate to that metal.
Topics: COSMIC DUST, SATELLITE OBSERVATION, SPACE PROBES, SATELLITE-BORNE INSTRUMENTS, EARTH ATMOSPHERE,...
578
578
Jul 26, 2010
07/10
by
NON
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The workshop brought together researchers involved in the NASA formal methods research effort for detailed technical interchange and provided a mechanism for interaction with representatives from the FAA and the aerospace industry. The workshop also included speakers from industry to debrief the formal methods researchers on the current state of practice in flight critical system design, verification, and certification. The goals were: define and characterize the verification problem for...
Topics: COMPACT GALAXIES, SPECTROSCOPY, STARS, COSMOLOGY, GALACTIC CLUSTERS, GRAVITATIONAL EFFECTS,...
Distribution of meteors in streams detected in the synoptic-year meteor sample plus a study of the fragmentation characteristics of the synoptic-year meteor sample are presented. Population coefficients and dispersion coefficients were determined for each meteor stream. These two parameters serve to determine the number of definite members of the stream in the sample used, and to estimate the actual space density of meteor streams. From results of the fragmentation study, it appears that the...
Topics: NASA Technical Reports Server (NTRS), FRAGMENTATION, METEOROID SHOWERS, RADAR TRACKING,...
Compact groups are small, relatively isolated, systems of galaxies with projected separations comparable to the diameters of the galaxies themselves. Two well-known examples are Stephan's Quintet (Stephan, 1877) and Seyfert's Sextet (Seyfert 1948a,b). In groups such as these, the apparent space density of galaxies approaches 10(exp 6) Mpc(sub -3), denser even than the cores of rich clusters. The apparent unlikeliness of the chance occurrence of such tight groupings lead Ambartsumyan (1958,...
Topics: NASA Technical Reports Server (NTRS), COMPACT GALAXIES, COSMOLOGY, GALACTIC CLUSTERS, GRAVITATIONAL...
Population parameters of 275 streams including 20 additional streams in the synoptic-year sample were found by a computer technique. Some 16 percent of the sample is in these streams. Four meteor streams that have close orbital resemblance to Adonis cannot be positively identified as meteors ejected by Adonis within the last 12000 years. Ceplecha's discrete levels of meteor height are not evident in radar meteors. The spread of meteoroid fragments along their common trajectory was computed for...
Topics: NASA Technical Reports Server (NTRS), COMPUTER TECHNIQUES, METEOR TRAILS, ORBITAL ELEMENTS, RADAR...
The FUSE observations of a non-radiative shock wave in the Cygnus Loop were obtained in June and October 2000. The two main results were near equilibration of the kinetic temperature of oxygen with protons and electrons and inferred 3D structure and pre-shock density for the shock including resonance scattering. The 3D structure in turn implies density fluctuations in keeping with the level expected for interstellar turbulence. Major results are contained in an ApJ paper in press and some...
Topics: NASA Technical Reports Server (NTRS), CYGNUS CONSTELLATION, HYDROGEN, SHOCK WAVES, RESONANCE...
243
243
May 23, 2011
05/11
by
Lin, Shu; Uehara, Gregory T
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In his research, we have proposed the (64, 40, 8) subcode of the third-order Reed-Muller (RM) code to NASA for high-speed satellite communications. This RM subcode can be used either alone or as an inner code of a concatenated coding system with the NASA standard (255, 233, 33) Reed-Solomon (RS) code as the outer code to achieve high performance (or low bit-error rate) with reduced decoding complexity. It can also be used as a component code in a multilevel bandwidth efficient coded modulation...
Topics: ANGULAR DISTRIBUTION, LOSSES, NEUTRON DECAY, PIONEER 11 SPACE PROBE, ELECTRONS, ENERGY SPECTRA,...
As very high energy (VHE) photons propagate through the extragalactic background light (EBL), they interact with the soft photons of the EBL and initiate electromagnetic cascades of photons and electrons. The collective intensity of a cosmological population emitting at VHEs (such as blazars) will be attenuated at the highest energies through interactions with the EBL and enhanced at lower energies by the resulting cascade. As such, depending on the space density and spectra of the sources and...
Topics: NASA Technical Reports Server (NTRS), ENERGY SPECTRA, CHARGED PARTICLES, BLAZARS, BACKGROUND...
Recent observations using the Hubble Space Telescope of the z = 0.156 QSO 3C 273 have discovered a surprisingly large number of Ly-alpha absorption lines. In particular, Morris et al. found 9 certain and 7 possible Ly-alpha lines with equivalent widths above 25 mA. This is much larger (by a factor of 5-10) than the number expected from extrapolation of the high-redshift behavior of the Ly-alpha forest. Within the context of pressure-confined models for the Ly-alpha clouds, this behavior can be...
Topics: NASA Technical Reports Server (NTRS), DARK MATTER, DISK GALAXIES, GALACTIC HALOS, LYMAN SPECTRA,...
From an examination of predicted column densities, the following conclusions were drawn: (1) The SiO ought to be visible in carbon stars which were generated from triple alpha burning, but absent from carbon stars generated from the CNO bi-cycle. (2) Variation in the observed relative strengths of TiO and ZrO is indicative of real differences in the ratio Ti/Zr. (3) The TiO/ZrO ratio shows a small variation as C/O and effective temperature is changed. (4) Column density of silicon dicarbide...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC MODELS, MOLECULAR SPECTROSCOPY, SPACE DENSITY,...
The author discusses the morphology of luminous Infrared Astronomy Satellite (IRAS) galaxies. A few comments are made about the direction to be taken in future observations of luminous IRAS galaxies.
Topics: NASA Technical Reports Server (NTRS), GALACTIC NUCLEI, GALACTIC STRUCTURE, INFRARED RADIATION,...
The results are presented from a study for the Space Station Planners Group of the Office of Space Sciences and Applications. The objectives of the study are: (1) the development of contamination protection requirements for protection of Space Station attached payloads, serviced payloads and platforms; and (2) the determination of unknowns or major impacts requiring further assessment. The nature, sources, and quantitative properties of the external contaminants to be encountered on the Station...
Topics: NASA Technical Reports Server (NTRS), AEROSPACE ENVIRONMENTS, ENVIRONMENT POLLUTION, SPACE SHUTTLE...
The energy spectra and angular distributions of electrons observed by Pioneer 11 as a function of radial distance in the inner magnetosphere of Saturn are reanalyzed and phase space densities are then calculated. The radial dependence of phase space density requires a distributed loss process. The loss is greatest in the region of the E ring (5.5 less than L less than 8.5) and is attributed to collisions with the ring particles in agreement with earlier work by Van Allen et al. (1980)....
Topics: NASA Technical Reports Server (NTRS), ANGULAR DISTRIBUTION, ELECTRONS, ENERGY SPECTRA, PLANETARY...
Although many properties of the Earth's magnetosphere have been measured and quantified in the past 30 years since it was discovered, one fundamental measurement (for zeroth order MHD equilibrium) has been made infrequently and with poor spatial coverage - the global electric field. This oversight is due in part to the neglect of theorists. However, there is renewed interest in the convection electric field because it is now realized to be central to many magnetospheric processes, including the...
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, EARTH MAGNETOSPHERE, ELECTRIC FIELDS,...
We have obtained XMM spectra for five red, 2MASS AGN, selected from a sample observed by Chandra to be X-ray bright and to cover a range of hardness ratios. Our results confirm the presence of substantial absorbing material in three sources which have optical classifications ranging from Type 1 to Type 2, with an intrinsically flat (hard) power law continuum indicated in the other two. The presence of both X-ray absorption and broad optical emission lines with the usual strength suggests either...
Topics: NASA Technical Reports Server (NTRS), X RAY ABSORPTION, COSMIC BACKGROUND EXPLORER SATELLITE,...
New observations of the 10 and 20 micron size of the emission region in Arp 220 are presented. Also given are ground based photometry from 1 to 32 micron including measurements of the strength of the silicate feature at 10 micron. The results show that the 20 micron size of Arp is smaller than 1.5 arcsec (500 pc); comparison of IRAS and ground based observations show that IRAS 12 micron flux measured with a large arcmin beam is the same as that seen from the ground with a 3 arcsec aperture. At...
Topics: NASA Technical Reports Server (NTRS), ACTIVE GALACTIC NUCLEI, COSMIC DUST, SEYFERT GALAXIES, SPACE...
A deep far-infrared survey is presented using over 1000 scans made of a 4 to 6 sq. deg. field at the north ecliptic pole by the IRAS. Point sources from this survey are up to 100 times fainter than the IRAS point source catalog at 12 and 25 micrometers, and up to 10 times fainter at 60 and 100 micrometers. The 12 and 25 micrometer maps are instrumental noise-limited, and the 60 and 100 micrometer maps are confusion noise-limited. The majority of the 12 micrometer point sources are stars within...
Topics: NASA Technical Reports Server (NTRS), FAINT OBJECTS, FAR INFRARED RADIATION, GALACTIC EVOLUTION,...
High-energy radiation processes in compact cosmic objects are often expected to have a strongly non-linear behavior. Such behavior is shown, for example, by electron-positron pair cascades and the time evolution of relativistic proton distributions in dense radiation fields. Three independent techniques have been developed to simulate these non-linear problems: the kinetic equation approach; the phase-space density (PSD) Monte Carlo method; and the large-particle (LP) Monte Carlo method. In...
Topics: NASA Technical Reports Server (NTRS), MONTE CARLO METHOD, PLASMA RADIATION, NONTHERMAL RADIATION,...
We analyze the spatial clustering properties of a new catalog of very rich galaxy clusters selected from the APM Galaxy Survey. These clusters are of comparable richness and space density to Abell Richness Class greater than or equal to 1 clusters, but selected using an objective algorithm from a catalog demonstrably free of artificial inhomogeneities. Evaluation of the two-point correlation function xi(sub cc)(r) for the full sample and for richer subsamples reveals that the correlation...
Topics: NASA Technical Reports Server (NTRS), GALACTIC CLUSTERS, RED SHIFT, COSMOLOGY, MAXIMUM LIKELIHOOD...
209
209
May 23, 2011
05/11
by
Hummel, R. E
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The ultimate goal of this research project is to understand the mechanisms, including transport rate, which are involved in thin film electrotransport. After careful consideration of the various methods to attack this problem three general ideas were selected. The are: (1) High precision electrical resistance measurements of several small portions of a thin film strip during electrotransport. This method was selected because it gives fairly fast quantitative results on the kinetics of the...
Topics: THREE DIMENSIONAL MODELS, MAGNETIC STORMS, PLASMA DECAY, ATMOSPHERIC MODELS, ION CHARGE, TWO...
The consequencies of diffusive acceleration of cosmic rays in supernova shocks propagation through an inhomogeneous interstellar medium are explored. The acceleration takes place in the hot, tenuous, intercloud gas, while nuclear collisions, leading to the production of cosmic ray secondaries, predominantly occur in those regions where the supernova shocks collide with interstellar clouds. A simple model is used to calculate the interaction of a (cosmic ray + gas) shock with a cloud, and thus...
Topics: NASA Technical Reports Server (NTRS), COSMIC RAY SHOWERS, GALACTIC COSMIC RAYS, GALACTIC STRUCTURE,...
This work is an extension of a previous ring current decay model. In the previous work, a two-dimensional kinetic model was constructed to study the temporal variations of the equatorially mirroring ring current ions, considering charge exchange and Coulomb drag losses along drift paths in a magnetic dipole field. In this work, particles with arbitrary pitch angle are considered. By bounce averaging the kinetic equation of the phase space density, information along magnetic field lines can be...
Topics: NASA Technical Reports Server (NTRS), EARTH MAGNETOSPHERE, MAGNETIC STORMS, RING CURRENTS, THREE...
Results from a study of the far infrared properties of the brightest galaxies in the IRAS survey are described. There is a correlation between the infrared luminosity and the infrared to optical luminosity ratio and between the infrared luminosity and the far infrared color temperature in these galaxies. The infrared bright galaxies represent a significant component of extragalactic objects in the local universe, being comparable in space density to the Seyferts, optically identified starburst...
Topics: NASA Technical Reports Server (NTRS), EXTRAGALACTIC RADIO SOURCES, FAR INFRARED RADIATION, GALACTIC...
A large scale program was initiated to identify IRAS point sources. At ROE the ideal facilities are at hand to undertake such a large program, viz. the rapid scanning capabilities of the COSMOS measuring machine to exploit the depth and resolution of the U.K. Schmidt Telescope J survey plates. Sources in 44 Schmidt plate areas were identified including 1300 sources and covering 1100 square degrees. The identification comprise 700 galaxy identifications and 600 stellar identifications. There are...
Topics: NASA Technical Reports Server (NTRS), GALACTIC CLUSTERS, GALACTIC STRUCTURE, POINT SOURCES,...
One of the outstanding problems in solar flare theory is how to explain the 10-20 keV and greater hard x-ray emissions by a thick target bremsstrahlung model. The model requires the acceleration mechanism to accelerate approximately 10(exp 35) electrons sec(exp -l) with comparable energies, without producing a large return current which persists for long time scales after the beam ceases to exist due to Lenz's law, thereby, producing a self-magnetic field of order a few mega-Gauss. In this...
Topics: NASA Technical Reports Server (NTRS), BREMSSTRAHLUNG, ELECTRON ACCELERATION, ELECTROSTATIC WAVES,...
This work is an extension of a previous ring current decay model. In the previous work, a two-dimensional kinetic model was constructed to study the temporal variations of the equatorially mirroring ring current ions, considering charge exchange and Coulomb drag losses along drift paths in a magnetic dipole field. In this work, particles with arbitrary pitch angle are considered. By bounce averaging the kinetic equation of the phase space density, information along magnetic field lines can be...
Topics: NASA Technical Reports Server (NTRS), THREE DIMENSIONAL MODELS, CHARGE EXCHANGE, RING CURRENTS,...
