Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “primordial”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Origin of planetary primordial rare gas - The possible role of adsorption.

The degree of physical adsorption of Ne, Ar, Kr, and Xe on pulverized samples of the Allende meteorite at 113 K has been measured. The observed pattern of equilibrium enrichment of heavy rare gases over light on the pulverized meteorite surfaces relative to the gas phase is similar to the enrichment pattern exhibited by planetary primordial rare gas when compared with the composition of solar rare gas. Results indicate that, at 113 K, a total nebular pressure of from .01 to .001 atm would be required to explain the Ar, Kr, and Xe abundances in carbonaceous chondrites with an adsorption mechanism. This pressure estimate is compatible with the range of possible nebular pressures suggested by astrophysical arguments. However, the subsequent mechanism by which initially adsorbed gas might have been transferred into the interiors of grains cannot be identified at present.

Fanale, F. P.↗
NASA NTRS1972

Primordial turbulence and the formation of galaxies.

The development of turbulence at early epochs in a Friedmann universe is studied, giving primary attention to the density fluctuations generated by vortical turbulence. Aspects of turbulence theory in a cosmogonical context are discussed together with a theory of turbulence in an expanding universe. It is suggested that small-amplitude density fluctuations generated by primordial turbulence before decoupling, rather than by the onset of supersonic turbulence after decoupling, can best account for the formation of galaxies. On the other hand, the requisite amount of angular momentum per unit mass to account for the rotation of galaxies is well explained by the turbulence parameters.

Silk, J.↗
NASA NTRS1973

Geochemistry of primordial Pb, Bi, and Zn in Apollo 15 samples

Primordial Pb as Pb-204 is present in Apollo 15 samples in concentrations ranging from less than 0.2 ppb in basalts to 6 ppb in soils. An acid soluble, pH-5-6, readily volatile component of this Pb is present, possibly as PbBr2; the remainder is correlated with the metal content of the sample. Leachable Bi and Pb-204 are correlated; residual Bi is probably present in a phosphate, possibly apatite. Zn is also highly leachable; residual Zn and Pb-204 are correlated.

Allen, R. O., Jr.↗
NASA NTRS1974

Evidence of a primordial solar wind

A model is reviewed which requires a T Tauri 'wind' and at the same time encompasses certain early-object stellar features. The theory rests on electromagnetic induction driven by the 'wind'. Plasma confinement of the induced field prohibits a scattered field, and all energy loss is via ohmic heating in the scatterer (i.e., planetary objects). Two modes, one caused by the interplanetary electric field (transverse magnetic) and the other by time variations in the interplanetary magnetic field (transverse electric) are present. Parent body melting, lunar surface melting, and a primordial magnetic field are components of the proposed model.

Sonett, C. P.↗
NASA NTRS1977

Primordial noble gases in chondrites - The abundance pattern was established in the solar nebula

Ordinary chondrites, like carbonaceous chondrites, contain primordial noble gases mainly in a minor phase comprising not more than 0.05 percent of the meteorite, probably an iron-chromium sulfide. The neon-20/argon-36 ratios decrease with increasing argon-36 concentration, as expected if the gas pattern was established by condensation from the solar nebula, and was negligibly altered by metamorphism in the meteorite parent bodies. Meteoritic and planetary matter apparently condensed over a substantial range of temperatures.

Alaerts, L.↗
NASA NTRS1978

Evidence for a primordial magnetic field during the meteorite parent body era

Data on 247 meteorites were examined, and a log-log plot of the magnetic moment/gm versus the susceptibility/gm reveals a straight-line relation with a slope of unity for a range of meteorite types extending from achondrites at the low Fe-Ni end to stony-irons. The relation holds for a span of parameter values ranging between four and five orders. The results support the hypothesis of a common background magnetic field at the time of meteorite formation. An equation relating the primordial field strength to the average carrier demagnetization factor, which can vary from 0 to 4 pi, is presented. The extreme lower limit for the field strength is 0.02 oersted, while for the mean field of 0.27 oersted determined from a study of individual meteorites (Stacy and Banerjee, 1974), the average value for the carrier demagnetization factor is 0.74, corresponding to elongated grains.

Sonett, C. P.↗
NASA NTRS1979

Aether drift and the isotropy of the universe: a measurement of anisotropies in the primordial black-body radiation

This experiment detected and mapped large-angular-scale anisotropies in the 3 K primordial black-body radiation with a sensitivity of 2x.0001k and an angular resolution of about 10 degs. It measured the motion of the Earth with respect to the distant matter of the Universe (Aether Drift), and probed the homogeneity and isotropy of the Universe (the Cosmological Principle). The experiment used two Dicke radiometers, one at 33 GHz to detect the cosmic anisotropy, and one at 54 GHz to detect anisotropies in the residual oxygen above the detectors. The system was installed in the NASA-Ames Earth Survey Aircraft (U-2), and operated successfully in a series of flights.

Muller, R. A.↗
NASA NTRS1979

Primordial inhomogeneities in the expanding universe. I - Density and velocity distributions of galaxies in the vicinities of rich clusters

The density profiles and Hubble flow deviations in the vicinities of rich galaxy clusters are derived for a variety of models of initial density and velocity perturbations at the recombination epoch. The galaxy correlation function, measured with respect to the Abell clusters, is used to normalize the theoretical models. The angular scales of the required primordial inhomogeneities are calculated. It is found that the resulting density profiles around rich clusters are surprisingly insensitive to the shape of the initial perturbations and also to the cosmological density parameter, Omega. However, it is shown that the distribution of galaxy radial velocities can provide a possible means of deriving Omega.

Silk, J.↗
NASA NTRS1979

Hydrodynamics of primordial black hole formation

The hydrodynamic picture of the formation of primordial black holes (PBH) at the early stages of expansion of the Universe is considered. It is assumed that close to singularity, expansion occurs in a quasi-isotropic way. Using an EVM, a spherically symmetrical nonlinear problem of the evolution of primary strong deviation from the Fridman solution was solved. What these deviations must be, so that the formation of PBH occurred was clarified. Attention was devoted to the role of pressure gradients. It is pointed out that at the moment of formation of PBH, only a small part of matter enters into it, primarily the component of perturbation. It is also pointed out that at this moment, the mass of PBH essentially is smaller than the mass considered within the cosmic horizon. The possibility of changing the mass of the PBH as a result of accretion is analyzed.

Nadezhin, D. K.↗
NASA NTRS1980

Primordial refractory metal particles in the Allende meteorite

Refractory metal particles containing Os, Re, W, Mo, Ir, and Ru were observed in a Ca-Al-rich inclusion in the Allende meteorite. These particles are the closest to unaltered primordial metal condensates from a nebula yet reported, and appear to have been isolated from the nebula before the condensation of refractories was complete. Computer calculations of condensation indicate that the temperature of isolation appears to be close to the calculated temperature of first formation of oxides (about 1620 K at 0.0001 atm) indicating that isolation may have been effected by coating of the particles by oxides.

Blander, M.↗
NASA NTRS1981

Aether Drift and the isotropy of the universe: A measurement of anisotropes in the primordial black-body radiation

Large-angular-scale anisotropies in the 3 K primordial black-body radiation were detected and mapped with a sensitivity of 2 x to the minus 4 power K and an angular resolution of about 10 deg. The motion of the Earth with respect to the distant matter of the Universe ("Aether Drift") was measured and the homogeneity and isotropy of the Universe (the "Cosmological Principle") was probed. The experiment uses two Dicke radiometers, one at 33 GHz to detect the cosmic anisotropy, and one at 54 GHz to detect anisotropies in the residual oxygen above the detectors. The system was installed in the NASA-Ames Earth survey aircraft (U-2), and operated successfully in a series of flights in both the Northern and Southern Hemispheres. Data taking and analysis to measure the anisotropy were successful.

Smoot, G. F.↗
NASA NTRS1983

The primordial helium abundance and the age of the universe

The value of the primordial helium abundance as a constraint on the age of the universe is discussed emphasizing the age of the oldest stars as an estimate of the age of the universe. The primary uncertainty in the globular cluster technique is that of the starting helium abundance. Investigations of this abundance are reviewed, and the consistency of the resulting findings with the age determinations obtained by cosmological dynamics and big bang nucleosynthesis studies is discussed. It is concluded that the age of the universe is probably between 8 and 19 billion years, and that the best fit age consistency determined by a combination of all techniques is about 15 billion years.

Schramm, D. N.↗
NASA NTRS1982

Asteroid compositional rings: Clues to the compositions of primordial planetesimals in the middle solar system

The distribution of asteroid taxonomic types at distances between 2.1 and 5.3 AU is discussed. There are four major, overlapping but compositionally distinct rings of asteroids present within this range of heliocentric distance. The rings, within which 80% of each of 4 major taxonomic types (S, C, P, and D) fall, are centered at 2.6 (0.7), 2.9 (0.8), 3.4 (0.7), and 4.6 (1.5) AU respectively, where the numbers in parentheses are the ring widths in AU. The overall physical resemblence between the asteroid rings and planetary rings is poor; physically the asteroid belt more closely resembles a debris strewn satellite system. Once the mineralogy of these taxonomic types is established, and complications arising from postaccretionary metamorphism are dealt with, they may be used as probes of physical conditions in the early solar system. The identification of primordial planetesimals can be used in studying the siblings of the planetesimals responsible for the final stage of planetary accretion.

Tedesco, E. F.↗
NASA NTRS1985

Earth's primordial differentiation, and its after-effects

The case for massive primordial melting on the Earth is circumstantial (i.e., based mainly on lunar evidence), but nonetheless compelling. The term magma ocean is probably a hyperbole. Among other things, ocean implies the system is virtually 100% liquid, with a mainly gas/liquid upper surface, and a water like viscosity of the order .01 poise. The preferred term for this phenomenon is magmasphere.

Warren, P. H.↗
NASA NTRS1985

The 4He1H ratios in the chemical compositions of solar flare particles and the primordial solar nebula

The chemical abundances of solar flare particles are similar to those of galactic cosmic rays at their sources. In order to infer the 4He/1H ratio in the solar atmosphere, this ratio as observed in the interstellar gases was considered in addition to those which were contained of galactic cosmic rays and the stars classified as the early types. Since it is clear that the most of these ratios ever deduced for both of the Sun and solar flare particles are lower than those for the interstellar gases, this ratio suggests that hydrogens are relatively overabundant in the chemical abundances of the Sun and the primordial solar nebula as compared to those of the interstellar gases currently observed.

Sakurai, K.↗
NASA NTRS1985

A calculation of the Rosseland mean opacity of dust grains in primordial solar system nebulae

The Rosseland mean opacity owing to grains was calculated as a function of temperature and density for nebulae having solar elemental abundances. The values of the mean opacity were evaluated with a generalized formulation allowing for anisotropic scattering. The values of the mean opacity do not depend sensitively on the choice of the particle size distribution function, provided that there are few particles having sizes in excess of several tens of microns. The results indicate that thermal convection in primordial nebulae occurs over broader ranges of altitudes at low temperatures than at high temperatures, and for size distributions for which extensive aggregation has not yet occurred.

Pollack, J. B.↗
NASA NTRS1986

On the tidal interaction between protoplanets and the primordial solar nebula. II - Self-consistent nonlinear interaction

A method to analyze the full nonlinear response and physical processes associated with the tidal interaction between a binary system and a thin disk in the steady state is presented. Using this approach, density wave propagation, induced by tidal interaction, may be studied for a wide range of sound speeds and viscosities. The effect of self-gravity may also be incorporated. The results of several calculations relevant to the tidal interaction between a protoplanet and the primordial solar nebula are also presented.

Lin, D. N. C.↗
NASA NTRS1986

Primordial nucleosynthesis with generic particles

A revision of the standard model for Big Bang nucleosynthesis is discussed which allows for the presence of generic particle species. The primordial production of He-4 and D + He-3 is calculated as a function of the mass, spin degrees of freedom, and spin statistics of the generic particle for masses in the range 0.01-100 times the electron mass. The particular case of the Gelmini and Roncadelli majoron model for massive neutrinos is discussed.

Walker, T. P.↗