Report of geology working group
Lunar geological explorations to determine evolution, composition, structure, and processes of moon - training of astronauts for mission
LUNAR EXPLORATION↗
SEARCH · Engineering Papers
Results for “structural evolution”
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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Research reports, July 1, 1964 - June 30, 1965
Compilation of research reports in astronomy, geophysics, nucleosynthesis, stellar structure and evolution, solar system origin, and atmospheric dynamics and turbulence
STELLAR EVOLUTION↗
Cosmology of our universe
Physical laws of universe, structure and evolution of universe, and cosmological theories of universe
Chiu, H.-Y.↗
Interplanetary shock waves. I - Gross structure.
Interplanetary shock waves structure and evolution, discussing propagation in collision free media by wave-particle interactions
Sonett, C. P.↗
Lunar gravimetry and mascons.
Lunar gravitational field data from Lunar Orbiter spacecraft reprocessed, discussing mascon effects on moon structure and evolution theories
Muller, P. M.↗
The gravitational field of the moon
Lunar structure and evolution based on satellite measurements of mass distribution, radius moments of inertia, gravity anomalies and topographic irregularities
Kaula, W. M.↗
Structure and evolutionary history of the solar system. I
Solar system origin, structure and evolution, discussing planet and satellite orbital motion, resonance effects, tides and postaccretional changes
Alfven, H.↗
Numerical study of strong plasma shock waves produced in an electromagnetic shock tube.
A set of two-fluid Navier-Stokes equations with classical physical transport coefficients is used to compute the evolution and structure of collisional plasma shock waves in an electromagnetic shock tube. Shock speeds up to 200 cm/microsec and shocked-plasma temperatures of the order of kilovolts are studied. A strong transverse bias magnetic field is employed, which significantly alters the size and shape of the shock profiles, when compared with the zero bias field case. The wave structure is different from that of a two-fluid gasdynamic shock without transverse magnetic field. Especially significant is the effect of the small ion Larmor radius in reducing the gasdynamic shock thickness by at least an order of magnitude in the transverse shock case, which permits collisional shocks to have thicknesses much smaller than the post-shock mean free path. These collisional shock waves produce very hot ions, the ion temperature increasing with shock speed, although the formation time and distances also increase substantially with shock speed.
Schneider, S. H.↗
Comet Kohoutek
A compilation of scientific observations (workshop) is presented. Topics discussed are: (1) tail form, structure, and evolution; (2) hydroxyl related observations; (3) molecules and atoms in the coma and tail; (4) photometry and radiometry; and (5) spacecraft and ground based observation data. Color photographs are shown.
Gary, Gilmer A.↗
A numerical investigation of severe thunderstorm gust fronts
A numerical model was developed to simulate the evolution and structure of severe thunderstorm gust fronts. The model is a non-hydrostatic, fine resolution, cross-sectional primitive equation model. Two-dimensional horizontal and vertical equations of motion, the continuity equation, and the thermodynamic energy equation were utilized. It was shown that two dominant factors influencing gust front configuration are surface friction and the solenoidal field coincident with the front. It is suggested that solenoidal accelerations oppose the deceleration of surface friction. After a downdraft is initiated in the model, these opposing tendencies soon reach a balance and the gust front achieves a quasi-steady configuration. Thus, the experiments indicate that surface friction does not induce a cycle of front formation and collapse. In addition, the effect of evaporative cooling in producing a vigorous downdraft was parameterized by a local cooling function. Greater cooling in the downdraft results in a more intense gust front that exhibits stronger wind maximums and greater shears. The ambient air stability was shown to be an important factor influencing the depth of the cold outflow.
Mitchell, K. E.↗
ATM observations - X-ray results
Preliminary results of the solar X-ray observations from Skylab are reviewed which indicate a highly structured nature for the corona, with closed magnetic-loop structures over a wide range of size scales. A description of the S-054 experiments is provided, and values are given for the parameters - including size, density, and temperature - describing a variety of typical coronal features. The structure and evolution of active regions, coronal holes, and bright points are discussed.
Vaiana, G. S.↗
Lunar surface gravimeter experiment
The lunar surface gravimeter used the moon as an instrumented antenna to search for gravitational waves predicted by Einstein's general theory of relativity. Tidal deformation of the moon was measured. Gravitational radiation is a channel that is capable of giving information about the structure and evolution of the universe.
Giganti, J. J.↗
Lunar mascons
Large positive anomalies have been discovered in the moon's gravitational field. The concept of mascons as the source of these anomalies was reviewed. Ideas set forth in the literature and related in some manner to mascons are summarized. Lunar structure and evolution are emphasized and it is concluded that more detailed studies of the moon by spacecraft are needed to solve remaining uncertainties.
Zharkov, V. N.↗
Compact sources of EUV radiation
Contrary to classical theoretical expectations extreme ultraviolet emissions from a number of stellar objects have been recently discovered. A combined EUV and optical study of these sources has revealed a wealth of new information on stellar structure and evolution especially for what regards the transition stage between planetary nebulae and white dwarfs. The current status of research in this field is reviewed with emphasis on the impact these observations are having on our view of the later stages of stellar evolution and on the future possibility that could be awaiting a sensitive all sky survey of the EUV spectrum.
Paresce, F.↗
6 centimeter observations of solar bursts with 6-inch resolution
During May 1974 data were collected on nine 6-cm solar bursts originating in two active regions. One-dimensional fan-beam scans were obtained every 30 seconds in order to study burst structure and evolution. Maximum burst flux was in the 0.34-12.0 sfu range. At maximum intensity the estimated brightness temperatures were in the 10 to the 6th to 2 x 10 to the 7th K range. Angular sizes ranged from 7-23 arcsec. In most cases an expansion of the burst core after maximum intensity was observed along with a drift in the position of the burst core. Four bursts were associated important H-alpha flares, and in all cases burst maximum occurred before flare maximum. The bursts were circularly polarized in the extraordinary mode sense during maximum intensity. Since the polarization was the same over the extent of the burst source, it is suggested that if the burst is associated with loop sources, the emission is associated with one leg of the loop.
Alissandrakis, C. E.↗
Coronal holes and solar magnetic fields
Since 1972 nearly continuous observations of coronal holes and their associated photospheric magnetic fields have been made using a variety of satellite and ground-based equipment. The present paper reviews the results of comparisons of these data and shows that the structure and evolution of coronal holes is basically governed by the large-scale distribution of photospheric magnetic flux. Nonpolar holes form in the decaying remnants of bipolar magnetic regions in areas with a large-scale flux imbalance. In addition, there is strong indirect evidence that the magnetic field in coronal holes is always open to interplanetary space, but not all open-field regions have associated coronal holes.
Harvey, J. W.↗
A synoptic view of galactic processes
The power of using synoptic galactic surveys in many wavelength bands in order to obtain a more complete picture and a better understanding of the dynamics of the interstellar medium and to study galactic structure and evolution on a large scale is discussed. The implications of the picture presented by mm wave CO, far infrared and X ray surveys of the Galaxy are emphasized.
Stecker, F. W.↗
The diffuse UV background
The diffuse radiation field in the UV (900-3,000 A) affects the structure of galactic molecular clouds and conveys important information concerning the physical characteristics and spatial distribution of gas and dust in the universe. Continuum emission in this range is probably dominated by interstellar dust scattering in our galaxy. For view directions and angular resolutions allowing observations in the rifts between galactic dust clouds, the background due to the integrated light of spiral galaxies may be detected, providing important information on their structure and evolution. The redshifted emission from an intergalactic medium may be observable in the regions between nearby bright galaxies. Present observations provide weak constraints on the radiation field required to ionize the intergalactic medium at the level required by the Gunn-Peterson test.
Paresce, F.↗