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At least 1,495 records · Page 83
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Elastic wave velocities and thermal diffusivities of Apollo 14 rocks.

The compressional- and shear-wave velocities of Apollo 14 lunar rocks 14311,50 and 14313,27 as functions of pressure up to 10 kb and the thermal diffusivity of sample 14311,50 over the temperature range 100 to 550 K have been measured. Both samples 14311 and 14313 are polymict fragmental rocks. The overall elastic and anelastic behavior of the Apollo 14 samples are similar to those of Apollo 11 and 12 samples; low velocity and low Q at pressures below 1 kb and rapid increase of velocity and Q with pressure are also typical of the Apollo 14 rocks. The available data of P- and S-wave velocities of lunar rocks show that Birch's law holds for the lunar rocks. The thermal diffusivity of a lunar rock in vacuum is found to be significantly lower than that in air at one atmospheric pressure.

Mizutani, H.↗
NASA NTRS1972

The Washougal meteorite.

Optical study of the Washougal (Wash.), howardite, and determination of the ranges of composition of plagioclase and pyroxenes from measurements of densities and indices of refraction. Notable among many unique xenoliths are a round object whose morphology is that of an armored chondrule; a stratified fragment; and a centimeter-sized dunite xenolith (olivine Fa sub 12.8). The abundances of 27 elements, including all major elements and 15 trace elements are reported. To a first approximation, the composition of Washougal corresponds to a mixture of 51 wt per cent of eucritic material and 49 per cent of a diogenitic component, but excesses of some elements suggest a minor component of chondritic composition.

Jerome, D. Y.↗
NASA NTRS1973

Visible and near-infra-red transmission and reflectance measurements of the Luna 20 soil.

Visible and near-infrared spectra of chemically analyzed grains of glass and minerals from the Luna 20 sample were compared with diffuse reflectance spectra of the bulk soil. As in the spectra of soil samples from other localities on the moon, pyroxene contributes two broad absorption features near 1 and 2 microns. The soil has a high integral reflectance (or albedo) arising from plagioclase, which appears to be the dominant mineral in the lunar highlands. The Luna 20 soil curve is most similar to the reflectance curves of the non-rayed soils at Apollo 16, in agreement with the generally similar mineralogy of these samples. The average pyroxene composition in the Luna 20 soil, as determined from the absorption bands in the diffuse reflectance spectra, and analyses of single crystals, is more calcic than in the lithic fragments. Thus, the soil appears to have a few per cent of admixed material derived from mare basalts. Comparison of the soil spectrum with telescopic curves of nearby areas reveals a close similarity.

Adams, J. B.↗
NASA NTRS1973

Chemistry and surface morphology of soil particles from Luna 20 LRL sample 22003.

Optical and scanning electron microscopy, scanning electron microprobes and energy dispersion techniques were applied in an analysis of six siliceous glass spheres, five siliceous glass-bonded agglutinates and one breccia fragment from Luna 20 sample 22003. It is theorized that local meteor impact processes might have been responsible for the formation of most of the glass spheres and that the impacts of relatively high velocity particles might have been responsible for the craters observed on the surfaces of the spheres. The concentrations of iron spherules on the surfaces of the glass spheres were generally lower than in similar Apollo 11 and 12 glass spheres.

Carter, J. L.↗
NASA NTRS1972

Chemical constraints on the origin of chondrules in ordinary chondrites.

Chemical variations found among 61 chondrules from the Chainpur (LL-3) chondrite are compared with those predicted for various mechanisms of chondrule formation. Neither crystal-liquid nor liquid-vapor fractionation accounts for the pattern of variation in Chainpur, which appears to reflect fragmentation of a crystalline precursor rock whose crystal dimensions were about 1/10 of the median chondrule diameter.

Dodd, R. T.↗
NASA NTRS1972

Are lunar rilles inverted eskers.

A proposed mechanism for the formation of lunar rilles argues that escaping volatiles (CO2 and H2O) could produce a sinuous channel between an impermeable basement surface and a developing surficial permafrost layer. Concurrent with the development of the subsurface channel would be the production of a large amount of fragmented ice mixed with rock debris at the surface above and along the sides of the sinuous subsurface channel. Eventual sublimation of the ice in the surficial material down to and perhaps including the subsurface would develop a feature at the surface that would be morphologically very similar to a valley produced by running water.

Helsley, C. E.↗
NASA NTRS1973

Martian surface coordinates.

This paper presents methods and results for primary and secondary triangulation of the Martian surface. The primary network is based on multiphotograph stereophotogrammetry in which the pictures are rotated around fixed centers; these centers are provided as spacecraft stations from the tracking data. The computations use the latest Mars spin axis determined by Mariner 9 experiments and the new first meridian passing through a small crater, Airy-0, seen on Mariner 9 imagery. The secondary triangulation is performed in the map plane using rectified pictures as map fragments, assumed to be of correct shape. In this paper, 1205 primary positions are given.

Davies, M. E.↗
NASA NTRS1973

Apollo 15 green glasses.

The samples analyzed include 28 spheres, portions of spheres, and angular fragments from soil 15101. Emerald green glasses from other soils are identical to those from 15101. The composition of the green glass is unlike that of any other major lunar glass group. The Fe content is comparable to that in mare basalts, but Ti is much lower. The Mg content is much higher than in most lunar materials analyzed to date, and the Cr content is also high. The low Al content is comparable to that of mare basalt glasses.

Ridley, W. I.↗
NASA NTRS1973

Distribution of gases within Apollo 15 samples - Implications for the incorporation of gases within solid bodies of the solar system.

The distribution of helium, neon, and argon isotopes within Apollo 15 samples results primarily from fractionated solar wind gases, accompanied by small quantities of cosmogenic gases. No unequivocal primordial lunar gases have been detected within various mineral, rock, or glass fragments. A vug from 15555 contains solar wind gases that have abundance ratios similar to those found in the Apollo 12 aluminum foil experiments. A comparison of these Apollo 15 results with previous laser probe mass spectrometric measurements from the gas-rich Kapoeta and Fayetteville meteorites, as well as with analyses of the Apollo 12 and 14 samples, indicates that the mechanism of solar wind implantation, followed by subsequent fractionation of the gases by impact brecciation and heating, was primarily responsible for the incorporation of the original gas phase within solid bodies of the solar system.

Megrue, G. H.↗
NASA NTRS1973

Ventifact evolution in Wright Valley, Antarctica.

Ventifacts occurring on extensive wind-deflated surfaces throughout the ice-free Wright Valley are the product of complex evolutionary processes. The wind produces a lag gravel which continues to evolve at a reduced rate as coarser granule and gravel fractions are removed. The morphology of ventifacts forming the lag gravels suggests that the distribution of wind-polished faces is determined largely by the shape of the original unpolished rock fragments. In the early stages ventifacts tend to be oriented either transverse or parallel to the wind direction. Salt weathering is also a major factor in determining the morphology of the Wright Valley ventifacts.

Lindsay, J. F.↗
NASA NTRS1973

Ablation debris and primary micrometeoroids in the stratosphere.

Analysis of micrometer-sized stratospheric particulates suggests that the majority of extraterrestrial material in the atmosphere is the product of ablation of larger bodies. Ablation debris is of considerable interest because of the possibility that much of it may have originated from classes of easily fragmented meteoroids that are incapable of surviving atmospheric entry to become meteorites. Comparison is made between the elemental abundance patterns found in stratospheric particulates and that found in fusion crusts of primitive meteorite types. Also discussed are criteria for distinguishing ablation products from primary unablated micrometeoroids.

Brownlee, D. E.↗
NASA NTRS1973

Studies related to the evolution of the lunar soil materials

Studies of the chemistry and morphology of the lunar samples are reported. The presence of fragments of plagoclase in the centers of the impact craters indicate that the glass spheres were derived by meteoritic impact from high velocity particles, while the glass was at high temperatures. From the study of the Apollo 16 samples, it is suggested that this material was formed in a hot impact ejecta blanket, or in an igneous environment, and later exposed to meteoritic impact. It is suggested that particles from Apollo 17 were formed in a cloud of siliceous vapors.

Carter, J. L.↗
NASA NTRS1973

Test of LOX compatibility for asphalt and concrete runway materials

A literature survey and a telephone canvass of producers and users of LOX is reported which yielded one report of an accident resulting from a LOX spill on asphalt, one discussion of hazardous conditions, and an unreferenced mention of an incident. Laboratory tests using standard LOX impact apparatus yielded reactions with both old and new alphalt, but none with concrete. In the final test, using a larger sample of asphalt, the reaction caused extensive damage to equipment. Initial field experiments using 2-meter square asphalt slabs covered with LOX, conducted during rainy weather, achieved no reaction with plummets, and limited reaction with a blasting cap as a reaction initiator. In a final plummet-initiated test on a dry slab, a violent reaction, which appeared to have propagated over the entire slab surface, destroyed the plummet fixture and threw fragments as far as 48 meters.

Moyers, C. V.↗
NASA NTRS1973

Combined observations of meteors by image-orthicon television camera and multi-station radar

Observations from multiple sites of a radar network and by television of 29 individual meteors from February 1969 through June 1970 are reported. Only 12 of the meteors did not appear to fragment over all the observed portion of their trajectories. From these 12, the relation for the radar magnitude to the panchromatic absolute magnitude was found in terms of velocity of the meteor. A very tentative fit to the data on the duration of long enduring echoes versus visual absolute magnitude is made. The exponential decay characteristics of the later parts of several of the light curves are pointed out as possible evidence of mutual coalescence of droplets into which the meteoroid has completely broken.

Cook, A. F.↗
NASA NTRS1973

On the manganese content of cosmic flakes from deep-sea sediments

Cosmic flakes belong to the category of cosmic microparticles. They occur together with cosmic spherules in sediments. These flakes appear to represent ablation products of iron meteorites burnt away during the passage of a meteorite through the atmosphere by friction against air molecules. Microprobe analyses of flakes from deep sea deposits proved the particles to consist of magnetite which in most cases had been altered into maghemite in the outer zones. This is in agreement with the assumption that they represent fragments of fusion crust of iron meteorites. Most of the flakes, however, contained a small percentage of manganese. This element is not a common constituent of iron meteorites. An attempt is made to explain the presence of manganese in flakes and its absence in cosmic spherules.

Utech, K.↗
NASA NTRS1973

Current evolution of meteoroids

The observed mass distribution of meteoroids at 1 AU from the sun is briefly reviewed in a survey that ranges over the bulk of the mass spectrum from micrometeoroids to meteorite parent objects. The evolution of meteoroids under the influence of collisions, planetary perturbations, the Poynting-Robertson effect and radiation pressure is then discussed. Most micrometeoroids are expelled from the solar system by radiation pressure shortly after their production as secondary ejecta during impact by larger objects or as dust ejected by comets. Particles that survive will eventually be swept out by the Poynting-Robertson effect. Meteoroids in the radio and photographic ranges are destroyed in collisions faster than they can be replaced by the production of secondary fragments during collisions between larger objects.

Dohnanyi, J. S.↗
NASA NTRS1974

Appendix A: Specimen 72275 documentation

The friability of the matrix of specimen 72275 caused numerous fragments and an abundance of fines to break away from the main mass during transport from the moon and handling in the lunar receiving laboratory. Samples 72275,1 to 72275,14 were labeled during PET examination. Samples 72275,1, 4, 6, 7, 8, and 9 were placed in storage, and the remainder were distributed.

Marvin, U. B.↗
NASA NTRS1974

The role of mechanical properties in cavitation erosion resistance

Methods for determining the correlations of erosion resistance and mechanical properties of materials are discussed. The most common method of testing cavitation erosion resistance of materials is the vibratory cavitation probe. The instrument and its operation are described. The use of the whirling arm device is considered as a second method. Metallographic investigations of the earliest stages of cavitation erosion damage of metallic materials was conducted. The materials show plastic deformation occurring during the incubation period and increasing until cracks form and metal fragments are lost. The parameters of the work done to cause material fractures are identified. The reactions obtained with specific materials are reported.

Gould, G. C.↗