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At least 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Electron microscopy of some experimentally shocked counterparts of lunar minerals.

Particulate samples of experimentally shocked olivine, enstatite, and apatite and their unshocked equivalents were thinned by ion bombardment and examined by transmission methods in a conventional (100 kV) electron microscope. Enstatite shock-loaded at a peak pressure of 250 kb was partly transformed to relatively dense inverse defect spinel. Magnesian olivine shocked at a peak pressure of 200 kb shows intense lattice deformation. Magnesian olivine shock-loaded at a peak pressure of 400 kb was recrystallized to very fine polycrystalline aggregates. Apatite shock-loaded at a peak pressure of 250 kb shows planar deformation elements and shock-induced imperfections.

Sclar, C. B.↗
NASA NTRS1972

CESEMI studies of Apollo 14 and 15 fines.

Quantitative size and shape analyses have been carried out on six lunar fines from Apollo 14 and 15 by computer evaluation of scanning electron microscope images (CESEMI). For the size range of 0.50 to 30 microns diameter, the distributions are log-normal on a number count basis. This finding is in contrast with results for coarser materials in the fines reported by King et al. suggesting the operation of a different process. Aspect ratios range from 0.1 to 1.0 with an average value of about 0.6. Only slight differences are observed among samples. A shape complexity factor (ratio of particle perimeter to ellipse perimeter) also varies only slightly among the six samples.

Gorz, H.↗
NASA NTRS1972

Profiling microcraters using stereomicrographs.

The determination of the population, shape, and size of microcraters on lunar rocks enables space scientists to study cosmic erosion, survival times of rocks on the lunar surface, and the flux of primary cosmic particles. A graphical method of profiling and contouring microcraters on lunar rocks from a pair of stereomicrographs obtained by a scanning electron microscope was developed. The graphical method utilizes the simple geometry of photography generated by a parallel bundle of rays, orthogonal to the image plane.

Malhotra, R. C.↗
NASA NTRS1973

Preliminary results from the noctilucent sampling from Kiruna in 1970.

On Aug. 8, 1970 at 0148 and 0354 local time, two Pandora sounding rocket payloads were launched from the ESRO range in Kiruna, Sweden, during a noctilucent cloud display. Large numbers of particles were collected, many of which appear to be micrometeorites coated with a low density material. Typical electron micrographs are shown, and numerical densities as a function of altitude are given. Particle composition information has been obtained by use of dispersive X-ray analysis equipment attached to our Philips EM 300 electron microscope.

Hallgren, D. S.↗
NASA NTRS1973

Unusual chemical compositions of noctilucent-cloud particle nuclei

Two sounding rocket payloads were launched from the ESRO range in Sweden during a noctilucent cloud display. Large numbers of submicron particles were collected, most of which appear to be made up of a high density material coated with a low density material. Typical electron micrographs are shown. Particle chemical compositions have been measured by use of dispersive X-ray analysis equipment attached to an electron microscope and have revealed that most of the high density particle nuclei have atomic weights greater than iron.

Hemenway, C. L.↗
NASA NTRS1974

Investigations in space-related molecular biology

Improved instrumentation and preparation techniques for high resolution, high voltage cryo-electron microscopic and diffraction studies on terrestrial and extraterrestrial specimens are reported. Computer correlated ultrastructural and biochemical work on hydrated and dried cell membranes and related biological systems provided information on membrane organization, ice crystal formation and ordered water, RNA virus linked to cancer, lunar rock samples, and organometallic superconducting compounds. Apollo 11, 12, 14, and 15 specimens were analyzed

Fernandez-Moran, H.↗
NASA NTRS1974

Research on wood bending in a macrosonic field

Woodworking often requires the wood to be bent into different shapes. In view of the fact that macrosonic waves compress and expand the medium through which they are being propagated we assumed that wood subjected to the action of these waves during the bending process would have enhanced plasticity as a result of the loosening-up that takes place in it, as well as of the reduction in effort. To this effect, the bending of wood plasticized in a macrosonic field was studied. This bending took place under good conditions, and structural analyses conducted with the aid of an electron microscope proved initial premises to be corrent. Applied on an industrial scale, this procedure would contribute to improving the technology of wood bending as well as to eliminating factory spoilage.

Filipovici, J.↗
NASA NTRS1973

The simulation of lunar micrometeorite impacts by laser pulses

Laser pulses of a finely focused beam were used to simulate micrometeorite impacts on lunar rocks and in lunar soil. The electron microscope pictures show the detailed effects so caused; it is possible to derive an estimate of the comparative amounts of erosion a given micrometeorite flux would cause in lunar rocks and lunar soil.

Bilson, E.↗
NASA NTRS1973

X ray analysis of balloon-collected particles erroneously considered as an October influx into the lower stratosphere

Individual particles were analyzed on the collection screens in a Jeolco scanning electron microscope using a Kevex Li-drifted silicon energy dispersive X ray detector. It was found that the bulk of the stratospheric samples studied comes from explosive squib devices. It is pointed out that this finding does not invalidate the extensive results obtained by Bigg et al. (1970, 1971) in previous sampling experiments.

Farlow, N. H.↗
NASA NTRS1973

Petrology of Apollo 16 lunar highland rocks

Four lunar highland rocks collected by the Apollo 16 astronauts were studied both optically and with the electron microscope. The compositions of cataclastic anorthosite 60025,132, feldspathic basalt 68416,78, spinel troctolite 62295,68, and recrystallized breccia 60315,62 are discussed and graphically presented. Melting experiments were carried out on troctolite 62295,49 and felspathic basalt 68416,21 at temperatures from 1,220 to 1375 C and at pressures from 5 to 12 kb. Hypotheses concerning their petrogenesis are presented.

Hodges, F. N.↗
NASA NTRS1974

Summary of in situ epitaxial nucleation and growth measurements

In situ nucleation and growth measurements of Ag and Au on single-crystal PbSe thin films were made using a transmission electron microscope. Properties studied were polymorphism, crystalline perfection, and the stoichiometric composition of the initial and the autoepitaxially thickened PbSe substrates. The quantitative nucleation and cluster growth measurements were limited to low-saturation conditions. The epitaxial orientations are discussed, and evidence is presented as to the stage of deposition at which the epitaxial order for Ag is introduced. Strong substrate/overgrowth interaction manifested itself by alloying and interdiffusion.

Poppa, H.↗
NASA NTRS1974

On the irradiation history and origin of gas-rich meteorites

Transmission electron microscope study of the track density gradients and irradiation geometries of track-rich grains and chondrules in sections of Fayetteville and Kapoeta, and in sections of lunar breccias and grains from lunar soil. A substantial fraction (50 to 90%) of the meteoritic track-rich grains and chondrules show evidence of having been irradiated anisotropically in their different faces, as would be expected for irradiation on the surface of a parent body. The observations thus support the hypothesis that the irradiation of these grains and chondrules took place on the regoliths of asteroidal-sized bodies. Measurements of steepest track density gradients indicate that, while there are finite differences between spectra exhibited by individual gas-rich meteorites, the average solar flare spectral shapes have been similar over the last 4 b.y. or so.

Rajan, R. S.↗
NASA NTRS1974

Ion implantation effects in 'cosmic' dust grains

Cosmic dust grains, whatever their origin may be, have probably suffered a complex sequence of events including exposure to high doses of low-energy nuclear particles and cycles of turbulent motions. High-voltage electron microscope observations of micron-sized grains either naturally exposed to space environmental parameters on the lunar surface or artificially subjected to space simulated conditions strongly suggest that such events could drastically modify the mineralogical composition of the grains and considerably ease their aggregation during collisions at low speeds. Furthermore, combined mass spectrometer and ionic analyzer studies show that small carbon compounds can be both synthesized during the implantation of a mixture of low-energy D, C, N ions in various solids and released in space by ion sputtering.

Bibring, J. P.↗
NASA NTRS1974

Radiation damage and structure recorded at high resolution in grains from fine fractions of Luna 16 surface material

Samples returned to earth by Luna 16, were studied with a high voltage electron microscope for ultramicroscopic features. The following amazing features were noted in particles of surface material returned in all the lunar trips: A very high density of tracks of nuclear particles, ultrathin amorphous shells, highly rounded forms, and amazingly good ordering of crystal lattice. These features were used along with calibration experiments in solving the following problems: (1) determining the energy spectrum and chemical abundances of the very heavy nuclei in the solar wind and in the solar cosmic rays; (2) studying the past activity of the sun; (3) obtaining data on lunar dynamic processes affecting dust particles; (4) analyzing composite effects caused by penetration of solar wind into the lunar surface material; and (5) establishing the existence of the ancient lunar atmosphere and magnetic field.

Durrieu, L.↗
NASA NTRS1974

Cathodoluminescence of regolith returned by Luna 16 automatic station

Observations of local variations in the intensity and spectral composition of the cathodoluminescence of lunar regolith are described. These variations are caused by structural features, by the kind and quantity of the material, and by the admixtures. In addition, cathodoluminescent emission is also associated with a change in the temperature of the lunar surface. Periodic diurnal illumination and darkening of the moon is responsible for a temperature gradient normal to the lines of longitude. These observations made of regolith, using a scanning electron microscope with an attachment for temperature variation, simulate the indicated thermal changes of the cathodoluminescent properties of lunar material.

Spivak, G. V.↗
NASA NTRS1974

Vacuum ultraviolet holography

The authors report the first demonstration of holographic techniques in the vacuum ultraviolet spectral region. Holograms were produced with coherent 1182 A radiation. The holograms were recorded in polymethyl methacrylate and read out with an electron microscope. A holographic grating with a fringe spacing of 836 A was produced and far-field Fraunhofer holograms of sub-micron particles were recorded.

Bjorklund, G. C.↗
NASA NTRS1975

Dynamic SEM wear studies of tungsten carbide cermets

Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined, and etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the tungsten carbide (WC) and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation, and the wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation, and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

Brainard, W. A.↗
NASA NTRS1975

Toxicologic evaluation of the migration of a plasticizer, DI (2-ethylhexyl) phthalate (DEHP) from vinyl plastics

The intravenous administration of DEHP solubilized by means of a number of different detergents leads to respiratory distress and death in rats. At autopsy the lungs are grossly enlarged, edamatous, and hemorrhagic. Light and electron microscopic evaluation of the lungs indicate engorgement of the interalveolar septa with edema fluid and polymorphonuclear leucocytes, degranulation of the leukocytes, and progessive destruction of the endothelial and epithelial cells. Consistent with the conclusion that solubilized DEHP results in a syndrome of "shock lung" is the associated massive fall in arterial blood pressure and the prevention of the lung pathology by pretreatment with pharmacologic doses of an antiinflammatory steroid, methylprednisolone. Evidence is also presented that suggests that the DEHP inadvertently administered to humans during transfusions is also in a solubilized state in the plasma.

Rubin, R. J.↗