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All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Chemistry of agglutinate fractions in lunar soils

Agglutinates are aggregates of crystalline grains and lithic fragments bonded together by glass. It is thought that glassy agglutinates are formed at the upper surface of the lunar regolith by impact-related melting and welding of soil particles, in response to meteoroid and micrometeoroid bombardment. A description is presented of an investigation in which bulk soils were separated into 'agglutinate' and 'nonagglutinate' fractions. The obtained fractions were analyzed for major, minor, and trace elements. The obtained chemical data for agglutinate and nonagglutinate fractions of lunar soils indicate that agglutinitic glass is enriched in mafic and most lithophile elements relative to the bulk soils. A model involving preferential melting and assimilation of mesostasis material and mafic soil components is proposed to account for the observed chemical data. It is suggested that glassy agglutinates may form more readily in mafic soils than in more feldspathic ones. Such selectivity should be most effective between mare and highland soils, but may possibly operate on a more local scale.

Rhodes, J. M.↗
NASA NTRS1996

Lithologic Distribution and Geologic History of the Apollo 17 Site: The Record in Soils and Small Rock Particles from the Highland Massifs

Through analysis by instrumental neutron activation (INAA) of 789 individual lithic fragments from the 2 mm-4 mm grain-size fractions of five Apollo 17 soil samples (72443, 72503, 73243, 76283, and 76503) and petrographic examination of a subset, we have determined the diversity and proportions of rock types recorded within soils from the highland massifs. The distribution of rock types at the site, as recorded by lithic fragments in the soils, is an alternative to the distribution inferred from the limited number of large rock samples. The compositions and proportions of 2 mm-4 mm fragments provide a bridge between compositions of less than 1 mm fines and types and proportions of rocks observed in large collected breccias and their clasts. The 2 mm-4 mm fraction of soil from South Massif, represented by an unbiased set of lithic fragments from station-2 samples 72443 and 72503, consists of 71% noritic impact-melt breccia, 7% Incompatible-Trace-Element-(ITE)-poor highland rock types (mainly granulitic breccias), 19% agglutinates and regolith breccias, 1% high-Ti mare basalt, and 2% others (very-low-Ti (VLT) basalt, monzogabbro breccia, and metal). In contrast, the 2 mm - 4 mm fraction of a soil from the North Massif, represented by an unbiased set of lithic fragments from station-6 sample 76503, has a greater proportion of ITE-poor highland rock types and mare-basalt fragments: it consists of 29% ITE-poor highland rock types (mainly granulitic breccias and troctolitic anorthosite), 25% impact-melt breccia, 13% high-Ti mare basalt, 31 % agglutinates and regolith breccias, 1% orange glass and related breccia, and 1% others. Based on a comparison of mass- weighted mean compositions of the lithic fragments with compositions of soil fines from all Apollo 17 highland stations, differences between the station-2 and station-6 samples are representative of differences between available samples from the two massifs. From the distribution of different rock types and their compositions, we conclude the following: (1) North-Massif and South-Massif soil samples differ significantly in types and proportions of ITE-poor highland components and ITE-rich impact-melt-breccia components. These differences reflect crudely layered massifs and known local geology. The greater percentage of impact-melt breccia in the South- Massif light-mantle soil stems from derivation of the light mantle from the top of the massif, which apparently is richer in noritic impact-melt breccia than are lower parts of the massifs. (2) At station 2, the 2 mm-4 mm grain-size fraction is enriched in impact-melt breccias compared to the less than 1 mm fraction, suggesting that the <1 mm fraction within the light mantle has a greater proportion of lithologies such as granulitic breccias which are more prevalent lower in the massifs and which we infer to be older (pre-basin) highland components. (3) Soil from station 6, North Massif, contains magnesian troctolitic anorthosite, which is a component that is rare in station-2 South-Massif,contains magnesian troctolitic in impact-melt breccia interpreted by most investigators to be ejecta from the Serenitatis basin.

Jolliff, Bradley L.↗
NASA NTRS1973

Darkening of silicate rock powders by solar wind sputtering.

Hydrogen ion irradiation of powdered igneous rocks, including Apollo rocks, has been observed in the laboratory to darken the powders and to make their optical properties similar to the moon's. An extensive series of investigations shows that this darkening is not spurious. These results are consistent with those of other investigators, including Nash (1967). Darkening of lunar igneous rock powders by the formation of solar wind-sputtered glass films is a real process which occurs on the moon. The time scale for darkening of undisturbed lunar soil is of the order of 50,000-100,000 yr. Comparison of the rates of the formation of glasses on the lunar surface by solar wind sputter-deposition, meteorite impact melting, and impact vaporization-deposition indicates that these processes are of comparable importance under the present flux of meteorites.

Hapke, B.↗
NASA NTRS1975

Mineralogy of lunar norite 78235 - Second lunar occurrence of P2 sub 1 ca pyroxene from Apollo 17 soils

A thin section of lunar rock 78235 is examined optically as well as with an electron microprobe and is shown to be a highly-shocked coarse norite. The rock is found to consist of approximately 30% low-Ca pyroxene, 55% Ca-rich plagioclase, and 15% glass veins. The composition of the glass veins is analyzed, and it is suggested that they resulted from shock melting of the norite. Comparisons with other noritic rocks indicate that the pyroxene in rock 78235 has P2 sub 1 ca symmetry. Based on this symmetry plus the coarse grain size, it is concluded that rock 78235 was formed under plutonic conditions. The origin of the minor phases in this rock is briefly considered.

Steele, I. M.↗
NASA NTRS1976

International Conference on Rapidly Quenched Metals, 2nd, Massachusetts Institute of Technology, Cambridge, Mass., November 17-19, 1975, Proceedings

The range of topics covered by the papers includes: rapid quenching (and specifically splat quenching) of metals, spin quenching, levitation melting, rapid quenching from liquid state; amorphous metal phases and metastable phases, metallic glasses, ribbons, splats, films, metal ribbon reinforced resins; crystallization of metallic glasses, and ferromagnetic amorphous alloys. Structural models for amorphous metals, splat-quenching equipment, and measurements of the properties of amorphous and noncrystalline metals and metallic glasses are also discussed, in addition to: fatigue events (crack propagation) in amorphous metals, fracture behavior in rapidly quenched metals, ductile superconducting Cu-Nb-Sn alloys, and semiconducting amorphous V205 alloy. Individual items are announced in this issue.

Source record↗
NASA NTRS1990

Geochemistry of Darwin impact glass and target rocks

Results are presented from major and trace element composition analyses of 18 Darwin (Australia) glass samples and seven target rocks from the Darwin crater area. It is found that the chemical composition of the glass samples is in agreement with an origin from terrestrial sediments during an impact. Analyses of the target rocks from the Darwin crater and mixing calculations show that the Darwin glass can be formed from the local target rocks. Evidence is presented for a loss of the volatile elements Ga, Zn, F, and B during the impact event. The elements Na, K, Rb, and Cs show lower abundance in the glass than in the target rocks. This suggests selective volatilization from the impact melt.

Meisel, Thomas↗
NASA NTRS1992

Coeval Ar-40/Ar-39 ages of 65.0 million years ago from Chicxulub crater melt rock and Cretaceous-Tertiary boundary tektites

Ar-40/Ar-39 dating of drill-core samples of a glassy melt rock recovered from beneath a massive impact breccia contained with the 180-kilometer subsurface Chicxulub crater yields well-behaved incremental heating spectra with a mean plateau age of 64.98 +/- 0.05 million years ago (Ma). The glassy melt rock of andesitic composition was obtained from core 9 (1390 to 1393 meters) in the Chicxulub 1 well. The age of the melt rock is virtually indistinguishable from Ar-40/Ar-39 ages obtained on tektite glass from Beloc, Haiti, and Arroyo el Mimbral, northeastern Mexico, of 65.01 +/- 0.08 Ma (mean plateau age for Beloc) and 65.07 +/- 0.10 Ma (mean total fusion age for both sites). The Ar-40/Ar-39 ages, in conjunction with geochemical and petrological similarities, strengthen the suggestion that the Chicxulub structure is the source for the Haitian and Mexican tektites and is a viable candidate for the Cretaceous-Tertiary boundary impact site.

Swisher, Carl C., III↗
NASA NTRS1994

Interface Shape and Convection During Solidification and Melting of Succinonitrile

An experimental study was conducted of the crystal growth of succinonitrile during solidification, melting, and no-growth conditions using a horizontal Bridgman furnace and square glass ampoule. For use as input boundary conditions to numerical codes, thermal profiles on the outside of the ampoule at five locations around its periphery were measured along the ampoule's length. Temperatures inside the ampoule were also measured. The shapes of the s/l interface in various two dimensional planes were quantitatively determined. Though interfaces were nondendritic and noncellular, they were not flat, but were highly curved and symmetric in only one unique longitudinal y-z plane (at x=O). The shapes of the interface were dominated by the primary longitudinal flow cell characteristic of shallow cavity flow in horizontal Bridgman; this flow cell was driven by the imposed furnace temperature gradient and caused a 'radical' thermal gradient such that the upper half of the ampoule was hotter than the bottom half. We believe that due to the strong convection, the release of latent heat does not significantly influence the thermal conditions near the interface. We hope that the interface shape and thermal data presented in this paper can be used to optimize crystal growth processes and validate numerical models.

Degroh, Henry C., III↗
NASA NTRS2005

Phase Equilibrium Investigations of Planetary Materials

This grant provided funds to carry out phase equilibrium studies on the processes of chemical differentiation of the moon and the meteorite parent bodies, during their early evolutionary history. Several experimental studies examined processes that led to the formation of lunar ultramafic glasses. Phase equilibrium studies were carried out on selected low-Ti and high-Ti lunar ultramafic glass compositions to provide constraints on the depth range, temperature and processes of melt generation and/or assimilation. A second set of experiments examined the role of sulfide melts in core formation processes in the earth and terrestrial planets. The major results of each paper are discussed, and copies of the papers are attached as Appendix I.

Grove, T. L.↗
NASA NTRS2002

Low Melt Viscosity Resins for Resin Transfer Molding

In recent years, resin transfer molding (RTM) has become one of the methods of choice for high performance composites. Its cost effectiveness and ease of fabrication are major advantages of RTM. RTM process usually requires resins with very low melt viscosity (less than 10 Poise). The optimum RTM resins also need to display high thennal-oxidative stability, high glass transition temperature (T(sub g)), and good toughness. The traditional PMR-type polyimides (e.g. PMR-15) do not fit this requirement, because the viscosities are too high and the nadic endcap cures too fast. High T(sub g), low-melt viscosity resins are highly desirable for aerospace applications and NASA s Reusable Launch Vehicle (RLV) program. The objective of this work is to prepare low-melt viscosity polyimide resins for RTM or resin film infusion (RFI) processes. The approach involves the synthesis of phenylethynyl-terminated imide oligomers. These materials have been designed to minimize their melt viscosity so that they can be readily processed. During the cure, the oligomers undergo both chain extension and crosslinking via the thermal polymerization of the phenylethynyl groups. The Phenylethynyl endcap is preferred over the nadic group due to its high curing temperature, which provides broader processing windows. This work involved the synthesis and polymerization of oligomers containing zig-zag backbones and twisted biphenyl structures. Some A-B type precursors which possessed both nitro and anhydride functionality, or both nitro and amine functionality, were also synthesized in order to obtain the well defined oligomers. The resulting zig-zag structured oligomers were then end-capped with 4-phenylethynylphthalic anhydride (PEPA) for further cure. The properties of these novel imide oligomers are evaluated.

Harris, Frank W.↗
NASA NTRS1975

Mare basalts - Melting experiments and petrogenetic interpretations

Equilibrium crystallization sequences are determined in melting experiments in vacuum at Fe saturation on synthetic mare basalt compositions 70215 and 15318 Red Glass (both high-Ti) as well as 15555-15016 (low-Ti). The experiments confirm that much of the chemical variation within both the high- and low-Ti suites is controlled by near-surface fractionation processes, although the two suites cannot be related by such mechanisms. The components and crystallization products of the liquidus at various temperatures and pressures are reported. Mare basalt petrogenesis is interpreted in terms of high-pressure equilibria at Fe saturation; it is suggested that low-Ti basalts represent partial melts of a differentiated olivine-pyroxenite lunar mantle at 240 km or deeper, while cumulus clinopyroxene in the source is responsible for their REE characteristics. The formation of high-Ti basalts is considered.

Kesson, S. E.↗
NASA NTRS1997

Studies of Magmatic Inclusions in the Basaltic Martian Meteorites Shergotty, Zagami, EETA 79001 and QUE 94201

Currently there are 12 meteorites thought by planetary scientists to be martian samples, delivered to the Earth after violent impacts on that planet's surface. Of these 12 specimens, 4 are basaltic: Shergotty, Zagami, EETA 79001 and QUE 94201. Basalts are particularly important rocks to planetary geologists- they are the most common rocks found on the surfaces of the terrestrial planets, representing volcanic activity of their parent worlds. In addition, because they are generated by partial melting of the mantle and/or lower crust, they can serve as guide posts to the composition and internal processes of a planet. Consequently these four meteorites can serve as 'ground-truth' representatives of the predominant volcanic surface rocks of Mars, and offer researchers a glimpse of the magmatic history of that planet. Unfortunately, unraveling the parentage of a basaltic rock is not always straightforward. While many basalts are simple, unaltered partial melts of the mantle, others have undergone secondary processes which change the original parental chemistry, such as assimilation of other crustal rocks, mixing with other magmas, accumulation, re-equilibration between mineral species after crystallization, loss of late-stage magmatic fluids and alteration by metamorphic or metasomatic processes. Fortunately, magmatic inclusions can trap the evolving magmatic liquid, isolating it from many of these secondary processes and offering a direct look at the magma during different stages of development. These inclusions form when major or minor phases grow skeletally, surrounding small amounts of the parental magma within pockets in the growing crystal. The inclusion as a whole (usually consisting of glass with enclosed crystals) continues to represent the composition of the parental magma at the time the melt pocket closed, even when the rock as a whole evolves under changing conditions. The four basaltic martian meteorites contain several distinct generations of melt inclusions; those found within early-forming pigeonite, intermediate and late-forming Ti, Fe-oxides and sulfides, and intermediate to late-forming phosphates. In this summer' s study we have made a detailed study of all of the various forms of inclusions found within the 4 basaltic martian meteorites listed above. Glasses and minerals within the inclusions were analyzed using the Camera SX-100 Electron Microprobe in Building 31. The mineralogy and textural context of the inclusions will then be used to explore the crystallization history of these specimens, and to investigate any differences in crystallization history or parental magma compositions between these rocks. In this manner, the magmatic inclusions provide a road map backwards toward the 'parental' compositions for the basaltic martian meteorites and provide significant insight into the igneous processes found within the crust of Mars.

Harvey, Ralph P.↗
NASA NTRS1985

Geology and petrology of the Apollo 15 landing site - Past, present, and future understanding

The main objectives of the Apollo 15 lunar mission were to investigate and sample materials from the Apennine Front (expected to be Imbrium ejecta and pre-Imbrian materials), the Hadley Rille, and the mare lavas of Palus Putredinis. The Hadley Rille was found to be a collapsed lava tube or channel, and from it, many mare basalt samples were collected which form two main chemical groups of the same age (3.3 b.y.), isotopic characteristics, and rate-earth element patterns. One group, olivine-normative, contains many vescular specimens and shows an olivine fraction trend. The other group, quartz-normative, is pigeonite-phyric and contains both vitrophyric and coarse-grained samples but exhibits little fractionation. The Apennine Front samples include such highland materials as ferroan anorthosites, spinel-bearing troctolites, norites, impact melts and metamorphosed breccias. A conspicuous component of the regolith breccias is volcanic green glass. The Apennine Front is characterized by a low-KREEP composition, a composition which has never been found as a pristine igneous rock type. Another unexpected discovey was the common occurrence of 3.5 b.y. old volcanic KREEP basalts. It is concluded that all major lunar processes can be profitably studied from the samples and observations at this single location.

Spudis, P. D.↗
NASA NTRS1992

Materials science research in microgravity

There are several important attributes of an extended duration microgravity environment that offer a new dimension in the control of the microstructure, processing, and properties of materials. First, when gravitational effects are minimized, buoyancy driven convection flows are also minimized. The flows due to density differences, brought about either by composition or temperature gradients will then be reduced or eliminated to permit a more precise control of the temperature and the composition of a melt which is critical in achieving high quality crystal growth of electronic materials or alloy structures. Secondly, body force effects such as sedimentation, hydrostatic pressure, and deformation are similarly reduced. These effects may interfere with attempts to produce uniformly dispersed or aligned second phases during melt solidification. Thirdly, operating in a microgravity environment will facilitate the containerless processing of melts to eliminate the limitations of containment for reactive melts. The noncontacting forces such as those developed from electromagnet, electrostatic, or acoustic fields can be used to position samples. With this mode of operation, contamination can be minimized to enable the study of reactive melts and to eliminate extraneous crystal nucleation so that novel crystalline structures and new glass compositions may be produced. In order to take advantage of the microgravity environment for materials research, it has become clear that reliable processing models based on a sound ground based experimental experience and an established thermophysical property data base are essential.

Perepezko, John H.↗
NASA NTRS1993

The concentration and isotopic composition of carbon in basaltic glasses from the Juan de Fuca Ridge, Pacific Ocean

The abundance and C-13/C-12 ratios of carbon were analyzed in basaltic glass from twenty locations along the Juan de Fuca Ridge using a 3-step combustion/extraction technique. Carbon released during the first two combustion steps at 400-500 C and 600-650 C is interpreted to be secondary, and only the carbon recovered during a final combustion step at about 1200 C is thought to be indigenous to the samples. For carbon released at about 1200 C, glasses analyzed as 1-2 mm chips contained 23-146 ppm C with delta C-13 values of -4.8 to -9.3 per mil, whereas samples crushed to 38-63 microns or 63-90 microns yielded 56-103 ppm C with delta C-13 values of -6.1 to -9.2 per mil. The concentrations and isotopic compositions of the primary carbon dissolved in the glasses and present in the vesicles are similar to those previously reported for other ocean-ridge basalts. The Juan de Fuca basaltic magmas were not in equilibrium with respect to carbon when they erupted and quenched on the sea floor. Evidence of disequilibrium includes (1) a large range of carbon contents among glasses collected at similar depths, (2) a highly variable calculated carbon isotopic fractionation between melt and vapor determined by comparing crushed and uncrushed splits of the same sample, and (3) a lack of correlation between vesicle abundance, carbon concentration, and depth of eruption. Variations in carbon concentration and delta C-13 ratios along the ridge do not correlate with major element chemistry. The observed relationship between carbon concentrations and delta C-13 values may be explained by late-stage, variable degrees of open-system (Rayleigh-like) degassing.

Blank, Jennifer G.↗
NASA NTRS1992

Chemistry and properties of poly(arylene ether 1,3,4-oxadiazole)s and poly(arylene ether 1,2,4-triazole)s

Poly(arylene ether)s containing l,3,4-oxadiazole and 1,2,4-triazole units were prepared by the aromatic nucleophilic displacement reaction of bisphenol oxadiazole and bisphenol triazole compounds with activated aromatic dihalides. The polymers exhibited glass transition temperatures (Tg) ranging from 182 to 242 C, and several polymers exhibited melting transitions (Tm) ranging from 265 to 390 C. Inherent viscosities ranged from 1.02 to 3.40 dl/g, indicating relatively high molecular weights. Thin films exhibited tensile strengths, moduli, and elongations at 23 C of 90-110 MPa, 2.7-3.6 GPa, and 4-7 percent, respectively. Titanium-to-titanium tensile shear specimens of a poly(arylene ether 1,3,4-oxadiazole) exhibited tensile shear strengths at 23 and 150 C of 22.1 and 17.9 MPa, respectively.

Connell, J. W.↗
NASA NTRS1994

Phenylethynyl-Terminated Polyimides

Phenylethynyl-terminated polyimides exhibit properties suitable for films, moldings, adhesives, and composite-material matrices. Polyimides synthesized at various molecular weights, selected to obtain desirable properties for specific applications. Thermally cured to form cross-linked molecular structures typically increasing resistance to solvents, glass-transition temperatures, and moduli of elasticity. Also have low molecular weights and low melt viscosities for easier processing into composites and adhesive bonds.

Jensen, Brian J.↗
NASA NTRS1984

Glass formation and properties in the gallia-calcia system

The critical cooling rate for glass formation was measured for five compositions in the Ga2O3-CaO system and varied from a low of (315 + or - 85) C/s for a eutectic melt containing 37.5 mol pct Ga2O3 to a high of (840 + or - 60) C/s for a melt containing 52 mol pct Ga2O3. The density and refractive index both increased with increasing Ga2O3 content, but the crystallization temperature and microhardness varied only slightly. The IR spectra of these glasses suggest that both GaO4 tetrahedra and GaO6 octahedra are present.

Whichard, G.↗