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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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At least 631 records · Page 35
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NASA NTRS1973

Martian surface and crust - Review and synthesis.

The nature of the classical marking of Mars are studied on the basis of Mariner 9 data and some earlier data. The analysis leads to a model of the Martian crust. Evidence for petrologic distinctions between surface materials in dark and light regions is obtained. It is shown that the classical markings are a complex result of three factors: (1) availability of two types of rock material transportable by wind, (2) topographic control of deposition, and (3) prevailing winds producing quasi-permanent preferential deposition patterns. The crust, especially in the Tharsis region, bears strong evidence of mantle-induced uplift of a type existing on earth. Such uplifts have obliterated ancient craters, caused fractures and graben systems, and have resulted in intense volcanism.

Hartmann, W. K.↗
NASA NTRS1974

Equilibration temperatures in enstatite chondrites

Equilibration temperatures for enstatite chondrites are calculated using a method suggested by Larimer (1968). The temperatures range from 640 to 840 C. The method yields temperatures which, in principle, are correct on a relative scale, but the absolute error may be as large as 150 C. There is a good correlation between the calculated temperatures and petrologic type as well as other mineralogic characteristics and bulk composition. Partial pressures of sulfur and oxygen at the time of equilibration ranged from about 10 to the minus 8th to 10 to the minus 12th atm and from about 10 to the minus 28th to 10 to the minus 37th atm, respectively.

Larimer, J. W.↗
NASA NTRS1974

Lunar highland rock types: Their implications for impact induced fractionation

The first step in a petrologic study must be a classification based on observed textures and mineralogy. Lunar rocks, may be classified into three major groups: (1) coarse-grained igneous rocks, (2) fine-grained igneous rocks and (3) breccias. Group 1 is interpreted as primitive lunar crustal rocks that display various degrees of crushing and/or annealing. Group 2 is interpreted as volcanic rocks. Group 3 is interpreted as resulting from impacts on the lunar surface and is subdivided on the basis of matrix textures into fragmental breccias, crystalline breccias that have been annealed, and crystalline breccias with igneous matrices. A synthesis of the relevant data concerning lunar highlands polymict breccias from the fields of petrography, chemistry, photogeology, and impact studies compels the prediction that the breccias should have homogeneous matrices from rock to rock within regions of the highlands of limited size where impact mixing has been efficient and extensive.

Phinney, W. C.↗
NASA NTRS1974

Geophysical, geochemical, and geological investigations of the Dunes geothermal system, Imperial Valley, California

The Dunes anomaly is a water-dominated geothermal system in the alluvium of the Salton Trough, lacking any surface expression. It was discovered by shallow-temperature gradient measurements. A 612-meter-deep test well encountered several temperature-gradient reversals, with a maximum of 105 C at 114 meters. The program involves surface geophysics, including electrical, gravity, and seismic methods, down-hole geophysics and petrophysics of core samples, isotopic and chemical studies of water samples, and petrological and geochemical studies of the cores and cuttings. The aim is (1) to determine the source and temperature history of the brines, (2) to understand the interaction between the brines and rocks, and (3) to determine the areal extent, nature, origin, and history of the geothermal system. These studies are designed to provide better definition of exploration targets for hidden geothermal anomalies and to contribute to improved techniques of exploration and resource assessment.

Elders, W. A.↗
NASA NTRS1974

Structural geology investigation in the republics of Dahomey and Togoland, Africa, using ERTS-1 multi-spectral images

The author has identified the following significant results. Recent geological studies in the Republics of Dahomey and Togoland put in light a new chronology and propose a schema indicating that the structural geology of this region is very complicated. The new observations made possible by the ERTS images concern the main orientations, the folded units, and the lithology. The correlation between different types of laterite and the petrology of the basement seems possible, and is the most significant result of this investigation but unfortunately conducted with poor quality images because of atmospheric haze.

Weecksteen, G.↗
NASA NTRS1974

Stratigraphy of the Descartes region /Apollo 16/ - Implications for the origin of samples

Analysis of terrain in the Apollo 16 Descartes landing region shows a series of features that form a stratigraphic sequence which dominates the history and petrogenesis at the site. An ancient 150-km diam crater centered on the Apollo 16 site is one of the earliest recognizable major structures. Nectaris ejecta was concentrated in a regional low at the base of the back slope of the Nectaris basin to form the Descartes Mountains. Subsequently, a 60-km diam crater formed in the Descartes Mountains centered about 25 km to the west of the site. This crater dominates the geology and petrogenetic history of the site. Stone and Smoky Mountains represent the degraded terraced crater walls, and the dark matrix breccias and metaclastic rocks derived from North and South Ray craters represent floor fallback breccias from this cratering event. The interpretation is developed that the stratigraphy of the Cayley and Descartes, and thus the historical record of the Apollo 16 region, documents the complex interaction of deposits and morphology of local and regional impact cratering events. Large local 60- to 150-km diam craters have had a dramatic and previously unrecognized effect on the history and petrology of the Apollo 16 site.

Head, J. W.↗
NASA NTRS1975

Mars sample return through parking orbit

A Mars surface sample return mission using Mars direct entry and Mars parking orbit return is described. The mission is designed for a minimum energy requirement and is relatively simple in comparison to the alternative Mars orbital rendezvous mode. The design calls for minimal science, and uses a single Titan IIIE/Centaur launch vehicle. The primary science areas included are biology, biochemistry, geochemistry, and petrology, for detecting life, age dating, and determining chemical compositions and rock types. The total minimum sample requirement would be 30 g. Sampling conditions and recommended measurements are discussed. Maximum use of hardware and experience from the Mariner, Pioneer, and Viking missions is contemplated. The profile for a 1979 conjunction-class mission would include a total time of 1025 days, including one year in Mars parking orbit after sampling. The lander structure, components, and recovery alternatives are explained.

Weaver, W. L.↗
NASA NTRS1975

Lunar polymict breccia 14321 - A petrographic study

A detailed description is given of the petrology and mineralogy of lunar polymict breccia 14321, which was returned from the Fra Mauro formation on the Apollo 14 mission. Electron probe microanalysis and microscopic studies were made of seven petrographic thin sections of the rock. Three broad genetic classes were found in the thin sections: (1) rounded fragments of pre-existing microbreccia with microscopically recognizable crystal and lithic fragments incorporated in a dark matrix; (2) igneous rock fragments of basaltic composition; and (3) a light colored, somewhat friable matrix which cements the other two classes. The components are classified according to chemical, mineralogical textural, and chronological criteria.

Grieve, R. A.↗
NASA NTRS1974

The geochemical evolution of the moon

Evidence for and implications of homogeneous accretion of the moon are considered. Interelement ratios are used to calculate the composition of the highland crust. The rare-earth data for the highlands show a positive Eu anomaly, allowing the deduction that the interior has a negative anomaly. The Cr/Ni ratios in the highlands are considered in regard to the overall lunar abundance of the siderophile elements. These abundance data and the constraints from the heat flow measurements are next used to set limits on the bulk composition for the moon. The geochemical constraints are integrated with the petrological and geophysical data in an attempt to provide a consistent model for the geochemical evolution of the moon.

Taylor, S. R.↗
NASA NTRS1975

The San Juan Capistrano meteorite

The San Juan Capistrano chondrite fell on 15 March 1973; the total recovered mass was 56 g. Electron microprobe, chemical and petrographic studies show it to be a member of the H group and of petrologic type 6. Rare gas studies show that only minor radiogenic gas loss has occurred and yield a K-Ar age of 4.6 billion years and a Kr-Kr exposure age of 29 million years.

Finkel, R. C.↗
NASA NTRS1975

A lunar core and the moon's magnetic field

The suggestion that the moon's magnetic field is due to adiabatic magnetohydrodynamic convection of a molten core has been made by a number of recent authors. Considerations based on petrology, mass and rotational inertia limit the size of this hypothetical core to a few hundred kilometers at the most. A proposal has been made that this core is either molten iron or iron sulfide. The properties are known of both molten iron and iron-sulfide at lunar core pressures. No way can be found to maintain circulation in a hypothetical lunar core, as circulation is contingent upon a temperature gradient being greater than the adiabatic gradient, or an internal heat source.

Kennedy, G. C.↗
NASA NTRS1975

Magnetochemistry of the Apollo landing sites

A coherent magnetochemical picture of lunar samples is presented which was determined from a synthesis of available magnetic-property data and corresponding chemical and petrographic data for soils and rock samples collected at the Apollo landing sites. The magnetic properties of the samples are correlated with Al/Si ratio as well as with telescope spectral reflectivity curves, and magnetochemical diagrams based on composition-sensitive magnetic parameters describing the Fe metal and Fe(2+) contents are used to classify the samples. It is shown that the relative metal-fraction size distribution and magnetic stability for different rock types and soils of varying Al/Si values are reflected in a plot of the ratio of saturation isothermal remanence to saturation magnetization vs the ratio of remanent coercive force to coercive force. It is concluded that all the Apollo landing sites have distinct telescope curves correlated with petrology, chemistry, Al/Si values, and magnetic properties. The established correlations suggest the possibility of estimating the magnetic properties of the regolith from remote-sensing observations.

Wasilewski, P. J.↗
NASA NTRS1976

Heterogeneity in titaniferous lunar basalts

Small but real chemical differences exist between subsamples of fine-grained quench-textured titaniferous lunar basalts. The existence of different textural domains with different chemistries is thought to account for most of this variation. In addition to the textural domains, lunar sample 74275 has a population of olivine 'megacrysts' as well as dunite fragments. These materials are thought to be extraneous and to compromise the primary nature of 74275. Recognition of the small chemical variations present may aid in understanding some discrepancies in the experimental-petrology literature. However, these small variations have a distressing petrogenetic significance since they severely limit resolution in recognizing the number and depth of origin of primary magmas.

Walker, D.↗
NASA NTRS1976

Formation of ferrobasalt at east Pacific midocean spreading centers

A numerical modeling using a least squares petrologic mixing program demonstrates that ridge ferrobasalts from three east Pacific regions are generated from normal midocean ridge balsalt by crystal fractionation of plagioclase, clinopyroxene, and minor olivine at shallow mantle depths. Clinopyroxene is an important fractionating phase in this model in contrast to most previously proposed fractionation models. Calculations demonstrate that the ferrobasalts represent a much smaller percentage of residual liquid than has previously been proposed. Implications of extensive shallow crystal fractionation for the determination of depths of magma generation are discussed. The different fields on an anorthite-olivine-hypersthene ternary diagram for basalts from east Pacific fast and moderate spreading ridges can be explained by variable degrees of shallow crystal fractionation rather than by different depths of magma generation as suggested by Bass (1971) and Scheidegger (1973).

Clague, D. A.↗
NASA NTRS1976

High-silica /greater than 60%/ lunar glasses in an Apollo 14 soil sample - Evidence for silicic lunar volcanism

The major-element compositions of 93 low-specific-gravity (less than 2.60) high-silica (greater than 60%) glass particles from a sample of lunar fines (14259,20) were determined by electron microprobe analyses. The size, shape, abundance, mineralogy, and major-element composition of more than 60% of the high-silica glasses is consistent with their being fragments of interstitial glass from mare basalts. However, one group of 30 glasses with between 72% and 78% SiO2 and an average of approximately 2.6% FeO can be distinguished from other high-silica glasses both chemically and petrographically. Glass particles with this composition do not contain crystalline inclusions and are fairly homogeneous not only within a single particle but also from particle to particle. The chemistry and petrology of these glasses suggest that they are not fragments of interstitial glass or shock-melted particles from a 'granitic' source rock. Rather, the homogeneity and lack of crystalline inclusions suggest that this group of high-silica glasses was the product of lunar acidic volcanism.

Glass, B. P.↗
NASA NTRS1977

Basis for interpretation regarding the ages of the Serenitatis, Imbrium and Orientale events

One of the most important objectives of lunar study is to relate the lunar sample data to important lunar events. This paper utilizes as the basis of interpretation consideration of the following: (1) photogeologic data, (2) the choice of a cratering model, (3) estimates of temperature of impact ejecta and shock-induced heating, (4) petrologic data of lunar breccias and their thermal and shock history, and (5) meaningful age measurements. Both the author's interpretations and alternative views are discussed. The age of the Serenitatis event is not yet known. The interpreted age of the Imbrium event is between 3.90 and 3.84 Ga. The age of the Orientale event is 3.84 Ga.

Chao, E. C. T.↗
NASA NTRS1977

Supercooling on the lunar surface - A review of analogue information

Terrestrial analog studies of the phase petrology of supercooled melts and rapid crystal growth are reviewed for possible light shed on lunar crystallization, supercooling, and petrogenic processes, in particular rapid consolidation of lavas extruded on the lunar surface, and impact liquids. Crystallization of major constituent minerals (olivine, pyroxene, plagioclase) in dendritic or skeletal forms is found much more characteristic of lunar igneous rocks than of terrestrial counterparts. Olivine and pyroxene occur often as skeletal phenocrysts, and their stage of crystallization is crucial to the genesis and cooling history of porphyritic lavas. Widespread occurrence of glass and of immature radiate crystallization, particularly of highly zoned pyroxenes and zoned plagioclase, is noted.

Donaldson, C. H.↗
NASA NTRS1977

Electronic absorption spectra of lunar minerals

Techniques for obtaining information on the crystal chemistry of transition-metal ions from measurement of the electronic absorption spectra of lunar minerals are reviewed along with the theory of spectral interpretation. Typical polarized absorption spectra are examined for lunar pyroxenes, pyroxferroite, olivine, and plagioclase feldspars. Oxidation states of Fe, Ti, and Cr in lunar minerals are discussed, and conditions under which they crystallized are considered. It is shown how information on the gross mineralogy and petrology of different regions of the moon's surface may be extracted from remote reflectivity measurements of that surface.

Vaughan, D. J.↗