SEARCH · Search NASA
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Tracks in crystals of feldspars, olivines, pyroxenes, and in several fragments of basalts from a sample of Luna 16 lunar surface material were studied. A high track density, exceeding 10 to the 8th power cm/2 was found. The tracks were produced mainly by iron group nuclei of cosmic galactic and solar rays.
A description is given of the modification of a theory on the reflectance of particulate media so as to apply it to analysis of the infrared spectra obtained by the IRIS instrument on Mariner 9. With the aid of this theory and the optical constants of muscovite mica, quartz, andesite, anorthosite, diopside pyroxenite, and dunite, modeling calculations were made to refine previous estimates of the mineralogical composition of the Martian dust particles. These calculations suggest that a feldspar rich mixture is a very likely composition for the dust particles. The optical constants used for anorthosite and diopside pyroxenite were derived during this program from reflectance measurements. Those for the mica were derived from literature reflectance data. Finally, a computer program was written to invert the measured radiance data so as to obtain the absorption coefficient spectrum which should then be independent of the temperature profile and gaseous component effects.
Eight of eleven Apollo 16 rake-sample anorthosites are very similar to each other, to hand-specimen Apollo 16 anorthosites, and to Apollo 15 anorthosites. They have feldspar An-96.6, both high- and low-Ca pyroxene with a restricted range of (low-magnesium) composition, minor olivine, traces of ilmenite and chromite, and originally coarse-grained, but now cataclastic texture. Such ferroan anorthosite is evidently a coherent, distinctive and widespread lunar rock type of cumulate origin which may not necessarily be very closely related genetically to other highland rock types.
Empirical oxygen barometers based on Eu(2+)/Eu(3+) ratios in plagioclase feldspar and magmatic liquid were developed using Philpott's (1970) approach and the experimental data of Drake (1972). Oxygen fugacities calculated on the basis of Eu(2+)/Eu(3+) ratios for terrestrial basalts cluster tightly around 10 to the negative seventh power. Oxygen fugacities for Apollo 11 and 12 lunar ferrobasalts cluster tightly around 10 to the negative 12.7 power. Calculated oxygen fugacities for achondritic meteorites are lower than for lunar samples by several orders of magnitude.
Optical, X-ray-diffraction and electron-microprobe techniques were used to investigate 0.26 gm of Apollo 14 soil sample 14259. Major element microprobe analyses were made of 470 mineral grains and 388 glass grains. The mineral abundances in the soil are 45% plagioclase, 41% pyroxene, 7% olivine, 3% oxides, 2% K-feldspar; 1% nickel-iron, and less than 1% troilite. The glasses have a wide range of compositions but preferred values are evident and are interpreted as representative of rock types contributing to the soil at the Fra Mauro site. Eleven per cent of the glasses have compositions like those of mare basalts or mare soils and are believed to be mare-derived. Eighty-six per cent of the glasses are equivalent in composition to basalts that have higher Al, and lower Ca/Al and Fe/Mg ratios than mare basalts. The most abundant compositional type is named Fra Mauro basaltic glass and is subdivided into three related types. The other major glass type in the soil corresponds in composition to anorthositic gabbro.
Two distinct chemical basalt types have been sampled at the Apollo 17 landing site. Very high-titanium basalts (about 13 wt % TiO2) are the dominant type and display a textural range from olivine-porphyritic, ilmenite vitrophyres to plagioclase-poikilitic, ilmenite microgabbros. Most of these rocks could have come from one flow. These basalts appear to represent partial melts from feldspar-ilmenite cumulates with an Ar-40/Ar-39 age of about 3.7 G.y., which have experienced little, if any, near-surface fractionation of olivine and Fe-Mg-Ti oxides. A second type of basalt virtually identical to the Apollo 11 (low-K) basalts is much less common.
The article studies the possible variation of mineralogy as a function of both grain size and depth within the core of less than 1 mm fines, for the core section 60004 from Apollo 16. Twelve samples of the fines were dry sieved. The grain size analysis showed a bimodal distribution for all samples, indicating a competing process of grain size degeneration and agglutinate formation. Approximately 99% of the minerals in the samples examined consisted of plagioclase feldspar, pyroxene and olivine, with plagioclase the dominant phase. The various minerals were analyzed, using standard electron microprobe techniques, as a function of size range for each sample, and the representative analyses are presented. Several types of glass were also analyzed, ranging in color from orange through yellow and green to colorless. The investigation of the chemical variations of mineral and lithic clasts from the top and the bottom of the core suggests that although minor variations are present, the regolith was derived from fairly homogeneous sources.
The Martian dust spectra obtained by the infrared interferometer spectrometer (Iris) experiment on Mariner 9 have been compared with modeling computations for various minerals and rocks. The model used was based upon a recently developed theory of absorption and scattering by particulate materials. The results indicate that the composition of Martian dust is biased toward silicate structures which involve a high degree of silicate oxygen sharing. A feldspar-rich dust of approximately 1-micron particle size appears to be the best candidate, although sheet-structure silicates cannot be ruled out.
The two Nakhlite meteorites (Nakhla and Lafayette) are described, and their possible origin is discussed. It is shown that both objects are cumulates of clinopyroxene with augite as the major mineral and with lesser abundances of olivine, plagioclase, K-feldspar, Fe-Ti oxides, FeS, pyrite, chalcopyrite, and possibly iddingsite. Also, both meteorites are unbrecciated, and their texture is dominated by elongate subhedral to euhedral prisms of clinopyroxene. The data are shown to be compatible with the Nakhlites' being cumulative rocks from a common basaltic parent liquid. It is established that these objects are not of lunar origin, and it is concluded that the position of the parent body relative to other planetary bodies remains to be determined.
An IR spectrum of asteroid Vesta, the first of any asteroid, has been recorded at a spectral resolution of 44/cm with a Fourier spectrometer. An electronic absorption band is observed that is assigned to an iron-rich pyroxene (pigeonite) spectroscopically similar to that found in certain eucrites. Other important rock-forming minerals such as olivine and plagioclase feldspar are not observed. There is no evidence for compositional variation with rotational phase angle. This spectroscopic picture of Vesta suggests considerable evolution including the melting and differentiation of silicates.
0.26 gm of Apollo 14 soil sample 14259 has been investigated by optical, X-ray diffraction and electron microprobe techniques. The mineral abundances in the soil are 45% plagioclase, 41% pyroxene, 7% olivine, 3% oxides, 2% K-feldspar, 1% nickel-iron and less than 1% troilite. Eleven percent of the glasses have compositions like those of mare basalts or mare soils and are believed to be mare-derived. Eighty-six percent of the glasses are equivalent in composition to basalts that have higher Al, and lower Ca/Al and Fe/Mg ratios than mare basalts. The most abundant compositional type is named Fra Mauro basaltic glass and is subdivided into three related types. The other major glass type in the soil corresponds in composition to anorthositic gabbro.
The mineralogical composition of asteroid Eros has been determined from its infrared spectrum (0.9-2.7 micrometers; 28/cm resolution). Major minerals include metallic Ni-Fe and pyroxene; no spectroscopic evidence for olivine or plagioclase feldspar was found. The IR spectrum of Eros is most consistent with a stony-iron composition.
The Lafayette meteorite is a calcium-rich achondrite composed predominantly of cumulus clinopyroxene with minor iron-rich olivine and rare interstitial feldspar. The opaque oxide minerals are magnetite-ilmenite intergrowths, an apparently homogenous Cr-rich titaniferous magnetite, and discrete ilmenite. Pyrite, the major sulfide mineral, occasionally displays lamellar intergrowths of marcasite that appear to be of primary origin. Troilite occurs as inclusions in ilmenite or interstitial to the silicate minerals. Bulk chemical composition of the glass in the fusion crust is comparable with that of the Nakhla meteorite. The glass contains abundant skeletal crystals of magnetite as well as very rare, zoned magnetite grains with rims enriched in Mg and depleted in Ti relative to the cores. Although no brecciation is visible in the Lafayette meteorite, the presence of deformed twin lamellae in the clinopyroxene indicates some deformation has occurred.
It is suggested that a series of ANT (anorthosite-norite-troctolite)-KREEP type rocks and the source material for mare basalts sampled by Apollo 11, 12, 15, and 17 may have been derived from a common magmatic differentiation. This differentiation is studied on the basis of a model which proposes that, in the early history of the moon, extensive melting occurred in the outer lunar shell and a magma layer of 100-200 km was formed. The presence of a residual liquid which has not yet been sampled is suspected between high-K KREEP and the Apollo 11 basalt materials. This residual liquid would have a FeO/MgO ratio greater than one and would be significantly enriched in apatite, zircon, K-feldspar, and ilmenite minerals.
Ureilites are a rare group of achondrites. They are composed mainly of olivine and pigeonite in a matrix of carbonaceous material, including graphite, lonsdaleite, diamond, and metal. In most respects Kenna is a typical ureilite with the requisite mineralogical and chemical properties of the group. Differences of the Kenna ureilite from previously studied ureilites are related to a greater density, the occurrence of exceedingly minute quantities of feldspar, and a very strong elongation lineation of the silicate minerals. A description is presented of a study which indicates a complex history for Kenna, including igneous, mild metamorphic, and shock processes.
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.
Fossil track analyses of impregnated core sections from the Apollo 15 and 16 deep drill cores were used to study two types of distinct layers of about 1 mm and about several mm thick in the lunar regolith. The data supports a mixing model hypothesis for the origin of the sampled soil column dominated by large, fresh feldspar fragments. The boundary track method and the track gradient method were used to study the compaction ages of lunar breccias.
Sample 66083,1 was a 0.5 g sample of 2-4 mm fines from a clod of white impact ejecta. Petrography of 12 fragments of it reveals the following types of fragments: a breccia with a glassy matrix containing about 20-30% of crystal fragments, a fragment of partly devitrified glass, a fine-grained feldspar-rich rock containing plagioclase laths with about 10% of interstitial pyroxene and olivine, a breccia consisting of clasts of plagioclase and plagioclase-rich rock in a fine-grained microcrystalline feldspathic groundmass, a fragment of plagioclase clasts in a fine-grained groundmass of plagioclase and ferromagnesians with some opaques, and a crystalline rock made of subequal amounts of plagioclase and ferromagnesians with some opaque material. For sample 67943,1, all but two fragments could be classed as brecciated anorthosites.