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Mineralogy of the Martian Mantle Inferred from Bulk Chemical Compositions of Mars
The mineralogical composition of a planet’s mantle determines the composition of the volcanism that plays an important role in the composition of the surface environment: crust, atmosphere and hydrosphere or biosphere. On Earth, mantle xenoliths and peridotite outcrops provide essential clues to the mineralogical composition of the mantle. The mineralogical composition of Mars’ mantle is not known from direct samples. In this study, the mineralogy of the martian mantle is constrained by using the MELTS code to model the solidus mineralogy of published estimates of the bulk composition of the martian mantle. Phase compositions from experimental studies of the melting of putative martian mantle compositions are used to validate the MELTS output.
Updated Atmospheric Composition Chemical Reanalysis and Emission Estimates
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Application of Laboratory Atomic Physics to Some Significant Stellar Chemical Composition Questions
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Oxygen isotope and chemical compositions of magnetite and olivine in the anomalous CK3 Watson 002 and ungrouped Asuka‐881595 carbonaceous chondrites: Effects of parent body metamorphism
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New Insights into the Chemical Composition of Five Oort Cloud Comets after Re-analysis of Their Infrared Spectra
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The Perils of Partition: Difficulties in Retrieving Magma Compositions from Chemically Equilibrated Basaltic Meteorites
The chemical compositions of magmas can be derived from the compositions of their equilibrium minerals through mineral/magma partition coefficients. This method cannot be applied safely to basaltic rocks, either solidified lavas or cumulates, which have chemically equilibrated or partially equilibrated at subsolidus temperatures, i.e., in the absence of magma. Applying mineral/ melt partition coefficients to mineral compositions from such rocks will typically yield 'magma compositions' that are strongly fractionated and unreasonably enriched in incompatible elements (e.g., REE's). In the absence of magma, incompatible elements must go somewhere; they are forced into minerals (e.g., pyroxenes, plagioclase) at abundance levels far beyond those established during normal mineral/magma equilibria. Further, using mineral/magma partition coefficients with such rocks may suggest that different minerals equilibrated with different magmas, and the fractionation sequence of those melts (i.e., enrichment in incompatible elements) may not be consistent with independent constraints on the order of crystallization. Subsolidus equilibration is a reasonable cause for incompatible- element-enriched minerals in some eucrites, diogenites, and martian meteorites and offers a simple alternative to petrogenetic schemes involving highly fractionated magmas or magma infiltration metasomatism.
The Cosmic Dust Analyzer for Cassini
The Cosmic Dust Analyzer (CDA) is designed to characterize the dust environment in interplanetary space, in the Jovian and in the Saturnian systems. The instrument consists of two major components, the Dust Analyzer (DA) and the High Rate Detector (HRD). The DA has a large aperture to provide a large cross section for detection in low flux environments. The DA has the capability of determining dust particle mass, velocity, flight direction, charge, and chemical composition. The chemical composition is determined by the Chemical Analyzer system based on a time-of-flight mass spectrometer. The DA is capable of making full measurements up to one impact/second. The HRD contains two smaller PVDF detectors and electronics designed to characterize dust particle masses at impact rates up to 10(exp 4) impacts/second. These high impact rates are expected during Saturn ring, plane crossings.
Microchemical analysis of the SCS-6 silicon carbide fiber
A detailed quantitative study of the microstructural variation of chemical composition of chemically vapor-deposited commercial SiC SCS-6 fiber is presented. Chemical etching and various electron-optical techniques including SEM, TEM, scanning Auger microscopy, AES, and parallel electron energy loss spectroscopy are used to analyze the chemical composition of the as-received fiber. In addition, some results on stereology of the high-temperature annealed fiber are presented. The results show that the carbon-to-silicon atom ratio in the SiC layers decreases in a stepwise fashion from about 3:2 to about 1:1 in going from the innermost layer to the outermost layer.
The XRD Amorphous Component in John Klein Drill Fines at Yellowknife Bay, Gale Crater, Mars
Drill fines of mudstone (targets John Klein and Cumberland) from the Sheepbed unit at Yel-lowknife Bay were analyzed by MSL payload elements including the Chemistry and Mineralogy (CheMin), APXS (Alpha Particle X-Ray Spectrometer), and Sample Analysis at Mars (SAM) instruments. CheMin XRD results show a variety of crystalline phases including feldspar, pyroxene, olivine, oxides, oxyhydroxides, sulfates, sulfides, a tri-octahedral smectite, and XRD amorphous material. The drill fines are distinctly different from corresponding analyses of the global soil (target Rocknest) in that the mudstone samples contained detectable phyllosilicate. Here we focus on John Klein and combine CheMin and APXS data to calculate the chemical composition and concentration of the amorphous component. The chemical composition of the amorphous plus smectite component for John Klein was calculated by subtracting the abundance-weighted chemical composition of the individual XRD crystalline components from the bulk composition of John Kline as measured by APXS. The chemical composition of individual crystalline components was determined either by stoichiometry (e.g., hematite and magnetite) or from their unit cell parameters (e.g., feldspar, olivine, and pyroxene). The chemical composition of the amorphous + smectite component (approx 71 wt.% of bulk sample) and bulk chemical composition are similar. In order to calculate the chemical composition of the amorphous component, a chemical composition for the tri-octahedral smectite must be assumed. We selected two tri-octahedral smectites with very different MgO/(FeO + Fe2O3) ratios (34 and 1.3 for SapCa1 and Griffithite, respectively). Relative to bulk sample, the concentration of amorphous and smectite components are 40 and 29 wt.% for SapCa1 and 33 and 36 wt.% for Griffithite. The amount of smectite was calculated by requiring the MgO concentration to be approx 0 wt.% in the amorphous component. Griffithite is the preferred smectite because the position of its 021 diffraction peak is similar to that reported for John Klein. In both cases, the amorphous component has low SiO2 and MgO and high FeO + Fe2O3, P2O5, and SO3 concentrations relative to bulk sample. The chemical composition of the bulk drill fines and XRD crystalline, smectite, and amorphous components implies alteration of an initially basaltic material under near neutral conditions (not acid sulfate), with the sulfate incorporated later as veins of CaSO4 injected into the mudstone.
Chemical and optical properties at the Apollo 15 and 16 sites
The bulk chemical composition, the surface chemical concentration of four major elements, and the optical albedo were determined for six core samples, for two sites and from four different depths below the lunar surface, and also for surface soil samples from the vicinity of the sites of the cores. The chemical composition of the core samples was found to be related to that of the surface samples from the same sites, and the correlation of the albedo with the surface iron plus titanium content that has previously been demonstrated for the surface samples was also verified for the core samples. A soil layer near the bottom of the Apollo 15 deep drill core was found to be unusual in two respects: the grain surface and the bulk chemical compositions were found to be more similar than is usual, and the albedo was exceptionally high, though still only 0.6 of the albedo of crushed rock of similar composition. The mechanism of darkening of lunar soil is discussed in the light of these observations.
A method for computing chemical-equilibrium compositions of reacting-gas mixtures by reduction to a single iteration equation
Computing equilibrium chemical composition and thermodynamic properties of reacting gas mixtures by reduction to single iterative equation
Thermochemical analysis of chemical processes relevant to the stability and processing of SiC-reinforced Si3N4 composite
Chemical processes relevant to the stability and processing of SiC-reinforced Si3N4 composites have been examined from thermochemical considerations. The thermodynamic stabilities of various interfaces, such as SiC-Si3N4, SiC-Si3N4-Si2ON2, and SiC-Si3N4-SiO2, have been examined as a function of temperature, and the temperatures above which these interfaces become unstable have been calculated. The degradation of SiC during the processing of the composite has been examined. The processing routes considered in this study include the reaction bonded silicon nitride (RBSN) process and the pressure-assisted sintering processes with suitable sintering additives.
Occurrences of sinoite, si sub 2 n sub 2 o, in meteorites.
Chemical composition and physical properties of mineral sinoite occurring in enstatite chondrites
Chemical mixing model studies of lunar orbital geochemical data - Apollo 16 and 17 highlands compositions
Chemical mixing model studies of lunar geochemical data for the central and Taurus-Littrow lunar highlands were performed utilizing pristine highland rock types as end member compositions. The central highlands show considerable diversity in composition; anorthosite is the principal rock type in the Apollo 16/Descartes region, while norite predominates in the highlands west of the landing site. This change in crustal composition is coincident with a major color boundary seen in earth-based multispectral data and probably represents the presence of distinct geochemical provinces within the central highlands. The Taurus-Littrow highlands are dominated by norite; anorthosite is far less abundant than in the central highlands. This suggests that the impact target for the Serenitatis basin was different than that of the Nectaris basin and further strengthens the hypothesis that the lunar highlands are petrologically heterogeneous on a regional basis. It is suggested that the lunar highlands should be viewed in terms of geochemical provinces that have undergone distinct and complex igneous and impact histories.
Spectral analysis of four meteors
Four meteor spectra are analyzed for chemical composition and radiative processes. The chemical compositions of the Taurid, Geminid, and Perseid meteors were found to be similar to that of a typical stony meteorite. The chemical composition of the sporadic meteor was found to be similar to that of a nickel iron meteorite. The radiation from optical meteors was found to be similar to that of a low temperature gas, except that strong, anomalous ionic radiation is superposed on the neutral radiation in bright, fast meteors.
Heat cascading regenerative sorption heat pump
A simple heat cascading regenerative sorption heat pump process with rejected or waste heat from a higher temperature chemisorption circuit (HTCC) powering a lower temperature physisorption circuit (LTPC) which provides a 30% total improvement over simple regenerative physisorption compression heat pumps when ammonia is both the chemisorbate and physisorbate, and a total improvement of 50% or more for LTPC having two pressure stages. The HTCC contains ammonia and a chemisorbent therefor contained in a plurality of canisters, a condenser-evaporator-radiator system, and a heater, operatively connected together. The LTPC contains ammonia and a physisorbent therefor contained in a plurality of compressors, a condenser-evaporator-radiator system, operatively connected together. A closed heat transfer circuit (CHTC) is provided which contains a flowing heat transfer liquid (FHTL) in thermal communication with each canister and each compressor for cascading heat from the HTCC to the LTPC. Heat is regenerated within the LTPC by transferring heat from one compressor to another. In one embodiment the regeneration is performed by another CHTC containing another FHTL in thermal communication with each compressor. In another embodiment the HTCC powers a lower temperature ammonia water absorption circuit (LTAWAC) which contains a generator-absorber system containing the absorbent, and a condenser-evaporator-radiator system, operatively connected together. The absorbent is water or an absorbent aqueous solution. A CHTC is provided which contains a FHTL in thermal communication with the generator for cascading heat from the HTCC to the LTAWAC. Heat is regenerated within the LTAWAC by transferring heat from the generator to the absorber. The chemical composition of the chemisorbent is different than the chemical composition of the physisorbent, and the absorbent. The chemical composition of the FHTL is different than the chemisorbent, the physisorbent, the absorbent, and ammonia.