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At least 415 records · Page 23

Final Report

Our accomplishments during the tenure of the grant include the chemical-petrographic characterization of chondrules from the highly unequilibrated ungrouped carbonaceous chondrite LEW85332, the examination of matrix materials in several unequilibrated ordinary chondrites, the exploration of the possibility that amoeboid olivine inclusions in CO chondrites were formed by the chondrule forming process at high nebular temperatures, and the interpretation of our results and those of others in terms of nebular agglomeration and parent-body compaction.

Wasson, John T.↗

Investigations of the Formation of Molecular Hydrogen on Dust Grain Analogues

In the last four years we have been working to investigate the formation of molecular hydrogen on surfaces of materials of astrophysical interest, such as silicates, carbonaceous particles and ices, and in conditions approximating the ones present in a variety of astrophysical environments. Our experimental studies - the first of their kind and complemented with computer simulations and theoretical analyses - have given not only hydrogen recombination rates under different ISM conditions, but they have also offered new insights into this fundamental astrophysical problem. Here we summarize our experimental methods and most significant results.

Vidali, Gianfranco↗

Li-Ion Electrolytes with Improved Safety and Tolerance to High-Voltage Systems

Given that lithium-ion (Li-ion) technology is the most viable rechargeable energy storage device for near-term applications, effort has been devoted to improving the safety characteristics of this system. Therefore, extensive effort has been devoted to developing nonflammable electrolytes to reduce the flammability of the cells/battery. A number of promising electrolytes have been developed incorporating flame-retardant additives, and have been shown to have good performance in a number of systems. However, these electrolyte formulations did not perform well when utilizing carbonaceous anodes with the high-voltage materials. Thus, further development was required to improve the compatibility. A number of Li-ion battery electrolyte formulations containing a flame-retardant additive [i.e., triphenyl phosphate (TPP)] were developed and demonstrated in high-voltage systems. These electrolytes include: (1) formulations that incorporate varying concentrations of the flame-retardant additive (from 5 to 15%), (2) the use of mono-fluoroethylene carbonate (FEC) as a co-solvent, and (3) the use of LiBOB as an electrolyte additive intended to improve the compatibility with high-voltage systems. Thus, improved safety has been provided without loss of performance in the high-voltage, high-energy system.

Smart, Marshall C.↗

Towards and Effective Method for the Analysis of Meteoritic Amides

The study of meteoritic organics in carbonaceous chondrites has shown how these extraterrestrial materials record valuable information about the formation of the Solar System and their potential as sources of starting materials for prebiotic organic synthesis [1]. In this study, a method for the analysis and quantification of aliphatic amides, a class of compounds that may have been precursors for other meteoritic organics, has been optimized and tested.

Jose L Ramirez--Colon↗

Analysis of laser extracted volatiles in carbonaceous chondrites

It is scientifically important to understand the composition of volatile compounds from interplanetary dust particles (IDPs) because they may be related to the primordial inventory of planetary materials which were necessary to provide environments conducive to the formation of life. The use of a laser microprobe to measure volatiles in IDPs was evaluated. Because primitive meteorites are thought to be closely related to IDPs, carbonaceous chondrites were used for the evaluation. Three sets of experiments were performed to determine the volatiles released from potential substrate materials, to analyze the volatiles released from matrices of bulk samples of carbonaceous chondrites, and to analyze volatiles released from approx. 100 to 200 micron meteorite particles to simulate IDPs. Aluminum appeared to be the best choice of substrate material. Mass ratios between carbonaceous chondrite matrices of Allende and Murchison show fair reproducibility with somewhat high uncertainties. Particles from the Orgueil, Murchison, and Allende meteorites produced measurable quantities of volatiles that appear to have mass spectra comparable to the bulk matrices.

Blanford, George E.↗

Everyone Wins: A Mars-Impact Origin for Carbonaceous Phobos and Deimos

Discussions of Phobos' and Deimos' origin(s) tend to feature an orthogonally opposed pair of observations: dynamical studies which favor coalescence of the moons from an orbital debris ring arising from a large impact on Mars; and reflectance spectroscopy of the moons that indicate a carbonaceous composition that is not consistent with Martian surface materials. One way to reconcile this discrepancy is to consider the option of a Mars-impact origin for Phobos and Deimos, followed by surficial decoration of carbon-rich materials by interplanetary dust particles (IDP). The moons experience a high IDP flux because of their location in Mars' gravity well. Calculations show that accreted carbon is sufficient to produce a surface with reflectance spectra resembling carbonaceous chondrites.

Fries, M.↗

Carbonate Mineralogy of the C1 Clasts in Kaidun Meteorite

The Kaidun meteorite is a polymict microbreccia weighing approximately 850 g that fell in the People's Republic of South Yemen on December 3, 1980. Although the host material is CR chondrite, it is unique in that it contains many clasts of various chondritic and achondritic materials. Chondritic clasts include EH3-5, EL3, C1, C2, CM1, CM2, CV3, and ordinary chondrite-related materials. Achondrites include a high-Ca primitive achondrite, fragments of alkali-rich differentiated materials, and an aubrite-like clasts [1]. In this study, we focused on C1 materials. There is plenty of evidence that aqueous alteration in the carbonaceous chondrite clasts in Kaidun occurred primarily on their parent bodies before accumulation to a Kaidun body/ Therefore, observations of the C1 materials, which are highly aqueously altered, can provide quantitative constraints on the geologic history of their asteroid parent bodies. In addition, although the lack of petrological features can make the classification of C1 material more difficult, recent studies and analysis of new meteorite fall and returned samples continue to emphasize the diversity of C1 materials.

K Ogiya↗

Carbonaceous Chondrite Fragments in the Polymict Eucrite Yamato 791834

Buchanan et al. and Zolensky et al. described carbonaceous chondrite fragments in a variety of howardites and concluded that the majority are CM2 and CR2 materials. Gounelle et al. also described similar, but very small, fragments in these meteorites. These clasts are important because they represent materials that were in orbital proximity to the HED parent body (4 Vesta) and they may be similar to the primitive materials that originally accreted to form this body. The present study describes two carbonaceous chondrite clasts in the Yamato 791834 (Y791834) polymict eucrite.

Buchanan, P. C.↗

Volatiles in interplanetary dust particles - A review

The paper presents a review of the volatiles found within interplanetary dust particles. These particles have been shown to represent primitive material from early in the solar system's formation and also may contain records of stellar processes. The organogenic elements (i.e., H, C, N, O, and S) are among the most abundant elements in our solar system, and their abundances, distributions, and isotopic compositions in early solar system materials permit workers to better understand the processes operating early in the evolutionary history of solar system materials. Interplanetary dust particles have a range of elemental compositions, but generally they have been shown to be similar to carbonaceous chondrites, the solar photosphere, Comet Halley's chondritic cores, and matrix materials of chondritic chondrites. Recovery and analysis of interplanetary dust particles have opened new opportunities for analysis of primitive materials, although interplanetary dust particles represent major challenges to the analyst because of their small size.

Gibson, Everett K., Jr.↗

The Spatial Distribution and Mineralogical Association of Organics in the Tagish Lake and Bells Carbonaceous Chondrites

Chondritic meteorites represent some of the most primitive Solar System materials available for laboratory analysis. While the presence of simple organic molecules has been well documented in such materials [1], little is known about their spatial distribution and to what extent, if any, they exhibit specific mineralogical associations. This dichotomy arises since organic analysis typically involves solvent extraction as a preliminary step. To address these issues we have used two-step laser mass spectrometry (L 2MS) to map in situ the spatial distribution of aromatic and conjugated organics at the micron scale in freshly exposed surfaces of the Tagish Lake and Bells carbonaceous chondrites. Our specific goals are two-fold; firstly to investigate if and how abundance of organic species varies within the meteorite matrix both as an ensemble, and with respect to functional group (e.g., R-OH vs. RCH3) and between members of the same homologous series (e.g., R-H vs. R-(CH2)H). Secondly, to determine whether observed spatial variations can be related to specific mineralogical and/or physical characteristics of the host matrix. In regard to the latter we are particularly interested in the role that carbonaceous nanoglobules [2] play as reservoirs of organic matter. Such globules, which are believed to have formed by photochemical processing of organic-rich ices in the presolar cold molecular cloud or the outermost reaches of the early protosolar disk, are abundant in both the Bells and Tagish Lake chondrites and are noteworthy for having particularly high enrichments in 2H and 15N [3,4].

Clemett, S. J.↗

Aqueous alteration in carbonaceous chondrites - Mass balance constraints on matrix mineralogy

Bulk chemical compositions of matrix material were determined in eleven Antarctic CM chondrites and five non-Antarctic CM and CI chondrites, using microprobe defocused-beam technique. The results, along with previously published data, are used to provide mass balance constraints on the relative proportions of intergrown and intermixed phyllosilicate phases in carbonaceous chondrite matrices. In terms of Fe, Si, and Mg, the CM matrix bulk compositions plot within a triangle defined by the compositions of PCP (a mixture of 25 percent tochilinite and 75 percent cronstedtite), Mg-rich serpentine, and Fe-rich serpentine. Results indicate differing amounts of PCP and serpentines in individual CM matrices. The discrepancies found between predicted and measured S and Ni values require additional sulfide phases. CI matrices were found to contain little, if any, PCP; they consist mostly of serpentine and montmorillonite.

Mcsween, Harry Y., Jr.↗

Moon - Possible nature of the body that produced the Imbrian Basin, from the composition of Apollo 14 samples.

Soils from the Apollo 14 site contain nearly three times as much meteoritic material as soils from the Apollo 11, Apollo 12, and Luna 16 sites. Part of this material consists of the ubiquitous micrometeorite component, of primitive (carbonaceous-chondrite-like) composition. The remainder, seen most conspicuously in coarse glass and norite fragments, has a decidedly fractionated composition, with volatile elements less than one-tenth as abundant as siderophiles. This material seems to be debris of the Cyprus-sized planetesimal that produced the Imbrian Basin. Compositionally this planetesimal has no exact counterpart among known meteorite classes, though group IVA irons come close. It also resembles the initial composition of the earth as postulated by the two-component model. Apparently the Imbrian planetesimal was an earth satellite swept up by the moon during tidal recession or capture, or an asteroid deflected by Mars into terrestrial space.

Ganapathy, R.↗

Spectral and Mineralogical Analyses of Aguas Zarcas in Search of Its Parent Body

Aguas Zarcas is an intriguing carbonaceous chondrite that fell in Aguas Zarcas district, San Carlos, Alajulea, Costa Rica on 23 April 2019 [1]. This carbonaceous chondrite was found to be a breccia at al all scales with diverse lithologies (metal-rich, brecciated CM, and CI) [2]. Here we present spectroscopic and PSD-XRD analyses of a sample of Aguas Zarcas(donated to NASA JSC by Robert Ward) to better understand the origin and parent body for this meteorite. The spectral and mineralogical analyses are placed in the context of the published petrological and geochemical analyses of Aguas Zarcas, and its spectra are compared to a suite of spectra of asteroidal materials, including cabon-bearing asteroids, asteroid returned samples, and carbonaceous chondrites. The focus of this investigation will be on hydrated minerals and carbon-bearing materials, including organics and carbonates.

D. Takir↗

Primary igneous carbon in ureilites - Petrological implications

The ureilite meteorites are carbonaceous olivine-pyroxene achondrites. They typically contain up to 4 wt.% carbon (carbonaceous matrix) as graphite, diamond, and lonsdaleite. Shock degradation has effectively obliterated primary textures in the carbonaceous matrix of previously described ureilites, a factor that has hampered efforts to explain the origin of this material. In contrast, the Antarctic ureilite ALHA78019 displays perfectly preserved primary textures in the carbonaceous matrix characterized by euhedral graphite blades intergrown with Fe-Ni metal and sulfide (diamonds are absent). This petrographic feature suggests that most graphite in ureilites originated by crystallization from a C-rich metallic phase. Assuming that fO2 is controlled by C-CO-CO2 reactions, the compositions of silicates and metals in ureilites imply a two-stage redox history. The noble gases and rare earths of ureilites are discussed in light of this model.

Berkely, J. L.↗

Constraints on Chondrule Generation, Disk Dynamics, and Asteroid Accretion from the Compositions of Carbonaceous Meteorites

The elemental and isotopic compositions of meteorites are expected to reflect several key processes that occurred in the early solar system, including the migration of gas and dust throughout the protoplanetary disk, the formation of chondrules, and the accretion of the first planetary bodies. However, the specific origins of the various compositions measured among these rocks are currently poorly constrained, limiting our understanding of these processes. Here, we use previously measured elemental and isotopic compositions of chondrites and iron meteorites to identify that carbonaceous (CC) meteorites are mixtures of noncarbonaceous (NC) material, calcium–aluminum-rich inclusion (CAI) material, and CI (Ivuna-like) material, in varying proportions. These trends indicate that chondrules in CO (Ornans-like), CM (Mighei-like), CV (Vigarano-like), and TL (Tagish Lake) chondrites share near-identical average proportions of CI material, arguing that they were generated through the remelting of preexisting NC chondrules all in the same disk environment. Because this proportion likely evolved over space and time throughout the disk, this similarity argues that these chondrules originate from a restricted spatial region and time interval, favoring their generation through a localized event. Moreover, the compositions of CR (Renazzo-like) chondrites indicate that their constituents formed through mechanisms different from those in CO, CM, CV, and TL chondrites. Furthermore, the recovered proportions of CI material in CC iron meteorites and chondrites together also argue for evolution in either the predominant direction of dust and gas motion in the first ~10 au of the disk or the radial distance of planetesimal accretion throughout the CC reservoir.

58 GEOSCIENCES↗

Sulfur volcanoes on Io

Widespread volcanism on Jupiter's satellite Io, if it occurred over the age of the solar system, would quickly reduce the inventory of most common volatiles needed to drive such volcanism. One exception is the volatile element sulfur. It is therefore postulated that sulfur is the driving volatile for Ionian volcanism. Its presence is consistent with a carbonaceous-chondrite-like bulk composition for the original material that formed Io 4.5 billion years ago. The ubiquity of sulfur on Io today demonstrates the importance of this element in the processes that formed its surface.

Consolmagno, G. J.↗