Publishing type：Research paper (scientific journal)   Publisher：{EDP} Sciences  

<jats:p><jats:italic>Context.</jats:italic> The current period is conducive to exploring our Solar System's origins with recent and future space sample return missions, which provide invaluable information from known Solar System asteroids and comets The Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) recently brought back samples from the surface of the Ryugu carbonaceous asteroid.</jats:p>
<jats:p><jats:italic>Aims.</jats:italic> We aim to identify the different forms of chemical composition of organic matter and minerals that constitute these Solar System primitive objects, to shed light on the Solar System's origins.</jats:p>
<jats:p><jats:italic>Methods.</jats:italic> In this work, we recorded infrared (IR) hyper-spectral maps of whole-rock Ryugu asteroid samples at the highest achievable spatial resolution with a synchrotron in the mid-IR (MIR). Additional global far-IR (FIR) spectra of each sample were also acquired.</jats:p>
<jats:p><jats:italic>Results.</jats:italic> The hyper-spectral maps reveal the variability of the functional groups at small scales and the intimate association of phyl-losilicates with the aliphatic components of the organic matter present in Ryugu. The relative proportion of column densities of the identified IR functional groups (aliphatics, hydroxyl + interlayer and/or physisorbed water, carbonyl, carbonates, and silicates) giving access to the composition of the Ryugu samples is estimated from these IR hyper-spectral maps. Phyllosilicate spectra reveal the presence of mixtures of serpentine and saponite. We do not detect anhydrous silicates in the samples analysed, at the scales probed. The carbonates are dominated by dolomite. Aliphatics organics are distributed over the whole samples at the micron scale probed with the synchrotron, and intimately mixed with the phyllosilicates. The aromatic C=C contribution could not be safely deconvolved from OH in most spectra, due to the ubiquitous presence of hydrated minerals. The peak intensity ratios of the organics methylene to methyl (CH<jats:sub>2</jats:sub>/CH<jats:sub>3</jats:sub>) of the Ryugu samples vary between about 1.5 and 2.5, and are compared to the ratios in chondrites from types 1 to 3. Overall, the mineralogical and organic characteristics of the Ryugu samples show similarities with those of CI chondrites, although with a noticeably higher CH<jats:sub>2</jats:sub>/CH<jats:sub>3</jats:sub> in Ryugu than generally measured in C1 chondrites collected on Earth, and possibly a higher carbonate content.</jats:p>

DOI： 10.1051/0004-6361/202244702

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Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Association for the Advancement of Science (AAAS)  

The Hayabusa2 spacecraft collected samples from the surface of the carbonaceous near-Earth asteroid (162173) Ryugu and brought them to Earth. The samples were expected to contain organic molecules, which record processes that occurred in the early Solar System. We analyzed organic molecules extracted from the Ryugu surface samples. We identified a variety of molecules containing the atoms CHNOS, formed by methylation, hydration, hydroxylation, and sulfurization reactions. Amino acids, aliphatic amines, carboxylic acids, polycyclic aromatic hydrocarbons, and nitrogen-heterocyclic compounds were detected, which had properties consistent with an abiotic origin. These compounds likely arose from an aqueous reaction on Ryugu’s parent body and are similar to the organics in Ivuna-type meteorites. These molecules can survive on the surfaces of asteroids and be transported throughout the Solar System.

DOI： 10.1126/science.abn9033

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PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Association for the Advancement of Science (AAAS)  

Samples of the carbonaceous asteroid (162173) Ryugu were collected and brought to Earth by the Hayabusa2 spacecraft. We investigated the macromolecular organic matter in Ryugu samples and found that it contains aromatic and aliphatic carbon, ketone, and carboxyl functional groups. The spectroscopic features of the organic matter are consistent with those in chemically primitive carbonaceous chondrite meteorites that experienced parent-body aqueous alteration (reactions with liquid water). The morphology of the organic carbon includes nanoglobules and diffuse carbon associated with phyllosilicate and carbonate minerals. Deuterium and/or nitrogen-15 enrichments indicate that the organic matter formed in a cold molecular cloud or the presolar nebula. The diversity of the organic matter indicates variable levels of aqueous alteration on Ryugu’s parent body.

DOI： 10.1126/science.abn9057

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PubMed

Publisher：ACS Earth and Space Chemistry  

Sulfur comprises various compound forms in natural environments and could have played important roles in chemical evolution in the universe. Various soluble organosulfur compounds and inorganic sulfur oxides were identified in the methanol extracts of three carbonaceous chondrites (Murchison, Tagish Lake, and Allende) using high-performance liquid chromatography coupled with high-resolution mass spectrometry. The most abundant S-bearing organic compound was hydroxymethane sulfonic acid (HMSA, HOCH2SO3H), which is reported from a meteorite for the first time, at a concentration of 201 nmol/g in the Murchison meteorite. Because HMSA is known to be produced by the reaction of formaldehyde (HCHO) and bisulfite (HSO3-), this result indicates that formaldehyde should be abundant prior to the reaction with HSO3- in the meteorite parent bodies. The bisulfite derivatives of glycolaldehyde and glyceraldehyde were further identified in the methanol extract, suggesting that the formose reaction had proceeded during the aqueous alteration. The finding of these sugar-HSO3- adducts suggests that the formose reaction might have been controlled by the presence of sulfur species in the body. Furthermore, alkylated sulfonic acids (CnH2n+1SO3H) were also present as a series of homologous compounds up to C14 in the Murchison meteorite, even though previous studies found only C1-C4 sulfonic acids. In addition to organosulfur compounds, variable inorganic polysulfur oxides and acids were detected. The abundant S-bearing compounds in the meteorites imply important roles of sulfur in the organic reactions in carbonaceous asteroids.

DOI： 10.1021/acsearthspacechem.2c00157

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing Ltd  

We have conducted a NanoSIMS-based search for presolar material in samples recently returned from C-type asteroid Ryugu as part of JAXA's Hayabusa2 mission. We report the detection of all major presolar grain types with O- and C-anomalous isotopic compositions typically identified in carbonaceous chondrite meteorites: 1 silicate, 1 oxide, 1 O-anomalous supernova grain of ambiguous phase, 38 SiC, and 16 carbonaceous grains. At least two of the carbonaceous grains are presolar graphites, whereas several grains with moderate C isotopic anomalies are probably organics. The presolar silicate was located in a clast with a less altered lithology than the typical extensively aqueously altered Ryugu matrix. The matrix- normalized presolar grain abundances in Ryugu are 4.8(-2.6)(+4.7) ppm for O-anomalous grains, 25(-)(5)(+)(6) ppm for SiC grains, and 11(-3)(+5) ppm for carbonaceous grains. Ryugu is isotopically and petrologically similar to carbonaceous Ivuna-type (CI) chondrites. To compare the in situ presolar grain abundances of Ryugu with CI chondrites, we also mapped Ivuna and Orgueil samples and found a total of 15 SiC grains and 6 carbonaceous grains. No O-anomalous grains were detected. The matrix-normalized presolar grain abundances in the CI chondrites are similar to those in Ryugu: 23(-6)(+7) ppm SiC and 9.0 (+5.4)(-3)(.6) ppm carbonaceous grains. Thus, our results provide further evidence in support of the Ryugu-CI connection. They also reveal intriguing hints of small-scale heterogeneities in the Ryugu samples, such as locally distinct degrees of alteration that allowed the preservation of delicate presolar material.

DOI： 10.3847/2041-8213/ac83bd

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Language：Japanese  

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Language：Japanese  

Web of Science

Publisher：Research Square Platform LLC  

Abstract

We performed in-situ analysis on a ~1 mm-sized Ryugu grain A0080 returned by the Hayabusa2 spacecraft to investigate the relationship of soluble organic matter (SOM) to minerals. The DESI-HRMS (desorption electrospray ionization-high resolution mass spectrometry) imaging using methanol spray identified more than 200 soluble organic compounds, which were assigned as CHN, CHO, CHO-Na (sodium adducted), and CHNO in molecular composition. Heterogeneous spatial distribution was observed for different compound classes of SOM as well as among the same alkylated homologues on the sample surface. The A0080 sample showed similar mineralogy to that of CI chondrite and contained two different lithologies, which are rich in magnetite, pyrrhotite, and dolomite (lithology 1) and poor in those minerals (lithology 2). CHN compounds were relatively concentrated in lithology 1 than in lithology 2, on the other hand, CHO, CHO-Na, and CHNO compounds were distributed in both lithologies. Such different spatial distribution of SOM is the result of interaction of the SOM with minerals, during precipitation of the SOM via fluid activity, or could be due to difference in transportation efficiencies of SOMs in aqueous fluid. However, organic-related ions measured by ToF-SIMS did not coincide with the spatial distribution revealed by DESI-HRMS imaging, indicating that the ToF-SIMS data would be mainly derived from methanol-insoluble organic matter in A0080. Alkylated homologues of CHN compounds with large C number appeared more abundant in lithology 2 than lithology 1. In contrast, fragments of the Murchison meteorite showed different features to of A0080, implying different formation or growth mechanisms for the alkylated CHN compounds by interaction with fluid and minerals on Murchison parent body and asteroid Ryugu. This difference might be mainly attributed to the carbonate grains, which would have played as a catalyst for CH₂ growth of CHN compounds. Future in-situ analysis of CI chondrite will provide more reliable constraints for the history of soluble organic compounds in asteroid Ryugu.

DOI： 10.21203/rs.3.rs-1812195/v1

Other Link： https://www.researchsquare.com/article/rs-1812195/v1.html

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

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DOI： 10.14862/geochemproc.69.0_104

CiNii Research

Language：Japanese  

DOI： 10.35848/1882-0786/abf319

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Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

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DOI： 10.14862/geochemproc.68.0_78

CiNii Research

Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

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DOI： 10.14862/geochemproc.67.0_80

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI  

Organic compounds are present as complex mixtures in extraterrestrial materials including meteorites, which may have played important roles in the origin of life on the primitive Earth. However, the distribution and formation mechanisms of meteoritic organic compounds are not well understood, because conventional analytical methods have limited resolution and sensitivity to resolve their molecular complexity. In this study, advanced instrumental development and analyses are proposed in order to study the trace organic compounds of extraterrestrial materials: (1) a clean room environment to avoid organic contamination during analysis; (2) high-mass-resolution analysis (up to similar to 150,000 m/Delta m) coupled with high-performance liquid chromatography (HPLC) in order to determine the elemental composition using exact mass for inferring the chemical structure; (3) superior chromatographic separation using a two-dimensional system in order to determine the structural and optical isomers of amino acids; and (4) in situ organic compound analysis and molecular imaging of the sample surface. This approach revealed a higher complexity of organic compounds with a heterogeneous distribution in meteorites. These new methods can be applied to study the chemical evolution of meteoritic organic compounds as well as the molecular occurrence in very-low-mass extraterrestrial materials such as asteroid-returned samples.

DOI： 10.3390/life9030062

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PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

High-resolution mass spectrometry (HRMS) imaging by desorption electrospray ionization (DESI) coupled with Orbitrap MS using methanol (MeOH) spray was performed on a fragment of the Murchison (CM2) meteorite in this study. Homologues of CnH2n-1N2+ (n = 7-9) and CnH2nNO+ (n = 9-14) were detected on the sample surface by the imaging. A high-performance liquid chromatography (HPLC)/HRMS analysis of MeOH extracts from the sample surface after DESI/HRMS imaging indicated that the CnH2n-1N2+ homologues corresponds to alkylimidazole, and that a few isomers of the CnH2nNO+ homologues present in the sample. The alkylimidazoles and CnH2nNO+ homologues displayed different spatial distributions on the surface of the Murchison fragment, indicating chromatographic separation effects during aqueous alteration. Moreover, the distribution pattern of compounds is also different among homologues. This is probably also resulting from the separation of isomers by similar chromatographic effects, or different synthetic pathways. Alkylimidazoles and the CnH2nNO+ homologues are mainly distributed in the matrix region of the Murchison by mineralogical observations, which is consistent with previous reports. Altered minerals (e.g., Fe-oxide, Fe-sulfide, and carbonates) occurred in this region. However, no clear relationship was found between these minerals and the organic compounds detected by DESI/HRMS imaging. Although this result might be due to scale differences between the spatial resolution of DESI/HRMS imaging and the grain size in the matrix of the Murchison, our results would indicate that alkylimidazoles and the CnH2nNO+ homologues in the Murchison fragment were mainly synthesized by different processes from hydrothermal alteration on the parent body.

DOI： 10.1111/maps.13211

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEOCHEMICAL SOC JAPAN  

Very complex mixtures of organic compounds occur in extraterrestrial materials such as carbonaceous meteorites. These intricate signatures of meteoritic organic matter can provide clues to elucidate chemical evolution processes in space. Previously, these complex organic molecules have not been well-resolved in primitive meteorites, so the formation mechanisms of extraterrestrial organics remain largely conjectural. In this study, the occurrence and abundance of soluble CHN organic compounds were examined in CM vs. CR meteorites to investigate possible chemical processes associated with the different parent bodies. Hydrogenated alkylpiperidines (CnH2n+1N) are more abundant in the CR chondrite, in contrast to more abundant aromatic alkylpyridines (CnH2n-5N) in the CM chondrites. Both alkylpyridines and alkylpiperidines are most likely synthesized from simple aldehydes and ammonia on meteorite parent bodies, but the differences between the distribution of N-cyclic compounds are consistent with different redox conditions of the parent bodies which influenced the organic molecular evolution processes in extraterrestrial materials.

DOI： 10.2343/geochemj.2.0546

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Language：Japanese  

DOI： 10.14909/yuseijin.27.3_253

Language：English   Publishing type：Research paper (scientific journal)   Publisher：MINERALOGICAL SOC AMER  

The Mg grain boundary diffusion coefficients were measured in forsterite aggregates as a function of pressure (1 atm and 13 GPa), temperature (1100-1300 K), water content (<1-350 wt. ppm bulk water), and oxygen fugacity (10(-18)-10(-0.7) bar) using a multi-anvil apparatus and a gas-mixing furnace. The diffusion profiles were analyzed by secondary ion mass spectrometer, whereas the water contents in the samples were measured by Fourier transform infrared spectrometer. The activation volume, activation enthalpy, water content exponent, and oxygen fugacity exponent for the Mg grain-boundary diffusion coefficients are found to be 3.9 +/- 0.7 cm(3)/mol, 355 +/- 25 kJ/mol, 1.0 +/- 0.1, and -0.02 +/- 0.01, respectively. By comparison with the Mg lattice diffusion data (Fei et al. 2018), the bulk diffusivity of Mg in forsterite is dominated by lattice diffusion if the grain size is larger than similar to 1 mm under upper mantle conditions, whereas effective grain-boundary and lattice diffusivities are comparable when the grain size is similar to 1-100 mu m.

DOI： 10.2138/am-2018-6480

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Other Link： http://orcid.org/0000-0003-0702-0533

Language：English   Publishing type：Research paper (scientific journal)   Publisher：John Wiley and Sons Ltd  

Rationale: Since extraterrestrial organic matter in meteorites is a very complex mixture that is hard to ionize due to its association with minerals, in situ analysis of polar organic compounds has never been performed. In addition, when studying powdered samples, spatial information of organic compounds is lost. Methods: In situ molecular analysis and chemical imaging of polar organic compounds were performed on a meteorite surface by desorption electrospray ionization coupled with high-resolution mass spectrometry (DESI-HRMS) using an Orbitrap mass spectrometer. Results: Many CHN compounds, including alkylated pyridine and imidazole homologues, were identified from the complex peaks by HRMS using a spray of electrically charged methanol with a spatial resolution of approximately 50 μm. The same alkylated homologues have the same spatial distribution in the meteorite matrix, while alkylpyridines occur in a different location from alkylimidazoles. Conclusions: The compound distribution suggests a different source for each compound series or a chromatographic separation effect associated with fluid movement in the meteorite parent body. The DESI-HRMS imaging will further our understanding of organic compound distribution with respect to mineral and water interactions in meteorites.

DOI： 10.1002/rcm.8121

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PubMed

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.epsl.2017.12.020

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A comprehensive study of the organic chemistry and mineralogy of an ultracarbonaceous micrometeorite (UCAMM D05IB80) collected from near the Dome Fuji Station, Antarctica, was carried out to understand the genetic relationship among organic materials, silicates, and water. The micrometeorite is composed of a dense aggregate of similar to 5 mm-sized hollow ellipsoidal organic material containing submicrometer-sized phases such as glass with embedded metal and sulfides (GEMS) and mineral grains. There is a wide area of organic material (similar to 15 x 15 mu m) in its interior. Low-Ca pyroxene is much more abundant than olivine and shows various Mg/(Mg + Fe) ratios ranging from similar to 1.0 to 0.78, which is common to previous works on UCAMMs. By contrast, GEMS grains in this UCAMM have unusual chemical compositions. They are depleted in both Mg and S, which suggests that these elements were leached out from the GEMS grains during very weak aqueous alteration, without the formation of phyllosilicates.
The organic materials have two textures-smooth and globular with an irregular outline- and these are composed of imine, nitrile and/or aromatic nitrogen heterocycles, and amide. The ratio of nitrogen to carbon (N/C) in the smooth region of the organics is similar to 0.15, which is five times higher than that of insoluble organic macromolecules in types 1 and 2 carbonaceous chondritic meteorites. In addition, the UCAMM organic materials are soluble in epoxy and are thus hydrophilic; this polar nature indicates that they are very primitive. The surface of the material is coated with an inorganic layer, a few nanometers thick, that consists of C, O, Si, S, and Fe. Sulfur is also contained in the interior, implying the presence of organosulfur moieties. There are no isotopic anomalies of D, C-13, or N-15 in the organic material.
Interstellar photochemistry alone would not be sufficient to explain the N/C ratio of the UCAMM organics; therefore, we suggest that a very small amount of fluid on a comet must have been necessary for the formation of the UCAMM. The GEMS grains depleted in Mg and S in the UCAMM prove a very weak degree of aqueous alteration; weaker than that of carbonaceous chondrites. Short-duration weak alteration probably caused by planetesimal shock locally melted cometary ice grains and released water that dissolved the organics; the fluid would likely have not mobilized because of the very low thermal conductivity of the porous icy body. This event allowed the formation of the large organic puddle of the UCAMM, as well as organic matter sulfurization, formation of thin membrane-like layers of minerals, and deformation of organic nanoglobules. (C) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.gca.2017.06.047

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Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

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DOI： 10.14862/geochemproc.64.0_134

Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEOCHEMICAL SOC JAPAN  

Many studies in the past decade have sought to explore the origin and evolution of water in planetary bodies based on the hydrogen isotopic compositions of apatite. However, no investigation has studied hydrogen diffusivity in apatite. This work reports hydrogen diffusion experiments using a natural Durango fluorapatite carried out under a saturated (H2O)-H-2/O-2 vapor flow at temperatures of 500-700(omicron)C. Diffusion depth profiles for H-1 and H-2 were measured using secondary ion mass spectrometry (SIMS), indicating that H-2 diffusion occurred by an exchange reaction between the original H-1 and H-2 during annealing. Hydrogen diffusion coefficients were obtained by the fitting of diffusion profiles of H-2 using Fick's second law; they followed an Arrhenius-type relationship. The temperature dependence of hydrogen diffusion parallel to the c-axis at 500-700(omicron)C can be expressed as D = 6.71X10(-13) exp(- 80.5 +/- 3.3) / RT) [m(2) / s]. Hydrogen diffusion coefficients in apatite are several orders of magnitude greater than those of other elements. Hydrogen diffusion in apatite occurs at relatively low temperatures (below 700(omicron)C). This study indicates that the hydrogen isotopic compositions of apatite are readily affected by the presence of water vapor through the H-1-H-2 exchange reaction without changing the total water content in the crystal.

DOI： 10.2343/geochemj.2.0460

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Event date： 2022.3

Language：English   Presentation type：Poster presentation  

Venue：The Woodlands, Texas/Online   Country：United States