¹Thierry Fouchet et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114773]
¹LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France
Copyright Elsevier

We present the Infrared spectrometer of SuperCam Instrument Suite that enables the Mars 2020 Perseverance Rover to study remotely the Martian mineralogy within the Jezero crater. The SuperCam IR spectrometer is designed to acquire spectra in the 1.3–2.6 µm domain at a spectral resolution ranging from 5 to 20 nm. The field-of-view of 1.15 mrad, is coaligned with the boresights of the other remote-sensing techniques provided by SuperCam: laser-induced breakdown spectroscopy, remote time-resolved Raman and luminescence spectroscopies, and visible reflectance spectroscopy, and micro-imaging. The IR spectra can be acquired from the robotic-arm workspace to long-distances, in order to explore the mineralogical diversity of the Jezero crater, guide the Perseverance Rover in its sampling task, and to document the samples’ environment. We present the design, the performance, the radiometric calibration, and the anticipated operations at the surface of Mars.

¹Nao NAKANISHI,¹Tetsuya YOKOYAMA,^1,2Satoki OKABAYASHI,³Hikaru IWAMORI,⁴Takafumi HIRATA
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.11.009]
¹Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
²Department of Applied Chemistry for Environment, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan
³Earthquake Research Institute, The University of Tokyo, Bunkyo, Tokyo 113-0032, Japan
⁴Geochemical Research Center, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo 113-0032, Japan
Copyright Elsevier

CR chondrites are suitable for understanding the genetic linkage between metals and chondrules due to the unique characteristics of the coexisting metal phases with chondrules. Metal grains are found in three different locations of CR chondrites; chondrule interior (“interior grain”), chondrule surficial shells (“margin grain”), and the matrix (“isolated grain”). Here we report the abundances of highly siderophile elements (HSEs) and major elements in three types of metals (interior, margin, and isolated grains) from three CR chondrites (NWA 801, NWA 7184, and Dhofar 1432) by using femtosecond LA-ICP-MS (fs LA-ICP-MS) and EPMA. Additionally, we report the isotopic compositions of Os and Fe in the metals by using micro-milling sampling coupled with N-TIMS and MC-ICP-MS. The CR metals have variations in 187Os/188Os and δ57Fe values ranging from 0.1193 to 0.1314 and from –1.05 to +0.25, respectively. HSE abundances, except for Pd and Au, in the three types of metals increase as the abundance of Ir increases. A possible explanation for the variations of HSE abundances within and among grains, 187Os/188Os values within each grain, and δ57Fe values among grains, is the condensation of liquid metal from a gaseous reservoir followed by fractional crystallization. Most of the CR metals have negative δ57Fe values, suggesting that Fe in metal phases might have formed by condensation prior to Fe condensation in silicate phases. The chondrules and three types of metal grains in CR chondrites are believed to have formed contemporaneously in the same region. The existence of large isolated metals in matrix and compound chondrules might be the result of collision and merging of the metal and silicate droplets.

¹M. F. Rabbi,²L. A. J. Garvie,³D. Cotto-Figueroa,⁴E. Asphaug,¹K. H. Khafagy,¹S. Datta,¹A. Chattopadhyay
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13761]
¹School for Engineering of Matter Transport and Energy, Arizona State University, PO Box 879106, Tempe, Arizona, 85287 USA
²School of Earth and Space Exploration, Arizona State University, PO Box 876004, Tempe, Arizona, 85287 USA
³Department of Physics and Electronics, The University of Puerto Rico at Humacao, Call Box 860, Humacao, Puerto Rico, 00792 USA
⁴Lunar and Planetary Laboratory, University of Arizona, PO Box 210092, Tucson, Arizona, 85721 USA
Published by arrangement with John Wiley & Sons

A comprehensive understanding of the mechanical strength and failure mechanisms of asteroids is essential for the development of hazard mitigation strategies and in situ resource extraction. In this study, the Aba Panu (L3) ordinary chondrite meteorite is investigated to understand its failure response under compressive loading. Compression experiments were conducted on ten 1 cm cubes under quasi-static conditions in constant displacement control mode at room temperature. Three-dimensional (3-D) digital image correlation (DIC) was used to measure the full-field deformation and strain. These data were used to determine the elastic modulus and local strain distribution, and investigate the effects of the mineralogical and structural heterogeneity on the crack formation and growth sites. Aba Panu exhibits brittle failure during compression with a range of failure strength from 361.7 to 578.0 MPa. Axial splitting and multiple fracturing occur during the uniaxial compressive state of stress. Ultrasonic tests were used to calculate elastic moduli from sound speeds and compared with the results of L-type ordinary chondrites from the literature. Characterization results from electron microprobe analysis identified different elements and areal distribution of mineral phases and pre-existing cracks. In general, the DIC results did not show correlations between crack initiation and specific mineralogical or textural components in this meteorite, such as chondrules or metals/sulfide grains, suggesting that the pre-existing microcracks and porosity control the Aba Panu failure mechanisms.

¹Sakiko Kikuchi,¹Takazo Shibuya,¹Mariko Abe,²Katsuyuki Uematsu
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.11.006]
¹Super-cutting-edge Grand and Advanced Research (SUGAR) program, Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa, 2370061, Japan
²Department of Marine & Earth Sciences, Marine Works Japan, Ltd., 3-54-1 Oppamahigashi, Yokosuka, Kanagawa 2370061, Japan
Copyright Elsevier

The presence of hydrous minerals in carbonaceous chondrites has been considered as an important evidence for the former presence of liquid water in parent asteroids. However, the evolution of water–rock reactions in hydrous asteroids remains not well constrained. Here, we conduct water–rock type experiments and chemical equilibria calculations under low-temperature hydrothermal and reducing conditions to investigate the alteration process and secondary mineral assemblages of chondritic rock in the earliest alteration stage. Using synthetic chondrite (mixtures of olivine (forsterite95), orthopyroxene (enstatite95), silicate glass, troilite and Femetal) as a starting material, our experiments were conducted at temperatures of 25°C–80°C for time periods between 1 to 460 days at a water-to-rock mass ratio of 10. A combination of X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses revealed that the primary secondary phases consisted of pyrrhotite, an amorphous SiO2-rich phase and saponite at 80°C, while the secondary phase consisted of an amorphous SiO2-rich phase and saponite at 25°C. At both temperatures, the SiO2-rich phases and saponite densely covered the surface of the primary phases. The Fe/Mg ratios of saponite and amorphous SiO2-rich phases showed clear difference between 80°C and 25°C. Saponite that was formed at 80°C was richer in Fe than the initial silicate phases, and the highest Fe/Mg ratios were obtained in the saponite encrusting the troilite and Femetal. These results suggest that the Fe distributed from the troilite and Femetal induced the formation of Fe-rich saponite. Some of the secondary minerals observed from our alteration experiments were consistent with those expected by chemical equilibria calculations. However, the formation of serpentine, the dominant secondary mineral expected from chemical equilibria calculations, was not observed in our experiments up to 460 days, probably because the preferential dissolution of SiO2-rich silicate glass in the earliest stage of alteration induced the formation of saponite rather than serpentine. The secondary mineral assemblage and its morphological characteristics, as observed by our alteration experiments, showed similarities with carbonaceous chondrites such as CM2 and CO3 chondrites. This alteration might be explained by water–rock reactions at low temperatures and by the short time alteration. These findings better constrain the temperatures and timescales of aqueous alterations in hydrous asteroids, as well as the role of water in the early solar system bodies.

¹Denggao Qiu,¹Fei Li,¹Jianguo Yan,¹Wutong Gao,¹Zheng Chong
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114778]
¹State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430070, China
Copyright Elsevier

The FeO and TiO2 contents are critical for distinguishing petrological properties of the Moon and for studying the distribution of the lunar maria and its multi-period volcanic activity. Traditional methods used the ratio between spectral reflectances to estimate FeO and TiO2 contents, which are empirical models. The development of machine learning algorithms offered new ideas for solving inversion problems, and these algorithms can automatically mine the data for potential correlations wherever possible. In this work, by using the Kaguya Multiband Imager data, we construct an optimized spectral inversion model using the Convolutional Neural Network (CNN) algorithm to produce a map of the FeO and TiO2 content on the lunar surface. The CNN models were compared with the traditional linear model and the Random Forest (RF) model. The results were indicated that the CNN models had higher accuracy and the CNN model eliminated the shortcoming of the RF model that the inversion results were limited by the training data, and certainly optimizes the impact of data striping. The CNN models can better describe the nonlinear relationship between spectral reflectance and oxide content. This also provides the basis for the inversion of the other oxides (e.g., MgO, Al2O3, CaO and SiO2). These new maps from the CNN model provide reference information for further studies of the geological evolution of the Moon.

¹Timo Hopp,¹Nicolas Dauphas,²Fridolin Spitzer,²Christoph Burkhardt,²Thorsten Kleine
Earth and Planetary Science Letters 577, 117245 Link to Article [https://doi.org/10.1016/j.epsl.2021.117245]
¹Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5743 South Ellis Avenue, Chicago, IL 60637, USA
²Institut für Planetologie, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
Copyright Elsevier

Nucleosynthetic Fe isotopic anomalies in meteorites may be used to learn about the early evolution of the solar system and to identify the origin and nature of the material that built the terrestrial planets. Using high-precision iron isotopic data of 23 iron meteorites from nine major chemical groups we show that all iron meteorites define the same dichotomy between non-carbonaceous (NC) and a carbonaceous (CC) meteorites previously observed for other elements. The Fe isotopic anomalies are predominantly produced by variations in 54Fe, where all CC iron meteorites are characterized by an excess in 54Fe relative to NC iron meteorites. This excess in 54Fe is accompanied by an excess in 58Ni observed in the same CC meteorite groups. Together, these overabundances of 54Fe and 58Ni are explained by nuclear statistical equilibrium either in type Ia supernovae or in the Si/S shell of core-collapse supernovae.

The Fe isotopic composition of Earth’s mantle plots on or close to correlations defined by Fe, Mo, and Ru isotopic anomalies in iron meteorites, indicating that throughout Earth’s accretion, the isotopic composition of its building blocks did not drastically change. While Earth’s mantle has a similar Fe isotopic composition to CI chondrites, the latter are clearly distinct from Earth’s mantle for other elements (e.g., Cr and Ni) whose delivery to Earth coincided with Fe. The fact that CI chondrites exhibit large Cr and Ni isotopic anomalies relative to Earth’s mantle, therefore, demonstrates that CI chondrites are unlikely to have contributed significant Fe to Earth and are not its main building blocks.

¹Sara S. Russell,¹M. D. Suttle,¹A. J. King
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13753]
¹Planetary Materials Group, Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD UK
Published by arrangement with John Wiley & Sons

We review the mineralogy, petrology, and abundance of petrological type 1 extraterrestrial material. Such material has been completely altered by aqueous processing on its parent bodies. As well as the four meteorite groups that contain type 1 members (CI, CM, CR, and CY), we summarize data from the 2019 fall Flensburg and a recent reanalysis of the “meteorite” Bench Crater found on the Moon, along with fine-grained micrometeorites, interplanetary dust particles, and xenoliths in meteorites. Type 1 materials exhibit a remarkably high diversity of alteration conditions (temperature, water-to-rock [W/R] ratios, and fluid composition) and starting mineralogy. Type 1 material comprises a significant component of the modern extraterrestrial flux to the Earth and was likely common throughout the solar system during the whole course of its history, pointing to both widespread accretion with ices and heating of parent bodies. Type 1 materials are composed predominantly of various phyllosilicates, carbonates, sulfides, and magnetite. Some type 1 materials appear to be part of a “CM clan” typified by serpentine-rich phyllosilicate compositions and an oxygen isotope composition that falls in the 16O-rich part of the CM field. Others span a wide range in δ18O (>30‰) and fall on or above the terrestrial fractionation line (+ve Δ17O). Positive Δ17O values are unusual for carbonaceous meteorites but are relatively common in type 1 materials. The wide variation in oxygen isotopes, as well as in textures, mineralogy, and bulk chemistry, points to multiple parent bodies that may originate in the inner and/or outer solar system. Cometary materials, or transition objects such as Main Belt comets or type D asteroids, are likely the source of much of the type 1 materials on Earth but relating them to specific parents requires more study.

^1,2Yogita Kadlag,²Jason Hirtz,¹Harry Becker,²Ingo Leya,³Klaus Mezger
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13756]
¹Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstr. 74-100, Berlin, 12249 Germany
²Physikalisches Institut, Universität Bern, Sidlerstrasse 5, Bern, 3012 Switzerland
³Institut für Geologie, Universität Bern, Baltzerstrasse 1+3, Bern, 3012 Switzerland
Published by arrangement with John Wiley & Sons

Different solar system objects display variable abundances of neutron-rich isotopes such as 54Cr, 50Ti, and 48Ca, which are commonly attributed to a heterogeneous distribution of presolar grains in different domains of the solar system. Here, we show that the heterogeneity of 54Cr/52Cr and the correlation of 54Cr/52Cr with Fe/Cr in metal fractions of EH3 chondrites and in inner solar system bodies can be attributed to variable irradiation of dust grains by solar energetic particles and variable mixing of irradiated material in the different domains of the inner solar nebula. The isotope variations in inner solar system objects can be generated by ∼300 y long local irradiation of mm- to cm-sized solids with average solar energetic particle fluxes of ∼105 times the modern value. The relative homogeneity of 53Cr/52Cr in inner solar system objects can be a consequence of the production of 53Mn by the early irradiation of dust, evaporation, and nebula-wide homogenization of Mn due to high temperatures, followed by Mn/Cr fractionation within the first few million years of the solar system. The 54Cr/52Cr of the Earth can be produced by irradiated pebbles and <15 wt% of CI chondrite like material. Alternatively, Earth may contain only a few % of CI chondrite like material but then must have an Fe/Cr ratio 10–15% higher than CI chondrites.

¹Åke V. Rosén,^1,2Beda A. Hofmann,³Frank Preusser,⁴Edwin Gnos,¹Urs Eggenberger,⁵Marc Schumann,⁶Sönke Szidat
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13758]
¹Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, Bern, 3012 Switzerland
²Natural History Museum Bern, Bernastrasse 15, Bern, 3005 Switzerland
³Institute of Earth and Environmental Sciences, University of Freiburg, Alberstrasse 23b, Freiburg, 79104 Germany
⁴Natural History Museum of Geneva, 1, Route de Malagnou, Geneva, 1208 Switzerland
⁵Institute of Physics, University of Freiburg, Hermann-Herder-Strasse 3, Freiburg, 79104 Germany
⁶Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, 3012 Switzerland
Published by arrangement with John Wiley & Sons

We combine the search for young meteorites in the Omani-Swiss collection (˜1140 fall events collected 2001–2018) using 22Na and 44Ti with luminescence and 14C sediment ages from the Ramlat Fasad (RaF) dense collection area (DCA) of Oman to obtain combined terrestrial ages and maximum accumulation times, and test whether the proportion of young meteorites is consistent with the models of meteorite flux and weathering. Gamma-ray spectrometry data for 22Na show that two (0.17%) of the meteorites in the collection fell during the 20 yr preceding this study, consistent with the rates of meteorite accumulation. In the RaF DCA, meteorites are found on Quaternary to Neogene sediments, providing constraints for their maximum terrestrial ages. 44Ti activities of the RaF 032 L6 strewn field found on deflated parts of active dunes indicate an age of 0.2–0.3 ka while dune sand optically stimulated luminescence ages constrain an upper age of 1.6 ka. Extensive sediment dating using luminescence methods in the RaF DCA area showed that all other meteorite finds were made on significantly older sediments (>10 ka). Dense accumulations of meteorites in RaF are found on blowouts of the Pliocene Marsawdad formation. Our combined results show that the proportion of meteorites with low terrestrial ages is low compared to other find areas, consistent with the previously determined high average terrestrial age Oman meteorites and significantly older than suggested by models of exponential decay. Oman meteorites may commonly have been buried within dunes and soils over extended periods, acting as a temporary protection against erosion.

¹Thomas Smith,^1,2,3Huaiyu He,⁴Shijie Li,¹P. M. Ranjith,^1,2Fei Su,⁵Jérôme Gattacceca,⁵Régis Braucher,⁵ASTER-Team
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13760]
¹State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 China
²Institutions of Earth Science, Chinese Academy of Sciences, Beijing, 100029 China
³College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049 China
⁴Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081 China
⁵Centre Européen de Recherche et d’Enseignement de Géosciences de l’Environnement (CEREGE), CNRS, Aix-Marseille University, IRD, INRAE, Aix-en-Provence, France
Published by arrangement with John Wiley

We measured noble gas concentrations and isotopic ratios (He, Ne, and Ar isotopes) in six recent ordinary chondrite falls: Mangui (L6), Viñales (L6), Ozerki (L6), Tamdakht (H5), Kheneg Ljouâd (LL5/6), and Katol (L6). Among them, the three L6 chondrites Mangui, Viñales, and Ozerki fell in only a few months interval; their apparent similar petrographic and mineralogic characteristics might indicate source crater pairing. To test this hypothesis, we have investigated those meteorites for their cosmic ray exposure (CRE) histories, using the cosmogenic noble gases 3He, 21Ne, and 38Ar. We systematically (re)calculated the CRE ages as well as the gas retention ages of these meteorites. The CRE age of the Mangui is, based on noble gases, <1 Ma, which is unusually short for an L chondrite. Indeed, the range of exposure ages for L chondrites is generally distributed between ˜1 and ˜60 Ma, with major peaks occurring around ˜5, ˜30, and ˜40 Ma. In addition, the cosmogenic 3Hecos data of two Mangui duplicates are consistent with a remarkably high loss of helium by diffusion due to heating by solar radiation. Such a short parent body-Earth transfer time (<1 Ma) can be explained by a delivery from an Earth-crossing object. Regarding the other L6 chondrites, Viñales has a nominal CRE age of ˜9.4 Ma, whereas the Ozerki meteorite has a nominal CRE age of ˜1.2 Ma, which is consistent with Korochantseva et al. (2019). Based on their CRE ages as well as on their gas retention ages, it appears that none of these three recent L6 chondrite falls are source crater paired, and therefore, all three originate from different meteoroids. The nominal exposure ages of Tamdakht, Kheneg Ljouâd, and Katol are ˜3.2, ˜11, and ˜30 Ma, respectively, and are consistent with identified age peaks on the exposure age histogram of H, LL, and L chondrites, respectively. The nominal CRE age of Tamdakht is consistent with previous observations for H chondrites and implies that they are dominated by small impact events occurring in several parent bodies.