¹Maxim Isachenkov,¹Svyatoslav Chugunov,²Zoe Landsman,¹Iskander Akhatov,²Anna Metke,¹Andrey Tikhonov,¹Igor Shishkovsky
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114873]
¹Skolkovo Institute of Science and Technology, Center for Design, Manufacturing, and Materials, 30 Bolshoy boulevard, bld, 1121205 Moscow, Russian Federation
²CLASS Exolith Lab, Florida Space Institute, 12354 Research Parkway, Orlando, FL 32826, United States of America
Copyright Elsevier

Lunar regolith is the most critical material for the in-situ resource utilization in the crewed Moon exploration missions. This natural material can be utilized for the additive manufacturing of concrete or ceramic parts on the Moon’s surface to support permanent human presence on the surface of Earth’s natural satellite. Due to the scarcity of regolith on Earth, its simulants are used in lab research to prepare the technology for Moon missions. The present study is devoted to the characterization of lunar regolith simulant material, recently developed by the University of Central Florida, that is considered as a suitable material for regolith-focused additive manufacturing technologies. This paper describes the characterization of the LHS-1 and LMS-1 simulants using XRF, XRD, SEM, EDX, DTA, TGA, UV/Vis/NIR spectroscopy, and Laser diffractometry methods to provide data on their mineral, chemical, and fractional composition, as well as, on their morphology and optical properties. The results were compared to the data of the previously developed simulants and the original lunar samples delivered by Apollo and Luna missions. It was found that LHS-1 and LMS-1 simulants well mimic the primary properties of the original lunar regolith and can be potentially used for ISRU research tasks.

¹Emanuele Plebani,²Bethany L.Ehlmann,^2,3Ellen K.Leask,⁴Valerie K.Fox,¹M. Murat Dundar
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114849]
¹Computer and Information Sciences Department, Indiana University – Purdue University, Indianapolis, 46202, IN, USA
²Div. of Geological & Planetary Sciences, California Institute of Technology, Pasadena, 91125, CA, USA
³John Hopkins University Applied Physics Laboratory, Laurel, 20723, MD, USA
⁴Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, 55455, MN, USA
Copyright Elsevier

Hyperspectral images collected by remote sensing have played a significant role in the discovery of aqueous alteration minerals, which in turn have important implications for our understanding of the changing habitability on Mars. Traditional spectral analyses based on summary parameters have been helpful in converting hyperspectral cubes into readily visualizable three channel maps highlighting high-level mineral composition of the Martian terrain. These maps have been used as a starting point in the search for specific mineral phases in images. Although the amount of labor needed to verify the presence of a mineral phase in an image is quite limited for phases that emerge with high abundance, manual processing becomes laborious when the task involves determining the spatial extent of detected phases or identifying small outcrops of secondary phases that appear in only a few pixels within an image. Thanks to extensive use of remote sensing data and rover expeditions, significant domain knowledge has accumulated over the years about mineral composition of several regions of interest on Mars, which allow us to collect reliable labeled data required to train machine learning algorithms. In this study we demonstrate the utility of machine learning in two essential tasks for hyperspectral data analysis: nonlinear noise removal and mineral classification. We develop a simple yet effective hierarchical Bayesian model for estimating distributions of spectral patterns and extensively validate this model for mineral classification on several test images. Our results demonstrate that machine learning can be highly effective in exposing tiny outcrops of specific phases in orbital data that are not uncovered by traditional spectral analysis. We package implemented scripts, documentation illustrating use cases, and pixel-scale training data collected from dozens of well-characterized images into a new toolkit. We hope that this new toolkit will provide advanced and effective processing tools and improve community’s ability to map compositional units in remote sensing data quickly, accurately, and at scale.

^1,2A.Khan,³P.A.Sossi,³C.Liebske,⁴A.Rivoldini,¹D.Giardini
Earth and Planetary Science Letters 578, 117330 Link to Article [https://doi.org/10.1016/j.epsl.2021.117330]
¹Institute of Geophysics, ETH Zürich, Zürich, Switzerland
²Physik Institut, University of Zürich, Zürich, Switzerland
³Institute of Geochemistry and Petrology, ETH Zürich, Zürich, Switzerland
⁴Royal Observatory of Belgium, Brussels, Belgium
Copyright Elsevier

Constraints on the composition of Mars principally derive from chemical analyses of a set of Martian meteorites that rely either on determinations of their refractory element abundances or isotopic compositions. Both approaches, however, lead to models of Mars that are unable to self-consistently explain major element chemistry and match its observed geophysical properties, unless ad hoc adjustments to key parameters, namely, bulk Fe/Si ratio, core composition, and/or core size are made. Here, we combine geophysical observations, including high-quality seismic data acquired with the InSight mission, with a cosmochemical model to constrain the composition of Mars. We find that the FeO content of Mars’ mantle is 13.7±0.4 wt%, corresponding to a Mg# of 0.81±0.01. Because of the lower FeO content of the mantle, compared with previous estimates, we obtain a higher mean core density of 6150±46 kg/m³ than predicted by recent seismic observations, yet our estimate for the core radius remains consistent around 1840±10 km, corresponding to a core mass fraction of 0.250±0.005. Relying on cosmochemical constraints, volatile element behaviour, and planetary building blocks that match geophysical and isotopic signatures of Martian meteorites, we find that the liquid core is made up of 88.4±3.9 wt% Fe-Ni-Co with light elements making up the rest. To match the mean core density constraint, we predict, based on experimentally-determined thermodynamic solution models, a light element abundance in the range of ≈9 wt% S, ⩾3 wt% C, ⩽2.5 wt% O, and ⩽0.5 wt% H, supporting the notion of a volatile-rich Mars. To accumulate sufficient amounts of these volatile elements, Mars must have formed before the nebular gas dispersed and/or, relative to Earth, accreted a higher proportion of planetesimals from the outer protoplanetary disk where volatiles condensed more readily.

¹Kohei Fukuda,^1,2Travis J.Tenner,³Makoto Kimura,⁴Naotaka Tomioka,¹Guillaume Siron,⁴Takayuki Ushikubo,^1,5Noël Chaumard,^1,6Andreas T.Hertwig,¹Noriko T.Kita
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.12.027]
¹WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, 1215 W. Dayton St., Madison, WI 53706, USA
²Chemistry Division, Nuclear and Radiochemistry, Los Alamos National Laboratory, MSJ514, Los Alamos, NM 87545, USA
³National Institute of Polar Research, Tokyo 190-8518, Japan
⁴Kochi Institute for Core Sample Research, JAMSTEC, Kochi 783-8502, Japan
⁵Fi Group, Direction scientifique, 14 terrasse Bellini, 92800, Puteaux, France
⁶Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 236, 69120 Heidelberg, Germany
Copyright Elsevier

Deciphering the spatial and temporal evolution of chondrules allows for a better understanding of how asteroidal seeds formed, migrated, and eventually accreted into parent asteroids. Here we report high precision Al-Mg ages and oxygen three-isotope ratios of fifteen FeO-poor chondrules from the least metamorphosed Mighei-like (CM) and Ornans-like (CO) carbonaceous chondrites, Asuka 12236 (CM2.9), Dominion Range 08006 (CO3.01), and Yamato-81020 (CO3.05). This is the first report of Al-Mg ages of chondrules from the CM chondrite group. All but one of the fifteen chondrules exhibit a restricted range of inferred initial ²⁶Al/²⁷Al ratios, and all ratios are ≤ 6.0 × 10⁻⁶, which is systematically lower than those of the majority of ordinary chondrite (OC) chondrules. These observations indicate that the majority of chondrules in the outer Solar System were produced ≥ 2.2 Ma after the formation of Ca-Al-rich inclusions (CAIs), which postdates OC chondrule formation in the inner Solar System (≤ 2.2 Ma after CAI formation). We propose that the discrete chondrule-forming events in different disk regions reflect a time difference in growth and orbital evolution of planetesimals within the first 4 Ma of the Solar System.

One chondrule from Asuka 12236 has an age of 1.9 Ma after CAI formation and is therefore significantly older than the other fourteen chondrules, meaning this chondrule formed contemporaneously with the majority of OC chondrules. This old chondrule also exhibits ¹⁶O-depleted oxygen isotope characteristics compared to the other chondrules, suggesting a distinct formation region, probably inside the disk region relative to where the majority of CM and CO chondrules formed. Our results indicate that this old chondrule has migrated from the inner to the outer part of the protoplanetary disk within ∼1 Ma and then accreted into the CM parent asteroid >3 Ma after CAI formation, although its formation exterior to the accretion region of the CM parent asteroid and subsequent inward migration cannot be ruled out completely.

^1,2Guy Libourel,²Kazuhide Nagashima,³Marc Portail,²Alexander N.Krot
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.12.026]
¹Université Côte d’Azur, OCA, CNRS, Laboratoire Lagrange, Boulevard de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
²Hawai‘i Institute of Geophysics and Planetology, School of Ocean, Earth Science and Technology, University of Hawai‘i at Mānoa, Honolulu, Hawai‘i 96821, USA
³CNRS-CRHEA (Centre de Recherches sur l’Hétéro-Epitaxie et ses Applications), Université Côte d’Azur, Sophia Antipolis, Rue Bernard Grégory, 06560 Valbonne, France
Copyright Elsevier

Using high-resolution cathodoluminescence (HR-CL) panchromatic imaging for the location of high-precision oxygen three-isotope analyses by secondary ion mass-spectrometry (SIMS), this study is aimed at characterizing the oxygen-isotope variations in Mg-rich olivines (≥ Fo99) of selected type I chondrules from the Yamato (Y) -81020 CO3.05 (Ornans-type) carbonaceous chondrite. Cathodoluminescence being extremely sensitive to faint changes in CL activator/quencher concentrations (Al, Cr, Mn, Fe) allows us to describe various overlooked cycles of growth and dissolution in Mg-rich olivines, which strongly suggest an intimate relationship with their gaseous environment during their formation. The present study confirms significant Δ17O variations of ten ‰ in Mg-rich olivines but does not support the relationship previously found between Mg# [MgO/(MgO+FeO)×100, mol%] and Δ17O among type I chondrules, nor the interpretation of redox changes that has been made of it. We instead show that Mg-rich olivines in Y-81020 chondrules exhibit a prominent 16O-enriched and 16O-depleted bimodal distribution, which is considered as the most primordial signature of type I chondrules from Y-81020 and very likely other carbonaceous chondrites. This signature is interpreted as a snapshot of the early stages of a mixing occurring between two clouds/environments in which chondrules formed and evolved by gas-melt interaction and mixed according to hydrodynamical instabilities imposed by the process responsible for the mixing. As far as this study allows, O-isotope variations of Mg-rich olivines seems to account for large scale dynamical instabilities while chemical variations highlighted by HR-CL (dissolution/growth) bear witness of smaller scale instabilities very likely occurring in the immediate vicinity of the chondrules. Without being able to decide on plausible astrophysical settings yet, we note however that processes like disruptive and vaporizing collisions between planetesimals offer a range of processes and physicochemical conditions, e.g., expansion, decompression, dynamical instabilities, that deserve to be explored in more detail, some of which resembling those highlighted in this study, e.g., gas-melt interaction, partial pressure fluctuations, heterogeneous materials, gas mixing.

¹Scott A.Whattam,^2,3Roger H.Hewins,⁴Jieun Seo,⁵Bertrand Devouard
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.12.022]
¹Department of Geosciences, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
²IMPMC, Sorbonne Univ., MNHN, UPMC Paris 06, UMR CNRS 7590, 75005 Paris, France
³Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, United States
⁴Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Korea
⁵Aix-Marseille Université, CNRS, IRD, CEREGE UM34, BP 80 Aix en Provence, 13545 France
Copyright Elsevier

The formation of chondrules involved major processes in the protoplanetary disk and therefore needs to be understood. Identifying possible precursors and the conditions of their transformation into chondrules is an essential step. Here we investigate whether refractory inclusions (RI) can be converted into Type IA chondrule analogs by isothermal heating and dynamic crystallization experiments, and report a new constraint on chondrule peak temperatures. We prepared synthetic calcium-aluminum-rich inclusions (CAI) by sintering <20 µm An + Di + Sp powder at 1200 °C and synthetic AOA analogs from crushed <5 µm Fo gel or San Carlos olivine mixed with nuggets of synthetic CAI. We used the AOA analogs as starting materials in experiments and were able to reproduce the textures and mesostasis compositions of Type IA chondrules. However, in the charges, the olivine lacks asymmetric zonation and our mesostasis compositions show olivine fractionation trends, two differences from Type I chondrules indicating the requirement of condensation of Mg and SiO in the latter. Relict spinel is present in isothermal runs up to 1550 °C, but is totally resorbed by 1600 °C. We conclude that CAI and AOA were sintered essentially at their condensation temperatures and are appropriate precursors for chondrules. Chondrules with relict spinel must have formed at <1600 °C, much lower than their liquidus temperatures (∼1750 °C). Such peak temperatures are consistent with models of condensation during chondrule formation. In typical chondrules with no inclusions of AOA or CAI, spinel is an indicator of their near complete assimilation. Grains of spinel (sensu stricto) in chondrules are relicts of RI and constitute a largely untapped cosmochemical resource for the investigation of chondrule provenance.

^1,2Andrea Patzer,¹Emma S.Bullock,¹ConelM. O’D. Alexander
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.12.021]
¹Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Rd. NW, Washington D.C. 20015, USA
²Geosciences Center, University of Goettingen, Goldschmidtstr. 1, 37077 Goettingen, Germany
Copyright Elsevier

Knowing how the major chondritic components evolved and what their initial compositions were is pivotal for our understanding of the processes that shaped the early Solar System. Here, we have extended to the CR chondrites our testing of chondrule-matrix complementarity and the four-component model, i.e., two very different explanations for the bulk compositions of the carbonaceous chondrites and their components. Combining point-counting with electron microprobe analyses, we have analyzed four relatively primitive Antarctic CRs and the fall Renazzo. Our results for the abundances of chondrules and matrix are in good agreement with literature data, and confirm that these abundances vary considerably amongst the CRs (80.4 ±2.3 wt.% and 18.5 ±2.8 wt.%, respectively, in the four Antarctic CRs vs. 62.3 ±3.4 wt.% and 33.2 ±2.2 wt.% in Renazzo). The significant differences make the determination of the average properties and bulk compositions of the CRs problematic. This is particularly true for the volatile elements that were predominantly accreted in matrix. Nevertheless, all major and many minor element concentrations reported in the literature for average bulk CRs are reproduced here to better than 10 %. By comparing our results to conventionally determined bulk compositions, we were able to verify the accuracy of our approach and identify elements likely affected by alteration or analytical artifacts (e.g., Ti, K, Co). Two particular compositional details of the CR chondrites investigated are (a) the relatively high contents of Mn in the chondrules compared to CO chondrules, and (b) the depletion of S in the matrix, relative to CI. In terms of the major elements Mg, Al, Si and Ca, our data suggest that unaltered chondrules and matrix exhibited CI-like relative abundances, supporting previous conclusions for the CO chondrites. Where observed, deviations of element abundances in the matrix from CI (Na, Mg, S, Ca, Fe, Ni) can be explained in terms of alteration (parent body and terrestrial) and pre-accretionary loss of forsterite and, possibly, sulfides. Overall, our results are more consistent with the predictions of the four-component model than they are with chondrule-matrix complementarity.

¹Maxence Regnault,¹Yves Marrocchi,¹Maxime Piralla,¹Johan Villeneuve,²Valentina Batanova,¹Nicolas Schnuriger,³Emmanuel Jacquet
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13778]
¹CRPG, UMR 7358, Université de Lorraine, CNRS, Vandœuvre-lès-Nancy, 54501 France
²ISTerre, UMR 5275, CNRS, Université Grenoble Alpes, Grenoble, 38000 France
³IMPMC, UMR 7590, CNRS & Muséum national d’Histoire naturelle, CP52, 57 rue Cuvier, Paris, 75005 France
Published by arrangement with John Wiley & Sons

Rumurutiites (R chondrites) are rare, highly oxidized chondrites belonging to the noncarbonaceous superclan and characterized by low chondrule abundances. Although textural and chemical features of Rumurutiite chondrules resemble those of ordinary chondrites (OCs), their formation conditions and potential genetic link remain debated. Here, we report high-resolution elemental X-ray mapping analyses and in situ O isotopic measurements of olivine grains from five chondrules and eight isolated olivine grains (IOGs) in the NWA 12482 R3 chondrite. The chondrules show chemical zonings similar to their counterparts in ordinary and carbonaceous chondrites (CCs), implying that gas–melt interaction processes between chondrule precursors and SiO- and Mg-rich gas were operative throughout the circumsolar disk. Our isotopic data show that R chondrules are isotopically similar to ordinary chondrules, although differences in their abundances of relict olivine grains and chondrule textural characteristics suggest different formation environments, with R chondrules being formed from 16O-poorer precursors. As with chondrules in OCs, the O isotopic characteristics of R chondrules and IOGs suggest limited transport between CC and noncarbonaceous reservoirs.

¹Hideyuki Hayashi,²Takashi Mikouchi,³Nak Kyu Kim,³Changkun Park,^4,5Yuji Sano,^6,7Atsushi Takenouchi,⁶Akira Yamaguchi,⁸Hiroyuki Kagi,⁹Martin Bizzarro
Meteoritics & Planetary Science (in Press) Link to Article [https://onlinelibrary.wiley.com/doi/10.1111/maps.13776]
¹Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
²The University Museum, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
³Division of Earth Sciences, Korea Polar Research Institute (KOPRI), 26 Songdomirae-ro, Yeonsu-gu, Incheon, 21990 Korea
⁴Atmosphere and Ocean Research Institute (AORI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba, 277-8564 Japan
⁵Center for Advanced Marine Core Research, Kochi University, Monobe, Nankoku, Kochi, B200 783-8502 Japan
⁶Antarctic Meteorite Research Center, National Institute of Polar Research (NIPR), 10-3 Midori-cho, Tachikawa, Tokyo, 190-8518 Japan
⁷The Kyoto University Museum, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto, 606-8501 Japan
⁸Geochemical Research Center, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
⁹Centre for Stars and Planet Formation, Globe Institute, University of Copenhagen, ØsterVoldgade 5-7, Copenhagen, DK-1350 Denmark
Published by arrangement with John Wiley & Sons

Northwest Africa (NWA) 7203 is a quenched angrite, showing mineralogical features typically not present in other quenched angrites. NWA 7203 exhibits textures whose grain size varies from fine grains (<10 μm) to coarse grains (~3 mm), while other quenched angrites show only single-sized textures. Fine-grained and coarse-grained lithologies have nearly the same bulk compositions. Cooling rates were estimated to be ~80 °C h⁻¹ for fine-grained lithologies and ~1 °C h⁻¹ for coarse-grained lithologies. Mg-rich olivines (~Fo₆₄) were found only in fine-grained lithologies. Crystallization of NWA 7203 started in the fine-grained lithologies with Mg-rich olivine grains acting as seeds for crystallization. Coarse-grained lithologies were subsequently formed under conditions of slower cooling. NWA 7203 shows clear shock metamorphic textures unlike other quenched angrites except for NWA 1670. We confirm that the oxygen isotopic ratios of NWA 7203 plot on the angrite fractionation line within uncertainty. However, the obtained Pb-Pb age of NWA 7203 is 4543 ± 19 Ma, younger than the ages of other quenched angrites, which might be a result of disturbance by shock metamorphism. The finding of shock metamorphism of NWA 7203 suggests that some angrites might be derived from asteroids that remained large (>10 km in diameter) during the late heavy bombardment.

¹Liubov V. Guda,¹Antonina N. Kravtsova,²Stanislav P. Kubrin,¹Alexander A. Guda,³Mikhail I. Mazuritskiy,¹Andrei A. Tereshchenko,⁴Yuri V. Popov,¹Alexander V. Soldatov
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13769]
¹The Smart Materials Research Institute, Southern Federal University, A. Sladkova str. 178/24, Rostov-on-Don, 344090 Russia
²Research Institute of Physics, Southern Federal University, Stachki ave. 194, Rostov-on-Don, 344090 Russia
³Physics Faculty, Southern Federal University, Sorge str. 5, Rostov-on-Don, 344090 Russia
⁴Institute of Earth Sciences, Southern Federal University, Sorge str. 40, Rostov-on-Don, 344090 Russia
Published by arrangement with john Wiley & Sons

Micro X-ray fluorescence (XRF) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Mössbauer and X-ray absorption near-edge structure (XANES) spectroscopies have been used to study the element and phase composition, and Fe and Ni oxidation states in ordinary chondrites. The meteorites have been initially classified as Markovka (H4 type), Polujamki (H4 type), Sayh al Uhaymir (SaU) 001 (L5 type), Dhofar (Dho) 020 (H4/5 type), and Jiddat al Harasis (JaH) 055 (L4-5 type). We have applied a set of spectroscopic methods to characterize and quantify the differences between samples. While the concentration of Fe in the meteorites is in agreement with the qualitative assignment of their types (L or H) made upon discovery, we observed extremely low Mg/Si and Al/Si values compared to the data published by Palme et al. (2014). Phase content of the meteorites has been studied by means of XRD, as well as by SEM and EDX. Mössbauer spectroscopy of Fe-containing phases has determined that Fe ions are present mainly in olivine and pyroxene phases in all studied samples. Goethite, hematite, and troilite phases were found in Markovka, Polujamki, and Sayh al Uhaymir 001, respectively. Markovka and Polujamki samples contained the largest concentration of Fe-Ni-Co metal grains. Fe and Ni K-XANES spectra were analyzed to estimate metal oxidation state in the chondrites and compared with the Mössbauer data. The multispectral data acquired in the present work are of importance for further understanding of meteoritic processes.