^1,2Yan Fan,¹Shijie Li,¹Shen Liu,³Hao Peng,⁴Guangming Song,⁵Thomas Smith
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13789]
¹State Key Laboratory of Continental Dynamics and Department of Geology, Northwest University, Xi’an, 710069 China
²Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081 China
³Xi’an Astronautics Composite Materials Institute, Xian, 710025 China
⁴Beijing Institute of Spacecraft Environment Engineering, Beijing, 100094 China
⁵State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 China
Published by arrangement with John Wiley & Sons

In recent years, numerous meteorites have been collected in desert areas in northern and western China. We describe the environment of some deserts in this region, and the petrological and mineralogical characteristics of 49 of the recovered ordinary chondrites. They consist of 14 H chondrites, 33 L chondrites, and 2 LL chondrites. Of the 300 desert meteorites with approved names from deserts in China, there have been 287 ordinary chondrites, six iron meteorites, one CO3 chondrite, one diogenite, one ureilite, one brachinite, one eucrite, and one EL7 chondrite. Forty-two dense meteorite collection areas (DCAs) have been defined, mainly located in northern and western China. The meteorites collected are mainly from the Kumtag DCA, followed by the Alatage Mountain, Loulan Yizhi, Hami, and Lop Nur DCAs. After tentative pairing of the meteorites, we estimate that the ordinary chondrites account for 72% of the desert meteorites collected in China, with 63 H chondrites, 133 L chondrites, and 20 LL chondrites. This dominance of L chondrites contrasts with other deserts, which may result from the insufficient collection or bias in pairing of ordinary chondrites. The mass distribution of meteorites from different DCAs in China is consistent with that from DCAs in Africa. Based on the available information and the meteorite flux model proposed by previous studies, we suggest that the time over which meteorites have been accumulated in the southern Hami DCA might be >10 kyr. Therefore, the southern Hami region is currently the most suitable area for meteorite collection in China.

¹A.C.Martin,¹J.P.Emery,^1,2M.J.Loeffler
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.114921]
¹Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ 86011, United States of America
²Center for Materials Interfaces in Research and Applications, Northern Arizona University, Flagstaff, AZ 86011, United States of America
Copyright Elsevier

Studies have long utilized laboratory derived spectra to understand the surface composition and other properties of planetary bodies. One variable that is believed to affect remotely acquired spectra in the mid-infrared (MIR; 5–35 μm) is the surface porosity of the airless body, yet there have been few laboratory studies to quantify this effect. Thus, here we report systematic laboratory experiments aimed at quantifying the effect that porosity has on the MIR spectra of silicate regoliths. To simulate the effects of regolith porosity, we mixed olivine powder with KBr powder of the same size range (< 20 μm, 20–45 μm, and 45–63 μm). Olivine was mixed with KBr from 0% – 90% with 10% intervals by weight. Finally, we measured spectra with a Fourier transform infrared (FTIR) spectrometer in the MIR. Our results indicate a transition from a primarily surface scattering regime to a primarily volume scattering regime with increasing regolith porosity. Evidence of the dominating regime transition includes: the primary Christiansen Feature at ~8.8 μm decreases in spectral contrast, and shifts slightly to longer wavelengths as regolith porosity increases, reststrahlen bands in the 10-μm do not shift significantly in wavelength but do decrease in spectral contrast, vibrational bands in the volume scattering regime (i.e., peaks in emissivity) increase in spectral contrast with increasing regolith porosity, and the spectral contrast of 10-μm plateau increases exponentially with increasing regolith porosity. The MIR spectral analysis of asteroids, such as Hektor, suggests a highly porous surface regolith (at least 81% void space) of fine-particulate silicates. These results demonstrate that some asteroids support highly porous regoliths whose spectra are not well-matched by standard (low porosity) laboratory spectra of powders. The spectra presented here enable analysis of both the porosity and mineralogy of olivine-rich, low porosity asteroid surfaces.

^1,2,3E.T.Dunham et al. (>10)
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2022.02.002]
¹Arizona State University (ASU), Center for Meteorite Studies, Tempe, AZ, 85287-1404
²Arizona State University, School of Earth and Space Exploration, Tempe, AZ 85287-1404
³The University of California, Los Angeles (UCLA), Department of Earth, Planetary and Space Sciences, Los Angeles CA 90095-1567
Copyright Elsevier

Short-lived radionuclides (SLRs) once present in the solar nebula can be used as probes of the formation environment of our Solar System within the Milky Way Galaxy. The first-formed solids in the Solar System, calcium-, aluminum-rich inclusions (CAIs) in meteorites, record the one-time existence of SLRs such as 10Be and 26Al in the solar nebula. We measured the 10Be–10B isotope systematics in 29 CAIs from several CV3, CO3, CR2, and CH/CB chondrites and show that all except for a FUN CAI record a homogeneous initial 10Be/9Be with a single probability density peak at 10Be/9Be = 7.4 × 10–4. Integrating these data with those of previous studies, we find that most CAIs (81%) for which 10Be–10B isotope systematics have been determined, record a homogeneous initial 10Be/9Be ratio in the early Solar System with a weighted mean 10Be/9Be = (7.1 ± 0.2) × 10–4. This uniform distribution provides evidence that 10Be was predominantly formed in the parent molecular cloud and inherited by the solar nebula. Possible explanations for why unusual CAIs (FUNs, PLACs, those from CH/CBs, and those irradiated on the parent body) recorded a 10Be/9Be ratio outside of 7.1 × 10−4 include the following: 1) They incorporated a component of 10Be that was produced in the nebula by irradiation; 2) they formed after normal CAIs; and 3) they were processed (post-formation) in a way that affected their original 10Be signatures. Given the rarity of these examples, the overall uniformity of initial 10Be/9Be suggests that Solar System 10Be was predominantly inherited from the molecular cloud.

¹J. Aléon,^1,3D. Lévy,²A. Aléon-Toppani,¹H. Bureau,⁴H. Khodja,⁵F. Brisset
Nature Astronomy (in Press) Link to Article [DOI https://doi.org/10.1038/s41550-021-01595-7]
¹Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, CNRS UMR 7590, Museum National d’Histoire Naturelle, Paris, France
²Institut d’Astrophysique Spatiale, Université Paris-Saclay, CNRS UMR 8617, Orsay, France
³Laboratoire des Fluides Complexes et leurs Réservoirs (LFCR), E2S UPPA – Université de Pau et des Pays de l’Adour, CNRS, Total, Pau, France
⁴Université Paris-Saclay, CEA, CNRS, NIMBE, LEEL, Gif sur Yvette, France
⁵Institut de Chimie Moléculaire et des Matériaux d’Orsay, Université Paris-Saclay, CNRS UMR 8182, Orsay, France

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Koichi Mimura,¹Riku Okada
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2022.01.030]
¹Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan
Copyright Elsevier

Shock experiments on an aqueous l-alanine solution were undertaken to examine the significance of cometary impacts in supplying prebiotic compounds to the early Earth. The shock pressures and temperatures ranged from 6.5 to 34.0 GPa and 516 to 963 K, respectively. Alanine in the shocked samples decreases in abundance and has higher d/l ratios as the shock temperature increases. The shocked sample at 963 K contained 33% of the starting alanine, which had a d/l value of 0.51. The shocked samples above 643 K all contained isomers of the alanine dimer Ala–Ala, including l-Ala–l-Ala, l-Ala–d-Ala, d-Ala–l-Ala, and d-Ala–d-Ala. A comparison of our study with previous studies indicates that water inhibits the decomposition of alanine and promotes racemization during shock compression. We calculated the shock temperatures at various impact velocities to determine the impact velocity at which alanine can survive when comets and meteorites impact the land or ocean at different impact angles. This impact velocity was much lower for comets than meteorites. The reduction in alanine decomposition caused by water is compensated for by the high shock temperature produced by the high porosity of comets. However, considering that comets are effectively decelerated by airburst and contain large amounts of organic materials, comets would be more important than meteorites in terms of delivering prebiotic compounds, including amino acid dimers with ll enantiomeric excesses, to the early Earth. Comets are likely to have played a key role in the biogeochemical evolution of the early Earth.

^1,2Hamm, M. et al. (>10)
Nature Communications 13, 364 Link to Article [DOI 10.1038/s41467-022-28051-y]
¹Institute of Mathematics, University of Potsdam, Potsdam, Germany
²Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹J.T.Germann,¹S.K.Fieber-Beyer,¹M.J.Gaffey
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.114916]
¹Department of Space Studies, University Ave. Stop 9008, University of North Dakota, 58202, USA
Copyright Elsevier

We present the initial results of our visible and near-infrared (VNIR) investigation into the spectral properties of the Tholen G-class asteroids to determine: 1) which spectral properties are common among the G-class, and 2) which surface minerals may be related to the spectral features present. Our study utilized both previously published and newly obtained spectra of five G-class asteroids. Our results indicate that four of these asteroids: (13) Egeria, (19) Fortuna, (84) Klio, and (130) Elektra, exhibit spectral features consistent with hydrated minerals in the VNIR (0.4–2.5-μm). The most notable absorption feature was located at 0.7-μm, which is related to the Fe2+ ➔ Fe3+ charge transfer transition in oxidized Fe-rich phyllosilicates. In addition, several of the asteroids also exhibit subtle absorption features located near 0.95-, 1.4-, 1.9-, and 2.3-μm, which may also be related to hydrated minerals. Only (1) Ceres’ spectrum lacked features related to hydrated minerals in the VNIR. This may indicate that either (1) Ceres contains lower concentrations of hydrated minerals at its surface, or that (1) Ceres has an opaque surface component, which may obscure weak hydrated VNIR features.

^1,2,3,4Yuhei Umeda et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.114901]
¹Graduate School of Engineering, Osaka, Japan
²Institute of Laser Engineering, Osaka University, Osaka, Japan
³Institute for Planetary Materials, Okayama University, Tottori, Japan
⁴Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan
Copyright Elsevier

Carbonate minerals, for example calcite and magnesite, exist on the planetary surfaces of the Earth, Mars, and Venus, and are subjected to hypervelocity collisions. The physical properties of planetary materials at extreme conditions are essential for understanding their dynamic behaviors at hypervelocity collisions and the mantle structure of rocky planets including Super-Earths. Here we report laboratory investigations of laser-shocked calcite at pressures of 200–960 GPa (impact velocities of 12–30 km/s and faster than escape velocity from the Earth) using decay shock techniques. Our measured temperatures above 200 GPa indicated a large difference from the previous theoretical models. The present shock Hugoniot data and temperature measurements, compared with the previous reports, indicate melting without decomposition at pressures of ~110 GPa to ~350 GPa and a bonded liquid up to 960 GPa from the calculated specific heat. Our temperature calculations of calcite at 1 atm adiabatically released from the Hugoniot points suggest that the released products vary depending on the shock pressures and affect the planetary atmosphere by the degassed species. The present results on calcite newly provide an important anchor for considering the theoretical EOS at the extreme conditions, where the model calculations show a significant diversity at present.

¹Karen Valencia,^1,2Aldemar De Moya,^3,4Guillaume Morard,⁵Neil L. Allan,^1,5Carlos Pinilla
American Mineralogist 107, 248–256 Link to Article [http://www.minsocam.org/msa/ammin/toc/2022/Abstracts/AM107P0248.pdf]
¹Departamento de Física y Geociencias, Universidad del Norte, Km 5 Via Puerto Colombia, Barranquilla, Colombia
²Departamento de Ciencias Naturales y Exactas, Universidad de la Costa, Calle 58 No. 55-66, Barranquilla, Colombia
³Sorbonne Université, Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), UMR CNRS 7590, IRD,Muséum National d’Histoire Naturelle, Paris, France
⁴Université Grenoble Alpes, CNRS, ISTerre, F-38000 Grenoble
⁵School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
Copyright: The Mineralogical Society of America

Using density functional theory electronic structure calculations, the equation of state, thermody-
namic and elastic properties, and sound wave velocities of Fe3S at pressures up to 250GPa have been
determined. Fe3S is found to be ferromagnetic at ambient conditions but becomes non-magnetic at
pressures above 50 GPa. This magnetic transition changes thec/a ratio leading to more isotropic com-
pressibility, and discontinuities in elastic constants and isotropic sound velocities. Thermal expansion,
heat capacity, and Grüneisen parameters are calculated at high pressures and elevated temperatures
using the quasiharmonic approximation. We estimate Fe-Fe and Fe-S force constants, which vary with
Fe environment, as well as the 56Fe/54Fe equilibrium reduced partition function in Fe3S and compare
these results with recently reported experimental values. Finally, our calculations under the conditions
of the Earth’s inner core allow us to estimate a S content of 2.7wt% S, assuming the only components
of the inner core are Fe and Fe 3S, a linear variation of elastic properties between end-members Fe
and Fe3S, and that Fe3S is kinetically stable. Possible consequences for the core-mantle boundary of
Mars are also discussed.

¹Katarina Kaiser et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13784]
¹IBM Research—Zurich, Rüschlikon, 8003 Switzerland
Published by arrangement with John Wiley & Sons

Using high-resolution atomic force microscopy (AFM) with CO-functionalized tips, we atomically resolved individual molecules from Murchison meteorite samples. We analyzed powdered Murchison meteorite material directly, as well as processed extracts that we prepared to facilitate characterization by AFM. From the untreated Murchison sample, we resolved very few molecules, as the sample contained mostly small molecules that could not be identified by AFM. By contrast, using a procedure based on several trituration and extraction steps with organic solvents, we isolated a fraction enriched in larger organic compounds. The treatment increased the fraction of molecules that could be resolved by AFM, allowing us to identify organic constituents and molecular moieties, such as polycyclic aromatic hydrocarbons and aliphatic chains. The AFM measurements are complemented by high-resolution mass spectrometry analysis of Murchison fractions. We provide a proof of principle that AFM can be used to image and identify individual organic molecules from meteorites and propose a method for extracting and preparing meteorite samples for their investigation by AFM. We discuss the challenges and prospects of this approach to study extraterrestrial samples based on single-molecule identification.