Synchrotron Fe‐K X‐ray absorption spectroscopy and transmission electron microscopy have been used to investigate the mineralogy and Fe‐redox variations in the space‐weathered (SW) rims of asteroidal samples. This study focuses on the FIB lift‐out sections from five Itokawa grains, returned by the Hayabusa spacecraft, including samples RB‐QD04‐0063, RB‐QD04‐0080, RB‐CV‐0011, RB‐CV‐0089, and RB‐CV‐0148

We report a NanoSIMS search for presolar grains in the CM chondrites Asuka (A) 12169 and A12236. We found 90 presolar O‐rich grains and 25 SiC grains in A12169, giving matrix‐normalized abundances of 275 (+55/−50, 1σ) ppm or, excluding an unusually large grain, 236 (+37/−34) ppm for O‐rich grains and 62 (+15/−12) ppm for SiC grains. For A12236, 18 presolar silicates and 6 SiCs indicate abundances of

The CM carbonaceous chondrites provide unique insights into the composition of the protoplanetary disk, and the accretion and geological history of their parent C‐complex asteroid(s). Of the hundreds of CMs that are available for study, the majority are finds and so may have been compromised by terrestrial weathering. Nineteen falls have been recovered between 1838 and 2020, and there is a hint of

In order to understand the effects of the earliest stages of hydrothermal alteration and fluid‐assisted metamorphism on the matrices of unequilibrated ordinary chondrites (UOCs), we have investigated the fine‐grained matrix of MET 00526 (L3.05) using multiple electron microscope techniques. Iron‐rich olivines (Fa50‐100) are present in all four representative fine‐grained matrix regions analyzed in

The Hamburg meteorite fell on January 16, 2018, near Hamburg, Michigan, after a fireball event widely observed in the U.S. Midwest and in Ontario, Canada. Several fragments fell onto frozen surfaces of lakes and, thanks to weather radar data, were recovered days after the fall. The studied rock fragments show no or little signs of terrestrial weathering. Here, we present the initial results from an

Quartz and cristobalite ballen aggregates surrounded by dendritic cristobalite in gneiss clasts of impact melt rocks from the Ries impact structure are analyzed by Raman spectroscopy, microscopy, and electron backscattered diffraction to elucidate the development of the characteristic polycrystalline ballen that are defined by curved interfaces between each other. We suggest that the investigated ballen

Lunar mare basalts represent flood volcanism between ~4.0 and 1.2 Ga, therefore, providing insights into the thermal and volcanic history of the Moon. The present study investigates the spectral and chemical characteristics as well as ages of the nearside mare basaltic units from the Grimaldi basin, namely Mare Grimaldi and Mare Riccioli, using a wealth of orbital remote sensing data. This study delineated

The Didim meteorite contains multiple lithologies and clasts of different petrologic types in a single stone. A mixture of H5 clasts in an unequilibrated H3 host was previously observed in Didim, according to the initial characterization reported in the Meteoritical Bulletin Database, providing an opportunity to investigate molecular composition that contains varying degree of equilibrium with varying

The abundances, relative distributions, and enantiomeric and isotopic compositions of amines, amino acids, and hydroxy acids in Miller Range (MIL) 090001 and MIL 090657 meteorites were determined. Chiral distributions and isotopic compositions confirmed that most of the compounds detected were indigenous to the meteorites and not the result of terrestrial contamination. Combined with data in the literature

Cassini mapping of Saturn’s mid‐sized icy moons of well‐preserved complex craters in the 45–95 km size range provides insight into cratering processes at lower surface gravity and on icy targets. These craters are characterized by steep rim scarps, rugged hummocky floor deposits of curvilinear ridges and scarps, and rugged conical central peaks. Ponded impact melt or related deposits are not observed

We present a novel methodology for recovering meteorite falls observed and constrained by fireball networks, using drones and machine learning algorithms. This approach uses images of the local terrain for a given fall site to train an artificial neural network, designed to detect meteorite candidates. We have field tested our methodology to show a meteorite detection rate between 75% and 97%, while

Impact rates in the first 500 Myr of the solar system are critical to an understanding of lunar geological history, but they have been controversial. The widely accepted, post‐Apollo paradigm of early lunar impact cratering (about 1975–2014) proposed very low or negligible impact cratering in the period from accretion (>4.4 Ga) to ~4.0 Ga ago, followed by an ~170 million year long spike of cataclysmic

All asteroid spins evolve due to collisions. Geophysical analysis (Mao and McKinnon 2018b) implies Ceres might have been modestly despun (by ~6.5%) by impacts. Vesta’s postaccretion rotation rate, before the formation of the Veneneia and Rheasilvia basins, has also been proposed to have been higher (by ~6%) than today (Fu et al. 2014). We have designed Monte Carlo simulations to investigate Ceres’

High‐precision SIMS analyses of seven spinel‐rich fine‐grained CAIs from the CV3 chondrites Efremovka, Kaba, and Vigarano and the LL3.0 chondrite Semarkona, two known to have volatility‐fractionated Group II REE patterns (likely condensates) and three more probably Group II, all give initial 26Al/27Al (26Al/27Al0) close to the solar system initial value of 5.2 × 10–5. Our data thus provide no evidence

The similarities between CV and CK chondrites are so substantial that some studies have argued for a common parent body origin. These similarities also mean that they are susceptible to misclassification as one another. It is, therefore, important to accurately classify CV and CK chondrites to properly compare the properties of the two groups and evaluate the single parent body hypothesis. In this

We describe a fragmented cryptocrystalline chondrule consisting solely of forsterite (Fo98) in the Murchison CM2 chondrite, with a peculiar porous texture of enigmatic origin.

The group IIF iron meteorites and Eagle Station pallasites (PES) have highly siderophile element abundances (HSE; Re, Os, Ir, Ru, Pt, and Pd) of metal that are consistent with formation in planetesimal cores by fractional crystallization with minor to major solid metal–liquid metal mixing. Modeling of HSE abundances of the IIF irons indicates a complex formation history that included the mixing of

This study aimed to determine the volatile content (Cl, F, OH) and hydrogen isotope (D/H) ratios of apatite grains within the Martian meteorite NWA 11522, a paired stone of the ungrouped polymict breccia NWA 7034. Apatite F:Cl:OH ratios were measured via SEM‐EDS analyses, and found to be strikingly similar in all grains, and dominated by Cl. Apatite D/H ratios were measured in situ via the Cameca ims

X‐ray absorption fine structure (XAFS) spectroscopy methods have been applied to focused ion beam (FIB) produced sections of olivine and pyroxene for determining the valence states of Ti, V, and Cr and inferring oxygen fugacities of formation for each element. High‐quality XAFS spectra were obtained for all three elements for analytical voxels of ~10 pg and usable spectra down to the pg level are achievable

The central elevated area is a postimpact morphological landmark in the otherwise flat eroded remnant of the Dhala impact structure, India. Its base is the Bundelkhand granitic complex followed by beds of Dhala and Kaimur Formations. The beds of the Dhala and Kaimur Formation present typical sedimentary textures and structures such as cross‐bedding. The grains are angular, sorting is moderate to poor

Tektite resistance to fluvial abrasion has become the core issue of several recent papers. Because of contradictory results of barrel observations, the experiment at hand was conceived and implemented. Monitored fluvial abrasion of moldavites had been carried out in a natural river stream. The subsequent results differ significantly from those obtained from barrel experiments. Moldavites can successfully

Calcium‐aluminum‐rich inclusions (CAIs) are the first solid materials formed in the solar nebula. Among them, ultrarefractory inclusions are very rare. In this study, we report on the mineralogical features and oxygen isotopic compositions of minerals in a new ultrarefractory inclusion CAI 007 from the CV3 chondrite Northwest Africa (NWA) 3118. The CAI 007 inclusion is porous and has a layered (core–mantle–rim)

Planar deformation features (PDFs) in quartz are a commonly used and well‐documented indicator of shock metamorphism in terrestrial rocks. The measurement of PDF orientations provides constraints on the shock pressure experienced by a rock sample. A total of 963 PDF sets were measured in 352 quartz grains in 11 granite samples from the basement of the Chicxulub impact structure’s peak ring (IODP‐ICDP

A large, igneous‐textured, and 2 cm‐sized spherical object from the L5/6 chondrite NWA 8192 was investigated for its chemical composition, petrography, O isotopic composition, and Hf‐W chronology. The petrography and chemical data indicate that this object closely resembles commonly found chondrules in ordinary chondrites and is therefore classified as a “macrochondrule.* As a result of metal loss

Micrometeorites (MMs) are extraterrestrial dust particles, in the size range of tens of µm to mm, recovered from the Earth’s surface primarily from deep‐sea sediments, Antarctica, and also from space. The present collection of MMs (>50 µm) obtained by melting ~50 t of ice near the Maitri station, Antarctica, has allowed us to investigate the abundance and properties of the particles by an unbiased

Here, we discuss the merits of non‐destructive UV laser‐induced fluorescence spectroscopy (LIF) as a flight or laboratory instrument to analyze organic and mineral material in samples on or returned from carbon‐rich asteroids such as (101955) Bennu by NASA’s OSIRIS‐REx mission. LIF is a unique instrument that is non‐destructive while acquiring data, and allows for no sample preparation, crushing, or

The wavelength dependence and temporal evolution of the hypervelocity impact self‐luminous plume (or “flash”) from CO2 ice, water ice, and frozen Martian and lunar regolith simulant targets have been investigated using the Kent two‐stage light‐gas gun. An array of 10 band‐pass filtered photodiodes and a digital camera monitored changes in the impact flash intensity during the different phases of the

The Vredefort impact structure, South Africa, is comparable to the Sudbury impact structure, Canada, in size, age, and target rock composition. Both impact structures feature impact melt dikes. The melt sheet of the Sudbury impact (Sudbury Igneous Complex; SIC) is genetically linked to the Sudbury offset dikes in the underlying target rock. At Vredefort, the melt sheet was eroded so that only the granophyre

Two forms of carbon‐rich microfossils were discovered in the breccias of the Onaping Formation, Sudbury impact structure. The first form is represented by single particles scattered in the matrix of the breccias and included in the vesicles in altered glass. These particles are leaf‐shaped, stem‐shaped, tubular, and spherical objects ranging from 5–10 μm to 200–300 µm in size. It is suggested that

Trace elements and extant and extinct isotopic attributes in Martian meteorites have been used to argue that Mars accreted quickly, differentiated into core and mantle, and established several mantle reservoirs, possibly within 10 Ma of T0. The partitioning of trace elements in the deep mantle has been relatively unstudied, despite the need for such knowledge in understanding magma ocean crystallization

We report the discovery of a unique, refractory phase‐bearing micrometeorite (WF1202A‐001) from the Sør Rondane Mountains, East Antarctica. A silicate‐rich cosmic spherule (~400 µm) displays a microporphyritic texture containing Ca‐Al‐rich inclusion (CAI)‐derived material (~5–10 area%), including high‐Mg forsterite (Fo98‐99) and enstatite (En98‐99, Wo0‐1). The micrometeorite also hosts a spherical

The alkali element K is moderately volatile and fluid mobile; thus, it can be influenced by both primary processes (evaporation and recondensation) in the solar nebula and secondary processes (thermal and aqueous alteration) in the parent body. Since these primary and secondary processes would induce different isotopic fractionations, K isotopes could become a potential tracer to distinguish them.

We report microscopic, cathodoluminescence, chemical, and O isotopic measurements of FeO‐poor isolated olivine grains (IOG) in the carbonaceous chondrites Allende (CV3), Northwest Africa 5958 (C2‐ung), Northwest Africa 11086 (CM2‐an), and Allan Hills 77307 (CO3.0). The general petrographic, chemical, and isotopic similarity with bona fide type I chondrules confirms that the IOG derived from them. The

The ungrouped achondrite Northwest Africa (NWA) 7325 parent body underwent a severe impact after primary crystallization, which completely melted plagioclase and partially melted pyroxene, followed by Mg diffusion into the adjacent plagioclase‐melt. The 26Al‐26Mg system was therefore modified, forming a pseudoisochron with an initial δ26Mg* of 0.094 ± 0.005‰ and an age of 4563.12 ± 0.33 Ma between

The Asuka (A)‐12236 meteorite has recently been classified as a CM carbonaceous chondrite of petrologic type 3.0/2.9 and is among the most primitive CM meteorites studied to date. Here, we report the concentrations, relative distributions, and enantiomeric ratios of amino acids in water extracts of the A‐12236 meteorite and another primitive CM chondrite Elephant Moraine (EET) 96029 (CM2.7) determined

Meteorites provide vast amounts of information on the makeup and history of the solar system. The physical properties help to understand meteor behavior in the atmosphere, model characteristics of parent bodies, and determine methods to deflect potentially hazardous objects. Density and porosity are two of the most important physical properties. All the examined ordinary chondrite falls have bulk densities

Petrogenetic relationships among members of the brachinite family were established by analyzing major and trace element concentrations of minerals for 9 representative specimens: Al Huwaysah 010, Eagles Nest, Northwest Africa (NWA) 4882, NWA 5363, NWA 7297, NWA 7299, NWA 11756, Ramlat as Sahmah (RaS) 309, and Reid 013. The brachinite family, which includes brachinites and ungrouped achondrites with

Mass fractions of the siderophile volatile elements S, Se, and Te were determined together with highly siderophile elements (HSE) and osmium isotope ratios in multiple aliquots of five lunar mafic impact melt breccias. The impactites were sampled from presumably Imbrium‐related ejecta deposits at the Apollo 14, 15, and 16 landing sites. As in many mafic impact melt breccias, all studied impactites

The chemical composition and texture of cosmic spherules are influenced by atmospheric conditions and the characteristics of their parent interplanetary particles. The objective of this study was to reproduce I‐type cosmic spherules, which consist mainly of Fe oxide and Fe‐Ni metal, and compare their textural characteristics with those of natural I‐type cosmic spherules. Thus, a series of rapid heating

Aubrites Peña Blanca Spring and Norton County were studied in the mid‐infrared reflectance as part of a database for the MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) instrument on the ESA/JAXA BepiColombo mission to Mercury. Spectra of bulk powder size fractions from Peña Blanca Spring show enstatite Reststrahlen bands (RB) at 9 µm, 9.3 µm, 9.9 µm, 10.4 µm, and 11.6 µm. The transparency

The sulfur isotope budget of Martian regolith breccia (NWA 7533) has been addressed from conventional fluorination bulk rock analyses and ion microprobe in situ analyses. The bulk rock analyses yield 865 ± 50 ppm S in agreement with LA‐ICP‐MS analyses. These new data support previous estimates of 80% S loss resulting from terrestrial weathering of NWA 7533 pyrite. Pyrite is by far the major S host

Northwest Africa (NWA) 8709 is a rare example of a type 3 ordinary chondrite melt breccia and provides critical information for the shock compaction histories of chondrites. An L3 protolith for NWA 8709 is inferred on the basis of oxygen isotope composition, elemental composition, diverse mineral chemistry, and overall texture. NWA 8709 is among the most strongly shocked type 3 chondrites known, and

Noble gases and nitrogen are investigated in eight individual chondrules of the Dhajala H3.8 chondrite. The mean cosmic ray exposure age of the chondrules using 21Ne and 38Ar is 5.9 ± 3.0 Ma. There is no significant evidence of a pre‐exposure for these chondrules. All the measured chondrules contain variable amounts of radiogenic 129Xe. Noble gas analysis indicates Q‐type gas incorporated in the chondrules

On November 27, 2015, at 10:43:45.526 UTC, a fireball was observed across South Australia by 10 Desert Fireball Network observatories lasting 6.1 s. An ~37 kg meteoroid entered the atmosphere with a speed of 13.68 ± 0.09 km s−1 and was observed ablating from a height of 85 km down to 18 km, having slowed to 3.28 ± 0.21 km s−1. Despite the relatively steep 68.5° trajectory, strong atmospheric winds

Kaitianite, Ti3+2Ti4+O5, is a new titanium oxide mineral discovered in the Allende CV3 carbonaceous chondrite. The type grain coexists with tistarite (Ti2O3) and rutile. Corundum, xifengite, mullite, osbornite, and a new Ti,Al,Zr‐oxide mineral are also present, although not in contact. The chemical composition of type kaitianite is (wt%) Ti2O3 56.55, TiO2 39.29, Al2O3 1.18, MgO 1.39, FeO 0.59, V2O3

The mineral apatite, Ca5(PO4)3(F,Cl,OH), is a ubiquitous accessory mineral, with its volatile content and isotopic compositions used to interpret the evolution of H2O on planetary bodies. During hypervelocity impact, extreme pressures shock target rocks resulting in deformation of minerals; however, relatively few microstructural studies of apatite have been undertaken. Given its widespread distribution

We investigated the back‐transformation mechanisms of ringwoodite and majorite occurring in a shock‐melt vein (SMV) of the Yamato 75267 H6 ordinary chondrite during atmospheric entry heating. Ringwoodite and majorite in the shock melt near the fusion crust have back‐transformed into olivine and enstatite, respectively. Ringwoodite (Fa~18) occurs in the SMV as a fine‐grained polycrystalline assemblage

We investigated the metal‐rich chondrite Sierra Gorda (SG) 009, a member of the new G chondrite grouplet (also including NWA 5492, GRO 95551). G chondrites contain 23% metal, very reduced silicates, and rare oxidized mineral phases (Mg‐chromite, FeO‐rich pyroxene). G chondrites are not related to CH‐CB chondrites, based on bulk O, C, and N isotopic compositions, mineralogy, and geochemistry. G chondrites

Anhedral metal grains of >micrometer size occur in many lunar rock types, including mare basalts, magnesian suite rocks (MGS), ferroan anorthosites (FAN), and impact melt rocks and breccias. Some metal grains are inherited from, or modified by, impactors striking the Moon into crustal materials. These grains have high Ni/Co resulting from the addition of chondritic or iron impactors. Metal grains in

Constraining the duration of magmatic activity on the Moon is essential to understand how the lunar mantle evolved chemically through time. Determining age and initial isotopic compositions of mafic lunar meteorites is a critical step in defining the periods of magmatic activity that occurred during the history of the Moon and to constrain the chemical characteristics of mantle components involved

Here, we apply recently developed high‐precision K isotope analyses to individual components of the LL4 chondrite Hamlet in order to investigate key processes which occurred during chondrite formation. The K isotopic compositions of all Hamlet chondrules range from −1.36‰ to −0.24‰ δ41K while the matrix and bulk samples show ranges of −0.89‰ to −0.80‰ and −0.86‰ to −1.08‰ δ41K, respectively. This range

In order to establish kinetic expressions for Raman spectroscopic parameters of organic matter in chondritic meteorites with heating, a series of heating experiments (at 600–900 °C for 3–48 h) of the Murchison (CM2) meteorite was conducted. For comparison, several carbonaceous chondrites with various metamorphic degrees—Allende (CV3.2), Moss (CO3.6), Yamato (Y‐) 793321 (heated CM2), and Tagish Lake

Strontium isotopes and selected trace elements (Rb, Sr, REE, Zr, Hf, Th, and U) were measured on samples of Libyan Desert Glass (LDG) and a series of terrestrial materials (rocks, LDG‐bearing soils, eolic sand) collected over a large area of southwestern Egypt to identify the LDG terrestrial parent material and the site where impact melting occurred. Samples include Upper Cretaceous hypersilicic sandstones

New δ13C and δ18O values were measured to constrain the formation mechanisms of two previously identified generations (Antarctica and Houston) of terrestrial weathering carbonates, nesquehonite, which formed on the surface of the Lewis Cliff 85320 ordinary chondrite. These two nesquehonite generations exhibit a characteristic carbon and oxygen isotopic trend which starts with a linear δ13C‐δ18O covariation

The study of organic compounds in astromaterials represents a unique window into organic matter in the interstellar medium, the solar nebula, and asteroid parent bodies, and insights into pathways that may relate organic matter in these diverse environments. Unfortunately, the Earth’s surface is awash in organic material, which forms a significant source of contamination, especially for specimens of

The Piancaldoli ordinary chondrite fell in northern Italy on August 10, 1968. Preliminary studies led to its classification as an LL3.4 unequilibrated ordinary chondrite. However, recent developments in classification procedures have prompted us to re‐examine its mineralogical, petrographic, spectroscopic, chemical, and isotopic features in a multi‐technique study. Raman spectra and magnetic properties