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The rapid recovery of meteorites mitigates the exposure of astromaterials to the terrestrial environment and subsequent contamination. Modern fireball observatories have enabled the more accurate triangulation of fireball trajectories, which has aided in the location of strewn fields, in the case of meteorite‐producing events. Despite this advancement, most meteorite searches still use manual searching to locate any meteorite falls, which is often labor‐intensive and has a slow coverage rate (km2 day−1). Recent work has begun exploring the application of drone technology to the recovery of meteorites; however, most of this work has focused on falls in arid environments. Our study examines the utilization of drones with thermal imaging technology to aid in the recovery of meteorites that have fallen on a snow‐covered field. We created a simulated strewn field that included meteorite specimens as well as Earth rocks with similar properties ("meteowrongs"). Thermal imagery was utilized to determine whether the thermal contrast between meteorites and snow could aid in the identification of meteorites. We found that the thermal contrast was significant enough that meteorites were readily identifiable within thermal images; however, it was not significant enough to distinguish between the meteorites and the meteowrongs. The utilization of thermal imagery in conjunction with visible imagery has the potential to aid in the rapid recovery of meteorites in snow‐covered landscapes. [ABSTRACT FROM AUTHOR]

Organic matter in astromaterials can provide important information for understanding the chemistry of our solar system and the prebiotic conditions of the early Earth. However, once astromaterials reach the Earth's surface, they can be readily contaminated through contact with the Earth's surface as well as during processing and curation. Here, we investigate how typical handling and curation materials interact with meteorite specimens by documenting hydrophobic organic compound contamination in the laboratory environment and on materials that might be used for their collection and storage. We use gas chromatography–mass spectrometry analysis of soluble organic compounds in dichloromethane extracts of these materials to gain insights into what materials and methods are best for the collection and curation of astromaterials. Our results have implications for how extraterrestrial samples—especially those containing significant intrinsic organic matter—are handled and curated to preserve them in their most pristine states. Following recommendations of other researchers in the area of returned sample curation, we advocate for a thorough investigation into the materials used in handling and curation of meteorites to create a contamination baseline to inform soluble organic analyses on astromaterials and enable the discrimination of terrestrial and extraterrestrial compounds. [ABSTRACT FROM AUTHOR]

Studying organic compounds in meteorites provides important insight into the chemical processes that occurred in the early solar system. Once meteorites reach the Earth's surface, they are subject to terrestrial organic contamination that may confound the conclusions that we draw from meteorite organic analyses. Within this study, specimens of the Tarda C2 ungrouped carbonaceous chondrite, collected within a few days of its fall on August 25, 2020, from a barren desert in Morocco, were analyzed for their organic compound contents. In addition, a sand sample from the strewn field was analyzed to confirm the sources of a handful of contaminating compounds detected in the Tarda stones. Using dichloromethane (DCM) rinses of the Tarda stone exteriors and DCM and hot water extractions of meteorite specimen powders and sand sample, and analysis of the soluble organics by gas chromatography‐mass spectrometry, we distinguish between extraterrestrial and contaminant sources for each organic compound. In this study, N‐tert‐butyldimethylsilyl‐N‐methyltrifluoroacetamide (MTBSTFA) was used to derivatize the hot water extractions to utilize its single‐step derivatization reaction ability. The compounds determined to be intrinsic to Tarda include propanoic acid, propanedioic acid, butanedioic acid, fumaric acid, methylmaleic acid, threonine, proline, glycine, urea, and cyclic octaatomic sulfur. We detected numerous terrestrial organic compounds, all of which were traced back to the meteorites' collection area, with several being confirmed in the sand sample. Our results have implications for best practices for the collection of freshly fallen meteorites, especially carbonaceous chondrites, as well as how specimens should be handled and curated after collection. [ABSTRACT FROM AUTHOR]

Soluble organic matter analyses of astromaterials can provide valuable information on the chemistry of our solar system and the processes that occur within it. The surface of the Earth, however, is a significant source of organic compounds due to the presence of life; this environment represents a major source of potential contamination for recently fallen meteorites. Here, we analyze select stones of the CM2 Aguas Zarcas carbonaceous chondrite, which fell on April 23, 2019, in Aguas Zarcas, San Carlos county, Alajuela province, Costa Rica, with the goal of determining the complement of intrinsic and contaminant soluble organic matter. The specimens were collected pre‐ and post‐rainfall, days to weeks after the stones fell on the Earth. Through gas chromatography‐mass spectrometry analysis of soluble organic matter in dichloromethane and hot water extracts of meteorite powders, we differentiate between extraterrestrial and contaminant sources for each organic compound detected. In this study, N‐tert‐butyldimethylsilyl‐ N‐methyltrifluoroacetamide (MTBSTFA) was used to derivatize the hot water extracts to test out its "one‐pot" extraction capabilities. The majority of the detectable organic compounds are contaminants and can be explained as being sourced from the terrestrial surface onto which the meteorite fell. Our results have implications for how environmental factors, such as land use and rainfall events in this case, can impact the intrinsic organics in carbonaceous chondrites. [ABSTRACT FROM AUTHOR]

By analyzing impact glass, the evolution of the impact melt at the Mistastin Lake impact structure was investigated. Impact glass clasts are present in a range of impactites, including polymict breccias and clast‐rich impact melt rock, and from a variety of settings within the crater. From the glass clasts analyzed, three petrographic subtypes of impact glass were identified based on their clast content, prevalence of schlieren, color, texture, and habit. Several alteration phases were also observed replacing glass and infilling vesicles; however, textural observations and quantified compositional data allowed for the identification of pristine impact glass. Although the various types of glasses show significant overlap in their major oxide composition, several subtle variations in the major oxide chemistry of the glass were observed. To investigate this variation, a least‐squares mixing model was implemented utilizing the composition of the glass and the known target rock chemistry to model the initial melt composition. Additionally, image analysis of the glass clasts was used to investigate whether the compositional variations correlated to textural difference in the lithologies. We propose that the textural and compositional dichotomy observed is a product of the evolution, assimilation, and emplacement of the glass. The dichotomy is reflective of the melt either being ballistically emplaced (group 2 glasses: occurring in melt‐poor polymict breccias at lowermost stratigraphic position outside the transient crater) or the result of late‐stage melt flows (group 1 glasses, occurring in melt‐bearing polymict breccias and impact melt rocks at higher stratigraphic positions outside the transient crater). [ABSTRACT FROM AUTHOR]

We present a procedure for the determination of the isotopic ratios of silicon and oxygen from the same aliquot of anhydrous silicate material. The sample is placed in a bromine pentafluoride atmosphere as it is heated with a CO2 laser system releasing silicon tetrafluoride and oxygen gasses. The oxygen gas is then purified to remove other reaction by‐products through several liquid nitrogen traps before being captured onto a molecular sieve and transferred to an isotope ratio mass spectrometer. The silicon tetrafluoride gas is then purified using a supplementary line by repeatedly freezing to −196°C with liquid nitrogen and then thawing with an ethanol slurry at −110°C through a series of metal and Pyrex traps. The purified gas is then condensed into a Pyrex sample tube before it is transferred to an isotope ratio mass spectrometer for silicon isotope ratio measurements. This system has silicon yields of greater than 90% for pure quartz, olivine, and garnet standards and has a reproducibility of ±0.1‰ (2σ) for pure quartz for both oxygen and silicon isotope measurements. Meteoritic samples were also successfully analyzed to demonstrate this system's ability to measure the isotopic ratio composition of bulk powders with precision. This unique technique allows for the fluorination of planetary material without the need for wet chemistry. Though designed to analyze small aliquots of meteoritic material (1.5 to 3 mg), this approach can also be used to investigate refractory terrestrial samples where traditional fluorination is not suitable. [ABSTRACT FROM AUTHOR]

The Dhofar 1673, Dhofar 1983, and Dhofar 1984 meteorites are three lunar regolith breccias classified based on their petrography, mineralogy, oxygen isotopes, and bulk chemistry. All three meteorites are dominated by feldspathic lithic clasts; however, impact melt rock clasts and spherules are also found in each meteorite. The bulk chemistry of these samples is similar to other feldspathic highland meteorites with the Al2O3 content only slightly lower than average. Within the lithic clasts, the Mg # of mafic phases versus the anorthite content of feldspars is similar to other highland meteorites and is found to plot intermediate of the ferroan‐anorthositic suite and magnesian suite. The samples lack any KREEPy signature and have only minor indications of a mare basalt component, suggesting that the source region of all three meteorites would have been distal from the Procellarum KREEP Terrane and could have possibly been the Feldspathic Highland Terrane. All three meteorites were found within 500 m of each other in the Dhofar region of Oman. This, together with their similar petrography, stable isotope chemistry, and geochemistry indicates the possibility of a pairing. [ABSTRACT FROM AUTHOR]

The impact of asteroids and comets with planetary surfaces is one of the most catastrophic, yet ubiquitous, geological processes in the solar system. The Chicxulub impact event, which has been linked to the Cretaceous-Paleogene (K-Pg) mass extinction marking the beginning of the Cenozoic Era, is arguably the most significant singular geological event in the past 100 million years of Earth's history. The Chicxulub impact occurred in a marine setting. How quickly the seawater re-entered the newly formed basin after the impact, and its effects of it on the cratering process, remain debated. Here, we show that the explosive interaction of seawater with impact melt led to molten fuel-coolant interaction (MFCI), analogous to what occurs during phreatomagmatic volcanic eruptions. This process fractured and dispersed the melt, which was subsequently deposited subaqueously to form a series of well-sorted deposits. These deposits bear little resemblance to the products of impacts in a continental setting and are not accounted for in current classification schemes for impactites. The similarities between these Chicxulub deposits and the Onaping Formation at the Sudbury impact structure, Canada, are striking, and suggest that MFCI and the production of volcaniclastic-like deposits is to be expected for large impacts in shallow marine settings. [ABSTRACT FROM AUTHOR]