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On September 24, 2023, NASA's OSIRIS‐REx mission dropped a capsule to Earth containing ~120 g of pristine carbonaceous regolith from Bennu. We describe the delivery and initial allocation of this asteroid sample and introduce its bulk physical, chemical, and mineralogical properties from early analyses. The regolith is very dark overall, with higher‐reflectance inclusions and particles interspersed. Particle sizes range from submicron dust to a stone ~3.5 cm long. Millimeter‐scale and larger stones typically have hummocky or angular morphologies. Some stones appear mottled by brighter material that occurs as veins and crusts. Hummocky stones have the lowest densities and mottled stones have the highest. Remote sensing of Bennu's surface detected hydrated phyllosilicates, magnetite, organic compounds, carbonates, and scarce anhydrous silicates, all of which the sample confirms. We also find sulfides, presolar grains, and, less expectedly, Mg,Na‐rich phosphates, as well as other trace phases. The sample's composition and mineralogy indicate substantial aqueous alteration and resemble those of Ryugu and the most chemically primitive, low‐petrologic‐type carbonaceous chondrites. Nevertheless, we find distinct hydrogen, nitrogen, and oxygen isotopic compositions, and some of the material we analyzed is enriched in fluid‐mobile elements. Our findings underscore the value of sample return—especially for low‐density material that may not readily survive atmospheric entry—and lay the groundwork for more comprehensive analyses. [ABSTRACT FROM AUTHOR]

We report primordial aqueous alteration signatures in water-soluble organic molecules from the carbonaceous asteroid (162173) Ryugu by the Hayabusa2 spacecraft of JAXA. Newly identified low-molecular-weight hydroxy acids (HO-R-COOH) and dicarboxylic acids (HOOC-R-COOH), such as glycolic acid, lactic acid, glyceric acid, oxalic acid, and succinic acid, are predominant in samples from the two touchdown locations at Ryugu. The quantitative and qualitative profiles for the hydrophilic molecules between the two sampling locations shows similar trends within the order of ppb (parts per billion) to ppm (parts per million). A wide variety of structural isomers, including α- and β-hydroxy acids, are observed among the hydrophilic molecules. We also identify pyruvic acid and dihydroxy and tricarboxylic acids, which are biochemically important intermediates relevant to molecular evolution, such as the primordial TCA (tricarboxylic acid) cycle. Here, we find evidence that the asteroid Ryugu samples underwent substantial aqueous alteration, as revealed by the presence of malonic acid during keto–enol tautomerism in the dicarboxylic acid profile. The comprehensive data suggest the presence of a series for water-soluble organic molecules in the regolith of Ryugu and evidence of signatures in coevolutionary aqueous alteration between water and organics in this carbonaceous asteroid. In this study, the authors report primordial aqueous alteration signatures in water-soluble organic molecules from the carbonaceous asteroid Ryugu. This provides evidence o coevolutionary aqueous alteration between water and organics in this asteroid. [ABSTRACT FROM AUTHOR]

We analyzed 12 Apollo 17 samples through the Apollo Next Generation Sample Analysis (ANGSA) program to determine the abundances of a variety of compound classes, including amino acids, aldehydes, ketones, amines, carboxylic acids, and cyanide‐releasing species. Analyzed samples included portions of double drive tube 73001/73002, the bottom half of which (73001) was hermetically sealed under lunar vacuum, as well as lunar regolith samples from three different illumination environments that had been curated frozen for ∼50 years. Consistent with previous results, we detected low levels of amino acids in the hot‐water extracts of most samples (0.55–12.03 nmol/g in unhydrolyzed samples; 0.53–72.38 nmol/g after acid hydrolysis of the extracts). We also detected one‐carbon and two‐carbon species of amines, aldehydes, and carboxylic acids (i.e., methylamine, ethylamine, formaldehyde, acetaldehyde, formic acid, acetic acid) not previously reported in lunar samples, as well as insoluble cyanide‐forming species. Although these compounds are potential precursor molecules for amino acids, no specific precursor relationships could be determined. Nylon contamination was the likely source of some amino acids. Abundances of some species (e.g., cyanide) decreased with increasing depth in the drive tube, suggesting that exogenous delivery and concentration mechanisms near the surface outweighed surface degradation processes. In addition, we observed the potential cold trapping of volatile amines in the persistently shadowed samples analyzed. Finally, we noted the effects of different curation conditions; hermetic sealing appeared to preserve higher amounts of volatile compounds, while frozen curation did not have a noticeable preservation effect on the organic volatiles analyzed here. Plain Language Summary: The Moon's surface may contain organic chemicals similar to those used by life on Earth, but previous studies have been limited. Some of the Moon rocks and dirt collected in 1973 by the Apollo 17 astronauts were set aside for future generations to study after new techniques could be developed. Recently, after nearly 50 years in curation, some of these samples were made available to researchers, including samples that had been sealed by astronauts on the lunar surface and not exposed to the Earth's atmosphere, as well as samples that were stored in a freezer after return to Earth. We examined these samples along with other Apollo 17 samples to search for small organic chemicals such as amino acids (like those in proteins in life on Earth) and related molecules. We found small amounts of volatile compounds such as formaldehyde, which had not previously been detected in Moon samples. We also found that storing the samples in special sealed containers may better preserve volatile chemicals, while freezing did not have a strong effect on the chemicals we examined. These results help us understand the chemical environment of the Moon and provide lessons for the storage of future returned samples. Key Points: Low (nmol/g) abundances of volatile organic compounds were detected in specially curated Apollo 17 samplesWe observed amino acids, cyanides, amines, aldehydes, ketones, and carboxylic acids, including some not previously known in lunar samplesHermetically sealed curation better preserved certain volatile compounds, while frozen curation may reduce organic contamination [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) are carbon‐containing chemicals that may evaporate rapidly at room temperature and standard pressure. Such organic compounds can be preserved inside carbonaceous chondrite matrices. However, unlike meteoritic soluble organic matter (SOM) and insoluble organic matter (IOM), VOCs are typically lost (at least in part) during sample processing (meteorite crushing) and exposure to terrestrial atmosphere and/or solvents. Like SOM and IOM, VOCs can provide valuable insights into the chemical inventory of the meteorite parent body and even the presolar cloud from which our solar system formed, as well as the composition and processes that occurred during the early formation of our solar system and the asteroidal stage. Thus, in this work, we designed and built an instrument that allowed us to access the VOCs present in samples of the carbonaceous chondrites Murchison and Sutter's Mill after mineral disaggregation by means of freeze–thaw cycling. We simultaneously evaluated the abundances and compound‐specific 13C‐distributions of the volatiles evolving after meteorite powdering at ~20, 60, and 100°C. Carbon monoxide (CO) and methane (CH4) were released from these meteorites as the most abundant VOCs. They were combusted together for analysis and showed positive δ13C values, indicative of their extraterrestrial origins. Carbon dioxide (CO2) was also an abundant VOC in both meteorites, and its isotopic values suggest that it was mainly formed from dissolved carbonates in the samples. We also detected aldehydes, ketones, and aromatic compounds in low amounts. Contrary to Murchison, which mostly yielded VOCs with positive δ13C values, Sutter's Mill yielded VOCs with negative δ13C values. The less enriched 13C isotope composition of the VOCs detected in Sutter's Mill suggest that they are either terrestrial contaminants, such as VOCs in compressed gas dusters and common laboratory solvents, or compounds disconnected from interstellar sources and/or formed through parent body processing. Understanding the relative abundances and determining the molecular distributions and isotopic compositions of free meteoritic VOCs are key in assessing their extraterrestrial origins and those of chondritic SOM and IOM. Our newly developed technique will be valuable in the study of the samples brought to the Earth from carbonaceous asteroid Bennu by NASA's OSIRIS‐REx mission. [ABSTRACT FROM AUTHOR]

X‐ray computed tomography (XCT) is a valuable reconnaissance tool for three‐dimensional imaging and identification of distinct lithologies in extraterrestrial samples. It will be used as part of the preliminary examination of samples returned from asteroid (101955) Bennu by the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx) mission. However, it must first be established whether x‐rays generated during XCT could degrade or alter the organic composition of the returned samples by radiolysis. To test this, we split a crushed sample of the Murchison CM2 meteorite, kept one portion as a control, and irradiated the other portion up to the maximum x‐ray dosage (~180 Gy) that a Bennu sample would experience during an XCT imaging experiment. We then extracted organic compounds from both splits and conducted (i) nontargeted soluble organic analyses to compare the chemical distributions of C‐, H‐, O‐, N‐, and S‐bearing species and (ii) targeted measurements to quantify the abundances of 96 individual soluble organic molecules that included protein amino acids, amines, carboxylic acids, hydroxy acids, carbonyl compounds, polycyclic aromatic hydrocarbons, alcohols, sugars, and N‐heterocycles. We found that XCT imaging of the Murchison meteorite had no measurable impact on the relative abundances or enantiomeric compositions of most of the soluble organic compounds targeted in this study. Elevated total abundances of several soluble organic compound classes were observed in the XCT‐scanned Murchison sample relative to the control. This is likely related to particle size heterogeneity and specific surface area differences between the sample aliquots used for the extractions, rather than a result of the x‐ray exposure. Assuming the samples returned from asteroid Bennu by OSIRIS‐REx have a similar composition to carbonaceous chondrites, these data provide confidence that XCT will not significantly alter their soluble organic compositions. [ABSTRACT FROM AUTHOR]

This study analyzed samples of the Murchison and Sutter's Mill carbonaceous chondrite meteorites in support of the future analysis of samples returned from the asteroid (10155) Bennu by the OSIRIS‐REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) mission. Focusing specifically on the insoluble organic matter (IOM), this study establishes that a total of 1.3 g of bulk sample from a single chondritic meteorite are sufficient to obtain a wide range of cosmochemical information, including light element analysis (H, C, and N), isotopic analysis (D/H, 13C/12C, and 15N/14N), and x‐ray fluorescence spectroscopy for major elemental abundances. IOM isolated from the bulk meteorite samples was analyzed by light element and isotopic analysis as described above, 1H and 13C solid‐state nuclear magnetic resonance spectroscopy, Raman spectroscopy, and complete noble gas analyses (abundances and isotopes). The samples studied included a pair from Murchison (CM2), one of which had been irradiated with high‐energy x‐rays in the course of computed tomographic imaging. No differences between the irradiated and non‐irradiated Murchison samples were observed in the many different chemical and spectroscopic analyses, indicating that any x‐ray–derived sample damage is below levels of detection. Elemental, isotopic, and molecular spectroscopic data derived from IOM isolated from the Sutter's Mill sample reveals evidence that this meteorite falls into the class of heated CM chondrites. [ABSTRACT FROM AUTHOR]

We performed in-situ analysis on a ~ 1 mm-sized grain A0080 returned by the Hayabusa2 spacecraft from near-Earth asteroid (162173) Ryugu to investigate the relationship of soluble organic matter (SOM) to minerals. Desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) imaging mapped more than 200 CHN, CHO, CHO–Na (sodium adducted), and CHNO soluble organic compounds. A heterogeneous spatial distribution was observed for different compound classes of SOM as well as among alkylated homologues on the sample surface. The A0080 sample showed mineralogy more like an Ivuna-type (CI) carbonaceous chondrite than other meteorites. It contained two different lithologies, which are either rich (lithology 1) or poor (lithology 2) in magnetite, pyrrhotite, and dolomite. CHN compounds were more concentrated in lithology 1 than in lithology 2; on the other hand, CHO, CHO–Na, and CHNO compounds were distributed in both lithologies. Such different spatial distribution of SOM is likely the result of interaction of the SOM with minerals, during precipitation of the SOM via fluid activity, or could be due to difference in transportation efficiencies of SOMs in aqueous fluid. Organic-related ions measured by time-of-flight secondary ion mass spectrometry (ToF–SIMS) did not coincide with the spatial distribution revealed by DESI-HRMS imaging. This result may be because the different ionization mechanism between DESI and SIMS, or indicate that the ToF–SIMS data would be mainly derived from methanol-insoluble organic matter in A0080. In the Orgueil meteorite, such relationship between altered minerals and SOM distributions was not observed by DESI-HRMS analysis and field-emission scanning electron microscopy, which would result from differences of SOM formation processes and sequent alteration process on the parent bodies or even on the Earth. Alkylated homologues of CHN compounds were identified in A0080 by DESI-HRMS imaging as observed in the Murchison meteorite, but not from the Orgueil meteorite. These compounds with a large C number were enriched in Murchison fragments with abundant carbonate grains. In contrast, such relationship was not observed in A0080, implying different formation or growth mechanisms for the alkylated CHN compounds by interaction with fluid and minerals on the Murchison parent body and asteroid Ryugu. [ABSTRACT FROM AUTHOR]

The pristine sample from the near-Earth carbonaceous asteroid (162173) Ryugu collected by the Hayabusa2 spacecraft enabled us to analyze the pristine extraterrestrial material without uncontrolled exposure to the Earth's atmosphere and biosphere. The initial analysis team for the soluble organic matter reported the detection of wide variety of organic molecules including racemic amino acids in the Ryugu samples. Here we report the detection of uracil, one of the four nucleobases in ribonucleic acid, in aqueous extracts from Ryugu samples. In addition, nicotinic acid (niacin, a B3 vitamer), its derivatives, and imidazoles were detected in search for nitrogen heterocyclic molecules. The observed difference in the concentration of uracil between A0106 and C0107 may be related to the possible differences in the degree of alteration induced by energetic particles such as ultraviolet photons and cosmic rays. The present study strongly suggests that such molecules of prebiotic interest commonly formed in carbonaceous asteroids including Ryugu and were delivered to the early Earth. Uracil was identified in the sample returned from the asteroid Ryugu. Having been provided to the early Earth as a component in such asteroidal materials, these molecules might have played a role for prebiotic chemical evolution on the early Earth [ABSTRACT FROM AUTHOR]

Evaluating the molecular distribution of organic compounds in pristine extraterrestrial materials is cornerstone to understanding the abiotic synthesis of organics and allows us to better understand the molecular diversity available during the formation of our solar system and before the origins of life on Earth. In this work, we identify multiple organic compounds in solvent extracts of asteroid Ryugu samples A0106 and C0107 and the Orgueil meteorite using two-dimensional gas chromatography and time-of-flight high resolution mass spectrometry (GC×GC–HRMS). Our analyses found similarities between the molecular distribution of organic compounds in Ryugu and the CI carbonaceous chondrite Orgueil. Specifically, several PAHs and organosulfides were found in Ryugu and Orgueil suggesting an interstellar and parent body origin for these compounds. We also evaluated the common relationship between Ryugu, Orgueil, and comets, such as Wild-2; however, until comprehensive compound-specific isotopic analyses for these organic species are undertaken, and until the effects of parent body processes and Earth's weathering processes on meteoritic organics are better understood, their parent–daughter relationships will remain unanswered. Finally, the study of organic compounds in Ryugu samples and the curation practices for the future preservation of these unvaluable materials are also of special interest for future sample return missions, including NASA's OSIRIS-REx asteroid sample return mission. [ABSTRACT FROM AUTHOR]

A Non-Dispersive Infra-Red (NDIR) gas analyzer has been designed, and a proof-of concept built and validated, to continuously monitor water vapor and carbon dioxide gas partial pressures, for a space-based instrument application, that requires the safe transfer of sublimated volatiles from a comet sample containment system to a gas containment system within the operational pressure-temperature conditions, e.g., water vapor, in the range 3 Torr (268 K) and 30 mTorr (223 K). The NDIR gas analyzer uses quad thermopile detectors integrated with spectral bandpass comprising filters centered at $2.7 ~ \mu \text{m}$ and $6.58 ~ \mu \text{m}$ for water absorption channels, spectral bandpass filter centered at $4.25 ~ \mu \text{m}$ for carbon dioxide absorption channel, and spectral band-pass filter centered at $4.0 ~ \mu \text{m}$ for the reference channel, paired with a pulsed infra-red source. The thermopile detector signals are measured and processed using a custom-built radiation-hard-by-design multi-channel digitizer (MCD) application specific integrated circuit (ASIC). The NDIR gas analyzer can detect water vapor partial pressures up to 3 Torr with a 30 mTorr resolution (1 sigma) and carbon dioxide partial pressures up to 175 Torr with a 50 mTorr resolution (1 sigma) within the temperature range 223–268 K. [ABSTRACT FROM AUTHOR]

The lack of pyrimidine diversity in meteorites remains a mystery since prebiotic chemical models and laboratory experiments have predicted that these compounds can also be produced from chemical precursors found in meteorites. Here we report the detection of nucleobases in three carbonaceous meteorites using state-of-the-art analytical techniques optimized for small-scale quantification of nucleobases down to the range of parts per trillion (ppt). In addition to previously detected purine nucleobases in meteorites such as guanine and adenine, we identify various pyrimidine nucleobases such as cytosine, uracil, and thymine, and their structural isomers such as isocytosine, imidazole-4-carboxylic acid, and 6-methyluracil, respectively. Given the similarity in the molecular distribution of pyrimidines in meteorites and those in photon-processed interstellar ice analogues, some of these derivatives could have been generated by photochemical reactions prevailing in the interstellar medium and later incorporated into asteroids during solar system formation. This study demonstrates that a diversity of meteoritic nucleobases could serve as building blocks of DNA and RNA on the early Earth. All DNA/RNA nucleobases were identified in carbonaceous meteorites. Having been provided to the early Earth as a component in carbonaceous meteorites, these molecules might have played a role for the emergence of genetic functions in early life. [ABSTRACT FROM AUTHOR]

Amino acid abundances in acid‐hydrolyzed hot water extracts of gold foils containing five Category 3 (carbon‐rich) Hayabusa particles were studied using liquid chromatography with tandem fluorescence and accurate mass detection. Initial particle analyses using field emission scanning electron microscopy with energy‐dispersive X‐ray spectrometry indicated that the particles were composed mainly of carbon. Prior to amino acid analysis, infrared and Raman microspectroscopy showed some grains possessed primitive organic carbon. Although trace terrestrial contamination, namely l‐protein amino acids, was observed in all Hayabusa extracts, several terrestrially uncommon non‐protein amino acids were also identified. Some Hayabusa particles contained racemic (d≈l) mixtures of the non‐protein amino acids β‐aminoisobutyric acid (β‐AIB) and β‐amino‐n‐butyric acid (β‐ABA) at low abundances ranging from 0.09 to 0.31 nmol g−1. Larger abundances of the non‐protein amino acid β‐alanine (9.2 nmol g−1, ≈4.5 times greater than background levels) were measured in an extract of three Hayabusa particles. This β‐alanine abundance was ≈6 times higher than that measured in an extract of a CM2 Murchison grain processed in parallel. The comparatively high β‐alanine abundance is surprising as asteroid Itokawa is similar to amino acid‐poor LL ordinary chondrites. Elevated β‐alanine abundances and racemic β‐AIB and β‐ABA in Hayabusa grains suggested these compounds have non‐biological and plausibly non‐terrestrial origins. These results are the first evidence of plausibly extraterrestrial amino acids in asteroid material from a sample‐return mission and demonstrate the capabilities of the analytical protocols used to study asteroid Ryugu and Bennu samples returned by the JAXA Hayabusa2 and NASA OSIRIS‐REx missions, respectively. [ABSTRACT FROM AUTHOR]

Obtaining carbon isotopic information for organic carbon from Martian sediments has long been a goal of planetary science, as it has the potential to elucidate the origin of such carbon and aspects of Martian carbon cycling. Carbon isotopic values (d13CVPDB) of the methane released during pyrolysis of 24 powder samples at Gale crater, Mars, show a high degree of variation (-137 ± 8‰ to +22 ± 10‰) when measured by the tunable laser spectrometer portion of the Sample Analysis at Mars instrument suite during evolved gas analysis. Included in these data are 10 measured d13C values less than -70‰ found for six different sampling locations, all potentially associated with a possible paleosurface. There aremultiple plausible explanations for the anomalously depleted 13C observed in evolved methane, but no single explanation can be acceptedwithout further research. Three possible explanations are the photolysis of biological methane released from the subsurface, photoreduction of atmospheric CO2, and deposition of cosmic dust during passage through a galactic molecular cloud. All three of these scenarios are unconventional, unlike processes common on Earth. [ABSTRACT FROM AUTHOR]

Investigating the organic contents of enstatite chondrite meteorites may offer insights into both early inner solar system and early Earth chemistry. Enstatite chondrite meteorites have highly reduced and anhydrous compositions, and their bulk isotopic compositions closely resemble terrestrial values, suggesting that their parent body asteroids accreted within the inner protoplanetary disk and were a primary contributor during Earth's late accretion (Javoy, 1995; Piani et al., 2020). Here, we present the first report of amino acids in enstatite chondrite meteorite samples. Three EH3 meteorites were analyzed (Dominion Range [DOM] 14021, Larkman Nunatak [LAR] 12001, and Larkman Nunatak 06252). The acid‐hydrolyzed water extracts of the meteorites contained low abundances (1.5–215.9 pmol g−1) of n‐ω‐amino acids (glycine, β‐alanine, γ‐amino‐n‐butyric acid [γ‐ABA], δ‐amino‐n‐valeric acid [δ‐AVA], and ε‐amino‐n‐caproic acid [ε‐ACA]), but amino acids were not present above detection limits in the nonhydrolyzed samples. The low amino acid abundances and the predominance of n‐ω‐amino acids resemble amino acid distributions previously observed for thermally altered chondrites. These results suggest that the parent body asteroid was not conducive to the synthesis and/or preservation of α‐amino acids, or free amino acids in general, and that EH3 chondrite‐like material may not have been a primary contributor of diverse or abundant free amino acids to the early Earth. [ABSTRACT FROM AUTHOR]

The abundances, distributions, and enantiomeric ratios of a family of three‐ and four‐carbon hydroxy amino acids (HAAs) were investigated in extracts of five CM and four CR carbonaceous chondrites by gas chromatography‐mass spectrometry analyses. HAAs were detected in both the acid hydrolysates of the hot water extracts and the 6 M HCl extracts of all the CM and CR chondrites analyzed here with total hot water and HCl extractable HAA concentrations ranging from 6.94 to 315 nmol g−1. The HAA analyses performed in this study revealed: (1) the combined (hot water + HCl) extracts of CR2 chondrites contained greater abundances of α‐HAAs than that of CM2 chondrites and (2) the combined extracts of CM and CR chondrites contained roughly similar abundances of β‐ and γ‐HAAs. Application of the new GC‐MS method developed here resulted in the first successful chromatographic resolution of the enantiomers of an α‐dialkyl HAA, d,l‐α‐methylserine, in carbonaceous chondrite extracts. Meteoritic α‐methylserine was found to be mostly racemic within error and did not show l‐enantiomeric excesses correlating with the degree of aqueous alteration, a phenomenon observed in meteoritic isovaline, another α‐dialkyl amino acid. The HAAs identified in CM and CR chondrite extracts could have been produced during parent body alteration from the Strecker cyanohydrin reaction (for α‐HAAs) and an ammonia‐involved formose‐like reaction (for β‐, and γ‐HAAs). [ABSTRACT FROM AUTHOR]

The organic compositions of carbonaceous chondrite meteorites have been extensively studied; however, there have been fewer reports of other meteorite classes, and almost none from iron meteorites, which contain much less carbon than carbonaceous chondrites but make up ~4% of observed meteorite falls. Here, we report the bulk amino acid content of three iron meteorites (Campo del Cielo, IAB; Canyon Diablo, IAB; and Cape York, IIIAB) and both the metal and silicate portions of a pallasite (Imilac). We developed a novel method to prepare the samples for analysis, followed by hot water extraction and analysis via liquid chromatography‐mass spectrometry. Free amino acid abundances ranging from 301 to 1216 pmol g−1 were observed in the meteorites, with the highest abundance in the silicate portion of the pallasite. Although some of the amino acid content could be attributed to terrestrial contamination, evidence suggests that some compounds are indigenous. A suite of C5 amino acids was observed with a distinct distribution favoring a straight chain (n‐pentanoic acid) structure; this straight chain dominance is suggestive of that observed in thermally altered stony meteorites. Amino acids were also observed in terrestrial iron granules that were milled and analyzed in the same way as the meteorites, although the distribution of detected amino acids was different. It is possible that similar formation mechanisms existed in both the meteorites and the terrestrial iron, or that observed amino acids resulted from reactions of precursors during sample preparation. This work suggests that iron meteorites should not be overlooked for contributions of amino acids and likely other soluble organic molecules to the early Earth. Future studies of iron–nickel meteorites and asteroids, such as Psyche, may provide further insights into their potential organic inventory. [ABSTRACT FROM AUTHOR]

The abundances, distributions, enantiomeric ratios, and carbon isotopic compositions of amino acids in two fragments of the Aguas Zarcas CM2 type carbonaceous chondrite fall and a fragment of the CM2 Murchison meteorite were determined via liquid chromatography time‐of‐flight mass spectrometry and gas chromatography isotope ratio mass spectrometry. A suite of two‐ to six‐carbon aliphatic primary amino acids was identified in the Aguas Zarcas and Murchison meteorites with abundances ranging from ~0.1 to 158 nmol/g. The high relative abundances of α‐amino acids found in these meteorites are consistent with a Strecker‐cyanohydrin synthesis on these meteorite parent bodies. Amino acid enantiomeric and carbon isotopic measurements in both fragments of the Aguas Zarcas meteorites indicate that both samples experienced some terrestrial protein amino acid contamination after their fall to Earth. In contrast, similar measurements of alanine in Murchison revealed that this common protein amino acid was both racemic (D ≈ L) and heavily enriched in 13C, indicating no measurable terrestrial alanine contamination of this meteorite. Carbon isotope measurements of two rare non‐proteinogenic amino acids in the Aguas Zarcas and Murchison meteorites, α‐aminoisobutyric acid and D‐ and L‐isovaline, also fall well outside the typical terrestrial range, confirming they are extraterrestrial in origin. The detections of non‐terrestrial L‐isovaline excesses of ~10–15% in both the Aguas Zarcas and Murchison meteorites, and non‐terrestrial L‐glutamic acid excesses in Murchison of ~16–40% are consistent with preferential enrichment of circularly polarized light generated L‐amino acid excesses of conglomerate enantiopure crystals during parent body aqueous alteration and provide evidence of an early solar system formation bias toward L‐amino acids prior to the origin of life. [ABSTRACT FROM AUTHOR]

Despite extensive studies on the formation of organic molecules in various extraterrestrial environments, it still remains under debate when, where, and how such molecules were abiotically formed. A key molecule to solve the problem, hexamethylenetetramine (HMT) has not been confirmed in extraterrestrial materials despite extensive laboratory experimental evidence that it can be produced in interstellar or cometary environments. Here we report the first detection of HMT and functionalized HMT species in the carbonaceous chondrites Murchison, Murray, and Tagish Lake. While the part-per-billion level concentration of HMT in Murchison and Tagish Lake is comparable to other related soluble organic molecules like amino acids, these compounds may have eluded detection in previous studies due to the loss of HMT during the extraction processes. HMT, which can yield important molecules for prebiotic chemistry such as formaldehyde and ammonia upon degradation, is a likely precursor of meteoritic organic compounds of astrochemical and astrophysical interest. This manuscript tackles the origin of organic molecules in carbonaceous meteorites. Identifying hexamethylenetetramine in three carbonaceous meteorites, the authors propose formation from ammonia and formaldehyde by photochemical and thermal reactions in the interstellar medium, followed by the incorporation into planetary systems. [ABSTRACT FROM AUTHOR]

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, suites of these compounds have now been analyzed in a set of six CR chondrites, spanning aqueous alteration types 2.0–2.8. Amino acid abundances ranged from 17 to 3300 nmol g−1 across the six CRs; hydroxy acid abundances ranged from 180 to 1800 nmol g−1; and amine abundances ranged from 40 to 2100 nmol g−1. For amino acids and amines, the weakly altered chondrites contained the highest abundances, whereas hydroxy acids were most abundant in the more altered CR2.0 chondrite. Because water contents in the meteorites are orders of magnitude greater than soluble organics, synthesis of hydroxy acids, which requires water, may be less affected by aqueous alteration than amines and amino acids that require nitrogen‐bearing precursors. Two chiral amino acids that were plausibly extraterrestrial in origin were present with slight enantiomeric excesses: L‐isovaline (~10% excess) and D‐β‐amino‐n‐butyric acid (~9% excess); further studies are needed to verify that the chiral excess in the latter compound is truly extraterrestrial in origin. The isotopic compositions of compounds reported here did not reveal definitive links between the different compound classes such as common synthetic precursors, but will provide a framework for further future in‐depth analyses. [ABSTRACT FROM AUTHOR]

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 by ultra‐high‐performance liquid chromatography time‐of‐flight mass spectrometry. EET 96029 was highly depleted in amino acids and dominated by glycine, while a wide diversity of two‐ to six‐carbon aliphatic primary amino acids were identified in A‐12236, which had a total amino acid abundance of 360 ± 18 nmol g−1, with most amino acids present without hydrolysis (free). The amino acid concentrations of A‐12236 were double those previously measured in the CM2.7 Paris meteorite, consistent with A‐12236 being a highly primitive and unheated CM chondrite. The high relative abundance of α‐amino acids in A‐12236 is consistent with formation by a Strecker‐cyanohydrin dominated synthesis during a limited early aqueous alteration phase on the CM meteorite parent body. The presence of predominantly free glycine, a near racemic mixture of alanine (d/l ~0.93–0.96), and elevated abundances of several terrestrially rare non‐protein amino acids including α‐aminoisobutyric acid (α‐AIB) and racemic isovaline indicate that these amino acids in A‐12236 are extraterrestrial in origin. Given a lack of evidence for biological amino acid contamination in A‐12236, it is possible that some of the l‐enantiomeric excesses (lee ~34–64%) of the protein amino acids, aspartic and glutamic acids and serine, are indigenous to the meteorite; however, isotopic measurements are needed for confirmation. In contrast to more aqueously altered CMs of petrologic types ≤2.5, no l‐isovaline excesses were detected in A‐12236. This observation strengthens the hypothesis that extensive parent body aqueous activity is required to produce or amplify the large l‐isovaline excesses that cannot be explained solely by exposure to circularly polarized radiation or other chiral symmetry breaking mechanisms prior to incorporation into the asteroid parent body. [ABSTRACT FROM AUTHOR]

Evaluating the water‐soluble organic composition of carbonaceous chondrites is key to understanding the inventory of organic matter present at the origins of the solar system and the subsequent processes that took place inside asteroid parent bodies. Here, we present a side‐by‐side analysis and comparison of the abundance and molecular distribution of aliphatic amines, aldehydes, ketones, mono‐ and dicarboxylic acids, and free and acid‐releasable cyanide species in the CM2 chondrites Aguas Zarcas and Murchison. The Aguas Zarcas meteorite is a recent fall that occurred in central Costa Rica and constitutes the largest recovered mass of a CM‐type meteorite after Murchison. The overall content of organic species we investigated was systematically higher in Murchison than in Aguas Zarcas. Similar to previous meteoritic organic studies, carboxylic acids were one to two orders of magnitude more abundant than other soluble organic compound classes investigated in both meteorite samples. We did not identify free cyanide in Aguas Zarcas and Murchison; however, cyanide species analyzed after acid digestion of the water‐extracted meteorite mineral matrix were detected and quantified at slightly higher abundances in Aguas Zarcas compared to Murchison. Although there were differences in the total abundances of specific compound classes, these two carbonaceous chondrites showed similar isomeric distributions of aliphatic amines and carboxylic acids, with common traits such as a complete suite of structural isomers that decreases in concentration with increasing molecular weight. These observations agree with their petrologic CM type‐2 classification, suggesting that these meteorites experienced similar organic formation processes and/or conditions during parent body aqueous alteration. [ABSTRACT FROM AUTHOR]

Sugars are essential molecules for all terrestrial biota working in many biological processes. Ribose is particularly essential as a building block of RNA, which could have both stored information and catalyzed reactions in primitive life on Earth. Meteorites contain a number of organic compounds including key building blocks of life, i.e., amino acids, nucleobases, and phosphate. An amino acid has also been identified in a cometary sample. However, the presence of extraterrestrial bioimportant sugars remains unclear. We analyzed sugars in 3 carbonaceous chondrites and show evidence of extraterrestrial ribose and other bioessential sugars in primitive meteorites. The 13C-enriched stable carbon isotope compositions (δ13C vs. VPDB) of the detected sugars show that the sugars are of extraterrestrial origin. We also conducted a laboratory simulation experiment of a potential sugar formation reaction in space. The compositions of pentoses in meteorites and the composition of the products of the laboratory simulation suggest that meteoritic sugars were formed by formose-like processes. The mineral compositions of these meteorites further suggest the formation of these sugars both before and after the accretion of their parent asteroids. Meteorites were carriers of prebiotic organic molecules to the early Earth; thus, the detection of extraterrestrial sugars in meteorites establishes the existence of natural geological routes to make and preserve them as well as raising the possibility that extraterrestrial sugars contributed to forming functional biopolymers like RNA on the early Earth or other primitive worlds. [ABSTRACT FROM AUTHOR]

Molecular hydrogen (H2) from volcanic emissions is suggested to warm the Martian surface when carbon dioxide (CO2) levels dropped from the Noachian (4100 to 3700 Myr) to the Hesperian (3700 to 3000 Myr). Its presence is expected to shift the conversion of molecular nitrogen (N2) into different forms of fixed nitrogen (N). Here we present experimental data and theoretical calculations that investigate the efficiency of nitrogen fixation by bolide impacts in CO2‐N2 atmospheres with or without H2. Surprisingly, nitric oxide (NO) was produced more efficiently in 20% H2 in spite of being a reducing agent and not likely to increase the rate of nitrogen oxidation. Nevertheless, its presence led to a faster cooling of the shock wave raising the freeze‐out temperature of NO resulting in an enhanced yield. We estimate that the nitrogen fixation rate by bolide impacts varied from 7 × 10−4 to 2 × 10−3 g N·Myr−1·cm−2 and could imply fluvial concentration to explain the nitrogen (1.4 ± 0.7 g N·Myr−1·cm−2) detected as nitrite (NO2−) and nitrate (NO3−) by Curiosity at Yellowknife Bay. One possible explanation is that the nitrogen detected in the lacustrine sediments at Gale was deposited entirely on the crater's surface and was subsequently dissolved and transported by superficial and ground waters to the lake during favorable wet climatic conditions. The nitrogen content sharply decreases in younger sediments of the Murray formation suggesting a decline of H2 in the atmosphere and the rise of oxidizing conditions causing a shortage in the supply to putative microbial life. Plain Language Summary: Climate models are able to warm early Mars when CO2 sources were strong but fail at later times when liquid water still flowed on the surface. A possible solution for the climate puzzle is the presence of abundant H2 arising from volcanic emissions that could have kept the planet from freezing. H2 could have also played a key role in the chemistry of the atmosphere. Curiosity discovered the presence of nitrites and nitrates, forms of fixed nitrogen that are required for the origin and sustainability of life in sediments in Gale crater. Here we present theoretical and experimental data that quantify the conversion of molecular nitrogen into fixed nitrogen in the presence and absence of H2 by the entry shocks of asteroids in the Martian atmosphere and surface. Fixed nitrogen was originally deposited on the surface of Gale crater and then transported to the lake during favorable wet climatic conditions. We found that H2 is required to yield sufficient fixed nitrogen to explain its detection. The levels of fixed nitrogen sharply dropped in younger sediments suggesting a decline of H2 in the atmosphere and the rise of oxidizing conditions causing a nitrogen crisis to putative microbial communities. Key Points: A hydrogen‐rich atmosphere is required to explain the levels of fixed nitrogen that are found in sediments encountered in Gale craterFixed nitrogen was deposited on the surface of the crater and then transported to the lake during favorable wet climatic conditionsThe levels of fixed nitrogen sharply decreased in younger sediments causing a shortage in the supply to putative microbial communities [ABSTRACT FROM AUTHOR]

X‐ray microcomputed tomography (μCT) is a useful means of characterizing cosmochemical samples such as meteorites or robotically returned samples. However, there are occasional concerns that the use of μCT may be detrimental to the organic components of a chondrite. Small organic compounds such as amino acids comprise up to ~10% of the total solvent extractable carbon in CM carbonaceous chondrites. We irradiated three samples of the Murchison CM carbonaceous chondrite under conditions akin to and harsher than those typically used during typical benchtop X‐ray μCT imaging experiments to determine if detectable changes in the amino acid abundance and distribution relative to a nonexposed Murchison control sample occurred. After subjecting three meteorite samples to ionizing radiation dosages between ~300 Gray (Gy) and 3 kGy with bremstrahlung X‐rays, we analyzed the amino acid content of each sample. Within sampling and analytical errors, we cannot discern differences in the amino acid abundances and amino acid enantiomeric ratios when comparing the control samples (nonexposed Murchison) and the irradiated samples. We conclude that a polychromatic X‐ray μCT experiment does not alter the abundances of amino acids to a degree greater than how well those abundances are measured with our techniques and therefore any damage to amino acids is minimal. [ABSTRACT FROM AUTHOR]

The analysis of water-soluble organic compounds in meteorites provides valuable insights into the prebiotic synthesis of organic matter and the processes that occurred during the formation of the solar system. We investigated the concentration of aliphatic monoamines present in hot acid water extracts of the unaltered Antarctic carbonaceous chondrites, Dominion Range ( DOM) 08006 ( CO3) and Miller Range ( MIL) 05013 ( CO3), and the thermally altered meteorites, Allende ( CV3), LAP 02206 ( CV3), GRA 06101 ( CV3), Allan Hills ( ALH) 85002 ( CK4), and EET 92002 ( CK5). We have also reviewed and assessed the petrologic characteristics of the meteorites studied here to evaluate the effects of asteroidal processing on the abundance and molecular distributions of monoamines. The CO3, CV3, CK4, and CK5 meteorites studied here contain total concentrations of amines ranging from 1.2 to 4.0 nmol g−1 of meteorite; these amounts are 1-3 orders of magnitude below those observed in carbonaceous chondrites from the CI, CM, and CR groups. The low-amine abundances for CV and CK chondrites may be related to their extensive degree of thermal metamorphism and/or to their low original amine content. Although the CO3 meteorites, DOM 08006 and MIL 05013, do not show signs of thermal and aqueous alteration, their monoamine contents are comparable to those observed in moderately/extensively thermally altered CV3, CK4, and CK5 carbonaceous chondrites. The low content of monoamines in pristine CO carbonaceous chondrites suggests that the initial amounts, and not asteroidal processes, play a dominant role in the content of monoamines in carbonaceous chondrites. The primary monoamines, methylamine, ethylamine, and n-propylamine constitute the most abundant amines in the CO3, CV3, CK4, and CK5 meteorites studied here. Contrary to the predominance of n-ω-amino acid isomers in CO3 and thermally altered meteorites, there appears to be no preference for the larger n-amines. [ABSTRACT FROM AUTHOR]

Kenig et al. comment on our 2015 reporting of laboratory analog experiments aimed at testing the stability of the hydrocarbon trap material used in the Sample Analysis on Mars (SAM) instrument on board the Curiosity Rover operating in Gale Crater on Mars. They propose chemical structures for some decomposition products of the Tenax TA polymer when it is exposed at high temperatures to the Cl2 and O2 gases formed by the thermal decomposition of perchlorate. Further, Kenig et al. propose that these decomposition products accumulate and then react further in cooler downstream sections of the SAM analytical pipeline to produce the chlorobenzene that was detected in the Cumberland mudstone of Gale Crater. However, numerous experiments conducted in the laboratory show that Tenax TA decomposition products only appear after repeated exposure to much higher levels of Cl2 and O2 than those seen by the flight instrument. Moreover, the sequence of chlorobenzene detections during gas chromatography‐mass spectrometry experiments conducted on Mars cannot be explained by Tenax TA decomposition, nor can the detection of chlorobenzene in Evolved Gas Analysis experiments that involve pathways devoid of Tenax TA. Kenig et al. are incorrect in their assertion that Tenax TA decomposition products can account for the chlorobenzene detected on Mars by SAM. Plain Language Summary: Calcium and magnesium salts of chlorate and perchlorate have been detected in surface sediments on Mars. The presence of these compounds, which emit corrosive gases when heated to high temperatures, can potentially compromise experiments aimed at detecting organic carbon compounds in Mars sediments. Perchlorate decomposition products also have the potential to damage components, namely the hydrocarbon trap, used in the construction of the Sample Analysis on Mars on instrument the Curiosity rover. In earlier work, we evaluated this possibility and provided evidence that the hydrocarbon trap was stable unless exposed to high concentrations of corrosive gases far beyond those that would be seen by the instrument operating on Mars. Experiments conducted by the SAM instrument have detected several organic compounds, including chlorobenzene, which cannot be explained by decomposition of organic materials carried on flight instrument. In particular, chlorobenzene was detected in the Cumberland mudstone in experiments that used pathways that did not include exposure to a hydrocarbon trap. Key Points: Kenig et al. (2019) speculate on the chemical structures and subsequent fate of two unknown compounds produced during repetitive laboratory testing of the Tenax TA polymer used in the SAM instrument on board the Curiosity RoverThey further speculate that Tenax TA decomposition products are the source of chlorobenzene detected by SAM in experiments on MarsMultiple lines of evidence show that chlorobenzene identified by SAM in Cumberland samples comes from an indigenous carbon source including Evolved Gas Analysis experiments that do not involve any sample contact with Tenax TA [ABSTRACT FROM AUTHOR]

X-ray microcomputed tomography and synchrotron X-ray microcomputed tomography (μ CT) are becoming popular tools for the reconnaissance imaging of chondrites. However, there are occasional concerns that the use of μ CT may be detrimental to organic components of a chondrite. Soluble organic compounds represent ~2-10% of the total solvent extractable carbon in CI and CM carbonaceous chondrites and amino acids are among the most abundant compounds in the soluble organic fraction. We irradiated two samples of the Murchison CM2 carbonaceous chondrite under conditions slightly harsher (increased beam exposure time) than those typically used for x-ray μ CT imaging experiments to determine if detectable changes in the amino acid abundance and distribution relative to a nonexposed control sample occurred. After subjecting two meteorite portions to ionizing radiation dosages of 1.1 kiloGray ( kGy) and 1.2 kGy with 48.6 and 46.6 keV monochromatic X-rays, respectively, we analyzed the amino acid content of each sample. Within analytical errors, we found no differences in the amino acid abundances or enantiomeric ratios when comparing the control samples (nonexposed Murchison) and the irradiated samples. We show with calculations that any sample heating due to x-ray exposure is negligible. We conclude that a monochromatic synchrotron X-ray μ CT experiment at beamline 13- BM-D of the Advanced Photon Source, which imparts ~1 kGy doses, has no detectable effect on the amino acid content of a carbonaceous chondrite. These results are important for the initial reconnaissance of returned samples from the OSIRIS- REx and Hayabusa 2 asteroid sample return missions. [ABSTRACT FROM AUTHOR]

The Sample Analysis at Mars (SAM) investigation on the Mars Science Laboratory (MSL) Curiosity rover has detected oxidized nitrogen-bearing compounds during pyrolysis of scooped aeolian sediments and drilled sedimentary deposits within Gale crater. Total N concentrations ranged from 20 to 250 nmol N per sample. After subtraction of known N sources in SAM, our results support the equivalent of 110-300 ppm of nitrate in the Rocknest (RN) aeolian samples, and 70-260 and 330-1,100 ppm nitrate in John Klein (JK) and Cumberland (CB) mudstone deposits, respectively. Discovery of indigenous martian nitrogen in Mars surface materials has important implications for habitability and, specifically, for the potential evolution of a nitrogen cycle at some point in martian history. The detection of nitrate in both wind-drifted fines (RN) and in mudstone (JK, CB) is likely a result of N2 fixation to nitrate generated by thermal shock from impact or volcanic plume lightning on ancient Mars. Fixed nitrogen could have facilitated the development of a primitive nitrogen cycle on the surface of ancient Mars, potentially providing a biochemically accessible source of nitrogen. [ABSTRACT FROM AUTHOR]

Exogenous delivery of amino acids and other organic molecules to planetary surfaces may have played an important role in the origins of life on Earth and other solar system bodies. Previous studies have revealed the presence of indigenous amino acids in a wide range of carbon-rich meteorites, with the abundances and structural distributions differing significantly depending on parent body mineralogy and alteration conditions. Here we report on the amino acid abundances of seven type 3-6 CK chondrites and two Rumuruti (R) chondrites. Amino acid measurements were made on hot water extracts from these meteorites by ultrahigh-performance liquid chromatography with fluorescence detection and time-of-flight mass spectrometry. Of the nine meteorites analyzed, four were depleted in amino acids, and one had experienced significant amino acid contamination by terrestrial biology. The remaining four, comprised of two R and two CK chondrites, contained low levels of amino acids that were predominantly the straight chain, amino-terminal ( n-ω-amino) acids β-alanine, and γ-amino- n-butyric acid. This amino acid distribution is similar to what we reported previously for thermally altered ureilites and CV and CO chondrites, and these n-ω-amino acids appear to be indigenous to the meteorites and not the result of terrestrial contamination. The amino acids may have been formed by Fischer-Tropsch-type reactions, although this hypothesis needs further testing. [ABSTRACT FROM AUTHOR]