Evaluating the distribution and diversity of solvent-soluble organic molecules in extraterrestrial materials provide information about the physicochemical environments where prebiotic chemistry occurred and is essential for assessing the inventory of prebiotic compounds available to the early Earth. In this work, we conducted a comprehensive molecular characterization of solvent-soluble organic compounds in a homogenized aggregate sample (ID: OREX-800107-128) of unsorted regolith from asteroid (101955) Bennu returned by NASA's OSIRISREx mission. Using two-dimensional gas chromatography coupled with high-resolution time-of-flight mass spectrometry (GC & times;GC-HRMS), we identified 87 organic compounds across several molecular classes, including alkanes, polycyclic aromatic hydrocarbons, and nitrogen-, oxygen-, and sulfur-bearing species. Comparison with the organic inventory of CI (Orgueil), C2-ungrouped (Tagish Lake and Tarda), and CM2 (Murchison) carbonaceous chondrites revealed that Bennu sample OREX-800107-128 is most similar to Tagish Lake and Tarda yet compositionally distinct from these meteorites. This Bennu sample exhibits a relatively high abundance of lowmolecular-weight aromatics (e.g., toluene), pyridine derivatives, and sulfur species such as dimethyl sulfite, consistent with episodic low-temperature aqueous alteration. The presence of these organic compounds suggests that this material experienced chemically diverse processes in the parent body conducive to complex organic synthesis, including aldol condensation reactions responsible for N- and O-bearing compounds. We also compared the molecular distributions of this Bennu sample and previously analyzed samples from (162173) Ryugu to assess potential common origins between these two carbonaceous asteroids. Bennu shows more chemically diverse and nitrogen-rich organic materials than Ryugu. While both asteroids share broadly similar primitive compositions, the observed chemical differences indicate distinct evolutionary histories within a likely common formation environment though whether Bennu and Ryugu derive from a single compositionally heterogeneous parent body or from multiple closely related progenitors remains unresolved. Further detailed comparative analyses of material from Bennu, Ryugu, and specific carbonaceous meteorites (e.g., Tagish Lake and Tarda) will provide new insights into how the N-rich molecular profile observed in Bennu samples was formed and evolved in the outer Solar System.

The measured abundance (30-50 ppb) of long-chain (C10-C12) alkanes and their possible carboxylic acid precursors found in the ancient Cumberland mudstone in Gale crater would have been substantially higher before the onset of exposure to ionizing radiation approximately 80 million years ago. Based on recent radiolysis experiments, we estimate conservatively that the Cumberland mudstone would have contained 120-7700 ppm of long-chain alkanes and/or fatty acids before ionizing radiation exposure. Such a high concentration of large organic molecules in martian sedimentary rocks cannot be readily explained by the accretion of organics from carbon-rich interplanetary dust particles and meteorites, nor by the deposition of hypothetical haze-derived organics from an ancient martian atmosphere. We discuss the feasibility of two additional mechanisms--one abiotic and one biological--that could have been capable of depositing this level of long-straight-chain organic molecules in the ancient martian mudstones: allochthonous transport of hydrothermally synthesized organics and autochthonous accumulation of organics from a hypothetical ancient Mars biosphere. To advance and test these and any additional working hypotheses put forth to explain such high concentrations of primary organics on Mars requires an understanding of the radiolytic degradation products expected for organics preserved in mineralogically comparable mudstones.

The CI (Ivuna-type) carbonaceous material returned from asteroids Ryugu and Bennu contain mobilized sodium from the evaporation or freezing of liquid water into brines, shedding light on the internal structure of ice-rich CI-type worlds and the formation of prebiotic organic compounds. The formation of brines has not been demonstrated in CM (Mighei-type) carbonaceous chondrites, which also supplied organic matter to the early Earth. Here, we announce the fall of a primitive meteorite from a daytime fireball over the New York metropolitan area in July 2024. It is a CM2 breccia that contains unique CM1 clasts rich in water and sodium. The meteorite contains abundant amino acids and other products of organic chemistry in brines that reveal subsurface processes on CM-type asteroid parent bodies.

We present an integrated analysis of the bulk elemental and isotopic compositions of H, C, and N in samples of diverse types returned from near-Earth asteroid (101955) Bennu collected by the OSIRIS-REx spacecraft (including homogenized aggregate mixtures and splits from individual angular, hummocky, and mottled particles). We also conducted elemental, isotopic and Raman spectroscopic analyses of extracted insoluble organic matter (IOM). In addition, we quantified the fraction of total C residing in carbonate minerals and measured their C and O isotopic compositions within the aggregate samples. Aggregate samples and extracted IOM from the carbonaceous chondrites Murchison and Tarda, as well as homogenized samples from the Tagish Lake (11L) meteorite, underwent parallel analyses for comparison with the Bennu materials. In the Bennu samples, the bulk H, C and N concentrations are 0.76-1.02 wt%, 3.54-4.70 wt% and 0.145-0.250 wt%, respectively. The bulk delta C-13 and delta N-15 of the samples ranges from -5.5 parts per thousand to 7.2 parts per thousand and from 43.6 parts per thousand to 109.5 parts per thousand, respectively. The delta D values for the homogenized aggregate, and the angular and hummocky particles ranged from 244 parts per thousand to 351 parts per thousand. The observed delta D variability among the subsamples of a mottled particle (350 parts per thousand to 641 parts per thousand) may be attributed to evaporative processes. The C in carbonate minerals accounts for similar to 0.6 wt% of the aggregate sample with delta C-13 of 72 parts per thousand and delta O-18 of 30 parts per thousand. Five IOM residues extracted from Bennu aggregate material exhibit an average H content of 4.0 +/- 0.2 wt%, C content of 68.0 +/- 2.5 wt% and N content of 2.9 +/- 0.1 wt%. The corresponding average isotopic compositions are delta D = 1111 +/- 30 parts per thousand, delta C-13 = -15.7 +/- 1.0 parts per thousand and delta N-15 = 47.2 +/- 0.8 parts per thousand. The elemental and isotopic compositions of H, C and N in the bulk Bennu and IOM samples generally support a genetic relationship between Bennu, Ryugu and other primitive carbonaceous chondrites, including the CIs, CMs, and the C2-ung Tagish Lake and Tarda. Based on the measured N/C and H/C atomic ratios, Bennu's IOM may have undergone a low degree of thermal alteration similar to that experienced by CIs, CMs, Tagish Lake 5b and Tarda. This alteration could have occurred in an aqueous environment, enabling the evolution of N/C and H/C atomic ratios to approximate those found in type-2 carbonaceous chondrites. Similar conclusions are supported for the evolution of the IOM delta D assuming H exchange between IOM and H2O under hydrothermal conditions. Furthermore, Raman vibrational spectra suggest that the Bennu IOM, akin to Murchison and Tarda IOM, is characterized by a higher degree of disorder than in heated CMs. Laboratory analyses of H, C and N in the returned Bennu samples confirm the major compositional inferences made from spacecraft-based spectra and reconcile Bennu's spectral heterogeneity with true lithologic variability, demonstrating that the asteroid's surface diversity reflects genuine compositional/mineralogical heterogeneity rather than observational artifacts.

We present the first investigation into the molecular structure of organic solids (insoluble organic matter, IOM) in samples of the carbonaceous asteroid (101955) Bennu returned by the OSIRIS-REx mission. We used 1H and 13C solid-sate nuclear magnetic resonance (ssNMR) to analyze three subsamples of aggregate Bennu material. However, the IOM isolated from two of the three subsamples exhibited substantial magnetic inhomogeneity, due to contaminant magnetic grains. The resulting magnetic interference degraded NMR signals for both 1H and 13C and likely introduced spectral distortions. The third subsample was pretreated with 6 N HCl prior to IOM isolation and exhibited minimal (i.e., typical) magnetic interference. In this subsample's IOM, we find a very low fraction of aromatic carbon, and a high fraction of aliphatic hydrogen, relative to IOM from Bennu's closest meteoritic analogs, the petrologic type 1 and 2 carbonaceous chondrites. Elemental analysis-isotope ratio mass spectrometry (EA-IRMS) further reveals a high H/C x 100 atomic values, relative to type 1 and 2 chondritic IOM. These data indicate that Bennu's organic solids, at least in this aggregate sample, suffered minimal to no molecular evolution from thermal perturbation throughout this material's long history-starting with accretion of a planetesimal, followed by disruption and gravitational reassembly to form a rubble-pile asteroid, and ultimately migration from the Main Belt to a near-Earth orbit. The state of molecular evolution recorded in IOM places a strong constraint on the magnitude of temperature and pressure derived from impact events that yielded the rubble-pile asteroid Bennu.

Samples collected from the carbonaceous near-Earth asteroid Bennu and delivered to Earth by NASA's OSIRIS-REx mission contain organic molecules relevant to prebiotic chemistry. Stable isotopic measurements of extraterrestrial soluble organic matter provide critical insights into the formation pathways and alteration histories of such molecules, which hold significance for understanding the origins of life. We leverage state-of-the-art techniques for picomolar-scale isotopic analyses of amino acids in samples of Bennu and, for comparison, the carbonaceous meteorite Murchison. We report intramolecular δ13C values for glycine, which have not previously been measured in extraterrestrial materials; molecular-averaged δ13C values for amino acids, aldehydes, and ketones; and δ15N values for glycine, β-alanine, and D/L-glutamic acid. Intramolecular carbon isotope patterns of glycine in Bennu contrast with those in Murchison, suggesting distinct formation pathways. We explore several formation mechanisms and hypothesize that the observed glycine in Murchison formed dominantly by a Strecker-like synthesis under aqueous conditions, whereas the glycine currently found in Bennu may have formed mainly by modified radical-radical reactions in primordial ices at the cold, outer reaches of the early Solar System and retained its isotopic values throughout accretion and multiple episodes of aqueous alteration. This hypothesis is supported by the highly 15N-enriched δ15N values in Bennu amino acids (+170 to 277‰). Differences in the δ15N values of D- and L-glutamic acid (Δ = 87‰) in Bennu affirm published reports of enantiomeric differences in meteoritic amino acids and challenge the assumption of isotopic uniformity between amino acid chiral pairs.

Carbonaceous asteroids preserve presolar grains—refractory stardust that predates the Solar System—recording both their stellar origins and subsequent alteration on their parent asteroids. Here we examine the distribution of presolar grains and isotopically anomalous organic matter in mottled particles from samples returned by the OSIRIS-REx mission from asteroid Bennu. Although the mottled samples contain organic matter with carbon and nitrogen isotopic compositions similar to those of other Bennu samples, they lack presolar silicate or oxide grains and show a markedly reduced abundance of presolar silicon carbide. In this work, we show that these findings are consistent with the slow destruction of silicon carbide grains during late-stage alteration by a low-temperature, oxidizing, alkaline brine. These brines, coinciding with evaporite salt formation, selectively erased chemically robust presolar phases while preserving isotopically anomalous organic matter. This shows that evolved aqueous fluids can fundamentally alter the presolar record of primitive asteroids. Samples from asteroid Bennu show that salty, alkaline fluids on its parent body slowly destroyed even the most refractory presolar stardust grains while leaving organic molecules intact, revealing how watery activity can erase a rock’s record of its stellar origins.

The recent discovery of all five canonical nucleobases in samples from Bennu provides compelling evidence that some of life's ingredients were synthesized abiotically in the parent body of this asteroid and/or its precedent components. However, due to the sample availability and the limited method for the analysis, the detailed distribution of nucleobases in the samples remains elusive. Here we report the concentrations of a diverse suite of nitrogen (N)-heterocycles including nucleobases extracted by 2% and 20% hydrochloric acid from a homogenized Bennu sample. The detection of both canonical and non-canonical nucleobase pairs confirms that these biologically important compounds are extraterrestrial. Pyrimidines are more abundant than purines-like the Orgueil meteorite, but unlike the Murchison meteorite and asteroid Ryugu samples-suggesting preferential synthesis in ammonia-rich ices from the outer Solar System. The distribution of other N-heterocycles is consistent with extensive aqueous alteration on the parent body. High concentrations of urea underscore its role in N-heterocycle synthesis. Our findings offer important information on the prebiotic inventory of N-heterocycles in the Solar System.

The search for organic matter on Mars has rapidly evolved in the past decade with simple aromatic, S-heterocycles, and aliphatic organic molecules detected in Gale crater. We report the in situ detection of >20 organic molecules from clay-bearing sandstones in the ~3.5-billion-year-old Knockfarrill Hill member of Glen Torridon, Gale crater, by the Sample Analysis at Mars instrument suite onboard the Curiosity rover. These molecules were liberated by the onboard tetramethylammonium hydroxide wet chemistry experiment. Diverse thermochemolysis products, including benzothiophene, methyl benzoate, and single and dicyclic aromatic molecules were released and detected by evolved gas analysis and gas chromatography-mass spectrometry. Results indicate the experiment successfully released molecules preserved in ancient macromolecular or free organic matter within Martian bedrock despite ~3.5 billion years of diagenesis and radiation exposure.

Extraterrestrial organic compounds are predominantly examined through the analysis of natural samples delivered to Earth via meteorites [1]. The focus has largely been on carbon-rich meteorites called carbonaceous chondrites. These meteorites are believed to be remnants of asteroids and are considered the oldest solid materials accessible for laboratory analysis within our solar system. The soluble organic compounds identified within carbonaceous chondrites serve as a comprehensive record of pre-solar chemical reactions, early solar system dynamics, and transformations arising from aqueous and thermal processes on the parent bodies [2]. Understanding the extraterrestrial origins of these compounds is crucial for unraveling the origins and evolution of our solar system and to determine if carbon-rich asteroids like Bennu could have delivered prebiotic molecules to the early Earth [3].Due to the unavoidable interaction of carbonaceous chondrites with Earth’s biosphere, analyses of the organic content in meteorites discovered on Earth often reveal different degrees of terrestrial contamination. To address the potential issue of contamination in extraterrestrial materials and to provide a sample from a known extraterrestrial source, NASA’s Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) mission delivered samples from the near-Earth asteroid (101955) Bennu to Earth on 24 September 2023 [4].Bennu materials will be extracted in dichloromethane at NASA Goddard Space Flight Center and will be analyzed by two-dimensional gas chromatography using a LECO GC-HRT+ 4D system (GC×GC high-resolution time of flight with mass spectrometry; GC×GC-HRMS). The use of GC×GC-HRMS offers the advantage of enabling an untargeted evaluation of the soluble organic contents in these samples. Through comparisons of data collected with the same technique from carbonaceous meteorites and from samples returned by JAXA’s Hayabusa2 mission from asteroid Ryugu, there is a potential to establish parent-daughter relationships between samples collected on Earth and asteroids [5]. Analyzing the organics of Bennu will contribute to understanding the intricate history and evolution of these compounds and their precursor molecules, spanning from the molecular cloud and protosolar nebulae to planetesimal formation and parent body processing. This study will center on the GC×GC-HRMS results obtained from solvent extracts of Bennu, which should reveal a diverse array of organic species. Acknowledgments: Supported by NASA under Award NNH09ZDA007O & Contract NNM10AA11C. References:[1] Simkus D. N. et al. (2019) Life 9, 47.[2] Glavin D. P. et al. (2018) Primitive Meteorites and Asteroids, pp. 205-271.[3] Chyba C. and Sagan C. (1992) Nature 355, 125-132.[4] Lauretta D. S. et al. (2022) Science 377, 285-291.[5] Aponte et al. (2023) Earth, Planets and Space 75, 28.

Carbonaceous chondrite (CC) meteorites are fragments of planetesimals that hold clues about the early solar system's organic matter. Amino acids are key to life on Earth; thus their study from extraterrestrial samples may help identify signs of prebiotic chemistry and life on other planets and may reveal how life as we know it began. This study analyzed amino acid concentrations and distributions in 42 CC samples, including returned samples from asteroids Ryugu and Bennu, to investigate the relationship between amino acid composition and parent body processes. We performed a statistical analysis of the amino acid molecular distributions and abundances in the context of meteoritic hydrogen, carbon, nitrogen, and carbonate total contents to explore the links between these organic species and thermal and aqueous processing experienced in the parent bodies. We also evaluated whether meteoritic amino acid ratios can be used as anti-biosignatures, and we re-evaluated the links between l-isovaline enantiomeric excesses and parent body aqueous alteration. While some trends were observed, correlations between amino acid distributions and alteration proxies (H, C, N, carbonates, enantiomeric excess) were generally weak, which indicates the need for larger sample sets. Thermal metamorphism correlated with lower amino acid and elemental [hydrogen (H), carbon (C), and nitrogen (N)] abundances, consistent with diverse parent bodies or localized processing. Ryugu samples exhibited significant amino acid variations despite similar bulk elemental compositions due to parent body heterogeneity. No strong statistical correlations were found between amino acid concentrations and H, C, or N content, which diminishes the reliability of predictions of amino acid abundances based solely on observed elemental abundances. While Ryugu and Bennu may share a common, Ceres-like parent body, observed differences in chemical composition suggest diverse evolutionary pathways. Finally, principal component analysis of amino acid and elemental data revealed distinct groupings that place Ryugu samples in a potentially unique subgroup and Bennu within the C2-ung chondrite group. These findings underscore the need for further study of such materials, especially given our discovery of their distinct nature, and emphasizes the insights gleaned from the ability to analyze returned asteroid samples.

The joint National Aeronautics and Space Administration and European Space Agency Mars Sample Return (MSR) Campaign is a proposed multi-mission effort to bring selected geological samples from Mars to Earth for the purpose of scientific investigation. Significant parts of these investigations could be affected by Earth-sourced contamination that is either misinterpreted as having a martian origin or that masks a martian signal. The Mars 2020 Perseverance rover implemented strict contamination control requirements to limit contamination of the samples during sample collection. Contamination control and contamination knowledge requirements have not yet been established for the samples after they arrive on Earth. The MSR Sample Receiving Facility (SRF) Contamination Panel (SCP) was tasked with defining the terrestrial biological, organic, and inorganic contamination limits for martian samples during their residence inside the SRF. To reach our recommendations, the SCP studied (i) the previously proposed limits and rationale of the Organic Contamination Panel, (ii) cleanliness levels achieved for sampling hardware by the M2020 mission, (iii) recent improvements in analytical technology and detection limits, (iv) updated information regarding the organic content of martian samples (e.g., from the Sample Analysis at Mars instrument on the Curiosity rover and laboratory analyses of martian meteorites), and (v) information about the composition and geologic context of samples being collected by the Perseverance rover for return to Earth.

Organic matter in meteorites reveals clues about early Solar System chemistry and the origin of molecules important to life, but terrestrial exposure complicates interpretation. Samples returned from the B-type asteroid Bennu by the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer mission enabled us to study pristine carbonaceous astromaterial without uncontrolled exposure to Earth’s biosphere. Here we show that Bennu samples are volatile rich, with more carbon, nitrogen and ammonia than samples from asteroid Ryugu and most meteorites. Nitrogen-15 isotopic enrichments indicate that ammonia and other N-containing soluble molecules formed in a cold molecular cloud or the outer protoplanetary disk. We detected amino acids (including 14 of the 20 used in terrestrial biology), amines, formaldehyde, carboxylic acids, polycyclic aromatic hydrocarbons and N-heterocycles (including all five nucleobases found in DNA and RNA), along with 10,000 N-bearing chemical species. All chiral non-protein amino acids were racemic or nearly so, implying that terrestrial life’s left-handed chirality may not be due to bias in prebiotic molecules delivered by impacts. The relative abundances of amino acids and other soluble organics suggest formation and alteration by low-temperature reactions, possibly in NH3-rich fluids. Bennu’s parent asteroid developed in or accreted ices from a reservoir in the outer Solar System where ammonia ice was stable. Rocks and dust from the asteroid Bennu contain some of the molecular building blocks of life on Earth, such as amino acids and nucleobases. They also carry ammonia that formed billions of years ago in cold, distant regions of our Solar System.

RationaleExtraterrestrial amines and ammonia are critical ingredients for the formation of astrobiologically important compounds such as amino acids and nucleobases. However, conventional methods for analyzing the composition and isotopic ratios of volatile amines suffer from lengthy derivatization and purification procedures, high sample mass consumption, and chromatographic interferences from derivatization reagents and non-target compounds.MethodsHere we demonstrate a highly efficient method to analyze the composition and compound specific isotopic ratios of C1 to C6 amines as well as ammonia based on solid phase micro-extraction (SPME) on-fiber derivatization. 2,3,4,5,6-pentafluorobenzyl chloroformate (PFBCF) adsorbed on a solid phase SPME fiber is subsequently exposed to the headspace of the water extract of the Murchison meteorite to selectively extract, derivatize and concentrate volatile amines and ammonia. PFBCF does not directly contact the aqueous solution containing other soluble organics.ResultsAn aliquot of volatile amines and ammonia in the headspace are selectively derivatized on the SPME fiber and subsequently thermally desorbed onto the GC injector for analysis. Only the amounts of amines required for either compositional or isotopic analysis are derivatized and consumed in the process, preserving the bulk fraction of amines and ammonia for other analyses, and the process does not affect other volatile compound classes. Carbon and hydrogen isotopic ratios of amines are obtained by isotopic mass balance.ConclusionsThe exceptional selectivity and sensitivity of SPME on-fiber derivatization of volatile amines in carbonaceous chondrite extracts allow minimization of sample consumption. Carbon and hydrogen isotopic values of individual amines in the Murchison meteorite are consistent with their extraterrestrial origin, with a substantial fraction inherited from interstellar molecular clouds. SPME on-fiber derivatization is well suited for analyzing extraterrestrial materials, especially precious asteroid return samples.

Nitrogen-containing organic compounds play key biological roles, and their identification in primitive astromaterials such as meteorites can shed light on the origin of life. However, meteorites are typically contaminated by uncontrolled exposure to Earth. Here we show that pristine samples returned from asteroid Bennu contain polymeric organics exceptionally rich in nitrogen and oxygen. These polymers contain a variety of functional groups including amines, amides, N-heterocycles, and aliphatic and aromatic hydrocarbons, among others. They are seen in a carbonaceous vein with mineral inclusions and in multilayered organic sheets. Their morphology and composition indicate formation from pre-aqueous N-rich precursors and later modification during aqueous alteration. These findings demonstrate that asteroids like Bennu contain complex nitrogen-rich organic phases formed by pre-aqueous and aqueous processes, and they expand the known inventory of potential prebiotic extraterrestrial compounds.

Evaporation or freezing of water-rich fluids with dilute concentrations of dissolved salts can produce brines, as observed in closed basins on Earth1 and detected by remote sensing on icy bodies in the outer Solar System2,3. The mineralogical evolution of these brines is well understood in regard to terrestrial environments4, but poorly constrained for extraterrestrial systems owing to a lack of direct sampling. Here we report the occurrence of salt minerals in samples of the asteroid (101955) Bennu returned by the OSIRIS-REx mission5. These include sodium-bearing phosphates and sodium-rich carbonates, sulfates, chlorides and fluorides formed during evaporation of a late-stage brine that existed early in the history of Bennu's parent body. Discovery of diverse salts would not be possible without mission sample return and careful curation and storage, because these decompose with prolonged exposure to Earth's atmosphere. Similar brines probably still occur in the interior of icy bodies Ceres and Enceladus, as indicated by spectra or measurement of sodium carbonate on the surface or in plumes2,3.

Deliveries of organic molecules from space, such as those found in carbonaceous meteorites, have long been hypothesized as a source of the inventory of the first life on Earth. This hypothesis is strengthened by detections of two of life’s fundamental building blocks—nucleobases and protein-building amino acids—in pristine samples returned by spacecraft from the carbonaceous asteroids Bennu and Ryugu. However, life also requires sugars, which cannot be searched for in Ryugu samples due to limited available mass, and their presence in some meteorites is equivocal owing to terrestrial exposure. Here we analyse an extract from a sample of asteroid (101955) Bennu collected by the OSIRIS-REx spacecraft and identify several bio-essential sugars, including ribose (RNA sugar) and glucose (metabolism substrate). These sugars complete the inventory of ingredients crucial to life. Their distribution is consistent with that in the condensation products of formaldehyde solution. Given that Bennu contains formaldehyde and originates from an ancient parent asteroid that underwent long-term alteration by aqueous fluids, we postulate that the detected sugars formed in the parent asteroid from brines containing formaldehyde. This indicates that material with all three components necessary to life could have been dispersed to prebiotic Earth and other inner planets. Samples returned from asteroid Bennu contain bio-essential sugars such as ribose and glucose that may have formed in the parent asteroid from brines containing formaldehyde, according to a geochemical study.

The Mars Sample Return (MSR) Campaign aims to retrieve a set of carefully selected and documented samples collected by NASA's Perseverance rover in and around Jezero Crater on Mars and deliver this set to Earth for comprehensive laboratory analyses. To emphasize the immense scientific return of this unique collection, this work presents a Sample Science Traceability Matrix (SSTM), a systematic framework that aligns each sample with the MSR campaign's defined science objectives, subobjectives, and critical research questions. The SSTM explicitly connects prioritized goals-including geologic history, astrobiology, planetary evolution, and human exploration science-to each of the individual samples gathered in and around Jezero Crater on Mars. This matrix offers a structured, quantitative method to assess each sample's capacity to address key scientific questions, while highlighting synergies across the sample suite and showcasing the overall value of the collection. The SSTM provides a valuable tool for guiding future sample analyses and identifying the most impactful samples that could be collected in the future to complete the set collected by the Mars 2020 mission. It also supports the next phase of Mars sample science and informs strategies for future Mars exploration missions. Key Words: Mars Sample Return-Perseverance-Jezero Crater-Laboratory-Sample collection-Science goals. Astrobiology 25, 725-741.

Organic molecules preserved in ancient Martian rocks provide a critical record of the past habitability of Mars and could be chemical biosignatures. Experiments conducted by the Sample Analysis at Mars instrument onboard the Curiosity rover have previously reported several classes of indigenous chlorinated and sulfur-containing organic compounds in Gale crater sedimentary rocks, with chemical structures of up to six carbons. Here, we report the detection of decane (C10H22), undecane (C11H24), and dodecane (C12H26) at the tens of pmol level, released from the Cumberland drilled mudstone sample, using a modified SAM analytical procedure optimized for the detection of larger organic molecules. Laboratory experiments support the hypothesis that the alkanes detected were originally preserved in the mudstone as long-chain carboxylic acids. The origin of these molecules remains uncertain, as they could be derived from either abiotic or biological sources.

Future missions dedicated to the search for extant life on Mars will require a clear understanding of the organic biosignature degradation processes in the shallow icy subsurface. Galactic and solar cosmic rays constantly bombard the martian surface and transform and degrade organic biomolecules over time, eventually destroying chemical evidence of life. We conducted radiolysis experiments by exposing individual amino acids in H2O-ice and silicate matrices and amino acids from dead Escherichia coli microorganisms in H2O-ice to gamma radiation as a proxy for cosmic ray exposure on the martian surface. The rates of amino acid radiolytic degradation were determined. We found that amino acids in the surface ice on Mars would survive over 50 million years of cosmic ray exposure, which is far greater than the expected age of the current surface ice deposits on Mars. Amino acids from dead E. coli organic matter in H2O-ice and isolated pure amino acids dissolved in H2O-ice tend to degrade at similar rates. We found that amino acid radiolytic degradation rates increased with increasing ice temperature in both abiotic and biological amino acids. Montmorillonite did not provide additional protection against gamma radiation to amino acids. Based on our experiments, locations with pure ice or ice-dominated permafrost would be the best places to look for recently deposited amino acids on Mars and, thus, should be considered as a target sampling location for future Mars missions searching for extant life.