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Initial analyses showed that asteroid Ryugu's composition is close to CI (Ivuna-like) carbonaceous chondrites (CCs) - the chemically most primitive meteorites, characterized by near-solar abundances for most elements. However, some isotopic signatures (for example, Ti, Cr) overlap with other CC groups, so the details of the link between Ryugu and the CI chondrites are not yet fully clear. Here we show that Ryugu and CI chondrites have the same zinc and copper isotopic composition. As the various chondrite groups have very distinct Zn and Cu isotopic signatures, our results point at a common genetic heritage between Ryugu and CI chondrites, ruling out any affinity with other CC groups. Since Ryugu's pristine samples match the solar elemental composition for many elements, their Zn and Cu isotopic compositions likely represent the best estimates of the solar composition. Earth's mass-independent Zn isotopic composition is intermediate between Ryugu/CC and non-carbonaceous chondrites (NCs), suggesting a contribution of Ryugu-like material to Earth's budgets of Zn and other moderately volatile elements.

The Perseverance rover continues to make progress on the task of collecting and documenting a set of Martian samples for future return to Earth by the Mars Sample Return program [1]. Near the end of 2022 the rover had acquired, sealed, and stored onboard a total of 15 rock cores, 2 regolith samples, 1 ambient atmosphere sample, and 3 witness tubes [2]. Of these 21 sealed tubes, 10 have been selected for inclusion in a first depot located in the Three Forks region on the floor of Jezero crater near an outflow basin [3]. In December of 2022 the rover began the construction of this depot. The Three Forks region was chosen for the depot location because it is an area with flat terrain, no large rocks, and enough area for the Perseverance rover and potential future robotic vehicles to maneuver around the depot without disturbing the sample tubes [4]. The individual sample core tips are imaged by the Mastcam-Z [5] and Cachecam [6] cameras prior to tube sealing and subsequent storage. These images document the texture and color of the samples and form an important component of the overall sample documentation data set [7]. After the sample tubes are dropped in the depot at pre-designated zones, images of the tubes are acquired with the Front Hazcam, Navcam cameras, and optionally the WATSON camera [8]. These images serve two purposes: a) to provide confirmation of the tube state to the operations team during sample depot construction and b) formally record the location of the tubes within the Three Forks region for the potential retrieval of the tubes by later missions. At the time of this writing, construction of the Three Forks sample depot by the rover operations team was underway, with depot completion expected by February 2023. References: [1] Farley, K.A., Space Sci Rev 216, 142 (2020). [2] Herd, C.D.K, et al., LPSC 2023. [3] September 2022 - MSR/M2020 Sample Depot Science Community Workshop. [4] N. Williams, Golombek, LPSC 2023. [5] Bell, J.F. III, Maki, J.N., et al. Space Sci Rev 217, 24 (2021). [6] Maki, J.N.. et al. Space Sci Rev 216, 137 (2020). [7] Maki et al., LPSC 2022. [8] Bhartia, R., et al., Space Sci Rev 217, 58 (2021).

Carletonmooreite (IMA 2018-68), Ni3Si, is a new nickel silicide mineral that occurs in metal nodules from the Norton County aubrite meteorite. These nodules are dominated by low-Ni iron (kamacite), with accessory schreibersite, nickelphosphide, perryite, and minor daubréelite, tetrataenite, taenite, and graphite. The chemical composition of the holotype carletonmooreite determined by wavelength-dispersive electron-microprobe analysis is (wt%) Ni 82.8 ± 0.4, Fe 4.92 ± 0.09, and Si 13.08 ± 0.08 (n = 6, total = 100.81) giving an empirical formula of (Ni2.87Fe0.18)Σ3.05Si0.95, with an end-member formula of Ni3Si. Further grains discovered in the specimen after the new mineral submission extend the composition, i.e., (wt%) Ni 81.44 ± 0.82, Fe 5.92 ± 0.93, Cu 0.13 ± 0.02, and Si 13.01 ± 0.1 (n = 11, total = 100.51 ± 0.41), giving an empirical formula (Ni2.83Fe0.22Cu0.004)Σ3.05Si0.95. The backscat tered electron-diffraction patterns were indexed by the Pm3m auricupride (AuCu3)-type structure and give a best fit to synthetic Ni3Si, with a = 3.51(1) Å, V = 43.2(4) Å3, Z = 1, and calculated density of 7.89 g/cm3. Carletonmooreite is silver colored with an orange tinge, isotropic, with a metallic luster and occurs as euhedral to subhedral crystals 1 × 5 µm to 5 × 14 µm growing on tetrataenite into kamacite. The dominant silicide in the Norton County aubrite metal nodules is perryite (Ni,Fe)8(Si,P)3, with carletonmooreite restricted to localized growth on rare plessite fields. The isolated nature of small euhedral carletonmooreite single crystals suggests low-temperature growth via solid-state diffusion from the surrounding kamacite and epitaxial growth on the tetrataenite. This new mineral is named in honor of Carleton B. Moore, chemist and geologist, and founding director of the Center for Meteorite Studies at Arizona State University, for his many contributions to cosmochemistry and meteoritics.

Correction to: Nature Astronomy https://doi.org/10.1038/s41550-022-01846-1. Published online 12 December 2022.

A close relationship between CM and CO chondrites has been suggested by previous petrologic and isotopic studies, leading to the suggestion that they may originate from similar precursor materials or even a common parent body. In this study, we evaluate the genetic relationship between CM and CO chondrites using Ti, Cr, and O isotopes. We first provide additional constraints on the ranges of ε50Ti and ε54Cr values of bulk CM and CO chondrites by reporting the isotopic compositions of CM2 chondrites Murchison, Murray, and Aguas Zarcas and the CO3.8 chondrite Isna. We then report the ε50Ti and ε54Cr values for several ungrouped and anomalous carbonaceous chondrites that have been previously reported to exhibit similarities to the CM and CO chondrite groups, including Elephant Moraine (EET) 83226, EET 83355, Grosvenor Mountains (GRO) 95566, MacAlpine Hills (MAC) 87300, MAC 87301, MAC 88107, and Northwest Africa (NWA) 5958, and the oxygen isotope compositions of a subset of these samples. We additionally report the ε50Ti, ε54Cr, and O isotopic compositions of additional ungrouped chondrites LaPaz Ice Field (LAP) 04757, LAP 04773, Lewis Cliff (LEW) 85332, and Coolidge to assess their potential relationships with known carbonaceous and ordinary chondrite groups. LAP 04757 and LAP 04773 exhibit isotopic compositions indicating they are low-FeO ordinary chondrites. The isotopic compositions of Murchison, Murray, Aguas Zarcas, and Isna extend the compositional ranges defined by the CM and CO chondrites in ε50Ti versus ε54Cr space. The majority of the ungrouped carbonaceous chondrites with documented similarities to the CM and/or CO chondrites plot outside the CM and CO group fields in plots of ε50Ti versus ε54Cr,Δ17O versus ε50Ti, and Δ17O versus ε54Cr. Therefore, based on differences in their Ti, Cr, and O-isotopic compositions, we conclude that the CM, CO, and ungrouped carbonaceous chondrites likely represent samples of multiple distinct parent bodies. We also infer that these parent bodies formed from precursor materials that shared similar isotopic compositions, which may indicate formation in regions of the protoplanetary disk that were in close proximity to each other.

Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measured the mineralogy and bulk chemical and isotopic compositions of Ryugu samples. The samples are mainly composed of materials similar to those of carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37° ± 10°C, about 5.2 − 0.7 + 0.8 million (statistical) or 5.2 − 2.1 + 1.6 million (systematic) years after the formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above ~100°C. The samples have a chemical composition that more closely resembles that of the Sun’s photosphere than other natural samples do.

The NASA Mars 2020 Perseverance rover mission will collect a suite of scientifically compelling samples for return to Earth. On the basis of orbital data, the Mars 2020 science team identified two notional sample caches to study (1) the geology of Jezero crater, collected during the prime mission and (2) the ancient crust outside of Jezero crater, collected during a possible extended mission. Jezero crater geology consists of well-preserved, Early Hesperian to Late Noachian deltaic and lacustrine deposits sourced from a river system that drained Noachian terrain. The crater floor comprises at least two distinct units of sedimentary or volcanic origin whose relationship to the deltaic deposits is presently unclear. Remotely-sensed data reveal signatures of carbonate+olivine and clay minerals within crater floor and crater margin units. Samples from within Jezero that comprise the prime mission notional sample collection thus include: crater floor units; fine- and coarse-grained delta facies, the former with potential to preserve organic matter and/or biosignatures, the latter to possibly constrain the type and timing of sediment deposition; chemical sediments with the potential to preserve biosignatures; a sample of crater rim bedrock; and at least one sample of regolith. The region of southern Nili Planum, directly outside the western rim of Jezero crater, is geologically distinct from Jezero crater and contains diverse Early or even Pre-Noachian lithologies, that may contain records of early planetary differentiation, magnetism, paleoclimate and habitability. The notional sample collection from this region will include: layered and other basement rocks; megabreccias, which may represent blocks of (pre-)Noachian crust; basement-hosted hydrothermal fracture fill; olivine+carbonate rocks that are regionally significant and may be related to units within Jezero crater; and mafic cap unit rocks. The samples described are notional and may change with ongoing surface investigations. However, the samples we anticipate collecting align well with community priorities for Mars exploration, addressing geologic diversity, potential ancient biologic activity on Mars, planetary evolution, volatiles, and human health hazards. Many other Mars 2020 team members were involved in this planning.

Beryllium-10 (t1/2 = 1.4 Ma) is a short-lived radionuclide present in the early Solar System. It is produced solely by irradiation reactions and can provide constraints on the astrophysical environment of the Sun's formation. Calcium- and aluminium-rich inclusions (CAIs), the first solids formed in the Solar System, show clear evidence for live 10Be at their time of formation, but it is unclear whether they record the same initial 10Be/9Be ratio. In this study, we examine the secondary ion mass spectrometry methods used to determine the initial 10Be/9Be ratio in meteoritic inclusions. Based on analyses of synthesised matrix-matched glass reference materials, we show that the effects of differing major element bulk compositions on the secondary ion yields of Be and B are minor for relevant phases. We demonstrate the importance of using the mean square weighted deviation (MSWD) to interpret the significance of the initial 10Be/9Be value. For thirty-two CAIs, we re-calculated the regressions using literature data, finding that several have unacceptably high MSWD. We calculate the effects of possible sources of isotopic disturbance. Finally, we outline best practices for reporting 10Be-10B data, to enable a more refined determination of the initial 10Be/9Be ratio in the early Solar System.

At present, meteorites collected in Antarctica dominate the total number of the world's known meteorites. We focus here on the scientific advances in cosmochemistry and planetary science that have been enabled by access to, and investigations of, these Antarctic meteorites. A meteorite recovered during one of the earliest field seasons of systematic searches, Elephant Moraine (EET) A79001, was identified as having originated on Mars based on the composition of gases released from shock melt pockets in this rock. Subsequently, the first lunar meteorite, Allan Hills (ALH) 81005, was also recovered from the Antarctic. Since then, many more meteorites belonging to these two classes of planetary meteorites, as well as other previously rare or unknown classes of meteorites (particularly primitive chondrites and achondrites), have been recovered from Antarctica. Studies of these samples are providing unique insights into the origin and evolution of the Solar System and planetary bodies. ▪ Antarctic meteorites dominate the inventory of the world's known meteorites and provide access to new types of planetary and asteroidal materials. ▪ The first meteorites recognized to be of lunar and martian origin were collected from Antarctica and provided unique constraints on the evolution of the Moon and Mars. ▪ Previously rare or unknown classes of meteorites have been recovered from Antarctica and provide new insights into the origin and evolution of the Solar System.

NASA's Genesis Mission returned solar wind (SW) to the Earth for analysis to derive the composition of the solar photosphere from solar material. SW analyses control the precision of the derived solar compositions, but their ultimate accuracy is limited by the theoretical or empirical models of fractionation due to SW formation. Mg isotopes are “ground truth” for these models since, except for CAIs, planetary materials have a uniform Mg isotopic composition (within ≤1‰) so any significant isotopic fractionation of SW Mg is primarily that of SW formation and subsequent acceleration through the corona. This study analyzed Mg isotopes in a bulk SW diamond‐like carbon (DLC) film on silicon collector returned by the Genesis Mission. A novel data reduction technique was required to account for variable ion yield and instrumental mass fractionation (IMF) in the DLC. The resulting SW Mg fractionation relative to the DSM‐3 laboratory standard was (−14.4‰, −30.2‰) ± (4.1‰, 5.5‰), where the uncertainty is 2ơ SE of the data combined with a 2.5‰ (total) error in the IMF determination. Two of the SW fractionation models considered generally agreed with our data. Their possible ramifications are discussed for O isotopes based on the CAI nebular composition of McKeegan et al. (2011).

The Mars Sample Return (MSR) Campaign must meet a series of scientific and technical achievements to be successful. While the respective engineering responsibilities to retrieve the samples have been formalized through a Memorandum of Understanding between ESA and NASA, the roles and responsibilities of the scientific elements have yet to be fully defined. In April 2020, ESA and NASA jointly chartered the MSR Science Planning Group 2 (MSPG2) to build upon previous planning efforts in defining 1) an end-to-end MSR Science Program and 2) needed functionalities and design requirements for an MSR Sample Receiving Facility (SRF). The challenges for the first samples brought from another planet include not only maintaining and providing samples in pristine condition for study, but also maintaining biological containment until the samples meet sample safety criteria for distribution outside of biocontainment. The MSPG2 produced six reports outlining 66 findings. Abbreviated versions of the five additional high-level MSPG2 summary findings are: Summary-1. A long-term NASA/ESA MSR Science Program, along with the necessary funding and human resources, will be required to accomplish the end-to-end scientific objectives of MSR. Summary-2. MSR curation would need to be done concurrently with Biosafety Level-4 containment. This would lead to complex first-of-a-kind curation implementations and require further technology development. Summary-3. Most aspects of MSR sample science could, and should, be performed on samples deemed safe in laboratories outside of the SRF. However, other aspects of MSR sample science are both time-sensitive and sterilization-sensitive and would need to be carried out in the SRF. Summary-4. To meet the unique science, curation, and planetary protection needs of MSR, substantial analytical and sample management capabilities would be required in an SRF. Summary-5. Because of the long lead-time for SRF design, construction, and certification, it is important that preparations begin immediately, even if there is delay in the return of samples.

The performance of multi-collector secondary ion mass spectrometry (MC-SIMS) for Mg isotope ratio analysis was evaluated using 17 olivine and 5 pyroxene reference materials (RMs). The Mg isotope composition of these RMs was accurately and precisely determined by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), and these measured isotope ratios were used to evaluate SIMS instrumental mass bias as a function of the forsterite (Fo) content of olivine. The magnitude of the Mg isotope matrix effects were ~3‰ in δ(25)Mg, and are a complex function of olivine Fo content, that ranged from Fo(59.3) to Fo(100). In addition to these Mg isotope matrix effects, Si(+) ion yields and Mg(+)/Si(+) ion ratios varied as a complex function of the Fo content of the olivine RMs. For example, Si(+) ion yields varied by ~33%. Based on the observations, we propose instrumental bias correction procedures for SIMS Mg isotope analysis of olivine using a combination of Mg(+)/Si(+) ratios and Fo content of olivine. Using this correction method, the accuracy of δ(25)Mg analyses is 0.3‰, except for analysis of olivine with Fo(86-88) where instrumental biases and Mg(+)/Si(+) ratios change dramatically with Fo content, making it more difficult to assess the accuracy of Mg isotope ratio measurements by SIMS over this narrow range of Fo content. Five pyroxene RMs (3 orthopyroxenes and 2 clinopyroxenes) show smaller ranges of instrumental bias (~1.4‰ in δ(25)Mg) as compared to the olivine RMs. The instrumental bias for the 3 orthopyroxene RMs do not define a linear relationship with respect to enstatite (En) content, that ranged from En(85.5 −96.3). The clinopyroxene RMs have similar En and wollastonite (Wo) contents but have δ(25)Mg values that differ by 0.5‰ relative to their δ(25)Mg values determined by MC-ICP-MS. These results indicate that additional factors (e.g., minor element abundances) likely contribute to SIMS instrumental mass fractionation. In order to better correct for these SIMS matrix effects, additional pyroxene RMs with various chemical compositions and known Mg isotope ratios are needed.

Larkman Nunatak (LAR) 12095 and LAR 12240 are recent olivine-phyric shergottite lnds. We report the results of petrographic and chemical analyses of these two samples to understand their petrogenesis on Mars. Based on our analyses, we suggest that these samples are likely paired and are most similar to other depleted olivine-phyric shergottites, particularly Dar al Gani (DaG) 476 and Sayh al Uhaymir (SaU) 005 (and samples paired with those). The olivine megacryst cores in LAR 12095 and LAR 12240 are not in equilibrium with the groundmass olivines. We infer that these megacrysts are phenocrysts and their major element compositions have been homogenized by diffusion (the cores of the olivine megacrysts have Mg# ~70, whereas megacryst rims and groundmass olivines typically have Mg# ~58-60). The rare earth element (REE) microdistributions in the various phases (olivine, low- and high-Ca pyroxene, maskelynite, and merrillite) in both samples are similar and support the likelihood that these two shergottites are indeed paired. The calculated parent melt (i.e., in equilibrium with the low-Ca pyroxene, which is one of the earliest formed REE-bearing minerals) has an REE pattern parallel to that of melt in equilibrium with merrillite (i.e., one of the last-formed minerals). This suggests that the LAR 12095/12240 paired shergottites represent the product of closed-system fractional crystallization following magma emplacement and crystal accumulation. Utilizing the europium oxybarometer, we estimate that the magmatic oxygen fugacity early in the crystallization sequence was ~IW. Finally, petrographic evidence indicates that LAR 12095/12240 experienced extensive shock prior to being ejected from Mars.

Comets hold answers to mysteries of the Solar System by recording presolar history, the initial states of planet formation and prebiotic organics and volatiles to the early Earth. Analysis of returned samples from a comet nucleus will provide unparalleled knowledge about the Solar System starting materials and how they came together to form planets and give rise to life: 1. How did comets form? 2. Is comet material primordial, or has it undergone a complex alteration history? 3. Does aqueous alteration occur in comets? 4. What is the composition of cometary organics? 5. Did comets supply a substantial fraction of Earth's volatiles? 6. Did cometary organics contribute to the homochirality in life on Earth? 7. How do complex organic molecules form and evolve in interstellar, nebular, and planetary environments? 8. What can comets tell us about the mixing of materials in the protosolar nebula?, Comment: White Paper submitted to the Planetary Science Decadal Survey 2023-2032 reflecting the viewpoints of three New Frontiers comet sample return missions proposal teams, CAESAR, CONDOR, and CORSAIR

Recent investigations of meteorites thought to originate from the asteroid 4 Vesta have suggested an early accretion of water on rocky bodies in the inner Solar System from a carbonaceous chondrite-like source. However, these studies have been based on the hydrogen isotope compositions (δD) of late-crystallizing apatite grains in eucrites that likely do not record the primary magmatic composition. We have determined the δD and H2O concentrations in some of the earliest-formed silicates (clinopyroxenes) from several eucrites with the goal of constraining the hydrogen isotope composition of their source reservoir on their parent body. The H2O concentrations in clinopyroxenes from eucrites Juvinas, Stannern and Tirhert range from 5 to 18 μg/g, with a weighted average δD of –263 ± 70‰. Their apatites and whitlockites exhibit a higher weighted average δD of –165 ± 73‰, possibly as a result of H2 degassing during or after phosphate crystallization. Thermal metamorphism of these eucrites has most probably resulted in the loss of H, and an increase in their original δD values. While the weighted average δD value for the eucrite clinopyroxenes reported here is inferred to reflect an upper limit for the isotopic composition of the silicate mantle reservoir on their parent asteroid 4 Vesta, the average δD value of Stannern clinopyroxenes is considered to be closest to the initial δD of the source mantle (i.e., –373 ± 127‰), which is lighter than that of Earth’s depleted upper mantle and most carbonaceous chondrites. We suggest that at least some of the water in 4 Vesta (and possibly other rocky bodies in the inner Solar System) was derived from a relatively deuterium-poor reservoir in the protosolar nebula, which was incorporated into planetesimals formed early in Solar System history.

The angrites are a class of achondrites that encompass a wide range of igneous textures from quenched, volcanic, and subvolcanic stones to slowly cooled, plutonic rocks. The compositions of the various geochemical reservoirs generating this variety of rocks have not been investigated fully because historically the numbers and masses of angrites available for study have been quite small. However, the rapid increase in meteorites from Northwest Africa (NWA) has enabled a renewed opportunity for such an investigation. In particular, three samples, NWA 2999, 4590, and 4801, have provided a new window into our understanding of the origin and petrogenesis of the coarse-grained (plutonic) angrites. We report here the trace element abundances in individual mineral grains of pyroxene, plagioclase, olivine/kirschsteinite, and phosphate and in the whole-rock samples. We utilize these data to constrain the petrogenetic history of each of these samples on the angrite parent body (e.g., parental melt compositions and oxygen fugacity conditions) and assess genetic relationships to previously investigated angrites. The trace element abundances in each of the three coarse-grained angrites studied here indicate a unique history for each. The observed trace element abundances and patterns in NWA 2999 show similarities with previously studied fine-grained, volcanic angrites and potentially indicate a common geochemical source reservoir, even though NWA 2999 is temporally distinct from the volcanic angrites. In contrast, NWA 4590 has trace element characteristics analogous to other coarse-grained angrites (e.g., Lewis Cliff [LEW] 86010), suggesting that these samples originated from geochemically similar source reservoirs. The third angrite, NWA 4801, exhibits geochemical characteristics most similar to the plutonic, coarse-grained angrites, but also appears to have some affinities in its trace element characteristics to the volcanic, fine-grained angrites. This suggests that NWA 4801 may represent a petrogenetic link between two distinct geochemical reservoirs on the angrite parent body. In aggregate, the trace element distributions in these three plutonic angrites suggest that while they may have originated up to several million years after the fine-grained angrites, they sampled a range of source reservoirs on the angrite parent body. Some of these source reservoirs were likely similar to those of the fine-grained angrites, but others had distinct geochemical characteristics.

Calcium-aluminum-rich inclusions (CAIs) are the first solids to form in the early Solar System, and they exhibit nucleosynthetic anomalies in many isotope systems. The overwhelming majority of isotopic data for CAIs has been limited to inclusions from the CV chondrite Allende and a select few other CV, CO, CM, and ordinary chondrites. It is therefore important to ascertain whether previously reported values for CAIs are representative of the broader CAI-forming region and to make a more rigorous assessment of the extent and implications of isotopic heterogeneity in the early Solar System. Here, we report the mass-independent Ti isotopic compositions of a suite of 23 CAIs of diverse petrologic and geochemical types, including 11 from Allende and 12 from seven other CV3 and CK3 chondrites; the data for CAIs from CK chondrites represent the first reported measurements of Ti isotope compositions of refractory inclusions from this meteorite class. The resolved variation in the mass-independent Ti isotopic compositions of these CAIs indicates that the CAI-forming region of the early Solar System preserved isotopic variability at their time of formation. Nevertheless, the range of Ti isotope compositions reported here for CAIs from CV and CK chondrites falls within the range observed in previously analyzed CAIs from CV, CO, CM, and ordinary chondrites. This implies that CAIs from CV, CK, CO, CM, and ordinary chondrites originated from a common nebular source reservoir characterized by mass-independent isotopic variability in Ti (and other select elements). We further interpret these data to indicate that the Ti isotope anomalies in CAIs represent the isotopic signatures of supernova components in presolar grains that were incorporated into the Solar System in an initially poorly mixed reservoir that was progressively homogenized over time. We conclude that the differing degrees of isotopic variability observed for different elements in normal CAIs are the result of distinct carrier phases and that these CAIs were likely formed towards the final stages of homogenization of the large-scale isotopic heterogeneity that initially existed in the solar nebula.

The NASA/ESA Mars Sample Return (MSR) Campaign seeks to establish whether life on Mars existed where and when environmental conditions allowed. Laboratory measurements on the returned samples are useful if what is measured is evidence of phenomena on Mars rather than of the effects of sterilization conditions. This report establishes that there are categories of measurements that can be fruitful despite sample sterilization and other categories that cannot. Sterilization kills living microorganisms and inactivates complex biological structures by breaking chemical bonds. Sterilization has similar effects on chemical bonds in non-biological compounds, including abiotic or pre-biotic reduced carbon compounds, hydrous minerals, and hydrous amorphous solids. We considered the sterilization effects of applying dry heat under two specific temperature-time regimes and the effects of γ-irradiation. Many measurements of volatile-rich materials are sterilization sensitive—they will be compromised by either dehydration or radiolysis upon sterilization. Dry-heat sterilization and γ-irradiation differ somewhat in their effects but affect the same chemical elements. Sterilization-sensitive measurements include the abundances and oxidation-reduction (redox) states of redox-sensitive elements, and isotope abundances and ratios of most of them. All organic molecules, and most minerals and naturally occurring amorphous materials that formed under habitable conditions, contain at least one redox-sensitive element. Thus, sterilization-sensitive evidence about ancient life on Mars and its relationship to its ancient environment will be severely compromised if the samples collected by Mars 2020 rover Perseverance cannot be analyzed in an unsterilized condition. To ensure that sterilization-sensitive measurements can be made even on samples deemed unsafe for unsterilized release from containment, contingency instruments in addition to those required for curation, time-sensitive science, and the Sample Safety Assessment Protocol would need to be added to the Sample Receiving Facility (SRF). Targeted investigations using analogs of MSR Campaign-relevant returned-sample types should be undertaken to fill knowledge gaps about sterilization effects on important scientific measurements, especially if the sterilization regimens eventually chosen are different from those considered in this report., Astrobiology, 22 (S1), ISSN:1531-1074, ISSN:1557-8070

Beryllium-10 (t(1/2) = 1.4 Ma) is a short-lived radionuclide present in the early Solar System. It is produced solely by irradiation reactions and can provide constraints on the astrophysical environment of the Sun’s formation. Calcium- and aluminium-rich inclusions (CAIs), the first solids formed in the Solar System, show clear evidence for live (10)Be at their time of formation, but it is unclear whether they record the same initial (10)Be/(9)Be ratio. In this study, we examine the secondary ion mass spectrometry methods used to determine the initial (10)Be/(9)Be ratio in meteoritic inclusions. Based on analyses of synthesised matrix-matched glass reference materials, we show that the effects of differing major element bulk compositions on the secondary ion yields of Be and B are minor for relevant phases. We demonstrate the importance of using the mean square weighted deviation (MSWD) to interpret the significance of the initial (10)Be/(9)Be value. For thirty-two CAIs, we re-calculated the regressions using literature data, finding that several have unacceptably high MSWD. We calculate the effects of possible sources of isotopic disturbance. Finally, we outline best practices for reporting (10)Be–(10)B data, to enable a more refined determination of the initial (10)Be/(9)Be ratio in the early Solar System.

Calcium-aluminum-rich inclusions (CAIs) are the oldest dated materials that provide crucial information about the isotopic reservoirs present in the early Solar System. For a variety of elements, CAIs have isotope compositions that are uniform yet distinct from later formed solid material. However, despite being the most abundant metal in the Solar System, the isotopic composition of Fe in CAIs is not well constrained. In an attempt to determine the Fe isotopic compositions of CAIs, we combine extensive work from a previously studied CAI sample set with new isotopic work characterizing mass-dependent and mass-independent (nucleosynthetic) signatures in Mg, Ca, and Fe. This investigation includes work on three mineral separates of the Allende CAI Egg 2. For all isotope systems investigated, we find that in general, fine-grained CAIs exhibit light mass-dependent isotopic signatures relative to terrestrial standards, whereas igneous CAIs have heavier isotopic compositions relative to the fine-grained CAIs. Importantly, the mass-dependent Fe isotope signatures of bulk CAIs show a range of both light (fine-grained CAIs) and heavy (igneous CAIs) isotopic signatures relative to bulk chondrites, suggesting that Fe isotope signatures in CAIs largely derive from mass fractionation events such as condensation and evaporation occurring in the nebula. Such signatures show that a significant portion of the secondary alteration experienced by CAIs, particularly prevalent in fine-grained inclusions, occurred in the nebula prior to accretion into their respective parent bodies. Regarding nucleosynthetic Fe isotope signatures, we do not observe any variation outside of analytical uncertainty in bulk CAIs compared to terrestrial standards. In contrast, all three Egg 2 mineral separates display resolved mass-independent excesses in (56)Fe compared to terrestrial standards. Furthermore, we find that the combined mass-dependent and nucleosynthetic Fe isotopic compositions of the Egg 2 mineral separates are well correlated, likely indicating that Fe indigenous to the CAI is mixed with less anomalous Fe, presumably from the solar nebula. Thus, these reported nucleosynthetic anomalies may point in the direction of the original Fe isotope composition of the CAI-forming region, but they likely only provide a minimum isotopic difference between the original mass-independent Fe isotopic composition of CAIs and that of later formed solids.

We advocate for the realization of volatile sample return from various destinations including: small bodies, the Moon, Mars, ocean worlds/satellites, and plumes. As part of recent mission studies (e.g., Comet Astrobiology Exploration SAmple Return (CAESAR) and Mars Sample Return), new concepts, technologies, and protocols have been considered for specific environments and cost. Here we provide a plan for volatile sample collection and identify the associated challenges with the environment, transit/storage, Earth re-entry, and curation. Laboratory and theoretical simulations are proposed to verify sample integrity during each mission phase. Sample collection mechanisms are evaluated for a given environment with consideration for alteration. Transport and curation are essential for sample return to maximize the science investment and ensure pristine samples for analysis upon return and after years of preservation. All aspects of a volatile sample return mission are driven by the science motivation: isotope fractionation, noble gases, organics and prebiotic species; plus planetary protection considerations for collection and for the sample. The science value of sample return missions has been clearly demonstrated by previous sample return programs and missions. Sample return of volatile material is key to understanding (exo)planet formation, evolution, and habitability. Returning planetary volatiles poses unique and potentially severe technical challenges. These include preventing changes to samples between (and including) collection and analyses, and meeting planetary protection requirements., Comment: White paper submitted to the Planetary Science and Astrobiology Decadal Survey 2023-2032

The ranges in chemical composition of ancient achondrite meteorites are key to understanding the diversity and geochemical evolution of planetary building blocks. These achondrites record the first episodes of volcanism and crust formation, the majority of which are basaltic. Here we report data on recently discovered volcanic meteorite Northwest Africa (NWA) 11119, which represents the first, and oldest, silica-rich (andesitic to dacitic) porphyritic extrusive crustal rock with an Al–Mg age of 4564.8 ± 0.3 Ma. This unique rock contains mm-sized vesicles/cavities and phenocrysts that are surrounded by quench melt. Additionally, it possesses the highest modal abundance (30 vol%) of free silica (i.e., tridymite) compared to all known meteorites. NWA 11119 substantially widens the range of volcanic rock compositions produced within the first 2.5–3.5 million years of Solar System history, and provides direct evidence that chemically evolved crustal rocks were forming on planetesimals prior to the assembly of the terrestrial planets., Achondritic meteorites can record volcanism and crust formation on planetesimals in the early Solar System. Here, the authors date the Northwest Africa 11119 meteorite with an Al-Mg age of 4564.8 ± 0.3 Ma indicating that this is the earliest evidence of silicic volcanism in the Solar System to date.

Determining the hydrogen isotopic compositions and H2O contents of meteorites and their components is important for addressing key cosmochemical questions about the abundance and source(s) of water in planetary bodies. However, deconvolving the effects of terrestrial contamination from the indigenous hydrogen isotopic compositions of these extraterrestrial materials is not trivial, because chondrites and some achondrites show only small deviations from terrestrial values such that even minor contamination can mask the indigenous values. Here we assess the effects of terrestrial weathering and contamination on the hydrogen isotope ratios and H2O contents of meteoritic minerals through monitored terrestrial weathering of Tissint, a recent Martian fall. Our findings reveal the rapidity with which this weathering affects nominally anhydrous phases in extraterrestrial materials, which illustrates the necessity of sampling the interiors of even relatively fresh meteorite falls and underlines the importance of sample return missions.

Chemical clues reveal stories from the birth of the Solar System. Chemical clues reveal stories from the birth of the Solar System.

Detailed petrologic, geochemical and isotopic analyses of a new FUN CAI from the Allende CV3 meteorite (designated CMS-1) indicate that it formed by extensive melting and evaporation of primitive precursor material(s). The precursor material(s) condensed in a 16O-rich region (δ17O and δ18O ∼ −49‰) of the inner solar nebula dominated by gas of solar composition at total pressures of ∼10−3–10−6 bar. Subsequent melting of the precursor material(s) was accompanied by evaporative loss of magnesium, silicon and oxygen resulting in large mass-dependent isotope fractionations in these elements (δ25Mg = 30.71–39.26‰, δ29Si = 14.98–16.65‰, and δ18O = −41.57 to −15.50‰). This evaporative loss resulted in a bulk composition similar to that of compact Type A and Type B CAIs, but very distinct from the composition of the original precursor condensate(s). Kinetic fractionation factors and the measured mass-dependent fractionation of silicon and magnesium in CMS-1 suggest that ∼80% of the silicon and ∼85% of the magnesium were lost from its precursor material(s) through evaporative processes. These results suggest that the precursor material(s) of normal and FUN CAIs condensed in similar environments, but subsequently evolved under vastly different conditions such as total gas pressure. The chemical and isotopic differences between normal and FUN CAIs could be explained by sorting of early solar system materials into distinct physical and chemical regimes, in conjunction with discrete heating events, within the protoplanetary disk.

Although there is limited direct evidence for supernova input into the nascent Solar System, many models suggest it formed by the gravitational collapse of a molecular cloud that was triggered by a nearby supernova. Existing lines of evidence, mostly in the form of short-lived radionuclides present in the early Solar System, are potentially consistent with this hypothesis, but still allow for alternative explanations. Since the natural production of 126Sn is thought to occur only in supernovae and this isotope has a short half-life (126Sn→126Te, t1/2 = 235 ky), the discovery of extant 126Sn would provide unequivocal proof of supernova input to the early Solar System. Previous attempts to quantify the initial abundance of 126Sn by examining Sn-Te systematics in early solids have been hampered by difficulties in precisely measuring Te isotope ratios in these materials. Thus, here we describe a novel technique that uses hydride generation to dramatically increase the ionization efficiency of Te—an approximately 30-fold increase over previous work. This introduction system, when coupled to a MC-ICPMS, enables high-precision Te isotopic analyses on samples with