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.

Introduction: The Blaubeuren meteorite was discovered in 1989 in southern Germany by a homeowner digging a cable trench in his garden, though it remained unrecognized as a meteorite until 2020. It is an H4-5 ordinary chondrite breccia weighing over 30 kg and the largest recovered stony meteorite in Germany [1]. 14C-10Be dating revealed a terrestrial age of 9.2 ± 0.3 ka. Repeated search campaigns by private meteorite hunters led to a newly recognized specimen in a forest close to the city of Schelklingen, ~3 km from the find location of the Blaubeuren meteorite.Figure 1: Cut face of the new specimen. The metal grains are remarkably unweathered.Results: To verify a potential relationship to Blaubeuren, the new specimen has been studied using various techniques (optical and electron microscopy, bulk chemical, radionuclide [14C, 26Al, 41Ca] and noble gas analyses). It is an only moderately weathered single stone with a mass of ~17 g showing remnants of weathered fusion crust. Its O isotopic composition places it in the field of H chondrites. Petrographic study shows a rock with chondrules and chondrule relics (Figure 2) and an only slightly weathered interior (W1/2) [2]. The rock is unbrecciated at the thin section scale. Olivine grains show mosaicism indicating a shock degree of C-S4 [3]. The mean composition of olivine is Fa18.4±0.3 and the low-Ca pyroxenes have a mean composition of Fs16.1±0.3. The terrestrial age of the specimen has been determined by 14C-dating and found to be 9.4±1.3 ka. Preliminary noble gas data give gas retention ages of ~3.1 Ga and ~3.7 Ga for 4He and 40Ar, respectively, and cosmogenic 3He, 21Ne, and 38Ar concentrations 2–4× lower than measured for Blaubeuren. Cosmogenic radionuclides (26Al/27Al and 41Ca/40Ca) of the Schelklingen specimen are comparable to those of Blaubeuren [1] pointing to similar recent exposure conditions.Figure 2: (a) Cross-polarized photograph of an area in the new specimen from close to Schelklingen with a chondrule and more metamorphosed material. (b) Cross-polarized photograph of an area in the Blaubeuren meteorite showing various types of chondrules and relics thereof.Discussion: A comparison of the newly found specimen found close to Schelklingen with Blaubeuren shows a very similar mineralogy. Major differences compared to the Blaubeuren meteorite are that the newly found specimen shows (1) a significantly lower degree of terrestrial weathering, (2) a higher shock degree (C-S4 versus C-S2 for Blaubeuren), and (3) lower cosmogenic noble gas concentrations. The significantly fresher appearance of the new specimen may be attributed to different alteration conditions on the different locations (forest slope vs. soil inside a valley for Blaubeuren). This could have resulted in lower soil moisture and therefore favorable preservation of the Schelklingen specimen as the type and extent of terrestrial alteration depends on various aspects [4]. Differences in the shock degree can easily be explained by heterogeneity at the sample size studied because shock effects can vary from clast to clast at the cm-scale [5]. Thus, C-S4 shocked clasts may well be present elsewhere in the main mass of Blaubeuren. The differences in the cosmogenic noble gas concentrations of Blaubeuren and the new specimen may indicate they originated from strongly different depths within a large meteoroid (i.e., >120 cm radius). This, however, is not consistent with the similar cosmogenic radionuclide data obtained for both meteorites. Instead, this could suggest a more complex exposure history, (1) either on the parent body with Blaubeuren having experienced pre-exposure close to the surface or (2) that the meteoroid was a rubble pile consisting of individual fragments that experienced individual exposure histories. We consider it extremely unlikely that Blaubeuren and the new Schelklingen specimen originate from different meteoroids, which impacted Earth roughly at the same time and same place: Although. H ordinary chondrites represent the second most abundant class of meteorite falls [6,7], finding two meteorites from separate fall events within ~3 km seems statistically not favorable.Conclusion: The new Schelklingen specimen and the Blaubeuren meteorite may be part of the same strewn field and therefore of the same meteoroid with a complex exposure history impacting Earth about 9 ka ago. Their differences in the shock degree and weathering may be explained by sample heterogeneity (as typical for breccias) at the cm-scale and different alteration conditions during the ~9 ka of terrestrial weathering.References: [1] Bischoff, A. et al. (2022) Meteoritics & Planetary Science 57:136-153. [2] Wlotzka, F. (1993). A weathering scale for the ordinary chondrites. Meteoritics, vol. 28, no. 3, volume 28, page 460-460, 28. [3] Stöffler, D., Hamann, C., & Metzler, K. (2018). Shock metamorphism of planetary silicate rocks and sediments: Proposal for an updated classification system. Meteoritics & Planetary Science, 53(1), 5-49. [4] Bland, P. A., et al. (2006). Meteorites and the early solar system II, 1, 853-867. [5] Sharp, T. G., & DeCarli, P. S. (2006). Meteorites and the early solar system II, 943, 653-677. [6] Kouvatsis, I., & Hofmann, B. A. (2020). Meteoritics & Planetary Science, 55(1), 67-76. [7] The Meteorite Bulletin Database, 2026; https://www.lpi.usra.edu/meteor/

Most ureilites are melt residues from the partially melted Ureilite Parent Body. The Ureilite Parent Body was catastrophically disrupted at 5 Ma after Calcium-Aluminum rich Inclusions (CAI) while it was still hot and the ureilites provide a unique window into early solar system magmatic processing. One ureilitic trachyandesite, one cumulate, and 16 melt residue ureilites, all from the Almahata Sitta meteorite strewn field, were analyzed for their noble gas compositions and, when such data was unavailable, for oxygen isotopes and petrology. Additionally, ureilite noble gas data from the literature was compiled together with petrology and oxygen isotope data of the same samples, this data is available in the supplementary materials. The compositions of noble gases and oxygen, as well as petrological characteristics, are similar to previously analyzed ureilites. This includes variable 36Artr/132Xe ratios of 20-1000 correlated with variable 84Kr/132Xe ratios of 0.15-2.5 and Xe isotopic compositions similar to the Q gases but with somewhat lower 134,136Xe/132Xe ratios. The well-established correlation between Mg-Fe olivine core composition and Delta'17O, interpreted as material mixing, is corroborated. There is no correlation between noble gas compositions and petrology or Delta'17O. Therefore, it is unlikely that the variable noble gas elemental ratios are due to mixing of noble gases from different sources, as previously suggested. We suggest that compositional variability was established during implantation of noble gases into disordered carbon prior to accretion and possibly during later processing. We discuss that partial graphitization resulted in noble gas loss, with noble gases remaining in un-graphitized organics, which were converted to diamond during the catastrophic disruption. Noble gases released during graphitization may have entered the melt. Isotopic compositions of trapped noble gases in the cumulate and trachyandesitic rocks, which crystallized from the melt are similar to those in the melt residue ureilites. The elemental noble gas composition of the cumulate shows evidence of a degassing stage and that the concentrations of noble gases in the ureilites were higher before melting. The noble gases in the trachyandesite contains radiogenic noble gases from decay of K, I, Th, and U, which were not enriched in the cumulate, showing that the trachyandesite crystallized from a more evolved melt. The cosmic-ray exposure ages of 15-22 Ma, with mostly overlapping uncertainties, are similar to those previously determined for ureilites from the Almahata Sitta strewn field and display a limited spread in contrast to ages previously detected in Almahata Sitta chondrites.

On October 24, 2024, an impressive fireball was visible over Austria. After the possible strewn field was calculated, the first sample of the Haag meteorite, with a mass of 8.76 g, was discovered on November 2, 2024, 8 days after the fireball event. Four more samples were found afterward putting the total sample mass at about 151 g. Short-lived radionuclides were measured shortly after recovery on a small sample, which was also used for almost all analyses presented here. Results confirm that the Haag meteorite derived from the bolide fireball event. Haag is a severely fragmented ordinary chondrite breccia and consists of typical equilibrated and recrystallized lithologies (LL4-6) as well as impact-related lithic clasts, such as dark, fine-grained impact breccias. Most fragments are highly recrystallized (type 6), but some show a well-preserved chondritic texture, which is of petrologic type 4 since the olivines are equilibrated. The olivines in the bulk rock have Fa contents of 29.5 +/- 0.5 mol%, whereas the low-Ca pyroxenes have compositions of Fs23.9 +/- 1.4Wo1.6 +/- 0.7 with slightly variable Fs contents up to 28 mol%. However, the occurrence of type 3 fragments in other parts of the rock cannot completely be ruled out. Many clasts are moderately shocked (S4; C-S4). Using the fragment with the lowest degree of shock to determine the bulk rock's shock degree, Haag has an overall shock degree of S2 (C-S2). The LL chondrite classification is also supported by O isotope data, the results of bulk chemical analysis, and the physical properties of density and magnetic susceptibility. The nucleosynthetic Ti and Cr isotope data confirm that Haag is an ordinary chondrite, related to the noncarbonaceous (NC) meteorites. Haag does not contain detectable amounts of solar wind-implanted noble gases, and we rule out any substantial exposure at the direct surface of the parent body. Based on noble gases, Haag has an exposure age of 21-24 Ma and a pre-atmospheric meteoroid radius of 20-85 cm with a sample depth between 4 and 5 cm below the meteoroid surface, consistent with constraints from cosmogenic radionuclides. The soluble organic compositions of Haag are consistent with the profiles of the Stubenberg (LL6) breccia and show characteristics consistent with the complex shock, brecciation, and lithification history of the breccia. Haag and Stubenberg fell near each other (110 km away) within just 8 years. Since only 8.5% (about 110) of meteorite falls worldwide are LL chondrites, it is remarkable that two LL chondrites fell near each other in such a short time.

The Hayabusa2 spacecraft sampled similar to 5.4 g of asteroid material from the Cb-type asteroid Ryugu. Initial analysis of the Ryugu materials revealed a mineralogical, chemical, and isotopic kinship to the CI chondrites. In this study, we have summarized the elemental abundances of Ryugu samples published to date, and evaluated their compositional variability associated with the CI chondrite data. The abundances of some elements (e.g., P, Ca, Mn, and rare earth elements) in individual Ryugu particles were found to show large relative dispersions compared to the other elements, presumably due to the nugget effect of aqueously formed minor secondary minerals (e.g., dolomite, apatite, magnetite, and pyrrhotite). Consequently, the mean abundances of Ryugu for these elements, calculated using currently available Ryugu data, are accompanied by a certain degree of uncertainties. We suggest establishing a consortium to determine the representative elemental abundances of Ryugu by measuring aliquots from a large homogenized powder sample that can mitigate the nugget effect. Our statistical calculation shows that at least 750 and 400 mg of homogenized samples from Chambers A and C, respectively, are needed to achieve within +/- 5% compositional heterogeneity. The data obtained throughout the consortium activity complement the scientific objectives of the Hayabusa2 mission. Moreover, we anticipate that the obtained Ryugu data, coupled with the elemental abundances of CI chondrites, provide new insights into the chemical composition of the Solar System, which will be used by multidisciplinary communities, including Earth and planetary sciences, astronomy, physics, and chemistry.

Mitigation of the threat from airbursting asteroids requires an understanding of the potential risk they pose for the ground. How asteroids release their kinetic energy in the atmosphere is not well understood due to the rarity of large impacts. Here we present a comprehensive, space-to-laboratory characterization of an impact of an L chondrite, which represents a common type of Earth-impacting asteroid. Small asteroid 2023 CX1 was detected in space and predicted to impact over Normandy, France, on 13 February 2023. Observations from several independent sensors and reduction techniques revealed an unusual but potentially high-risk fragmentation behaviour. The nearly spherical 650 +/- 160 kg (72 +/- 6 cm diameter) asteroid catastrophically fragmented at a dynamic pressure of 4 MPa around 28 km altitude, releasing 98% of its total energy in a concentrated region of the atmosphere. The resulting shock wave was spherical, not cylindrical, and released more energy closer to the ground. This type of fragmentation increases the risk of substantial damage at ground level. These results warrant consideration for a planetary defence strategy for cases where a >3-4 MPa dynamic pressure is expected, including planning for evacuation of areas beneath anticipated disruption locations.

The Aguas Zarcas (Costa Rica) CM2 carbonaceous chondrite fell during nighttime in April 2019. Security and dashboard camera videos of the meteor were analyzed to provide a trajectory, light curve, and orbit of the meteoroid. The trajectory was near vertical, 81° steep, arriving from an ~109° (WNW) direction with an apparent entry speed of 14.6 ± 0.6 km s −1 . The meteoroid penetrated to ~25 km altitude (5 MPa dynamic pressure), where the surviving mass shattered, producing a flare that was detected by the Geostationary Lightning Mappers on GOES‐16 and GOES‐17. The cosmogenic radionuclides were analyzed in three recovered meteorites by either gamma‐ray spectroscopy or accelerator mass spectrometry (AMS), while noble gas concentrations and isotopic compositions were measured in the same fragment that was analyzed by AMS. From this, the pre‐atmospheric size of the meteoroid and its cosmic ray exposure age were determined. The studied samples came from a few cm up to 30 cm deep in an object with an original diameter of ~60 cm that was ejected from its parent body 2.0 ± 0.2 Ma ago. The ejected material had an argon retention age of 2.9 Ga. The object was delivered most likely by the 3:1 or 5:2 mean motion resonances and, without subsequent fragmentation, approached the Earth from a low i < 2.8° inclined orbit with a perihelion distance q = 0.98 AU close to the Earth's orbit. The steep entry trajectory and high strength resulted in deep penetration in the atmosphere and a relatively large fraction of surviving mass.

On the evening of February 14, 2023, at 17:58 UT, a fireball was detected by three cameras of the Italian PRISMA network (FRIPON network). The first samples of the Matera meteorite, collected 3 days after the fall, lay on the balcony of a private home. Meanwhile, four samples weighing more than 10 g (including the main mass of 46.21 g) and many minor samples (less than 10 g each) were recovered, with a total mass of 117.5 g. The analyses show that Matera is a monomict chondrite breccia, exhibiting no weathering (W0) and shock (S1). Based on the mineral compositions of olivine and low‐Ca pyroxene (Fa 18.0±0.3 and Fs 17.0±0.3 , respectively), the rock is an H‐group ordinary chondrite. Since all low‐Ca pyroxene is orthoenstatite, an H5‐type classification is appropriate; although texturally, a type 4 classification could be assigned to distinct portions of the rock with well‐defined chondrules. The analyzed oxygen isotopes also align with an H chondrite (δ 17 O‰ = 2.750 ± 0.051; δ 18 O‰ = 4.036 ± 0.103; Δ 17 O‰ = 0.650 ± 0.004). X‐ray tomography and a structured light 3D scanner yielded a mean bulk density of 2.87 ± 0.04 g cm −3 , whereas ideal gas pycnometry yielded grain densities of 3.47 ± 0.05 g cm −3 , resulting in a porosity of 17.2 ± 1.2 vol%. The magnetic susceptibility of this meteorite is log χ = 5.46 ± 0.05. The radionuclides and fireball observations suggest that the Matera meteoroid was relatively small (with a maximum radius of 20 cm, though more likely around 15 cm). This datum is also consistent with ( 21 Ne/ 22 Ne) cos , which suggests the origin of Matera samples from the uppermost cm of a small meteoroid, ≤10 cm radius. Different from many other H chondrites, the transfer time in space for Matera, based on 3 He alone, is 10–12 Ma. Moreover, the Matera meteorite does not contain solar wind gases. In conclusion, the Matera meteorite is not a fairly typical ordinary chondrite, due to its low bulk density and high total porosity. The presence of ordinary chondrites with these physical characteristics must be taken into account during the asteroid modeling process, as in the case of the Didymos–Dimorphos binary system.

The nitrogen isotope compositions of two samples returned from the asteroid Ryugu were determined using a stepwise combustion method, along with Ivuna (CI) and Y-980115, a CI-like Antarctic meteorite, as references. The two Ryugu samples A0105-07 and C0106-07 showed bulk delta N-15 values of +1.7 +/- 0.5 parts per thousand and +0.2 +/- 0.6 parts per thousand, respectively, significantly lower than Ivuna with +36.4 +/- 0.4 parts per thousand, but close to Y-980115 with +4.0 +/- 0.3 parts per thousand. The Ryugu samples are further characterized by C/N and Ar-36/N ratios up to 3.4x and 4.9x the value of Ivuna, respectively. Among all Ryugu samples and CI chondrites, a positive correlation was observed between nitrogen concentrations and delta N-15 values, with samples with lower nitrogen concentrations exhibiting lower delta N-15. This trend is explained by a two-component mixing model. One component is present at a constant abundance among all CI-related samples, with a delta N-15 value around 0 parts per thousand or lower. The other varies in abundance between different samples, and exhibits a delta N-15 value of +56 +/- 4 parts per thousand. The first N-15-poor endmember is seemingly tightly incorporated into a carbonaceous host phase, whereas the N-15-rich endmember can be mobilized and decoupled from carbon, potentially because it is in the form of ammonia. Asteroid materials with volatile compositions that are similar to those reported here for the Ryugu samples are attractive candidates for the volatile sources among Earth's building blocks.

Elmshorn fell April 25, 2023, about 30 km northwest of the city of Hamburg (Germany). Shortly after the fall, 21 pieces were recovered totaling a mass of 4277 g. Elmshorn is a polymict and anomalous H3-6 chondritic, fragmental breccia. The rock is a mixture of typical H chondrite lithologies and clasts of intermediate H/L (or L, based on magnetic properties) chondrite origin. In some of the 21 pieces, the H chondrite lithologies dominate, while in others the H/L (or L) chondrite components are prevalent. The H/L chondrite assignment of these components is based on the mean composition of their olivines in equilibrated type 4 fragments (similar to Fa(21-22)). The physical properties like density (3.34 g cm(-3)) and magnetic susceptibility (log chi <5.0, with chi in 10(-9) m(3) kg(-1)) are typical for L chondrites, which is inconsistent with the oxygen isotope compositions: all eight O isotope analyses from two different fragments clearly fall into the H chondrite field. Thus, the fragments found in the strewn field vary in mineralogy, mineral chemistry, and physical properties but not in O isotope characteristics. The sample most intensively studied belongs to the stones dominated by H chondrite lithologies. The chemical composition and nucleosynthetic Cr and Ti isotope data are typical for ordinary chondrites. The noble gases in Elmshorn represent a mixture between cosmogenic, radiogenic, and primordially trapped noble gases, while a solar wind component can be excluded. Because the chondritic rock of Elmshorn contains (a) H chondrite parent body interior materials (of types 5 and 6), (b) chondrite parent body near-surface materials (of types 3 and 4), (c) fragments of an H/L chondrite (dominant in many stones), (d) shock-darkened fragments, and (e) clasts of various types of impact melts but no solar wind-implanted noble gases, the different components cannot have been part of a parent body regolith. The most straightforward explanation is that the fragmental breccia of Elmshorn represents a reaccreted rock after a catastrophic collision between an H chondrite parent body and another body with H/L (or L) chondrite characteristics but with deviating O isotope values (i.e. that of H chondrites), complete disruption of the bodies, mixing, and reassembly. This is the only straightforward way that the implantation of solar wind gases could have been avoided in this kind of complex breccia. The gas retention ages of about 2.8 Gyr possibly indicate the closure time after the catastrophic collision between H and H/L (or L) chondrite parent bodies, while the cosmic ray exposure age for Elmshorn, which had a preatmospheric radius of 25-40 cm, is similar to 17-20 Myr.

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.

In 1889 the German poet and novelist Theodor Fontane wrote the popular literary ballad "Herr von Ribbeck auf Ribbeck im Havelland." The Squire von Ribbeck is described as a gentle and generous person, who often gives away pears from his pear trees to children passing by and continued donating pears after his death. Now, 135 years later the rock called Ribbeck is giving us insight into processes that happened 4.5 billion years ago. The meteorite Ribbeck (official find location: 52 degrees 37 ' 15 '' N, 12 degrees 45 ' 40 '' E) fell January 21, 2024, and has been classified as a brecciated aubrite. This meteoroid actually entered the Earth's atmosphere at 00:32:38 UTC over Brandenburg, west of Berlin, and the corresponding fireball was recorded by professional all sky and video cameras. More than 200 pieces (two proved by radionuclide analysis to belong to this fresh fall) were recovered totaling about 1.8 kg. Long-lived radionuclide and noble gas data are consistent with long cosmic ray exposure (55-62 Ma) and a preatmospheric radius of Ribbeck between 20 and 30 cm. The heavily brecciated aubrite consists of major (76 +/- 3 vol%) coarse-grained FeO-free enstatite (En99.1Fs<0.04Wo0.9), with a significant abundance (15.0 +/- 2.5 vol%) of albitic plagioclase (Ab95.3 An2.0Or2.7), minor forsterite (5.5 +/- 1.5 vol%; Fo99.9) and 3.5 +/- 1.0 vol% of opaque phases (mainly sulfides and metals) with traces of nearly FeO-free diopside (En53.2Wo46.8) and K-feldspar (Ab4.6Or95.4). The rock has a shock degree of S3 (U-S3), and terrestrial weathering has affected metals and sulfides, resulting in the brownish appearance of rock pieces and the partial destruction of certain sulfides already within days after the fall. The bulk chemical data confirm the feldspar-bearing aubritic composition. Ribbeck is closely related to the aubrite Bishopville. Ribbeck does not contain solar wind implanted gases and is a fragmental breccia. Concerning the Ti- and O-isotope compositions, the data are similar to those of other aubrites. They are also similar to E chondrites and fall close to the data point for the bulk silicate Earth (BSE). Before the Ribbeck meteoroid entered Earth's atmosphere, it was observed in space as asteroid 2024 BX1. The aphelion distance of 2024 BX1's orbit lies in the innermost region of the asteroid belt, which is populated by the Hungaria family of minor planets characterized by their E/X-type taxonomy and considered as the likely source of aubrites. The spectral comparison of an average large-scale emission spectrum of Mercury converted into reflectance and of the Ribbeck meteorite spectrum does not show any meaningful similarities.

Introduction: On January 24th, 2016, 15:27 UTC, a bright daytime fireball was observed in Florida and registered by weather radar and a dash-board camera. Eight fusion-crusted stones with a total mass of 1.1 kg were found [1]. Osceola is now the 33rd meteorite (and the 9th L chondrite) with a published orbit [2].Methods. Orbit. The atmospheric trajectory was reconstructed based on a dash-cam video recording with account for atmospheric conditions, using the methods described in [3,4]. The orbit (a=1.486 au; e=0.3406, i=13.20°, W=303.9°, w=169.0) was calculated based on this trajectory with the open source software Meteor Toolkit [5]. Noble gases. Four chips (total mass = 118.2 mg) were analyzed at ETH Zurich after problems were encountered during the analysis of the first two chips. Pending detailed analysis, we only report here the results for the second two chips (Os-3 and Os-4). Extraction was done by total fusion in a single temperature step (Table 1), and each measurement was bracketed by blanks. We measured 3,4He, 20,21,22Ne, 36,38,40Ar, 84Kr, 129,132Xe and some potentially interfering (isobaric) species [6]. We calculate meteoroid radius, shielding depth and cosmic-ray exposure (CRE) ages using [7,8] and the bulk chemistry for L chondrites given therein. Radiogenic gas retention (RGR) ages are based on typical abundances of 0.013, 0.043, 825 ppm adopted for U, Th, K, respectively [9]. Cosmogenic radionuclides. Results are forthcoming and will be presented and discussed at the conference.Results & Discussion. Orbit. The aphelion of Osceola’s barely Earth-crossing orbit is located just inside the inner edge of the asteroid belt, at ca. 2 au, i.e. the orbit is dynamically evolved (Figure 1). In that respect, it is comparable, among L chondrites, only to Creston [10]. Noble gas inventory. Unsurprising for an equilibrated L chondrite, the noble gases in Osceola are cosmogenic and radiogenic for He and Ne, with only minor trapped Ar, and Q-like 84Kr/36Ar, 132Xe/36Ar. Meteoroid size and cosmic history. The cosmogenic 22Ne/21Ne ratio of ~1.07 in both chips suggests irradiation in a meteoroid with a radius >50 cm, at a depth of >40 cm [7], consistent with the size estimate based on the fireball deceleration using the mass calculation method detailed in [11]. Under these shielding conditions, we expect a cosmogenic 3He/21Ne ratio of ~4.5, which fits well with the values measured in Os-3 and -4 (4.60 and 4.40), suggesting no significant loss of He relative to Ne during cosmic-ray exposure. Using 22Ne/21Ne-based production rates from [8], 3He and 21Ne in both chips give a consistent CRE age o 18±2 Ma, while 38Ar yields ~22 Ma. The former is our preferred age, since 38Ar can be more affected by sample inhomogeneities (i.e., distribution of Ca, which is the primary target for production of 38Ar) than 3He and 21Ne. This CRE age does not fall on any prominent peak in the CRE-age-histogram of the L chondrites (e.g., [12]). The CRE age is compatible with the expected collisional lifetime of a R >50 cm meteoroid in the asteroid belt (>14 Ma [13]). The U,Th-He retention age (4He corrected for the contribution of cosmogenic 4He = ~6 × 3He) of the two chips is 460 and 420 Ma, respectively, close to the age of the L chondrite parent body disruption event ca. 470 Ma ago [14]. Given the uncertainties inherent in these ages, it seems at least plausible that Osceola, like a large fraction of the L chondrites falling today, was affected by this shock event. The K-Ar retention ages for the two chips is are 1.5 and 1.1 Ga. The higher age from the K-Ar system might either be due to a contribution of atmospheric 40Ar (given that the measured 40Ar/36Ar ratios of the two chips are lower than the atmospheric value), or incomplete degassing of radiogenic 40Ar during the shock event 470 Ma ago. Dissimilar shock-degassing patterns for the U,Th-He and K-Ar systems are frequently observed for meteorites with shock stages S3 and S4 [15], consistent with the shock classification of Osceola of S4 [1].Table 1: He, Ne, Ar in Osceola All concentrations given in units of 10-8 cm3STP/g (uncertainty in amounts

The Dominion Range (DOM) and Miller Range (MIL) dense collection areas (DCAs) have yielded more than 20 and 200 CO3 chondrites (carbonaceous chondrites of the Ornans chemical group), respectively, over multiple field seasons. Several samples have exhibited primitive characteristics and have been the focus of interest. With so many CO3s recovered from this area, a natural question is if there are multiple pairing groups (where pairing refers to two or more meteorites that are part of a single fall) and if there is additional primitive material that would interest the meteorite community. This comprehensive study looks at all samples using several approaches: field and macroscopic observations; magnetic susceptibility; Cr in ferroan olivine; bulk elemental and isotopic analysis of H, C, N, and noble gas analyses to determine cosmic ray exposure (CRE) ages. Magnetic susceptibilities (measured as log chi) for all samples correlate with their type II (i.e., FeO-rich) olivine Cr contents, with the most primitive CO3s (3.00) have log chi values near 5, while the higher grade CO3s have log chi values as low as 4.17. Altogether, there appear to be two distinct CO3 pairing groups and five other unpaired CO3s recovered at the Dominion Range: (a) the main DOM 08004 pairing group (16 specimens with a CRE age of 10-16 Ma), (b) the DOM 08006 group (2 specimens incl. DOM 10847 with a CRE age of 25 Ma), (c) DOM 14359 with a CRE age of 6 Ma, (d) DOM 18070 with a CRE age of 8 Ma (these two samples have similar ages but distinct trapped Ne-20 contents), (e) DOM 10900 with a CRE age of 5.5 Ma, (f) DOM 18286 (with a CRE age of similar to 59 Ma), and (g) DOM 19034 (with a CRE age of similar to 43 Ma). There are three distinct age groupings of 3.00-3.05 COs, highlighting the diverse pristine CO3 materials present in the DOM area. There is one large MIL pairing group (MIL 07099; n = 199; 9-14 Ma CRE age where measured) and one smaller pairing group with distinctly lower Cr2O3 in type II olivines (8 samples of unknown CRE age), and five unpaired or unique CO3s. Notably, the large DOM and MIL pairing groups have 9-16 Ma exposure ages that could have been delivered in a single large fall event spanning similar to 200 km, two separate falls that were ejection paired, or two separate falls from two separate ejections. Finally, we recommend reclassifying several CO3 to CM2 based on new data and that from previous studies.