The NASA OSIRIS-REx mission returned a sample of ~120 grams from the carbonaceous near-Earth asteroid Bennu. Laboratory analyses of the returned sample revealed that it is dark, featuring brighter inclusions and veins, and contains millimeter-sized stones predominantly exhibiting hummocky, mottled, and angular patterns (Lauretta, Connolly, et al. 2024; Connolly, Lauretta, et al. 2025). These laboratory analyses confirmed that Bennu underwent aqueous alteration, akin to other carbonaceous asteroids, such as asteroid Ryugu (Nakamura et al. 2022).

As part of a NASA Laboratory Analysis of Returned Samples (LARS) study, we have received a chip of the asteroid Bennu, weighing ~113 mg, from NASA's Johnson Space Center curation (OREX-800084-0). This study aims to evaluate the relationship between organic and carbonate phases and their relationship to aqueous processes on the asteroid's parent body. The Bennu chip was transported and stored in a Teflon bag inside a sealed stainless-steel canister before being opened inside a nitrogen-purged glovebox for spectroscopic analyses. The spectroscopic measurements of the Bennu sample were conducted at the Johns Hopkins University (JHU) Applied Physics Laboratory (APL), where we used a nitrogen-purged glovebox to prevent contamination by terrestrial water while opening the sample container and manipulating the sample (installing it on the sample holder).

Figure 1. (Left) Microscope image (0.75X) of the Bennu chip OREX-800084-0. The length of the chip is about 9 mm across. (Right) An image (300x200 µm) of a bright clast in the Bennu sample that was spectrally analysed.

Upon opening the canister and unwrapping the Teflon bag in the glovebox, we examined the Bennu chip and found it to have an angular shape (~9 mm x 4 mm x 4 mm) with some bright clasts (~0.5 mm x 1 mm) (Fig. 1, left). Subsequently, we used a nitrogen-purged transfer and measurement container to transport the sample to the APL Geological Near-IR Optimized Microspectroscopic Experiment (GNOME) lab for measurements under nitrogen purge. Reflectance measurements were collected using a Hyperion 2000 FTIR microscope and Invenio-R spectrometer with a spectral field of view of ~100 µm. We collected infrared microscopic (~1.25-28.65 µm) and imaging data from various regions of interest in the Bennu sample (e.g., Fig. 1, right).

Figure 2.  The spectrum we acquired of a bright clast in the Bennu sample is plotted with spectra of other Bennu samples (Lauretta et al. 2024), OSIRIS-REx OVIRS (Hamilton et al. 2019), and CM and CI carbonaceous chondrites (Takir et al. 2013).

Figure 2 presents the measured infrared reflectance spectrum of one of the bright spots shown in Figure 1  (right) from ~ 2 to 4 μm. The longer wavelength data are still being analyzed. The spectrum confirms a narrow absorption band centered at ~ 2.72 μm, which is indicative of Mg-rich serpentine and clay minerals. This absorption feature aligns with those found in CM chondrites, such as LAP 02277, and CI chondrites, like Ivuna. This observation suggests that both Bennu and these meteorites likely experienced similar aqueous alteration environments.

Additionally, the spectrum of the bright clast in the Bennu sample displays two prominent doublet absorptions attributed to the planar carbonate CO₃^2- ion (Buijs & Schutte 1961, Hunt, G.R. &  Salisbury 1971); these are located at ~ 3.2-3.4 μm (the overtone 2ν₃ of the fundamental vibration ν₃ at 6.9 μm) and at ~ 3.8-4.0 μm (a combination of ν₁ and ν₃, where ν₁ corresponds to the fundamental vibration at 9 μm and ν₃ at 6.9 μm). This carbonate feature is consistent with dolomite, as Figure 3 (upper) illustrates.

Organic features due to carbon-hydrogen (C-H) bond stretching typically overlap with one of the carbonate doublets at ~3.4 μm. However, the feature observed in the Bennu sample at ~3.4 μm indicates the presence of pure carbonates with no organics (Fig. 3, lower). In this talk, we will discuss additional spectra of the Bennu sample and their implications for constraining the evolution of carbon reservoirs during secondary processing events (e.g., aqueous alteration) experienced by asteroid Bennu.

Figure 3. (Upper) The 3-to-4-μm region of the spectrum of the Bennu sample is compared with those of various carbonaceous phases compiled from the RELAB spectral library. The carbonate feature observed in Bennu is consistent with dolomite and inconsistent with calcite. (Lower) The spectrum of our Bennu sample is plotted alongside the spectra of calcite and coal mixtures (Hancock et al., 2025).

Acknowledgements: We would like to acknowledge the support of the NASA LARS grant 80NSSC23K0402. We would also like to thank the OSIRIS-REx mission, including scientists, engineers, and other team members, for their years of dedication to return this sample, as well as the NASA JSC OSIRIS-REx curation team for their work to make the sample available for analysis.

References:

Buijs, K.,  and Schutte, C.J.H. 1961, Spectrochimica Acta, vol. 17, pp. 927-932.

Connolly Jr., H. C., Lauretta, D. S., et al. 2025, MAPS,1-18.

Hancock, A., et al. 2025, LPSC meeting, Abstract #1350.

Hunt, G.R. &  Salisbury,J.W. 1971) Mod. Geol. 2, 23–30.

Lauretta, D. S., Connolly Jr., H. C., et al. 2024, MAPS, 59, Nr 9, 2453–248.

Nakamura, T. et al. 2022, Science, 379, Issue 6634.

Takir, D. et al. 2013, Meteor. Planet. Sci., 48, 1618.

How to cite: Takir, D., Hibbitts, C., Miller, K., and Wagoner, C.: Infrared Spectroscopy of Bennu Sample OREX-800084-0, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-678, https://doi.org/10.5194/epsc-dps2025-678, 2025.

Introduction: Carbonaceous asteroid samples offer a unique opportunity to access primitive materials from the early solar system. Alteration processes that occurred during the evolution of asteroids and their parent bodies have affected the structural and spectral characteristics of their surface materials. The JAXA Hayabusa2 and NASA OSIRIS-REx missions successfully returned samples from the asteroids Ryugu and Bennu [1,2]. Using returned samples—preserved from terrestrial contamination— can significantly improve our understanding of alteration mechanisms that occur during the early evolution of the solar system.

The OSIRIS-REx mission returned approximately 120 g of surface material from Bennu in September 2023 [2]. Preliminary analyses of NASA's Bennu samples have revealed similarities with Ryugu samples and CI chondrites, notably a composition rich in phyllosilicates [2]. Here, we present a first characterization of these phyllosilicates using NIR and MIR measurements on Bennu pristine samples, without exposure to the terrestrial environment that could affect their properties.

Samples and Methods: Through a sample exchange agreement between NASA and JAXA, a 0.6 g portion of the Bennu sample, divided into five aggregate samples, was delivered to JAXA’s Extraterrestrial Sample Curation Center (ESCuC) in Sagamihara in August 2024. The Bennu – and Ryugu – samples are now stored there in dedicated ultraclean and N₂-purged facilities to prevent from any terrestrial contamination. For this specific study, initial characterization was performed within their preservation chamber first using MicrOmega, a near-infrared hyperspectral imaging microscope developed by the Institut d’Astrophysique Spatiale (Université Paris-Saclay/CNRS) [3] coupled with a LEICA visible microscope. This instrument operates in the 0.99-3.65 µm spectral range with a spatial resolution of 22.5 x 22.5 µm² per pixel. Additional measurements were then conducted with a µ-FTIR point by point spectrometer with a spectral range between 2 and 12 µm on chosen 70-100 µm spots. Here, we focus on individual mm-sized grains of Bennu samples that were extracted from initial aggregate samples ORX-19000 and ORX-29000 [5]. We investigated the OH vibration band at ~2.7 µm with MicrOmega on ~100 individual grains and the Si-O band at ~10 µm with the µ-FTIR on about half of these grains. For each grain, several spectral parameters were extracted. For the OH band, in the NIR, these include peak position, band depth, reflectance factor at 2.5 µm, and NIR spectral slope. For the Si-O band, in the MIR, key parameters include the positions of the main Reststrahlen band, the Christiansen feature and the first derivative peak, along with the relative distances between them. The results were compared with MicrOmega measurements of Ryugu samples performed within the Curation Facility (e.g., [5]), as well as with external laboratory measurements conducted on Ryugu samples [6,7] and on meteorites [8].

Results and discussion: The OH band properties derived from the average spectra of individual Bennu grains measured with MicrOmega reveal some similarities with those of the Ryugu grains initially analyzed by [5]. Approximately 10% of the Bennu grains exhibit a more redshifted OH band peak position than the rest of the population. In particular, this subset includes grain ORX-10001 [9], measured on both sides with the instruments, which shows a clear spectral dichotomy between its two faces. For these grains, the Si–O stretching band appears broader and presents a redshifted Reststrahlen peak, while the Christiansen feature remains unchanged, compared to the rest of the Bennu collection and to laboratory measurements of Ryugu samples [6,7].

It has been previously suggested that the redshifted Ryugu grains from Chamber A (from the first sampling site) experienced more space weathering [5]. This may indicate varying degrees of surface alteration among the Bennu samples, efficiently probed by the variable position of the OH band. The shift observed in the Si-O band follows the same trend as that seen in ion irradiation in laboratory on carbonaceous chondrites, such as Alais and Tagish Lake [8]. This spectral behavior, however, not identified in Ryugu samples, may indicate a distinct alteration process specific to a fraction of the Bennu material.

These findings suggest peculiar alteration histories of the two bodies, offering new insights into the formation and evolution of planetesimals. Ongoing investigations aim to further understand the alteration processes responsible for this heterogeneity in Bennu, which, at this stage, appears to align with irradiation-induced changes observed in the laboratory on CI meteorites.

Acknowledgments: We thank the Curation Facility team of JAXA for their work on the samples. We also thank the Graduate school of physics of Paris-Saclay University and the CNES for their financial support.

References: [1] Yada, T. et al. (2022) Nat. Astron. 6, p. 214-220. [2] Lauretta, D.S. et al. (2024) Meteorit Planet Sci, 59: 2453-2486. [3] Bibring et al. (2017) Astrobiology 17, 621-626. [4] Fukai, R. et al. (2025) LPSC #1311. [5] Le Pivert-Jolivet, T. et al. (2023) Nature Astronomy 7, 1445–1453. [6] Dionnet, Z. et al. (2023) Meteorit Planet Sci, 59,10.1111/maps. 14068. [7] Amano, K. et al. (2023), Sci Adv. 9, eadi3789. [8] Lantz, C. et al. (2024) Planet. Sci. J. 5 201. [9] Nardelli, L. et al. (2025) LPSC #1928.

How to cite: Nardelli, L., Brunetto, R., Pilorget, C., and Hatakeda, K. and the ISAS/IAS MicrOmega Curation Team: Spectral variations of phyllosilicate features in Bennu grains: evidence from NIR and MIR measurements of pristine returned samples at ISAS Curation Facility., EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-984, https://doi.org/10.5194/epsc-dps2025-984, 2025.

Introduction: Samples returned from the asteroid Bennu by NASA’s OSIRIS-REx mission [1], and previously from the asteroid Ryugu by JAXA’s Hayabusa2 mission [2], offer unprecedented access to pristine carbonaceous asteroid material, preserved from terrestrial contamination. Ongoing laboratory investigations have shown that phosphates in Bennu occur in various forms, including isolated grains, surface coatings, and vein fillings, present primarily as Mg,Na-phosphates and Ca-phosphates [1]. These materials are often associated with high-reflectance phases in mottled particles and may be linked to bright veins seen in Bennu’s boulders. At the JAXA Extraterrestrial Sample Curation Center (ESCuC) in Sagamihara, Japan, 0.6 g of these samples are stored and analyzed in a controlled, pure N₂-purged environment, enabling high-resolution spectral analysis under conditions that prevent terrestrial contamination [3-6].

Characterizing hydrated phosphorus-bearing phases, particularly phosphates, is critical for understanding the role of fluid-mediated alteration processes in carbonaceous asteroids and the potential availability of bioessential elements like phosphorus in early Solar System materials.

Our study focuses on the diversity of hydrated phosphorus-bearing grains in Bennu, with particular interest in grains resembling Hydrated Ammonium-Magnesium-Phosphorus-rich (HAMP) phases previously detected in Ryugu material [3].

Methods: In September 2024, five bulk Bennu samples (~0.6 g total) were analyzed at ESCuC using the MicrOmega near-infrared hyperspectral microscope and µFTIR point spectroscopy while samples were held in an N₂-purged environment to prevent terrestrial contamination [4-5]. The same instrumentation and protocols used for MicrOmega observation of Ryugu [6] enabled comparison across the two bodies.

MicrOmega collects spectra spanning 0.99-3.6 μm with spatial resolution of 22.5 μm per pixel [7]. Spectral image cubes are collected of each bulk at multiple viewing geometries. At 4 azimuths (0, 90, 180, 270^o), ~15 MicrOmega images were collected over the bulk sample holder to span the entire bulk sample with overlap so no grains were visible only at image boundaries; this yields ~70 images per bulk sample which were analyzed for spectral variation.  The incident angle of 35^o allows for variation of illumination conditions as the viewing azimuths are changed. A LEICA visible microscope is coupled to MicrOmega at ESCuC which allows for high resolution visible imagery of the grains within the bulk samples. A secondary bulk campaign was carried out in April-May 2025 to reanalyze bulk samples after removal of the largest individual grains for grain analyses, yielding newly visible smaller grains.

µFTIR point spectra were collected in a N₂-purged chamber connected to the MicrOmega purged chamber so that samples could be transferred without terrestrial exposure. The µFTIR point spectrometer collects spectra spanning 2-12 μm over points of interest previously identified with MicrOmega, with spot size 70-100 μm. This spectral range allows for comparison of the 3 μm absorption visible in MicrOmega while also capturing the range of the P-O vibrations at longer wavelengths associated with phosphates [3,8]. 

Spectra were analyzed for H₂O features including a ~3 µm broad absorption in both MicrOmega and µFTIR data. µFTIR spectra were analyzed for the same HAMP-like absorptions as MicrOmega spectra, as well as spectral features visible at longer wavelengths including at 6.9 μm (N-H) and ~9.5 μm (P-O) [3]. The visible features of grains were analyzed using the LEICA visible microscope imagery.

Results and Discussion: We document the breadth of hydrated phosphorus-rich grains found in the 5 Bennu bulk samples returned to Earth by the OSIRIS-REx mission. We identified hydrated (strong absorptions at 3 µm) phosphorus rich (~9.5 µm feature) material, and investigated their visible features and spectral characteristics at multiple viewing geometries. The hydrated phosphorous-rich grains detected also form one population of Bennu’s bright grains.

 We compare these spectra of interest with spectra of possible phosphate analogs as well as Ryugu HAMPs. Phosphates are observed as bright grains or inclusions embedded within the low-albedo matrix. Many phosphate spectra are blue-sloped from 1.0-2.7 μm. A subset exhibits the absorptions spectrally consistent with HAMP grains from Ryugu [3], as seen in both MicrOmega and μFTIR spectra. Ongoing analysis will inform on further compositional diversity within Bennu samples.

Future work will expand this dataset with analyses of individually extracted grains. All results will contribute to the JAXA Bennu sample catalog, to be made accessible via AOs. Phosphorous is typically a minor component in carbonaceous material including Bennu [1], so while phosphates were not previously detected via remote sensing of the asteroid’s surface, their observation in returned samples can point to localized, chemically complex alteration histories within Bennu’s regolith.

References: [1] Lauretta D. S. et al., Met. and Planet. Sci. 59, 9, p. 2453-2486 (2024), [2] Yada T. et al., Nat. Astron. 6, p. 214-220 (2022), [3] Pilorget C. et al., Nat. Astron. 6, p. 221-225 (2024), [4] Fukai et al., Lunar and Planetary Science Conference, #1311, (2025), [5] Fukai et al. this conference, [6] Pilorget C., Okada, T. Hamm, V. et al. 2022, Nature Astronomy, 6, 221, [7] Bibring J.-P., Hamm V., Pilorget C., Vago J. L., & the MicrOmega Team. 2017, Astrobiology, 17, 621. [8] Jastrzebski W., Sitarz M., Rokita M., Bulat K. Spectrochimica Acta Part A, 79, 722-727.

How to cite: Sheppard, R., Pilorget, C., Baklouti, D., Loizeau, D., Jiang, T., Nardelli, L., Bibring, J.-P., Mahlke, M., Poulet, F., Brunetto, R., Aleon-Toppani, A., Lantz, C., Hatakeda, K., Okada, T., Fukai, R., Abe, M., Enokido, Y., Kawasaki, S., Riu, L., and Miyazaki, A. and the JAXA team: Characterization of hydrated phosphorous-rich material within Bennu returned samples using near-infrared to mid-infrared spectra, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-1622, https://doi.org/10.5194/epsc-dps2025-1622, 2025.

Introduction: Aqueous alteration was a fundamental early geological process in the Solar System, significantly shaping the mineralogical composition of primitive asteroids. Carbonate minerals serve as important tracers for understanding the physicochemical conditions during these alteration events on early planetesimals [1, 2]. This study presents a comprehensive characterisation of carbonate minerals found in the returned samples from asteroids (162173) Ryugu and (101955) Bennu [3, 4], which provide pristine materials analogous to CI chondrites but without terrestrial alteration. Sample analysis was performed using the MicrOmega instrument, operated collaboratively between ISAS, Japan, and IAS, France, at the JAXA Extraterrestrial Sample Curation Center in Sagamihara, Japan [5].

Method: The Hayabusa2 mission returned a total of 5.42g of Ryugu material, split over the chambers A (surface sample) and C (at least in part subsurface sample after artificial cratering) [3]. In August 2024, NASA provided approx. 0.6g of Bennu samples to the ISAS curation facility, containing larger and smaller grains from both inside and outside the OSIRIS-REx sample container.

MicrOmega is a near-infrared hyperspectral microscope, operating between 0.99-3.60µm with a spatial resolution of 22.5µm per pixel on a 250x256 pixel grid [6]. Sample measurements are performed in N₂-purged chamber, preventing terrestrial contamination. Between December 2020 and June 2024, we have imaged the entire returned Ryugu mass with MicrOmega as bulk samples and about half in more detail in smaller “sub-bulks” and as individual grains. Since September 2024, we are analysing both sub-bulk samples and individual grains of Bennu with MicrOmega under identical measurement conditions as Ryugu. Measurements include multiple observing geometries (varying azimuth and focus depth) for each sample.

Carbonate-rich pixels were identified using absorption depth criteria and χ2 comparison with synthetic carbonate reference spectra, focusing on the characteristic doublet feature around 3.4µm sensitive to carbonate composition [7, 8]. Pixel detections were grouped into contiguous regions-of-interest, assumed to represent individual carbonate inclusions, and assigned a dominant species (e.g., dolomite, breunnerite, calcite) based on the best spectral match, refined by visual inspection.

Results: We identified 709 distinct carbonate inclusions in Ryugu and 90 in Bennu, with typically two or more measurements by MicrOmega. Inclusion sizes range from single pixel (~20µm in equivalent diameter, i.e. diameter of a circle with equal area) to several hundred pixels (several hundred µm in equivalent diameter). On both asteroids, dolomite (CaMg(CO₃)₂) and Mg-rich breunnerite ((Mg,Fe)CO₃) are the dominant carbonate phases, comprising slighty less than two thirds and one third of inclusions respectively, with minor amounts of calcite (CaCO₃) (~5%). Fe-rich breunnerite and tentative Mg-siderite were also found in Ryugu. The mean compositions (inferred from spectral features) of dolomite and breunnerite match closely between the two bodies, as do their relative abundances in terms of total pixel area (~1:1 dolomite:breunnerite ratio overall). These assemblages resemble those in CI chondrites. On both asteroids, carbonates are intimately mixed with phyllosilicates, showing characteristic 2.7µm absorptions. The shape of the 2.7µm signatures in carbonate assemblages differ between both asteroids, suggesting different matrix environments. Breunnerites are the largest inclusions (median ~100-120µm equivalent diameter), followed by dolomites (~70-90µm), while calcites are small (generally one or two pixel, though likely smaller than MicrOmega’s pixel scale of 22.5µm). We observe a spatial separation of dolomite and breunnerite inclusions in samples from both asteroids; they generally do not occur in close proximity. Zoning within inclusions is not detected at the MicrOmega pixel scale. We further note a significant difference between Ryugu's chambers: Chamber C has considerably more breunnerite, while Chamber A is richer in dolomite.

Discussion: The similarity in carbonate assemblages suggests convergent alteration pathways on the parent bodies of Ryugu and Bennu, despite (minor) differences in their isotopic signatures (H, N, O), indicative of different formation environments [4]. Nevertheless, we observe slight differences in the host matrix of the carbonates, based on the shape of the 2.7µm band. We interpret the consistent spatial separation of dolomite and breunnerite at the 10-100µm size scale as remnant of a spatially heterogeneous local water-rock (W/R) ratio that persisted over time. We propose that intermediate W/R ratios favoured dolomite precipitation, while high local W/R ratios suppressed dolomite formation due to Ca²⁺ dilution and promoted breunnerite precipitation. This W/R-driven mechanism explains the large-scale spatial patterns observed with MicrOmega, however, we note that this pattern breaks at smaller size scales (<10µm), where dolomite-breunnerite assemblages have been observed by other studies [9, 10]. The heterogeneity between Ryugu's chambers suggests they sampled different mixtures of parent body lithologies experiencing different dominant W/R conditions, reinforcing the concept of limited large-scale mixing. We observe no systematic difference in the 2.7µm absorption around dolomites and breunnerites, aligning with isotopic data suggesting Mg incorporation into clays prior to carbonate formation [9].

Conclusion: MicrOmega hyperspectral analysis reveals remarkably similar carbonate populations on Ryugu and Bennu, dominated (at the MicrOmega size scale of 10-100µm) by dolomite and breunnerite with minor calcite, suggesting convergent aqueous alteration pathways. The consistent spatial separation of dolomite and breunnerite suggests the controlling influence of local W/R ratio heterogeneity. Different dolomite-breunnerite ratios between Ryugu's chambers indicate heterogeneity at the sampling scale. These results highlight the critical role of local physicochemical conditions, particularly W/R ratio, in governing carbonate speciation during aqueous alteration on primitive asteroids.

References:

[1] Fredriksson, K. & Kerridge, J. F. 1988, Meteoritics, 23, 35

[2] Endress, M. & Bischoff, A. 1996, Geochim. Cosmochim. Acta, 60, 489

[3] Yada, T. et al. 2022, Nature Astronomy, 6, 214

[4] Lauretta, D. S. et al. 2024, Meteoritics & Planetary Science, 59, 2453

[5] Pilorget, C. et al. 2021, Nature Astronomy, 6, 221

[6] Bibring, J.-P. & the MicrOmega Team. 2017, Astrobiology, 17, 621

[7] Loizeau, D. et al. 2023, Nature Astronomy

[8] Bishop, J. L. et al. 2021, Earth and Space Science, 8

[9] Yamaguchi, A. et al. 2023, Nature Astronomy, 7, 398

[10] McCoy, T. J. et al. 2025, Nature, 637, 1072

How to cite: Mahlke, M., Lantz, C., Pilorget, C., Baklouti, D., Brunetto, R., Hatakeda, K., Jiang, T., Loizeau, D., and Sheppard, R. and the MircOmega: Tracing water's reach: Carbonate mineralogy of Ryugu and Bennu as seen by MicrOmega, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-1228, https://doi.org/10.5194/epsc-dps2025-1228, 2025.

Introduction
Samples returned from asteroids Ryugu and Bennu exhibit mineralogical and isotopic similarities to CI carbonaceous chondrites [1–3]. Although CIs are among the leading candidates for delivering the building blocks of life to terrestrial planets [4], their distribution in the solar system remains poorly understood. This is largely due to the featureless nature of primitive asteroids, as well as terrestrial weathering in meteorites. With the availability of pristine spectra from the returned samples, we are now better positioned to identify CI-like asteroids among the large population of primitive asteroids observed in the past decades.

However, remote sensing of Ryugu and Bennu have revealed that space weathering effects may be more complex on primitive asteroids than previously assumed, and its mechanism needs to be better understood to infer the bulk asteroid composition from telescopic data. Despite their compositional and physical similarities, Ryugu and Bennu exhibit differences in their visible spectra. More intriguingly, their visible spectra likely evolved in opposite directions. On Ryugu, fresher craters are brighter and bluer [5, 6], whereas on Bennu, fresher craters are darker and redder [7]. Notably, the spectra of the freshest materials on both asteroids are similar, suggesting a similar initial state. These observations imply that compositionally similar asteroids can undergo divergent spectral evolution, leading to differences in their global spectra [8].

In this study, we investigate the causes of the opposing spectral evolutions of Ryugu and Bennu by integrating spectral analyses of returned samples with remote-sensing measurements of crater spectrophotometry and thermal inertia.

Methods
We measured multi-band visible spectra of over 400 grains and aggregates from Ryugu samples and approximately 660 mg of Bennu aggregate samples at the JAXA curation facility.

We analyzed the visible spectra and phase function slopes of 119 craters on Ryugu based on ONC-T data and 568 craters on Bennu based on MapCam/PolyCam data. The phase function slope was determined by fitting all available photometric data using a Hapke model [9] and calculating the ratio of radiance factors observed under incidence angle (i), emission angle (e), and phase angle (α) of i = 5°, e = 0°, α = 5°, and i = 15°, e = 0°, α = 15°. Thermal inertia values for the craters were obtained from previous studies [10–12].

Results
Limited influence from solar wind and micrometeorites: Our spectral analyses of returned samples suggest that the opposing evolutions of visible spectra may not be fully explained by classical space weathering mechanisms involving solar wind irradiation and micrometeorite bombardment. Although morphological and compositional signatures of these processes—including microcraters, amorphization, and dehydration—have been identified in Ryugu samples [13, 14], the average visible spectra of weathered grains are not statistically distinguishable from those of less weathered grains. Furthermore, although previous studies suggested that solar wind irradiation can exert opposite spectral effects when the hydration state of the material differs [15, 16], the comparable phyllosilicate abundance and bulk hydrogen content of Ryugu and Bennu samples argue against this hypothesis.

Spectral evolution driven by the evolution of surface microphysical properties: We propose that changes in surface microphysical properties —grain size, porosity, and roughness— through thermal fatigue, impacts, and electrostatic levitation may be a more important mechanism. Remote-sensing data show that fresher craters on Ryugu have brighter radiance factor, bluer spectral slope, higher thermal inertia, and shallower phase function slope. All of these trends are inverted on Bennu. Such coevolution of visible spectra with phase function slope and thermal inertia, which are known indicators of microphysical properties, suggests that the opposite evolution of microphysical properties may have driven the opposite spectral evolutions on Ryugu and Bennu.

These results are further validated by the significant spectral change observed after minor powder adhesion on Ryugu grains. A millimeter-sized Ryugu grain (C0179) showed a bluer spectral slope than the remote-sensing spectra after removing the powders adhered to the surface by brushing and high-pressure gas. In contrast, the powders (<50 µm) produced from the same grain exhibited spectral slopes more than twice as red as the remote-sensing spectrum. Remarkably, covering just ~10% of the surface area of the powder-free grain with these fine powders reproduced the global spectrum. This result indicates a direct causal link between microphysical properties and spectra. Nevertheless, the powder-free grain remains bluer than the remote-sensing spectrum of Bennu. This suggests that additional factors—such as a potentially higher abundance of phosphates on Bennu [17]—may also have a non-negligible contribution.

Discussion
Model calculation of grain-size evolution on asteroid surfaces [18] suggests that the difference in asteroid size may be one influential factor causing the opposite microphysical evolutions. On small bodies, electrostatic lofting is the primary mechanism controlling fine grain abundance. Due to a twofold difference in escape velocity, the maximum loftable grain size is ~60 µm for Ryugu and ~32 µm for Bennu. Consequently, fine grains on the order of tens of microns tend to accumulate on Ryugu’s surface but are preferentially lost from Bennu.

Such a mechanism provides the first comprehensive model for explaining the spectral discrepancy revealed by remote sensing and the compositional similarity from sample analyses of Ryugu and Bennu. This further implies that asteroids composed of CI-like materials likely do not correspond to a single spectral type, but may instead be distributed across C, Cb, and B types, due to their diverse microphysical evolution.

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[18] Hsu et al. (2022). NatAstron, 6(9).

How to cite: Yumoto, K., Tatsumi, E., Sakatani, N., Kanemaru, R., Cho, Y., Morota, T., Yokota, Y., Hamm, M., Golish, D., Kouyama, T., Lauretta, D., Barucci, A., and Sugita, S. and the Hayabusa2 Optical Navigation Camera Team: Skin-deep difference between Ryugu and Bennu driven by the microphysical evolution of surface materials, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-1344, https://doi.org/10.5194/epsc-dps2025-1344, 2025.

Japan Aerospace Exploration Agency (JAXA) has a strategic small-body sample return program to understand the formation, evolution, and migration of planetary building blocks, water, and organics in the early solar system. The JAXA's sample return program started with Hayabusa for S-type asteroid Itokawa in 2010, followed by Hayabusa-2 for C-type asteroid Ryugu in 2020, and the future mission of Martian Moons eXploration (MMX) for Phobos in 2031 (Fig. 1). My presentation covers the recent achievements of Hayabusa 2 and OSIRIS-REx curation at ISAS/JAXA and the recently launched Ryugu Reference Project. I also present an overview of MMX, particularly how we leverage the Hayabusa 2/OSIRIS-REx experience to develop the MMX curation. 

The Hayabusa 2 curation is unique in that it acts as a "bridge" between the remote sensing and sample analysis communities. Along with the conventional curation tools (e.g., optical microscope and balance), JAXA installed remote sensing instruments (e.g., ONC: Optical Navigation Camera) in the curation facility for ground truthing. Moreover, a flight spare of MicrOmega (infrared hyperspectral microscope) detected important minor phases (clays, carbonates, organics) in the apparently black Ryugu samples in the early stage of the curation.

Such a unique Hayabusa 2 curation policy expands the activities of OSIRIS-REx curation for JAXA's Bennu fractions (0.66 g) transferred from JSC/NASA on August 21, 2024. Since we received the Bennu fractions, we have completed the basic characterization of bulk fractions; the basic characterization is continued for selective individual grains. The basic characterization includes optical microscopy and further hyperspectral infrared measurements using MicrOmega and an FT-IR attached to the OSRIS-REx clean chamber.

Extending JAXA's curation activity incubates a new project (RRP: Ryugu Reference Project) to maximize the potential merit of the returned sample. The RRP aims to set an international standard for the elemental and isotopic abundances in the solar system using samples from the asteroid Ryugu. This project involves forming a Measurement Definition Team (RRP-MDT) to outline scientific goals and analysis methods. The RRP-MDT will document them in a white paper to ensure that the findings are accessible and beneficial for future research. Based on the MDT's white paper, JAXA will evaluate the significance and scientific merit of proceeding with RRP. 

JAXA plans a Phobos sample return mission, MMX, in 2026-2031. The MMX spacecraft is scheduled to be launched in 2026, orbit Phobos and Deimos (multiple flybys), and retrieve and return >10 g of Phobos regolith to Earth in 2031. The Phobos regolith represents a mixture of endogenous Phobos building blocks and exogenous materials that contain solar system projectiles (e.g., interplanetary dust particles and coarser materials) and ejecta from Mars and Deimos. The MMX Sample Analysis Working (SAWT) team outlined the curation and sample analysis protocol to identify Phobos' fragments with different origins. Following the MMX-SAWT report, JAXA curation is designing the MMX curation facility and instrumentation for the system requirement review in 2026.

Figure 1: Sample return missions by JAXA (Hayabusa, Hayabusa 2, and MMX) and by international partners (OSIRIS-REx).

How to cite: Usui, T.: From Asteroids to Martian Moons: Recent Achievements and Future Challenges of JAXA's Small-Body Sample Return Missions, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-1880, https://doi.org/10.5194/epsc-dps2025-1880, 2025.

The Hayabusa2 mission, led by the Japan Aerospace Exploration Agency (JAXA), represents one of the most ambitious space missions in terms of both technological achievement and scientific return. The mission successfully collected samples from two distinct locations on the surface of asteroid Ryugu, returning approximately 5 grams of material to Earth in December 2020 for laboratory analysis. The first touchdown (TD1) retrieved surface materials stored in Chamber A, while the second touchdown (TD2) collected subsurface materials from approximately 1 meter depth, stored in Chamber C [1].

Preliminary analyses revealed that Ryugu particles share mineralogical similarities with CI chondrites [2], featuring matrices rich in phyllosilicates, iron sulfides (pyrrhotite and pentlandite), carbonates (dolomite and an iron-bearing variety of magnesite known as brunnerite), magnetite, and hydroxyapatite [3,4,5].

In this study, we conducted a comparative analysis of three millimeter-sized particles (A0226-1, A0226-2 (both from Chamber A), and C0242 (from Chamber C) [6]). Sample A0226-2 became detached from A0226-1 during the mounting process. Using a combined FT-IR and Raman spectroscopy approach, we investigated surface differences among these particles.

Methods:

Each particle’s surface was characterized in the mid-IR (2.5 – 16 µm) using a Lumos II FT-IR microscope, with 8× magnification in reflectance mode using MCT-LN mapping (256 scans, 4 cm⁻¹ spectral resolution, 80 µm aperture). A gold plate served as the standard. Measurements were conducted in a nitrogen-enriched glovebox to limit terrestrial alteration.

Raman spectra of graphite within Ryugu particles A0226-1 and C0242 were acquired using a Horiba Jobin-Yvon LabRam IR spectrometer coupled with an Olympus BX41 optical microscope at the University of Firenze, employing a 632.8 nm laser and 1800 gr/mm grating. The maximum laser power was ~ 10 mW (1 mW with a 10% filter) and acquisitions ranged from 10-12 integrations of 5-20s depending on the intensity of spectra and sensitivity of phases, with most measurements comprising 10×10s integrations. All measurements were conducted in an inert nitrogen (N₂) environment to minimize alteration from terrestrial atmospheric exposure.

Results and discussion

Median FT-IR spectral analysis (Fig.1) indicates that particles from Chamber A exhibit greater degrees of space weathering than those from Chamber C. Specifically, the 2.72-μm OH-band depth is ~10% shallower in grains A0226-1 and -2 relative to C0242 (~20% and ~30% respectively), consistent with NIRS3 observations showing deeper 2.72-μm bands in fresher subsurface material [7,8] . Additionally, the Si–O stretching band in A0226-1 is red-shifted by ~150 nm relative to C0242, a shift potentially attributable to space weathering effects [9] .

Figure 1: Median reflectance spectra of particles A0226-1 (blue), A0226-2 (green), and C0242 (orange) over the 2–16 µm range.

Raman spectroscopy revealed notable differences in the D- and G-band profiles between grains from Chamber A and C. Graphites in A0226-1 exhibited higher degrees of graphite disorder, represented by the D-band ~1365 cm^-1, suggesting increased amorphization due to space weathering [e.g., 10], while graphites in the subsurface grain from Chamber C had little-to-no noticeable D-bands (Fig. 2). Furthermore, the G-band shows a minor decrease in Raman shift and increase in FWHM between Chamber C and A, indicative of organic matter (OM) disruption as a result of weathering [10,11]. Finally, systematic differences in fluorescence between the two sample sites may reflect variations in thermal metamorphism and/or moisture content within OM, consistent with previous findings [12,13,14].

Figure 2: Median Raman spectra obtained from two Ryugu grains A0226-1 and C0242. Vertical dashed lines are at ~ 1365 cm-1 and 1590 cm-1 to represent approximate locations of D- and G-bands respectively.

Finally, investigations into surface compositional variability are being carried out using spectral clustering. Initially, eight spectral parameters were evaluated, followed by dimensionality reduction to facilitate clustering. The analysis revealed four distinct spectral clusters, highlighting subtle heterogeneities across particle surfaces.

References

[1] Tsuda et al., 2020, Acta Astronautica, 171, June 2020, pp. 42-54.

[2] Nakamura et al., 2022. Science, 379, pp.

[3] Nakamura et al., 2022. Proceedings of the Japan Academy, Series B, 98(6), pp. 227-282.

[4] Nakamura et al., 2022. 379(6634): pp.

[5] Yokoyama et al., 2022  Science, 379(6634): eabn7850.

[6] ASRG, ISAS, JAXA et al. (2022)

[7] Galiano et al., 2020 Volume 351, 113959

[8] Kitazato et al., 2021 Nature Astronomy 5, pp. 246–250.

[9] Brunetto et al., 2018. Planetary and Space Science, 158, pp. 38-45.

[10] Bonal et al., 2006. Geochimica et Cosmochimica Acta, 70(7), pp. 1849-1863.

[11] Rotundi et al., 2008. Meteoritics & Planetary Science, 43(1), pp. 367-397.

[12] Brunetto et al., 2014. Icarus, 273, pp. 278-292.

[13] Henry et al., 2019. Earth Science Reviews, 198, article id. 102936.

[14] Bonal et al., 2024. Icarus, 408, article id. 115826.

[15] Komatsu et al., 2024. Meteoritics & Planetary Science, Volume 59, Issue 8, pp. 2166-2185

Acknowledgments: The Ryugu samples used in this paper were distributed through the 2AO Announcement of Opportunity for Hayabusa2 samples (AO2). These samples were referred to the Ryugu Sample Database at https://www.darts.isas.jaxa.jp/curation/hayabusa2/ .

Funding: This work was supported by the National Institute of Astrophysics (INAF) by the PRESTIGE (Pristine Returned Sample Testing InvestiGation and Examination) project

How to cite: Angrisani, M., Palomba, E., Grant, H., D'Amore, M., Romani, M., Shehaj, X., Catelani, T., Arpaia, L., Longobardo, A., Dirri, F., Viviani, G., Cestelli Guidi, M., and Pratesi, G.: Space Weathering and Compositional Variations in Ryugu Samples: FTIR and Raman Spectroscopic Insight, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-786, https://doi.org/10.5194/epsc-dps2025-786, 2025.

• Introduction

The JAXA Hayabusa2 mission represents a significant milestone in planetary science. In December 2020, the mission successfully returned samples from two distinct sites of the carbonaceous, C-type, asteroid Ryugu. These samples were expected to provide critical insights into the origin of volatiles including water and organics on Earth, the thermal and aqueous histories of primitive bodies, and the physicochemical processes that related to the earliest stage of our Solar System.

F Following the successful recovery of the re-entry capsule, initial curation activities, primarily consisting of non-destructive observations (such as optical microscopy, FT-IR, MicrOmega, and weight measurements), were conducted at JAXA’s Extraterrestrial Sample Curation Center. Subsequently, the expanded analytical phase was launched to facilitate advanced and multi-institutional investigations by six initial analysis teams and the two Phase2 Curation teams including the Phase2 Curation Kochi team (Ph2K) [1-10].

• Preserve Pristine Nature of Ryugu sample: Contamination Control from curation facility to the institutes

The Ryugu samples are invaluable to planetary science due to their minimal terrestrial contamination, preserving volatiles and complex microstructures of minerals and organics. They preserve volatiles and complex microstructures of minerals and organics, providing insights into the early evolution of the Solar System [3-10]. To minimize contamination during transport to institutes both nationwide and internationally, we developed the Facility-to-Facility Transfer Container (FFTC) and individual sample containers [11] (Fig. 1). These were designed for use within Ryugu-dedicated clean chambers at the JAXA and prioritized ease of cleaning, use of same materials with the clean chamber, operability with thick Viton-coated butyl gloves, and long-term sealing using pure nitrogen.

• A Cross-Platform Pipeline for Extraterrestrial Sample Analysis

The cross-platform analytical pipeline of the Ph2K is designed to establish comprehensive protocols for the analysis of small-volume, volatile-rich extraterrestrial materials from asteroid Ryugu. Its primary objective is to characterize the mineralogical, petrological, chemical, and isotopic properties of the Ryugu samples at mm- to micrometer scales. To maximize scientific gain from the limited sample mass, the protocol follows a “non-destructive-first” strategy, advancing sequentially through increasingly invasive and ultimately destructive analytical techniques (Figs. 2, 3) [11-13].

• Results in case of Ryugu sample analysis by Ph2K

Ph2K plays a vital role in understanding of primitive Solar System materials. Samples returned from asteroid Ryugu exhibit bulk chemical compositions and oxygen isotopic compositions closely matching those of CI chondrites which is similar chemical compositions of the Sun, suggesting that Ryugu represents one of the most chemically primitive materials in the Solar System [e.g., 3-6, 13]. Our analyses revealed abundant hydrated minerals, such as phyllosilicates (i.e., serpentine and saponite) and carbonates, as well as isotopically heavy hydrogen and nitrogen isotopic compositions, pointing to low-temperature alteration and a formation in the cold outer Solar System. Organic matter, rich in aliphatic hydrocarbons, was associated with coarse-grained phyllosilicates, implying that these minerals may have provided environments favorable for organics. These findings support a scenario in which Ryugu accreted from icy and organic-rich particles, migrated inward, and potentially contributed to the delivery of water and organics to early Earth. Further studies of samples from other planetary explorations meteorite, and interplanetary dust particles are essential to expand our understanding of volatile transport and preservation in the early Solar System.

Additional findings by Ph2K include the identification of Ryugu’s precursor body [14], early aqueous alteration within 1.8–5.0 Myr after CAI formation [15], and low ejecta yields from asteroid during impacts [16]. Primitive noble gases with high xenon concentrations [17] and amorphous phases containing phosphorus and ammonium ions were also discovered, suggesting relevance to prebiotic chemistry on a carbonaceous asteroid [18]. Atmospheric exposure experiments further revealed rapid terrestrial alteration for the importance of meteorites and future returned sample curation and storage processes [19].

• Conclusion and perspective

Results from Ph2K have revealed mineralogical inventories, fine-scale isotopic variations, and signatures of low-temperature aqueous alteration with the complex water-mineral-organics coevolution on a carbonaceous asteroid. These findings may support the hypothesis that Ryugu and similar bodies may have played a key role in the delivery of water and organics to the early Earth.

The cross-platform pipeline by Ph2K will serve as a benchmark not only for Ryugu studies but also for future sample return missions, including MMX (Martian Moons eXploration). The continued refinement of small-sample analytical techniques will contribute significantly to the planetary science and the development of next-generation curation protocols [20].

• References

[1] Yada, T. et al. (2021) Nat. Astron. [2] Pilorget, C. et al. (2021) Nat. Astron. [3] Ito, M. et al. (2022) Nat. Astron. [4] Nakamura, E. et al. (2022) Proc. Jpn. Acad. B. [5] Yokoyama, T. et al. (2022) Science. [6] Nakamura, T. et al. (2022) Science. [7] Noguchi, T. et al. (2022) Nat. Astron. [8] Okazaki, R. et al. (2022) Science. [9] Naraoka, H. et al. (2023) Science. [10] Yabuta, H. et al. (2023) Science. [11] Ito, M. et al. (2020) Earth Planets Space. [12] Uesugi, M. et al. (2020) Rev. Sci. Instrum. [13] Yamaguchi, A. et al. (2023) Nat. Astron. [14] Liu, M-C. et al. (2022) Nat. Astron. [15] McCain, K. A. et al. (2023) Nat. Astron. [16] Tomioka, N. et al. (2023) Nat. Astron. [17] Verchovsky, A. B. et al. (2024) Nat. Commun. [18] Pilorget, C. et al. (2024) Nat. Astron. [19] Imae, N. et al. (2024) Meteor. Planet. Sci. [20] Grady, M. et al. (2025) Nat. Astron.

How to cite: Ito, M., Tomioka, N., Uesugi, M., Uesugi, K., Yamaguchi, A., Imae, N., Ohigashi, T., Shirai, N., Nakato, A., Yogata, K., Yada, T., Abe, M., Liu, M.-C., Greenwood, R., Yuzawa, H., and Kimura, M.: Design and Implementation of a Cross-Platform and Multi-Scale Workflow for Volatile-Rich Extraterrestrial Sample Analysis: From Contamination Control to Coordinated Analysis, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-89, https://doi.org/10.5194/epsc-dps2025-89, 2025.

Introduction: On June 25th, 2024, China’s Chang’e-6 (CE-6) mission successfully returned the first lunar farside sample from the South Pole–Aitken (SPA) basin [1]. Orbital investigations have revealed hemispheric asymmetries between the lunar farside and nearside, including disparities in crustal thickness, magmatic activity, and geochemical compositions [2-4]. The origin of these fundamental dichotomies remain a subject of debate [5-10]. Notably, all lunar samples collected prior to CE-6 mission, ranging from Apollo 11 to Chang’e-5 (CE-5), were exclusively sourced from the nearside. Comparative studies of lunar samples from both hemispheres could provide key constraints on our understanding of the lunar evolution. Therefore, CE-6 basalts offer a unique opportunity to investigate the composition and evolution of the previously inaccessible farside of the Moon.

Samples and methods: The basalt fragments analysed in this study were from the scooped samples of CE-6 mission allocated by the China National Space Administration (CNSA). The petrography was carried out on a Zeiss Supra 55 field emission scanning electron microscopy (SEM). The major element compositions of plagioclase, pyroxene, olivine, ilmenite and spinel were analysed with a JEOL JXA8230 electron probe. The bulk chemistry of CE-6 lunar basaltic fragments were determined by X-ray fluorescence spectrometry (XRF) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP–MS), respectively.

Results and discussion: The CE-6 basalt fragments studied here are composed of clinopyroxene, plagioclase, and ilmenite, as well as minor amounts of silica, fayalite, ulvöspinel, troilite, phosphates, and Zr-bearing minerals. According to their petrographic characteristics, the basalt fragments can be classified into four distinct textural subtypes: vitrophyric, porphyritic, subophitic, and poikilitic (Figure 1).

The vitrophyric clasts consist of glass and needle-like microcrystals of plagioclase, pyroxene, and ilmenite, which are typically less than 10 μm in size (Figure 1a). The phenocrysts are mainly clinopyroxene (Wo_29.7-36.8En_29.0-36.1Fs_29.2-36.2), ranging from 50 to100 μm, accompanied by a minor amount of slender plagioclase.

The porphyritic clasts display coarse-grained  clinopyroxene and plagioclase (An_88.7-92.3) phenocrysts (approximately 50 ´ 300 μm) embedded within fine-grained matrix (<10 μm, Figure 1b). The matrix is primarily composed of acicular plagioclase (An_76.3-85.2), interstitial clinopyroxene and tiny ilmenite (<5 μm). In contrast to the phenocrysts, the clinopyroxene within the matrix exhibits higher FeO but lower MgO and Cr₂O₃ contents. Ilmenite needles commonly intersect the matrix plagioclase and pyroxene, indicating a late-stage crystallisation phase.

The subophitic clasts show a diverse range of grain sizes from 20 to 300 μm and consist mainly of plagioclase, clinopyroxene, ilmenite, with minor ulvöspinel, troilite, olivine and cristobalite (Figure 1c). Both clinopyroxene and olivine have compositional zoning, with Mg-rich cores and Fe-rich rims. Plagioclase shows euhedral to subhedral shape with anorthite-rich composition (An_83.6-92.0).

The poikilitic clasts are composed of clinopyroxene, plagioclase, ilmenite, and accessory ulvöspinel, troilite, and a mesostasis phase including K-feldspar, fayalite, cristobalite, baddeleyite, tranquillityite, zirconolite, and phosphates (Figure 1d). Plagioclase is anorthite-rich composition (An_81.9-94.3). Clinopyroxene displays a large compositional range (Wo_8.5-38.9En_0.2-55.7Fs_20.8-89.8), systematically characterized by Mg-rich cores and Fe-rich rims. Small amounts of Fe-rich olivine (fayalite, Fo_1.6) associated with cristobalite, baddeleyite, tranquillityite, zirconolite, and phosphates occur as mesostasis phases representing the late-stage crystallisation products.

The major mineral compositions of basalt fragments with different textures show that the anorthite content in plagioclase varies from 81.1 to 94.3, with an average composition of An_87.5Ab_12.1Or_0.4 (n = 305). Pyroxene in the basalt is predominantly augite, with an average composition of Wo_27.4En_28.7Fs_43.9 (n = 354). Pigeonite is less abundant, with an average composition of Wo_15.6En_28.5Fs_55.9 (n = 169). The composition of ilmenite is homogeneous, with average contents of 51.7% TiO₂ and 47.0% FeO. According to the Fe# vs. Ti# correlation diagram of pyroxene, the basalts with porphyritic, subophitic and poikilitic textures in the CE-6 samples are all classified as low-Ti basalts (Fig. 2). Although the composition of vitrophyric pyroxene falls within the range of the high-Ti basalts, petrographic evidence suggests that the ilmenite crystallized after the clinopyroxenes and plagioclase phenocrysts, which follows the typical crystallization sequence of low-Ti basalts [11]. Therefore, we conclude that the CE-6 basalts with different textures in this study are all low-Ti basalts.

References: [1] Li et al., 2024, National Science Review, 11, nwae328. [2] Zuber et al., 1994, Science, 266, 1839-1843. [3] Jolliff et al., 2000, Journal of Geophysical Research, 105, 4197-216. [4] Wieczorek et al., 2013, Science, 339, 671-675. [5] Loper and Warner, 2002, Journal of Geophysical Research, 107, 13-11-13-17. [6] Zhong et al., 2000, Earth and Planetary Science Letters, 177, 131-140. [7] Parmentier et al., 2002, Earth and Planetary Science Letters, 201, 473-480. [8] Zhu et al., 2019, Journal of Geophysical Research, 124, 2117-2140. [9] Jones et al., 2022, Science Advance, 8, eabm8475. [10] Zhang et al., 2022, Nature Geoscience, 15, 37-41. [11] Shearer et al., 2006, Reviews in Mineralogy and Geochemistry, 60, 365-518.

Figure 1: BSE image of typical basaltic fragments with various textures.

Figure 2: Ti# versus Fe# diagram of the pyroxene from CE6 basalt fragments. Fields represent variation in Fe# and Ti# in Apollo very low-Ti, low-Ti, and high-Ti mare basalts.

How to cite: Zhou, Q., Li, C., Liu, J., Liu, B., and Li, H.: Petrology and mineralogy of Chang’e-6 basalts sampled from the South Pole-Aitken Basin, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-552, https://doi.org/10.5194/epsc-dps2025-552, 2025.

China’s Chang’E-5 (CE-5) mission successfully returned 1,731 grams of lunar samples from the northeastern region of Oceanus Procellarum in December 2020 (C. Li et al., 2022; Zhou et al., 2022). The landing site, among the Moon’s youngest mare basalts (Morota et al., 2011; Qian et al., 2021; Che et al., 2021; Li et al., 2021), is located at a higher latitude than those explored by NASA’s Apollo and the USSR’s Luna missions, offering a unique opportunity to study previously unexamined lunar material.

Approximately 1 gram of surface-scooped sample (CE5C0100) and 0.5 gram of drilled sample (CE5Z0800) were offered to France. These samples are currently stored at the Muséum National d’Histoire Naturelle (MNHN) in Paris in a dedicated glovebox under ultra-dry and ultra-pure nitrogen. A curation project was initiated to conduct non-destructive, preliminary characterization of the samples and provide reference data before their allocation to the French scientific community under the supervision of CNES. The proposed curation activities are described below.

The CE-5 samples arrived in France stored in glass vials within an aluminum container. To obtain preliminary data on both the samples and containers, X-ray Computed Tomography (XCT) was performed at AST-RX platform (MNHN). The XCT scans at a spatial resolution of 60 µm/pixel enabled measurement of the container’s bottom thickness (~5 mm), empty volume (~800 cm³), and sample volumes (~700 mm³ for the scooped sample and ~360 mm³ for the drilled sample). The XCT images also identified 10–20 grains larger than 500 µm and revealed grains with higher density, heterogeneity, or void space (possible agglutinate).

The container will be opened in a glovebox at MNHN under a controlled atmosphere (<1 ppm O₂ and <1 ppm H₂O). Part of the samples will be transferred to a new custom-made glovebox in a dedicated clean room (ISO7) at Institut de Physique du Globe de Paris (IPGP). A gas extraction procedure will be performed on the drilled sample container using a custom-designed extraction system developed in collaboration between IMPMC and IPGP. The container’s base will be punctured, and the gas will be transferred into an ultra-high vacuum bottle. The gas will then be analysed using a custom-built infrared optical spectrometer at Liphy (CNRS, Grenoble Alpes University).

Non-invasive measurements—including mass and magnetic susceptibility—will be conducted on each bulk sample in the vials. The samples will then be separated in different batches and transferred to a stainless-steel cylinder with a glass window for storage. An optical sensor on the glass window will allow continuous monitoring of O₂ levels inside the cylinder without opening it.

Rehearsals will be conducted using new equipments, including a micro-manipulator located in a new glovebox and dedicated materials and tools to test manipulation, measurements and storage procedures. We are planning to extract the largest grains from the bulk material for dedicated characterization. Both bulk powder and grain samples will undergo basic weighing and imaging. Subsamples will be placed on sapphire dishes, sealed in faculty-to-faculty transfer containers (FFTCs), and sent to collaborating laboratories for infrared spectroscopy, XCT, and X-ray diffraction (XRD). The remaining samples will remain untouched in the storage cylinders in the glovebox at MNHN for future analysis.

Infrared microanalysis of both bulk powder and large grains will be conducted at the Institut d'Astrophysique Spatiale (IAS) using MicrOmega (near-infrared: 0.99–3.65 µm, 22 µm/pixel, Bibring et al., 2017) and FTIR (mid-infrared: 2.5-12.5 µm (4,000-800 cm^-1), 5 µm/pixel). Both hyperspectral imagers will aid in identifying characteristic mineral phases (e.g., olivine, pyroxene, plagioclase) in the samples. High-resolution XRD will be conducted at IMPMC, while XCT analysis at micron or sub-micron scale of large grains will be performed at the French synchrotron facility SOLEIL.

These analyses will provide a comprehensive dataset to documenting the samples’ mass, morphology, and mineralogy of both individual grains and bulk-powder batches. The results will be compiled into a catalog database and shared via a dedicated website under CNES supervision. Further details will be presented at the conferences.

Acknowledgements:

We thank the Chang’E-5 mission project for sharing these invaluable lunar samples. We also thank CNES for its full support on the curation activities. The curation activities at MNHN received funding from DIM ACAV+ (Région Ile de France, project C3E), CNES (APR CE5-CURE), the PEPR Origins, project MARCUS (ANR-22-EXOR-0010). The X-ray Computed Tomography (XCT) was performed at the AST-RX, plateau d'Accès Scientifique à la Tomographie à Rayons X du MNHN, UAR 2700 2AD CNRS-MNHN, Paris.

References:

Bibring, J-P., et al. "The micrOmega investigation onboard Hayabusa2." Space Science Reviews 208 (2017): 401-412.

Che, Xiaochao, et al. "Age and composition of young basalts on the Moon, measured from samples returned by Chang’e-5." Science 374.6569 (2021): 887-890.

Li, Chunlai, et al. "Characteristics of the lunar samples returned by the Chang’E-5 mission." National science review 9.2 (2022): nwab188.

Li, Qiu-Li, et al. "Two-billion-year-old volcanism on the Moon from Chang’e-5 basalts." Nature 600.7887 (2021): 54-58.

Morota, Tomokatsu, et al. "Timing and characteristics of the latest mare eruption on the Moon." Earth and Planetary Science Letters 302.3-4 (2011): 255-266.

Qian, Yuqi, et al. "China's Chang'e-5 landing site: Geology, stratigraphy, and provenance of materials." Earth and Planetary Science Letters 561 (2021): 116855.

Zhou, Changyi, et al. "Scientific objectives and payloads of the lunar sample return mission—Chang’E-5." Advances in Space Research 69.1 (2022): 823-836.

How to cite: Jiang, T., Duprat, J., Viennet, J.-C., Poulet, F., Pilorget, C., Brunetto, R., Avice, G., Vayrac, F., Morand, M., Amand, L., Garino, Y., Boccato, S., Engrand, C., Delauche, L., Gattacceca, J., Maurel, C., Kassi, S., Rocard, F., and Mustin, C.: Curation activities progress on the Chang’E-5 samples in France, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-1012, https://doi.org/10.5194/epsc-dps2025-1012, 2025.

The stratosphere at altitudes ranging from 30 to 40 km is one of the most suitable and accessible environments to collect pristine interplanetary and interstellar dust particles, where the terrestrial dust component, e.g. volcanic, aeolian and anthropogenic aerosol, is negligible [1-3]. The DUSTER (Dust in the Upper Stratosphere Tracking Experiment and Retrieval) project is a balloon-borne sampling instrument specifically developed to collect Interplanetary Dust Particles (IDPs) with minimal contamination and structural integrity, at collection speed of 7 m/s and flow rates > 1 m³/h. DUSTER includes an adhesive-free collection substrate (Collector), fitted with 13 Transmission Electron Microscope (TEM) grids, directly exposed to the stratospheric airflow. The collection strategy is designed to ensure low-speed impact and capture, avoiding particle fragmentation or heating. The Collector and the Blank, i.e. an identical but unexposed collector, are imaged pre- and post-flight to identify possible pre-existing non-stratospheric particles to be excluded from the sample collection, if observed on the Collector, and to be considered as contaminants, if observed on the Blank. The conceived stringent contamination control protocol positions DUSTER as the only system capable of returning ultra-clean cosmic dust for high-resolution up-to-date laboratory investigations. Four DUSTER stratospheric balloon campaigns have successfully collected IDPs: Svalbard, Norway (2008) and Kiruna, Sweden (2011, 2019, 2021) [4,5]. We focus here on particles coming from the most recent campaigns (Kiruna, 2019 and 2021). These collections yielded hundreds of particles ranging in size from 0.1 to 50 µm, with a predominance in the 1 µm range. The preliminary SEM-based morpho-classification reveals a compositional and structural diversity including compact mineral fragments, porous aggregates, and spherules. Energy-dispersive X-ray (EDX) analyses confirmed the presence of silicates and carbonates, [4,5].

Figure 1. Schematic overview of the DUSTER collection concept:  Interplanetary Dust Particles (IDPs) from comets, asteroids, and meteoroid collisions, as well as interstellar dust from supernovae and dense molecular clouds, enter Earth’s atmosphere. Most man-made and terrestrial materials, e.g. volcanic, remain confined to the troposphere or lower stratosphere. The high-altitude stratospheric window, 30 - 40 km, is a unique reservoir for extraterrestrial matter, allowing DUSTER to collect stratospheric particles in a near-contamination-free environment, enabling the recovery of pristine IDPs and possible interstellar dust, intercepted due to the solar system's motion within the Milky Way.

Figure 2. SEM and EDX elemental maps of a stratospheric particle collected by DUSTER. The right image shows a secondary electron micrograph of the collected particle, highlighting its irregular morphology and fragile structure. Elemental maps obtained via EDX reveal the distribution of major elements: calcium (Ca), oxygen (O), aluminum (Al), silicon (Si), and iron (Fe).

The PRIN 2022 research project “Cosmic Dust II: Cosmochemistry and Space Tweezers Technologies for Solar System Science and Exploration", uses this collection to investigate   the cosmochemical and mineralogical characteristics of extraterrestrial particles with sizes ranging from about 0.5 µm to 50 µm, a dimension gap yet to be filled. Within this framework, selected subsets of DUSTER IDPs i.e., a total of 11 particles with sizes > 10 µm and of 10 particles with sizes < 5 µm, are undergoing a comprehensive multi-analytical technique campaign. These particles have been selected based on their size, morphology, mineralogy, and surface preservation. For particles larger than 10 µm in size an initial high-resolution SEM imaging, followed by non-destructive spectroscopic techniques, including micro-Infrared (µIR), micro-Raman, and nano-Raman spectroscopy are employed. This facilitates the mapping of mineral phases and organic functional groups, allowing us to identify silicates, sulfides, and carbonaceous matter. IDPs smaller than 5 µm in size are observed with high-resolution transmission electron microscopy (HR-TEM) and 3D electron diffraction tomography (EDT), offering structural and chemical characterization at nanometer scale and discriminate of amorphous versus crystalline domains. A subset of particles will undergo destructive analytical techniques, including nano-scale Secondary Ion Mass Spectrometry (nanoSIMS) for measurement of isotopic compositions at sub-micron scale. This last analysis is critical for tracing potential presolar grains and to understand the source-region signatures within the solar system, but also very challenging when applied to DUSTER collections.

Through this correlated microscopic protocol we aim to build an integrated dataset for each particle, allowing us to characterize its composition, formation history, and potential astrobiological significance. These results are expected to have implications not only for understanding the composition of the near-Earth dust complex and identifying its parent bodies, but also for the broader goals of astrobiology, planetary geology, and Solar System exploration.

References

[1] Flynn, 1997. Collecting interstellar dust grains. Nature, 387, 248. [2] Brownlee 1985. Cosmic dust: collection and research. Annu. Rev. Earth Planet. Sci. 13(1),147-173. [3] Della Corte & Rotundi, 2021. Collection of samples. In Sample Return Missions: The Last Frontier of Solar System Exploration, ed. A. Longobardo. Elsevier, 269-293. [4] Della Corte et al., 2012. In Situ Collection of Refractory Dust in the Upper Stratosphere: The DUSTER Facility. Space Science Reviews, 169, 159-180. [5] Rietmeijer et al., 2016. Laboratory analyses of meteoric debris in the upper stratosphere from settling bolide dust clouds. Icarus, 266, 217-234.

Acknowledgements: we acknowledge the PRIN2022/MUR “Cosmic Dust II: Cosmochemistry and Space Tweezers Technologies for Solar System Science and Exploration” project, ID# 2022S5A2N7, CUP n. I53D23000740006.

How to cite: Tonietti, L., Della Corte, V., Rotundi, A., Dionnet, Z., Folco, L., Maragò, O., Foti, A., Infusino, M., Magazzù, A., Brucato, J. R., Bertini, I., Inno, L., Stefani, S., Rubino, S., Piccioni, G., Suttle, M. D., Davies, F., Ottaviani, S., Cozzolino, F., and Mennella, V.: Uncontaminated Cosmic Dust from the Upper Stratosphere: DUSTER Collections and Multi-Analytical Characterization of micron and sub-micron particles, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-1032, https://doi.org/10.5194/epsc-dps2025-1032, 2025.

Introduction:  Recent missions, Hayabusa2 and OSIRIS-REx, successfully brought back significant samples from the near-Earth asteroids Ryugu and Bennu [1, 2]. Hayabusa and its successor employed a method of collecting surface grains through impact mobilization. In contrast, OSIRIS-REx used pressurized nitrogen gas to push material into its collection device. Although Touch-And-Go (TAG) manoeuvres are commonly used for asteroid sampling, recent lunar missions, such as the Luna and Chang'e programs [3, 4], have adopted more controlled techniques involving landers that drill and scoop material. During the Apollo program, astronauts primarily collected samples manually using various tools. For the MarcoPolo-R mission study [5], an alternative sampling method, the Brush Wheel System (BWS), was developed and tested, though ultimately not implemented. This system aimed to brush material into a container during landing [6]. To explore and refine another sampling mechanism suitable for both TAG and landing manoeuvres, previous work [6-8] has been examined. This mechanism will be adapted and optimized for a mission profile different from MarcoPolo-R, with the goal of effectively sampling a broad spectrum of grain sizes, applicable to both lunar and asteroidal environments.

Sampler Design:  The APOphiS SUrface saMpler (APOSSUM) concept has undergone investigation and development in two concurrent engineering studies at DLR Bremen in 2024, in collaboration with DLR and MPS Göttingen [9, 10]. The initial mission design targeted Apophis' flyby in 2029, when it will pass Earth at a distance of less than 32,000 km. The Brush Wheel System (BWS) was developed as the primary instrument for acquiring grains up to 5 cm in diameter during a TAG maneuver. Currently, the APOSSUM (renamed to Asteroid PrObe Sampler and Sample retUrn Mission) system shall be implemented as a payload for the PRIAMOS mission proposal to sample regolith from a D-type asteroid and  for the CoSi mission proposal to study the uppermost surface of a comet. The design of the Brush Wheel System (BWS) features two cylindrical brushes, each 100 mm in length and 100 mm in diameter, driven independently by brushless DC motors. Surface particles ranging from sub-millimeter to centimeter sizes are captured, lifted, and moved into the sampling tube for subsequent collection. A test setup was created to simulate a Touch-And-Go (TAG) maneuver within a 45 cm square sample box. To achieve this, the sampler is suspended by four Dyneema strings, enabling a controlled descent at speeds up to 20 cm/s and at varying angles relative to gravity and/or the sample surface. The flight instrument design incorporates two cameras, providing views of both the surface interaction area and inside the sampling tube. Unlike the breadboard, the flight design may adopt a four-brush configuration, which will be evaluated against the two-brush design based on sampling efficiency, system redundancy, and overall complexity.

First Test Results: The breadboard design underwent extensive testing across a broad spectrum of parameters within our dedicated facility. Particle size and the BWS motor speed emerged as crucial factors influencing sampling efficiency. Notably, particles up to 5 cm in diameter could be sampled with satisfactory efficiency even under Earth's gravity. Currently, porous clay (LECA) and fractured Ytong rocks serve as analogue materials, which can be optionally combined with sand to simulate finer regolith. The use of lunar and Martian soil simulants is also feasible and planned to validate the concept with specific grain size distributions. Motor speeds in the range of 300 to 400 rpm struck a favorable balance between sampling efficiency and motor power requirements, a finding corroborated by our tests. Brush blockage occurred more frequently at lower rotation speeds (e.g., 200 rpm) and at 400 rpm, particles around 40 mm in size were ejected several decimeters from the surface. Other tested parameters included the relative surface angle, particle shapes and sizes, and contact force. Overall, the concept demonstrated robustness against these variations, although sampling efficiency was affected. In the event that a particle larger than the gap between the brushes causes them to jam, a reverse rotation can clear the obstruction, allowing for a subsequent sampling attempt.

Upcoming Development: The Brush Wheel System (BWS) is currently undergoing modifications to ensure compatibility with vacuum environments including brushless DC motors. It will be tested in zero-gravity and simulated lunar gravity conditions during two campaigns in June and October at the Drop-Tower and GraviTower facilities at ZARM in Bremen. Key objectives of these campaigns are to: 1) investigate the interaction between the brushes and the surface material, and 2) validate the system's efficiency under zero- and low-gravity for a range of system parameters. These parameters are consistent with those tested in the atmospheric setup described in the preceding section. Additionally, breadboard model incorporating four brushes is tested under Earth's gravity. Initial test results from the zero-gravity and simulated lunar gravity campaigns will be presented at the conference.

Acknowledgement: We acknowledge financial support by the DLR Agency (50OO2511).

Fig. 1: a) CAD model of the BWS flight design consisting of 4 diamond-shaped brushes, a flap to close the sampling tube and two cameras (blue) to observe surface interaction and material inside the sampling tube. b) BWS breadboard with two cylindrical brushes. c) Test facility to simulate TAG maneuver under Earth gravity.

Fig. 2: Snapshot from a video during a test with a brush rotation speed of 400 rpm and an approach velocity of 20 cm/s on ~30-40 mm LECA clay and Ytong rocks. After surface contact many particles are lifted and partially flying up to a meter high (arrow) reaching velocity of ~1 m/s.

References:

[1] Watanabe S. I., et al. (2017) Space Science Reviews, 208, 3-16.

[2] Lauretta D. S. et al. (2024) Meteorit. Planet. Sci., 59, 2453-2486.

[3] Florensky et al (1977) Proc. 8th Lunar Sci. Conf., 3257-3279.

[4] Xiao et al. (2021), Sample return missions, 195-206.

[5] Barucci M. A. et al. (2012) Exp. Astron., 33, 645–684.

[6] Bonitz R. (2012) IEEE Aerospace Conference, Big Sky, MT, USA, pp. 1-6.

[7] Zhang J. et al. (2022) Acta Astronautica, 198, 329-346.

[8] Luo H. et al. (2023) Front. Mech. Eng., 18, 16.

[9] Grundmann J. T. et al. (2025) Apophis T-4 Workshop.

[10] Goldmann M. et al. (2025) Apophis T-4 Workshop. 

How to cite: Gundlach, B., Patzek, M., Goldmann, M., Güttler, C., Klingenberg, G., Aussel, B., Grundmann, J. T., and Hilchenbach, M.: APOSSUM – A Brush Wheel System Sampler for Asteroidal Regolith , EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-1251, https://doi.org/10.5194/epsc-dps2025-1251, 2025.