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Constraints on Solar System early evolution by MicrOmega analysis of Ryugu carbonates


The samples returned from a C-type asteroid (Ryugu) by the Hayabusa2 mission constitute unprecedented access to carbonaceous material never exposed to Earth’s atmosphere that may still contain phases formed in the earliest stages of the Solar System. We present an extensive analysis of a large set of grains and bulks of the Ryugu samples, performed directly within the Japan Aerospace Exploration Agency Curation Center in Japan with the near-infrared hyperspectral microscope MicrOmega, to identify and characterize the carbonate component of the samples, which has recorded early evolutionary steps. We reveal a large presence of carbonates within the collection distributed over two main size-dependent populations: generally small (<100 µm) dolomite-rich and larger (up to hundreds of µm) breunnerite-rich areas, some with complex elongated morphologies. Similarities with C-chondrites suggest that such characteristics may emerge as a general property of primitive materials in the outer part of the asteroid belt. These two carbonate populations likely translate distinct processes and stages of formation in the early Solar System that might have taken place while CO2 ice was still present (possibly before accretion of the Ryugu parent body) and/or from C-rich phases.

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Fig. 1: Examples of carbonate ROIs.
Fig. 2: Carbonate size distribition.
Fig. 3: Ryugu spectral carbonate endmembers.

Data availability

Each of these carbonate detections will be available in the catalogue of Ryugu samples available at, including the location of the detection and its average spectrum.


  1. Yada, T. et al. Preliminary analysis of the Hayabusa2 samples returned from C-type asteroid Ryugu. Nat. Astron. 6, 214–220 (2021).

    Article  ADS  Google Scholar 

  2. Bibring, J.-P., Hamm, V., Pilorget, C. & Vago, J. MicrOmega team, the MicrOmega investigation onboard ExoMars. Astrobiology 17, 621–626 (2017).

    Article  ADS  Google Scholar 

  3. Pilorget, C. et al. First compositional analysis of Ryugu samples by the MicrOmega hyperspectral microscope. Nat. Astron. 6, 221–225 (2021).

    Article  ADS  Google Scholar 

  4. Nakato, A. et al. Morphological classification of Ryugu returned samples based on Curation initial description. 53rd Lunar and Planetary Science Conference, The Woodlands, TX, 7–11 March 2022. LPI Contribution No. 2678, 2022, id.1810.

  5. Yamaguchi, A. et al. Petrology of asteroid Ryugu particles allocated to the Phase2 Curation Kochi Team. 53rd Lunar and Planetary Science Conference, The Woodlands, TX, 7–11 March 2022. LPI Contribution No. 2678, 2022, id.1822.

  6. Yurimoto, H. et al. Chemical and isotopic characterization of asteroid Ryugu. 53rd Lunar and Planetary Science Conference, The Woodlands, TX, 7–11 March 2022. LPI Contribution No. 2678, 2022, id.1377.

  7. Lantz, C. et al. Visible and IR hyperspectral imaging of Ryugu samples compared to meteorites and to remote sensing of Bennu and other primitive asteroids. 53rd Lunar and Planetary Science Conference, The Woodlands, TX, 7–11 March 2022. LPI Contribution No. 2678, 2022, id.1866.

  8. Johnson, C. A. & Prinz, M. Carbonate compositions in CM and CI chondrites and implications for aqueous alteration. Geochim. Cosmochim. Acta 57, 2843–2852 (1993).

    Article  ADS  Google Scholar 

  9. De Leuw, S., Rubin, A. E. & Wasson, J. T. Carbonates in CM chondrites: complex formational histories and comparison to carbonates in CI chondrites. Meteorit. Planet. Sci. 45, 513–530 (2010).

    Article  ADS  Google Scholar 

  10. Lee, M. R., Lindgren, P. & Sofe, M. R. Aragonite, breunnerite, calcite and dolomite in the CM carbonaceous chondrites: high fidelity recorders of progressive parent body aqueous alteration. Geochim. Cosmochim. Acta 144, 126–156 (2014).

    Article  ADS  Google Scholar 

  11. Alexander, C. O. D., Bowden, R., Fogel, M. L. & Howard, K. T. Carbonate abundances and isotopic compositions in chondrites. Meteorit. Planet. Sci. 50, 810–833 (2015).

    Article  ADS  Google Scholar 

  12. Alfing, J., Patzek, M. & Bischoff, A. Modal abundances of coarse-grained (> 5 μm) components within CI-chondrites and their individual clasts–mixing of various lithologies on the CI parent body(ies). Geochemistry 79, 125532 (2019).

    Article  Google Scholar 

  13. Endress, M., Ernst Zinnert, E. & Bischoff, A. Early aqueous activity on primitive meteorite parent bodies. Nature 379, 701–703 (1996).

    Article  ADS  Google Scholar 

  14. Steele, R. C., Heber, V. S. & McKeegan, K. D. Matrix effects on the relative sensitivity factors for manganese and chromium during ion microprobe analysis of carbonate: implications for early Solar System chronology. Geochim. Cosmochim. Acta 201, 245–259 (2017).

    Article  ADS  Google Scholar 

  15. Clark, R. N., King, T. V. V., Klejwa, M., Swayze, G. A. & Vergo, N. High spectral resolution reflectance spectroscopy of minerals. J. Geophys. Res. Solid Earth 95, 12653–12680 (1990).

    Article  Google Scholar 

  16. Bishop, J. L. et al. Spectral properties of anhydrous carbonates and nitrates. Earth Space Sci. 8, e2021EA001844 (2021).

    Article  ADS  Google Scholar 

  17. Hunt, G. R. & Salisbury, J. W. Visible and near infrared spectra of minerals and rocks. II. Carbonates. Mod. Geol. 2, 23–30 (1971).

    ADS  Google Scholar 

  18. Gaffey, S. J. Spectral reflectance of carbonate minerals in the visible and near infrared (0.35–2.55 um): anhydrous carbonate minerals. J. Geophys. Res. 92, 1429–1440 (1987).

    Article  ADS  Google Scholar 

  19. Michikami, T. et al. Boulder size and shape distributions on asteroid Ryugu. Icarus 331, 179–191 (2019).

  20. Dionnet, Z. et al. Small Ryugu fragments analyzed by IR micro-spectroscopy and tomography: a description of the 3D heterogeneity at the micrometric scale. 53rd Lunar and Planetary Science Conference, The Woodlands, TX, 7–11 March 2022. LPI Contribution No. 2678, 2022, id.1534.

  21. Schröder, S. et al. Spectrophotometric analysis of the Ryugu rock seen by MASCOT: searching for a carbonaceous chondrite analog. Planet. Sci. J. 2, 58 (2021).

    Article  Google Scholar 

  22. Michel, P. et al. Collisional formation of top-shaped asteroids and implications for the origins of Ryugu and Bennu. Nat. Commun. 11, 2655 (2020).

    Article  ADS  Google Scholar 

  23. Fredriksson, K. & Kerridge, J. F. Carbonates and sulfates in CI chondrites: formation by aqueous activity on the parent body. Meteoritics 23, 35–44 (1988).

    Article  ADS  Google Scholar 

  24. Endress, M. & Bischoff, A. Carbonates in C1 chondrites: clues to parent body evolution. Geochim. Cosmochim. Acta 60, 489–507 (1996).

    Article  ADS  Google Scholar 

  25. Yokoyama, T. et al. Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meterorites. Science (2022).

  26. McCain K. A. et al. Early fluid activity on the Ryugu parent asteroid inferred from 53Mn/53Cr ages of Ryugu carbonate. 85th Annual Meeting of The Meteoritical Society, 2022. LPI Contribution No. 2695.

  27. Fujiya, W. et al. Migration of D-type asteroids from the outer Solar System inferred from carbonate in meteorites. Nat. Astron. 3, 910–915 (2019).

    Article  ADS  Google Scholar 

  28. de Leon, J. et al. Expected spectral characteristics of (101955) Bennu and (162173) Ryugu, targets of the OSIRIS-REx and Hayabusa2 missions. Icarus 313, 25–37 (2018).

    Article  ADS  Google Scholar 

  29. Tatsumi, E. et al. Spectrally blue hydrated parent body of asteroid (162173) Ryugu. Nat. Commun. 12, 5837 (2021).

    Article  ADS  Google Scholar 

  30. DeMeo, F. E. & Carry, B. The taxonomic distribution of asteroids from multi-filter all-sky photometric surveys. Icarus 226, 723–741 (2013).

    Article  ADS  Google Scholar 

  31. DeMeo, F. E. & Carry, B. Solar System evolution from compositional mapping of the asteroid belt. Nature 505, 629–634 (2014).

    Article  ADS  Google Scholar 

  32. Riu, L. et al. Calibration and performances of the MicrOmega instrument for the characterization of asteroid Ryugu returned samples, Rev. Sci. Instrum. 93, 054503 (2022).

  33. Milliken, R. E., Hiroi, T. & Patterson, W. The NASA Reflectance Experiment Laboratory (RELAB) facility: past, present, and future. 47th Lunar and Planetary Science Conference, The Woodlands, TX, 21–25 March 2016. LPI Contribution No. 1903, id.2058.

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We thank the whole Hayabusa2 team for the quality and quantity of samples returned from Ryugu, which are already a landmark achievement in the science of asteroids. We thank the French space agency CNES for its full support. T.Y. received support from the Japan Society for the Promotion of Science KAKENHI, grant number JP18K03830. We would like to offer special thanks to B. Gondet, who, although no longer with us, contributed greatly to this work.

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Authors and Affiliations



D.L., C.P., L.R., R.B., J.-P.B., A.N., K.Y., T.Y., T.O., T.U. and M.A. designed, conceived and planned the experiment at the Curation Center. D.L., C.P., L.R., R.B., J.-P.B., A.N., K.H., K.Y., T.L.P.-J., T.Y., T.O., C.L., A.M., M.N., K.N., K.K. and Y.H. performed the MicrOmega analyses. D.L., C.P., L.R., R.B., J.-P.B. and J.C. analysed the data concerning the carbonate detections. D.L., C.P., L.R., R.B., A.N., A.A.-T., J.C., T.L.P.-J., Y.L., C.L., D.B., T.S., S.T., S.N., Y.T. and S.W. contributed materials and analysis tools to the study.

Corresponding author

Correspondence to D. Loizeau.

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Nature Astronomy thanks E. Cloutis and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Carbonate size distribution between grain inclusions and loose grains.

Histograms of the distribution of the carbonate ROIs in the analysed samples, by carbonate species, and between carbonates as grain inclusion and as loose grain. Diameters are given for equivalent circular ROIs, but shapes can be very irregular. ‘Inclusions’ are for carbonate ROIs detected within a part of a larger grain, ‘loose grains’ are for grains that appear entirely carbonate-bearing. Extracted grains (mostly > 1 mm in width) are deposited in individual sample holders. Small grains (mostly <100 µm in width) are found with them in the same sample holders, either transported together with the main grain during extraction from the bulks, or detached from the main grain during movements of the sample holder. In the category ‘extracted grains’, the large carbonate inclusions (plain colour) are within the main grains, but small carbonate loose grains (hashed colour) are also detected around. The majority of carbonate inclusions are in the extracted grains, which is expected as only the largest grains were extracted. In the sub-bulks, which mostly contain a finer fraction of the grains, carbonate ROIs correspond mostly to loose carbonate grains.

Extended Data Fig. 2 Cumulative size distributions of the carbonate ROIs in the analysed samples.

Cumulative size distributions of the carbonate ROIs in the analysed samples, one from all detected carbonates in the bulks (grey), and the other from carbonate inclusions within the characterized individual grains (black). The power indices of the distributions are respectively indicated in black and grey, and may be compared with the previously derived power index of the size distribution of Ryugu’s collected particles of −3.881, and the one of Ryugu’s boulders >5 m of −2.6519.

Extended Data Fig. 3 Comparison of the 3.3–3.5 µm band with different reference endmembers.

Comparison of the 3.3–3.5 µm band from two carbonate-rich areas with different reference endmembers after normalization and application of an offset. Left: spectrum from grain C0041 (average over 342 MicrOmega pixels) with a best fit with an (Mg,Fe)CO3 carbonate breunnerite; right: spectrum from grain A0033 (average over 56 MicrOmega pixels) with a best fit with an (Mg,Ca)CO3 carbonate dolomite. Results of the goodness-of-fit test, indicating in each case what endmember provides the best fit (right: Caragonite = 0.00699543, Cbreunnerite = 0.00178846, Ccalcite = 0.00613925, Cdolomite = 0.000463486, Cmagnesite = 0.00604942, Csiderite = 0.00483010; left: Caragonite = 0.0555209, Cbreunnerite = 0.00264406, Ccalcite = 0.0489774, Cdolomite = 0.0175524, Cmagnesite = 0.0301949, Csiderite = 0.0329548). The final identification also includes a check of (1) the position of the edges of the 3.3–3.5 µm band, as well as the different peaks, and (2) the presence or not of an absorption below 1.5 µm (diagnostic of the presence of iron). MicrOmega spectral sampling is 10 cm–1 in this spectral domain. Such spectral sampling allows us to see a shift of the minima between the carbonate spectra. For example, from breunnerite to dolomite, there is a shift from 3.43 to 3.45 µm of the second minimum of the 3.3–3.5 µm doublet band. This shift corresponds to a 17 cm–1 difference in wavenumber, thus corresponding to 1–2 spectral channels, which is sufficient to discriminate between these two endmembers.

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Loizeau, D., Pilorget, C., Riu, L. et al. Constraints on Solar System early evolution by MicrOmega analysis of Ryugu carbonates. Nat Astron 7, 391–397 (2023).

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