First NIR hyperspectral imaging of Hayabusa2 returned samples by the MicrOmega microscope within the ISAS Curation Facility
1Pilorget, C.; 2,3Okada, T.; 1Hamm, V.; 1Brunetto, R.; 2Yada, T.; 1Loizeau, D.; 2Riu, L.; 2,3Usui, T.; 4Moussi-Soffys,A.; 2,5Hatakeda, K; 2Nakato, A.; 2Yogata, K.; 2,6Abe, M.; 1Aléon-Toppani, A.; 1Carter, J.; 1Chaigneau, M.; 1Crane, B.;1
Gondet, B.; 2,5Kumagai, K.; 1Langevin, Y.; 1Lantz, C.; 1Le Pivert-Jolivet, T.; 1Lequertier, G.; 1Lourit, L.; 2Miyazaki,A.; 2Nishimura, M.; 1Poulet, F.; 7Arakawa, M.; 8Hirata, N.; 8Kitazato, K.; 2Nakazawa, S.; 9Namiki, N.; 2Saiki, T.;
3Sugita, S.; 2,3Tachibana, S.; 2,6,10Tanaka, S.; 2,6Yoshikawa, M.; 2,6Tsuda, Y.; 11Watanabe, S.; 1Bibring, J.-P.
[1] Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91400 Orsay, France, [2] Institute of Space andAstronautical Science, Japan Aerospace Exploration Agency, Sagamihara 252-5210, Japan, [3] University of Tokyo,Bunkyo, Tokyo 113-0033, Japan, [4] Centre National d'Etudes Spatiales, 18 Avenue E. Belin, 31401 Toulouse,France, [5] Marine Works Japan, Ltd., Yokosuka 237-0063, Japan, [6] The Graduate University for Advanced Studies(SOKENDAI), Hayama 240-0193, Japan, [7] Kobe University, Kobe 657-8501, Japan, [8] The University of Aizu,Aizu-Wakamatsu 965-8580, Japan, [9] National Astronomical Observatory of Japan, Mitaka 181-8588, Japan, [10]University of Tokyo, Kashiwa 277-8561, Japan, [11] Nagoya University, Nagoya 464-8601, Japan.
Introduction: On December 6, 2020, the Hayabusa2 mission successfully returned to Earth ~ 5.4 g of samples collected at the surface of the C-type asteroid Ryugu [1,2]. Its surface was first sampled on February 22, 2019, then on
July 11, 2019, close to a 15-meter large artificial crater, so as to possibly access sub-surface material [3]. The collected
samples are now kept at the Extraterrestrial Samples Curation Center of JAXA at ISAS in Sagamihara, Japan, for a
first round of preliminary analyses, with the objective of characterizing in a non-destructive manner both the bulk
samples and a few hundreds of grains extracted from them [4]. In particular, the goal is 1) to support their further
detailed characterization by the international Initial Analysis Teams, and 2) to build a catalogue of the grains, accessible to the international community through AO selection, starting mid-2022.
Methods: The preliminary characterization of these samples is being conducted with a visible microscope withfive color filters, a FTIR spectrometer operating in the 1-4 µm range, and MicrOmega, a hyperspectral NIR microscope
developed at Institut d'Astrophysique Spatiale (Université Paris-Saclay/CNRS, Orsay, France), operating in the nearinfrared range (0.99-3.65 µm) [5]. This is the first time that preliminary analyses of returned extraterrestrial samples
include a characterization by a NIR hyperspectral microscope.
Results: Preliminary outcomes of the analyses performed with MicrOmega will be presented. In particular, therepresentativity of the samples collected by the Hayabusa2 spacecraft will be addressed through the comparison ofthe spectra obtained by MicrOmega and of the NIRS3 remote sensing IR spectrometer [6] which performed a spectral
characterization (1.8-3.2 µm) of Ryugu's surface, including the sites of the samples' collection [7,8].
At a global scale, all bulks exhibit similar features, with a dominant OH- 2.7 µm component and a 3.3 – 3.5 µm
band centered around 3.4 µm. Their variation at different spatial scales and significance will be presented. Specificsignatures, detected in grains typically present in <1% of the pixels, but of high relevance regarding the processes
determining Ryugu formation and evolution, will also be presented and discussed.
References: [1] Binzel R. P. et al. (2002), Physical Properties of Near-Earth Objects. pp. 255-271, [2] Vilas F.
(2008) The Astronomical Journal 135 (4), 1101-1105, [3] Morota et al. (2020) Science 368, Issue 6491, pp. 654-659,[4] Yada T. et al., Nature Astronomy, submitted, [5] Bibring J.-P. et al. (2017) Astrobiology 17, Issue 6-7, pp.621626, [6] Iwata T. et al. (2017) Space Science Reviews 208 (1-4), 317-337, [7] Kitazato K. et al. (2019) Science 364(6437), 272-275, [8] Kitazato K. et al. (2020) Nature Astronomy, Volume 5, p. 246-250.