[U-06_28PM1] 太陽系小天体研究の新展開

[U06-16] はやぶさ帰還試料中の炭素質物質の起源同定の試み

*上椙 真之¹、奈良岡 浩²、伊藤 元雄³、薮田 ひかる⁴、北島 富美雄²、高野 淑識³、三田 肇⁵、癸生川 陽子⁶、矢田 達¹、唐牛 譲¹、石橋 之宏¹、佐竹 渉⁷、岡田 達明¹、安部 正真¹ (1.独立行政法人宇宙航空研究開発機構、2.九州大学大学院理学研究院地球惑星科学部門、3.海洋研究開発機構　高知コア研究所、4.大阪大学大学院理学研究科宇宙地球科学専攻、5.福岡工業大学工学部生命環境科学科、6.北海道大学　大学院理学研究院　 自然史科学専攻　地球惑星システム科学、7.東京大学大学院理学系研究科地球惑星科学専攻)

Extraterrestrial Sample Curation Team (ESCuTe) recovered more than 50 carbonaceous particles from the sample catcher of the Hayabusa spacecraft. Those carbonaceous materials, named as category 3, were found in the form of particles with similar size range of the silicate particles those confirmed as Itokawa regolith particles. Initial description by the SEM-EDS analysis shows variable textures and chemical compositions of them, suggesting the multiple origins of the carbonaceous materials. Preliminary examinations of category 3 particles were carefully processed in parallel with those of silicate materials. However, we could not obtain the information for the origin of category 3 particles before the opening of international announcement of opportunity (A/O). The ESCuTe and preliminary examination team of category 3 particles have continued the investigations. In this paper, we report the several recent results obtained from the sequential analyses. Samples allocated for the preliminary examinations of category 3 are RA-QD02-0008, RA-QD02-0120, RA-QD02-0180, RB-QD04-0001, RB-QD04-0037-01 and RB-QD04-0047-02. RA-QD02-0008 was lost during the manipulation at first preliminary examination. Three samples, RA-QD02-0120, RB-QD04-0001, and RB-QD04-0047-02, were pressed on the Au plate and fixed without any adhesive materials. We analyzed H, C and N isotopic composition by nano-SIMS in the beginning of the sequential study, in order to investigate the isotopic anomaly which is a direct evidence of extraterrestrial origin of organic materials [8]. FT-IR and micro-Raman spectroscopy were also applied for the pressed samples [9]. After ToF-SIMS analysis of those particles, the samples were sliced by FIB in order to investigate the fine structure of the samples by XANES and TEM/STEM [10]. We performed those analyses with determining the effect on the subsequent analyses, such as sample damages and contaminations. The rest two particles, RA-QD02-0180 and RB-QD04-0037-01 were pressed on indium plates, because significant disturbance by Au on the ToF-SIMS analyses was found. We will also report the construction of the sequential analysis flow of tiny carbonaceous particles. In parallel with the Hayabusa-returned particles, we processed observation and analysis of insoluble organic matter (IOM) of A881458 (CM2) and several possible materials of the origin of the category 3 particles, such as viton, silicon rubber, vectran and particles collected from the Hayabusa2 clean room. We did not obtain any signature of extraterrestrial origin from category 3 particles so far. We are planning to continue the preliminary examination of category 3 by the end of March 2014. We are also planning to open the category 3 particles to the future International A/O, with the data of preliminary examinations before the end of 2014.References: [1] Yada et al. 2011. Meteoritics & Planetary Science 32:A74. [2] Nakamura et al. 2011. Science 333:1113-1116. [3] Yurimoto et al. 2011. Science 333:1116-1119. [4] Ebihara et al. 2011. Science 333:1119-1121. [5] Noguchi et al. (2011) Science 333:1121-1125. [6] Tsuchiyama et al. 2011. Science 333:1125-1128. [7] Nagao et al. 2011. Science 333:1128-1131. [8] Ito et al. 2013. Abstract of Hayabusa Symposium, [9] Kitajima et al., 2013 Abstract of Hayabusa Symposium, [10] Uesugi et al. 2013. Abstract of Hayabusa Symposium