Initial analysis of Ryugu samples
Shogo Tachibana1
1
Department of Natural History Sciences, Hokkaido UniversityHayabusa2 spacecraft will bring back surface samples of a near-Earth C-type asteroid Ryugu late 2020. The Hayabusa2
returned-samples will be classified into (1) millimeter-sized coarse grains, (2) <100 µm-sized fine grains, and (3) volatiles
components that will be extracted from the sample container prior to its opening [1–3]. After the first characterization at thecuration facility of Institute of Space and Astronautical Science (ISAS), JAXA, the initial analysis of Ryugu samples will bedone by the Hayabusa2 mission to maximize the scientific achievement of the project for 12 months to prove the potential of
the samples.
Initial analysis of returned samples will focus on revealing the formation and evolution of Ryugu in the early Solar System.
The scientific objectives of sample analysis are listed in the following table, which covers from the presolar history to thecurrent geological activity of the near-Earth asteroid [1].
The initial analysis team will consist of six sub-teams for 1) chemistry (elements and isotopes), 2) petrology andmineralogy of coarse grains (mm-sized grains), 3) petrology and mineralogy of fine grains (<100 µm-sized grains), 4) volatiles,
5) macromolecular organics (insoluble organic matter), and 6) organic molecules (soluble organic matter).
Each sub-team will be an international analysis team led by a researcher who can have a research base in Japan at least ayear before the delivery of the samples (the end of 2020) and throughout the initial analysis phase (2021–2022). The sub-teamleaders will make an analysis and work flow plan in their sub-teams with the IAT members to make the best effort in fulfillingthe scientific goals of the mission through integration of analytical results from each sub-team and on- site remote-sensing data.
The Hayabusa2 project opened a call for nomination of the sub-team leaders in October 2016. All the nominations were
thoroughly reviewed by the Hayabusa2 Sample Allocation Committee (HSAC). The HSAC recommended candidates of thesub-team leaders to the Hayabusa2 Joint Science Team (HJST) for approval. The initial analysis plan of Ryugu samples will
be presented with the names of approved sub-team leaders at the symposium.

References[1] Tachibana, S., Abe M., Arakawa M., Fujimoto M., Iijima Y., Ishiguro M., K. Kitazato, Kobayashi N., Namiki N., Okada T.,
Okazaki R., Sawada H., Sugita S., Takano Y., Tanaka S., Watanabe S., Yoshikawa M., Kuninaka H. and the Hayabusa2
Project Team (2014) Hayabusa2: Scientific importance of samples returned from C-type near-Earth asteroid (162173) 1999
JU3. Geochem. J. 48, 571-587. doi:10.2343/geochemj.2.0350 [2] Okazaki R., Sawada H., Yamanouchi S., Tachibana S., MiuraY. N., Sakamoto K., Takano Y., Abe M., Itoh S., Yamada K., Yabuta H., Okamoto C., Yano H., Noguchi T., Nakamura T.,Nagao K. and The Hayabusa2 SMP Team (2016) Hayabusa2 sample catcher and container: Metal-seal system for vacuum
encapsulation of returned samples with volatiles and organic compounds recovered from C-type asteroid Ryugu. Space Sci.
Rev. 208, 107-124. doi:10.1007/s11214-016-0289-5 [3] Sawada H., Okazaki R., Tachibana, S., Sakamoto K., Takano Y.,Okamoto C., Yano H., Miura Y. N., Abe M., Hasegawa, S., Noguchi T. and the Hayabusa2 SMP Team (2017) Hayabusa2sampler: Collection of asteroidal surface material. Space Sci. Rev. 208, 81-106. doi:10.1007/s11214-017-0338-8