ANALYSIS OF HAYABUSA2 RETURNED SAMPLES.
S. Tachibana, Department of Narural History Sciences, Hokkaido University,
N10W8, Sapporo, Hokkaido 060-0810, Japan.
Hayabusa2 and Its Scientific Goal: Hayabusa2 spacecraft will bring back surface samples of a near-Earth
C-type asteroid (162173) Ryugu at the end of 2020. Because the C-type asteroids, of which reflectance spectra
are similar to carbonaceous chondrites, are highly likely to record the long history of the solar system from thebeginning to planet formation including the supply of volatiles to terrestrial planets, the main scientific goals ofthe Hayabusa2 mission are the investigations of (I) the origin and evolution of the solar system and (II) the formation process and structure of the asteroid. These scientific goals are further subdivided into (1) thermal evolution from planetesimal to near-Earth asteroid (thermal processes in a planetesimal in the early solar system; heating and space-weathering on the surface of near-Earth asteroid at its current orbit), (2) destruction and accumulation of rubble pile body (planetesimal formation; impact processes throughout the solar system history), (3) diversification of organic materials through interactions with minerals and water in planetesimal (origin and evolution of volatile components in the early solar system; final state of organic matter and water prior to their delivery to rocky planets), and (4) chemical heterogeneity in the early solar system (mixing of “fire” and “ice”
components during dynamical evolution of the protosolar disk). To fulfill these scientific objectives, a tightlinkage between on-site geologic observations (kilometer to millimeter scale) and return sample analyses (downto atomic scale) is crucial. The scientific instruments on board the spacecraft are a laser altimeter (LIDAR), amulti-band telescopic camera (ONC-T), wide-angle cameras (ONC-W1 and -W2), a near-infrared spectrometer(NIRS3), a thermal infrared imager (TIR), a small carry-on impactor (SCI), a deployable camera (DCAM3), asampler (SMP) [1], and a lander (MASCOT).
Samples and Analysis of Returned Samples: Initial analysis will be done by the Hayabusa2 mission tomaximize the scientific achievement of the project for 12 months after Phase-1 curation (sample description at
the ISAS curation facility). The initial analysis should be a good showcase to prove the potential of the samples.
Along with the initial analysis, the Phase-2 curation of returned samples will include integrated thorough analysis and description of samples to build a sample database and to obtain new scientific perspective from thoroughanalysis of samples. The Phase-2 curation will be done both in ISAS and also in several research institutes outside JAXA led by the ISAS curation facility.
Initial Analysis Team: 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 [2], which covers from the presolar history to the current geological activity of the near-Earth asteroid.

Hayabusa2 project has called for nomination of sub-team leaders of Initial Analysis Team (IAT). The IAT
consists of six sub-teams for 1) chemistry (elements and isotopes), 2) petrology and mineralogy 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-teamwill be an international team led by a researcher (sub-team leader) who can have a research base in Japan at leasta year before the delivery of the samples (the end of 2020) and throughout the initial analysis phase (2021–2022).
The sub-team leaders will make an analysis and work-flow plan in their sub teams with the IAT members tomake a best effort in fulfilling the scientific goals of the mission through integration of analytical results fromeach sub-team and on-site remote-sensing data.
References: [1] Okazaki R. et al. (2016) Space Sci. Rev., doi:10.1007/s11214-016-0289-5. [2] Tachibana S.
et al. (2014) Geochemical J. 49, 571–587.