Analysis of Hayabusa Returned Samples

Abstract

The spacecraft Hayabusa has returned to the earth in 2010. The event was closed up and widely broadcast because the spacecraft succeeded in returning back tiny particles from the asteroid Itokawa. Preliminary examination team of Hayabusa returned samples investigated the small particles around a few tens μm, and found a lot of facts about the past evolution and future evolution of the small asteroid. Challenges on the analysis of the Hayabusa returned samples were to maximize the scientific gain from 40 tiny samples with a coordinated analytical flow with the sequences of various analytical methods. Mounting of the small precious samples on the holders is always problematic because the sample was damaged or even lost during such procedures. Moreover, accuracy of the analysis largely depends on such sample preparation procedure. In the analysis of the Hayabusa returned samples, the team applied the sequence which was used for the analysis of a previous sample return project, though they could not investigate the samples with atmosphere shielded environment, for all samples. The Hayabusa2 spacecraft, a next generation spacecraft for sample return missions, successfully touched down on the asteroid Ryugu, which will contain water and organic materials. Thus, it should be much difficult to analyze the samples than that of the Hayabusa returned samples because those water and organic materials are easily damaged and contaminated by terrestrial materials. In this paper, we report the processes of trial and error for the analysis of the Hayabusa returned samples, and preparation for the analysis of the Hayabusa2 returned samples based on the learning by the trial and error.