Detection of Ethanol Related to the O-ring Cleaning Process in Ryugu Samples (Preliminary Report)

Detection of Ethanol Related to the O-ring Cleaning Process in Ryugu Samples (Preliminary Report)

November 10, 2025
Astromaterials Science Research Group (ASRG)

In May 2025, ethanol was detected during the analysis of the Ryugu samples.

Subsequent investigation revealed that the ethanol most likely originated from the O-rings used for sealing the FFTC sample containers, which released ethanol absorbed during the cleaning process.Astromaterials Science Research Group (ASRG) has identified the cause and implemented countermeasures. The revised cleaning and drying procedures for the O-rings have been confirmed to significantly reduce the release of volatile components. We will distribute samples using FFTCs with the newly developed cleaning procedures.

At this time, the impact on the scientific evaluation of previously distributed samples is considered to be limited, and no hindrance to ongoing research has been identified. A detailed report will be presented at the Hayabusa Symposium in November 2025, followed by publication in a peer-reviewed journal.