Abstract
The Extraterrestrial Sample Curation Center of JAXA curates the Hayabusa-returned samples in conditions of minimum terrestrial contaminants, because these samples are very tiny. We evaluated the cleanliness of the handling instruments, the cleanroom environments and the sample storage chamber to improve the cleanliness of particles, organic molecules and metallic elements to a level not to affect the analyses of the Hayabusa-returned samples. In the environment of the clean chamber No. 2 where the samples have been stored, the organic molecule abundance was lower than the detection limit, furthermore, metallic elemental concentrations were the lowest among other evaluated place. A multi-stage ultrasonic cleaning by organic solvents and the ultrapure water have been applied to instruments made of stainless steel and/or aluminum alloy, and additionally, acid-alkali liquids cleaning have been performed for those made of quartz glasses. For the cleanliness of quartz glasses after the cleaning, the organic molecules abundances were blank level, and the metallic element concentrations were 1～100×109atom/cm2/24 h. It was confirmed by optical microscope that no particle of size more than 10 μm was observed on quartz glasses after the cleaning.
