The 10.000 was a misquote from the original paper they referenced: https://www.nature.com/articles/s41550-021-01550-6 https://www.nature.com/articles/s41550-02

The 10.000 was a misquote from the original paper they referenced: https://www.nature.com/articles/s41550-021-01550-6 https://www.nature.com/articles/s41550-021-01550-6 Here you can read that, in fact, a class 1.000 cleanroom was used. This is also consistent with the description of the facility: https://en.wikipedia.org/wiki/Extraterrestrial_Sample_Curation_Center https://en.wikipedia.org/wiki/Extraterrestrial_Sample_Curati... According to the paper, five different chambers were used. You can read the entire procedure down to materials of cleaning spatulas.