Seriously, though, it seems that the first South Korean astronaut was disqualified by the Russians for--
The wrong stuff.
SEOUL, South Korea - South Korea said Monday a female engineer would become the country's first person in space by going aboard a Russian spacecraft, after Moscow rejected Seoul's first choice because he violated reading rules during training.
The Ministry of Education, Science and Technology said at a news conference that Yi So-yeon will replace Ko San as the country's choice to fly on a Russian Soyuz capsule to the International Space Station in early April.
The Russian authorities said Ko took a book out of the [space training] center without permission and sent it to his home in South Korea in September, Lee [Sang-mok, a senior ministry official] said. Ko later returned the book, explaining he accidently sent it home together with other personal belongings, Lee added.
In February, Ko again violated a regulation by getting a book from the center through a Russian colleague — material he was not supposed to read, Lee said. Officials did not give details about the book's contents, but South Korean officials portrayed both of his infractions as minor. [emphasis added]
I wonder what that book was about.