I felt so free in space, flying around and unrestrained by any social relationships, but my life since has changed a lot. Now I am extra-careful about what I say and do because everyone recognises me.

If you ask me what's harder, being famous or flying to space, I'd say fame is much harder.

Only in space did I realize how lucky I am to be Korean. Only in Korea could I have gone to space before turning 30 years old.

They gave me 18 experiments to complete in my 10 days in the ISS. That's a lot. Everyone told me I didn't have to complete all of them, that it wasn't expected of me. But I knew everyone was watching me, so I gave up meals and sleep and completed all 18 experiments. It's a very Korean thing to do.

On Earth, men are seen as superior because of their physical strength, but it means nothing in space, where there is no gravity.

I feel bad that I'm the one always blamed for the failure of the space business - even though there are problems with government policy toward the space business.