How do you become an astronaut?
Super-star spaceman Chris Hadfield has been telling Newsround what it takes to become a top astronaut.
That was just one of the questions you sent to us for Martin to ask the Commander when we caught up with him.
Chris also answered your questions on how to go to the toilet in space, what it feels like to be an inspiration and how he deals with missing his family.
Check out here and also watch here.