Like many other children in urban China, Nie Tianxiang and Fei Di have busy fathers who are always away from home. In their case their fathers are further away than most - in space. They are understandably very proud of their famous astronaut fathers, colonels Nie Haisheng and Fei Junlong . 'I guess I will say 'I am very, very happy' and 'I'm proud of you' when my father returns. And I would like to wish him happy birthday again,' Tianxiang said in an interview with Sina.com. The 11-year-old said she had prepared a special birthday gift. 'They're origami cranes ... I haven't counted how many I have folded.' Folding 1,000 origami cranes is said to bring good health and a long life, not only to the folder but to the recipient as well. Tianxiang sang her father Happy Birthday from the Mission Command Centre as Colonel Nie celebrated his 41st birthday in orbit on Thursday. Tianxiang, which literally means 'flying in the sky' in Chinese, said training had kept her father so busy she seldom talked to him. 'He had a very tight training schedule before the liftoff, so we rarely communicate ... He was busy with training from Monday to Thursday, so I tried not to disrupt him. [We talk] more on Saturday and Sunday.' Tianxiang said having an astronaut father had not changed her life a lot, although classmates would sometimes ask her questions about Shenzhou VI. 'They ask me things like the structure of Shenzhou VI ... I don't know how to answer their questions,' she said. Fei Di, 11, said he was very proud yet a bit nervous when he watched his father blasting off from the mission command centre. He said he would ask his father to go fishing with him when he returned. 'We went fishing five times recently ... he caught more fish than I did.' Fei Di described his father as humorous and steady. 'Since my father is an astronaut, he has to tend to his own business, so he doesn't have that much time to take care of mine. It's usually my mum who takes cares of my studies,' he said. Tianxiang and Fei Di said the chances of them following in their fathers' footsteps were slim - as they are both short-sighted.