Visitors experience a simulative space journey in a capsule during a science exhibition in Beijing, capital of China, May 19, 2013. The exhibition is a part of the National Science and Technology Week and will last till May 25. (Xinhua/Luo Xiaoguang)

Visitors look at a presentation of a simulative star field during a science exhibition in Beijing, capital of China, May 19, 2013. The exhibition is a part of the National Science and Technology Week and will last till May 25. (Xinhua/Luo Xiaoguang)

Visitors look at a model of the manned submersible "Jiaolong" during a science exhibition in Beijing, capital of China, May 19, 2013. The exhibition is a part of the National Science and Technology Week and will last till May 25. (Xinhua/Luo Xiaoguang)

Children experience science experiments during a science exhibition in Beijing, capital of China, May 19, 2013. The exhibition is a part of the National Science and Technology Week and will last till May 25. (Xinhua/Luo Xiaoguang)

Visitors look at the model of an unmanned helicopter during a science exhibition in Beijing, capital of China, May 19, 2013. The exhibition is a part of the National Science and Technology Week and will last till May 25. (Xinhua/Luo Xiaoguang)

Competitors take part in a robot competition during a science exhibition in Beijing, capital of China, May 19, 2013. The exhibition is a part of the National Science and Technology Week and will last till May 25. (Xinhua/Luo Xiaoguang)

An assistant demonstrates a simulated shoulder-fired anti-aircraft missile during a science exhibition in Beijing, capital of China, May 19, 2013. The exhibition is a part of the National Science and Technology Week and will last till May 25. (Xinhua/Luo Xiaoguang)