Beijing, China - Recent (CCTV - No access Chinese mainland)
1. Various of astronauts undergoing underwater training
2. SOUNDBITE (Chinese) Yin Rui, deputy commander, Astronaut Center of China:
"The main purpose of this mission is to verify the feasibility of all the extravehicular activities. Our astronauts in underwater training suits are having training in the same-size mock-up of the Chinese space station in the state of neutral buoyancy."

China - Recent (CCTV - No access Chinese mainland)
3. Various of astronauts undergoing training

Beijing, China - Recent (CCTV - No access Chinese mainland)
4. SOUNDBITE (Chinese) Yin Rui, deputy commander, Astronaut Center of China:
"As for the spacewalk in the future, each mission is now designed to last about six hours. It's a huge physical challenge for the astronauts."

FILE: In space - Oct 20-25, 2016 (CCTV - No access Chinese mainland)
5. Various of astronaut Jing Haipeng showing silkworm in space lab
6. Jing showing rotating arm in space lab

FILE: In Space - June 20, 2013 (CCTV - No access Chinese mainland)
7. Various of Zhang Xiaoguang (L), Chinese astronaut and cameraman of lecture, Wang Yaping (C), Chinese female astronaut and teacher at lecture, Nie Haisheng (R), commander of Shenzhou-10 space mission

FILE: Date and Location Unknown (CCTV - No access Chinese mainland)
8. Animations of spacecraft docking with space module, astronauts getting into space module

Chinese astronauts are toughening up training in an underwater tank to prepare for the spacewalk missions at the future Chinese space station.

The astronauts wearing specially-designed underwater space suits are undergoing intensive training in a full-sized test tank of the space station.

"The main purpose of this mission is to verify the feasibility of all the extravehicular activities. Our astronauts in underwater training suits are having training in the same-size mock-up of the Chinese space station in the state of neutral buoyancy," said Yin Rui, deputy commander of the Astronaut Center of China.

Given frequent extravehicular activities conducted by Chinese astronauts, the heavy workload is physically and mentally demanding to astronauts.

According to Yin, the then 42-year-old astronaut Zhai Zhigang did a very great job during the Shenzhou-7 manned space mission in 2008 by doing a spacewalk for nearly 20 minutes, which was regarded as a milestone in China's aerospace industry.

"As for the spacewalk in the future, each mission is now designed to last about six hours. It's a huge physical challenge for the astronauts," Yin said.

China plans to start assembling its space station in 2020. It is scheduled to become fully operational around 2022.