Final preparations are underway to bring the two Chinese astronauts back to earth on Shenzhou-11.[Photo/Xinhua]

The Shenzhou XI-Tiangong II mission is China's sixth manned spaceflight and is expected to pave way for a permanent space station, which the country plans to start building in 2018 and put into service in about 2022.

Jing is an experienced astronaut, having been a member of the Shenzhou VII mission in 2008 and the Shenzhou IX mission in 2012. He celebrated his 50th birthday during his stay in Tiangong II.

Chen is the first man in the second generation of Chinese astronauts to make a spaceflight. Two of his female counterparts in the group, Liu Yang and Wang Yaping, have traveled to space, becoming national heroines.

During the astronauts' stay in the space lab, they worked for eight hours a day, six days a week, completing more than 40 experiments, according to Huang Weifen, deputy research head of the Astronaut Center of China.

As part of their assignments, the astronauts verified the life-support capability of the spacecraft-space lab combination and planted seeds to study the growth of vegetables in space.

They used a treadmill and exercise bike in Tiangong II to maintain their physical health, and even conducted a video call with President Xi Jinping on Nov 9.

China launched its first space lab, Tiangong I, in September 2011. With a designated life span of two years, the Tiangong I was in service for four and a half years, and conducted six automatic and astronaut-controlled dockings with the Shenzhou VIII, Shenzhou IX and Shenzhou X spacecraft before retiring in March this year.