China's space station is expected to host six astronauts from two spaceships by the end of 2022, according to the chief designer of the country's manned space program.

The Shenzhou-13 crew has been in orbit for 140 days. They are in good health, and have so far completed all planned or added tasks as needed. They are expected to return to Earth in mid-April, Zhou Jianping said.

This year, China will launch two lab modules for the space station, two manned spacecraft and two cargo spacecraft. The Shenzhou-14 crew will witness the arrival of two lab modules during their stay in orbit, said Zhou, who is also a member of the 13th National Committee of the Chinese People's Political Consultative Conference, the country's top political advisory body.

The Shenzhou-15 crew will fly to the space station before the end of this year and join the Shenzhou-14 crew in space. At that time, the space station will consist of three modules, two manned spacecraft and one cargo spacecraft, with a total mass of nearly 100 tonnes, Zhou said.

The space station will carry a large number of high-level space experiment devices covering fields such as the life sciences, biological science, material science, combustion science, microgravity fluid science and basic physics, he said.