Yang Hong, the module's chief designer at the China Academy of Space Technology, said Tianhe is designed to accommodate long-term visits and support spacewalks, which will be essential for assembly of the station, assessments of its external integrity and repair of broken parts.

The astronauts' living and working space is about 50 cubic meters, much larger than that of previous Chinese manned spacecraft. Once the space station is completed, the occupants will have as much as 110 cu m of usable space, Yang said.

By comparison, the usable space in a crewed spaceship in the Shenzhou series is about 7 cu m.

Zhang Hao, a senior designer at the academy who took part in the module's development, said that compared with previous Chinese manned spaceships, the module features better living conditions.

"There are separate quarters for working, sleeping, personal hygiene, dining, healthcare and physical exercise," he said.

"Each astronaut has their own bed and they share a dedicated washroom, the first to feature on a Chinese spacecraft. We installed many appliances to make the stay easier, such as an air conditioner, microwave oven, refrigerator and water dispenser, as well as a treadmill."

Each astronaut has a specially designed smartphone capable of not only making calls between the crew and people on the ground, but also of remotely controlling the capsule's internal equipment, he added.