Astronauts start work inside space lab

The first lab component of the Tiangong station, Wentian was launched on Sunday afternoon by a Long March 5B heavy-lift rocket from the Wenchang Space Launch Center in Hainan province.

The vehicle consists of three major parts－a crew working compartment, an airlock cabin and an unpressurized service module.

Weighing 23 metric tons, the space lab is 17.9 meters tall, roughly equivalent to a six-story residential building, and has a diameter of 4.2 meters. It is the largest and heaviest spacecraft China has ever built and also the world's heaviest self-propelled spaceship in service, according to designers at the China Academy of Space Technology.

Before Wentian's docking, Tiangong consisted of the Tianhe module, the Tianzhou 4 cargo ship and the Shenzhou XIV spacecraft.

Mission planners said the Tiangong station's second lab, Mengtian, will be lifted by a Long March 5B from Wenchang in October.