Chinese astronauts on the Shenzhou XIV mission have started their work inside the Wentian space lab, according to the China Manned Space Agency.

The agency said in a brief news release on July 25 that the Shenzhou XIV mission crew — mission commander Senior Colonel Chen Dong, Senior Colonel Liu Yang and Senior Colonel Cai Xuzhe — opened the hatch door of Wentian and entered the lab at 10:03 am, about seven hours after the lab docked with the Tianhe core module of China's Tiangong space station.

In a video clip published by the agency, Chen was the first to float into Wentian and was followed by Liu and Cai.

He said in the video that the space lab has become his team's second living and working cabin in orbit and its arrival marked a new stride in the country's space station program.

"We are feeling very proud and happy," the mission commander said.

In the same clip, Liu said the Wentian's deployment opened the multi-module stage of the Tiangong station while Cai said the astronauts will work hard to make the best use of the space station.

In the coming days, Chen and his teammates will work with ground controllers to adjust the Tiangong's orbital posture, carry out tests on Wentian's robotic arm and the joint arm once it is linked with the major arm on Tianhe, and also conduct spacewalks through the airlock cabin on the lab module, according to the agency.

The first lab component of the Tiangong station, Wentian was launched on the afternoon of July 24 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.