China launches Wentian space lab

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, said Zhang Qiao, a head designer of Wentian's overall structure.

The flexible solar panels of the lab are the largest of their kind in China. When fully unfolded, they are more than 55 meters long and have a combined area of nearly 280 square meters.

After Wentian is connected to the Tianhe module, its airlock cabin will replace the one on Tianhe to become the major place for astronauts to put on their spacewalk suits and move out of the space station.

"Its inner space is bigger than that of the airlock cabin on the core module while its hatch is wider, making it easier for astronauts to make preparations and carry out spacewalks," Zhang said.

Inside the gigantic lab, there are eight scientific cabinets and they will mainly be used to serve biological and life science studies and can support research on the growth, aging and genetic traits of plants, animals and microbes in the space environment.

Outside the airlock cabin, there are 22 extravehicular payload adapters capable of carrying scientific experiments needed to be exposed to the space environment, cosmic rays, vacuum, and solar winds, according to him.

"In addition to its scientific functions, Wentian also serves as a backup control station to the Tianhe core module in case of emergencies or malfunctions. It has all flight-control devices same to those inside the core module to operate the entire Tiangong station," Zhang said.