The commander in charge of launching the China Space Station modules, the Tianhe core module, Wentian lab module and Mengtian lab module, said all the missions need great precision in timing and coordination among all units.

Liao Guorui is the launch commander for the Long March-5B carrier rocket system responsible for sending the three China Space Station modules into space.

He has conducted 39 launch missions at the Wenchang Spacecraft Launch Site and says each mission is unique.

"We need to coordinate more than 20 teams and get them to finish tasks at precise times," Liao said.

"The Tianhe core module was launched in April last year. It was the first module and kick-started the construction of China Space Station in orbit, and thus has very great significance," he said.

Reflecting on the Wentian lab module launch in July last year, Liao recalled the Zero Window launch system used to send the module into space.

"A Zero Window launch requires great precision," he said. "We did a lot of preparation, including a number of contingency measures. There are 266 separate projects related to the mission. We developed a flexible countdown system."

"Looking back, I think we did a very thorough job; I am confident in that," Liao said.

Explaining the process that went into launching the Mengtian lab module mission, Liao shared many facts and figures.

"The Mengtian lab module is the heaviest spacecraft China has launched so far. It's 72 kilograms heavier than the Wentian lab. This mission poses more precise challenges because the launch window of the Mengtian lab is not consistent," he said.

"We need to be more precise in every step to send it into space and dock with the other modules," he explained.

After the Mengtian lab launch mission, the China Space Station would form a T shape in the low-earth orbit, which Liao said is a big step.

"This is a result of hard effort and total dedication within China's 30-year Manned Space Program. I feel greatly honored to participate in this. I am really, really honored," he said.

The launch commander also answered a question from CGTN viewers on his personal feelings and emotions toward the Long March-5B carrier rocket.

"Scientifically, the Long March-5B is propelled by low-temperature fuel. But in my eyes, it is a warm symbol of passion – it carries the space dreams of all our aerospace workers, and it's also the exclusive carrier of all modules of our space station," he said.

(Cover: Liao Guorui, launch commander for the Long March-5B carrier rocket system. /Wenchang Spacecraft Launch Site)