The Tiangong space station -- crewed by teams of three astronauts that are exchanged every six months -- is the crown jewel of China's space programme, into which billions of dollars have been poured in a bid to catch up with the United States and Russia.

The Shenzhou-21 mission is set to blast off at 11:44 pm on Friday (1544 GMT) from the Jiuquan Satellite Launch Center in northwest China, said China Manned Space Agency (CMSA) spokesperson Zhang Jingbo.

Flight engineer Wu Fei, who has just turned 32, is set to become the youngest Chinese astronaut to undertake a space mission, authorities said.

"I feel incomparably lucky," he told reporters on Thursday. "Being able to integrate my personal dreams into the glorious journey of China's space programme is the greatest fortune this era has bestowed upon me."

He will be commanded by veteran space pilot Zhang Lu, 48, who took part in the Shenzhou-15 mission more than two years ago.

Payload specialist Zhang Hongzhang, 39, makes up the third member of the crew.

Also along for the ride are four mice -- two male and two female -- which will be the subjects of China's first in-orbit experiments on rodents, CMSA spokesperson Zhang said.

Commander Zhang Lu said he was confident his team would "report back to our motherland and its people with complete success".

Beijing's space programme, the third to put humans in orbit, has also landed robotic rovers on Mars and the Moon.

China has ramped up plans to achieve its "space dream" under President Xi Jinping.

Beijing says it aims to send a crewed mission to the Moon by 2030, where it intends to construct a base on the lunar surface.

The CMSA said on Thursday it was "holding firm" to that goal and outlined a series of "crucial upcoming tests" it was undertaking in preparation, including testing its Lanyue lunar lander and Mengzhou manned spacecraft.