China is preparing to send three astronauts to live on its space station for six months — a new milestone for a programme that has advanced rapidly in recent years.

It will be China’s longest crewed space mission and will set a record for the most time spent in space by Chinese astronauts.

The Shenzhou-13 spaceship is expected to be launched into space on a Long March-2F rocket early on Saturday morning from Jiuquan Satellite Launch Centre on the edge of the Gobi Desert in north-western China.

The first crew who served a 90-day mission aboard the main Tianhe core module of the space station returned in mid-September.

The new crew has two veterans of space travel. Pilot Zhai Zhigang, 55, performed China’s first spacewalk, and Wang Yaping, 41 and the only woman on the mission, carried out experiments and led a science class in real-time while travelling on one of China’s earlier experimental space stations.

Ye Guangfu, 41, will be traveling into space for the first time.

China Space
The Shenzhou-13 manned spaceship on a Long March-2F carrier (Wang Jiangbo/Xinhua/AP)

The mission is expected to continue the work of the initial crew, who conducted two spacewalks, deployed a 10-metre mechanical arm, and held a video call with Chinese President Xi Jinping.

China Manned Space Agency deputy director Lin Xiqiang said the rocket is fuelled and ready to fly.

“All systems conducting the Shenzhou-13 mission have undergone a comprehensive rehearsal. The flight crew is in good condition and our pre-launch preparations are in order,” Mr Lin said at a briefing.

The crew’s scheduled activities include up to three spacewalks to install equipment in preparation for expanding the station, verifying living conditions in the module and conducting experiments in space medicine and other areas, he added.

China’s military, which runs the space programme, has released few details but says it will send multiple crews to the station over the next two years to make it fully functional.

Shenzhou-13 will be the fifth mission, including uncrewed trips to deliver supplies.

When completed with the addition of two more modules — named Mengtian and Wentian — the station will weigh about 66 tons, a fraction of the size of the International Space Station, which launched its first module in 1998 and will weigh around 450 tons when completed.

China was excluded from the ISS largely due to US objections over the Chinese programme’s secretive nature and close military ties.

It made plans to build its own space stations in the early 1990s and had two experimental modules before starting on the permanent station.

US law requires congressional approval for contact between the American and Chinese space programmes, but China is co-operating with space experts from countries including France, Sweden, Russia and Italy.

China has sent 14 astronauts into space since 2003, when it became only the third country after the former Soviet Union and the US to do so on its own.

Along with its crewed missions, China has expanded its work on lunar and Mars exploration, including placing a rover on the little-explored far side of the moon and returning lunar rocks to Earth for the first time since the 1970s.

China this year also landed its Tianwen-1 space probe on Mars, where the accompanying Zhurong rover has been exploring for evidence of life.

Other programmes aim to collect soil from an asteroid and bring back additional lunar samples.

China has also expressed an aspiration to land people on the moon and possibly build a scientific base there, although no timeline has been proposed.

A highly secretive space plane is also reportedly under development.