Shenzhou X, China’s fifth manned spacecraft, atop an upgraded Long March-2F carrier rocket, blasts off from Jiuquan Satellite Launch Center at 5:38 pm on Tuesday. Zou Hong / China Daily

Three astronauts aboard the spacecraft for China's longest mission, paving way for space station in 2020

Shenzhou X and three astronauts blasted off from Jiuquan Satellite Launch Center, Gansu province, into a clear blue sky on Tuesday, bringing the nation one step closer to setting up its own space station in 2020.

Two men, mission commander Nie Haisheng and Zhang Xiaoguang, and China's second female astronaut, Wang Yaping, are expected to stay in space for 15 days.

They will educate young people about science and perform two space dockings, between Shenzhou X and the unmanned Tiangong-1 space module, a technically difficult procedure that brings two vessels together in high-speed orbit.

The trip is the country's fifth manned space mission, 10 years after the country's first astronaut, Yang Liwei, went into space in 2003.

President Xi Jinping arrived at Jiuquan Satellite Launch Center on Tuesday to observe the launch.

At a sending-off ceremony just hours before the launch, the president, who had just returned from visiting the United States, wished the three astronauts a successful journey.

"The mission's members carry the nation's space dream and represent the lofty aspirations of the Chinese people to explore space," Xi told the astronauts.

"I wish you success and look forward to your triumphant return."

The carrier rocket blasted off at 5:38 pm. About 20 minutes later, Shenzhou X entered its orbit. Zhang Youxia, chief commander of the manned space program, announced the lift-off was a success.

Xi responded by shaking hands with mission control personnel and congratulating them.

At Beijing Aerospace Control Center, Premier Li Keqiang watched a live broadcast of the launch and congratulated scientists.

The mission is the first application-oriented flight of the Shenzhou spacecraft, meaning the program has moved beyond the test phase.

"The past nine Shenzhou flights all served the purpose of making technical breakthroughs. The tests have been done. Now, as a product, the spacecraft is put into application," said Zhou Jianping, chief designer of the manned space program.

This signals that China's Earth-to-space transport system — comprised of Shenzhou spacecraft and the Long March-2F carrier rocket — has become one of the world's two operational systems ferrying astronauts and supplies between Earth and in-orbit vehicles, Zhou said. The other is Russia's Soyuz spacecraft.

Zhang Bainan, chief designer of Shenzhou, said the Shenzhou X mission and following flights will improve the spacecraft's reliability and safety.

It is planned that the country will launch a space lab after three spacecraft have completed docking experiments with Tiangong 1, which was launched in 2011. Space rendezvous and docking technologies are crucial for assembling a space station in orbit.

Zhou said in March that a space lab will be launched within two years. Also, a freighter will be launched to conduct a fueling experiment that is vital for the building of a space station.