China will launch three more astronauts to its newest space station in June after the last crew returned this weekend after a six-month stay in orbit, an official said on Sunday.

The Shenzhou 14 capsule crew will spend six months at Tiangong to add two modules to the station, Hao Chun, director of the China Office of Manned Space Engineering, told a news conference.

China’s ambitious space program launched its first astronaut into orbit in 2003, landed robots on the Moon in 2013 and on Mars last year. Officials discussed a possible manned mission to the moon.

Tiangong’s core module, or Heavenly Palace, was launched in April 2021. Plans call for completion of construction this year.

The Wentian module will be released in July and the Mengtian module in October, Hao said.

Toward the end of the Shenzhou 14 crew’s mission, three more astronauts will be launched aboard the Shenzhou 15 for a six-month stay, Hao said. He added that the two teams would overlap for three to five days, marking the first time the station has six people on board.

On Saturday, the crew of Shenzhou 13 landed in the Gobi Desert of northern Inner Mongolia.

During the mission, astronaut Wang Yaping performed the first spacewalk by a Chinese woman. Wang, Commander Zhai Zhigang and crewmate Ye Guangfu also broadcast physics lessons to high school students.

China was the third nation to launch an astronaut into space on its own, after the former Soviet Union and the United States. Tiangong is China’s third space station after predecessors launched in 2011 and 2016.

The government announced in 2020 that China’s first reusable spacecraft had landed after a test flight, but no photos or details were released.

China is excluded from the International Space Station due to US discomfort that its space program is run by the military wing of the Communist Party, the People’s Liberation Army.