BEIJING (AP) — China launched a rocket Tuesday carrying three astronauts to complete construction of the country's permanent orbiting space station.

The crew of the Shenzhou-15 will overlap for several days with the 3-member crew already onboard the Tiangong station, who will then return to Earth after their six-month mission.

Their spaceship blasted off atop a Long March-2F carrier rocket from the Jiuquan Satellite Launch Center on the edge of the Gobi Desert at 11:08 p.m. Tuesday.

The six-month mission, commanded by Fei Junlong and crewed by Deng Qingming and Zhang Lu, will be the last in the construction phase of China’s space station, according to the China Manned Space Agency.

Fei, 57, is a veteran of the 2005 four-day Shenzhou-6 mission, the second time China sent a human into space. Deng and Zhang are making their first space flights.

The station’s third and final module docked with the station earlier this month, one of the last steps in China’s more than decade-long effort to maintain a constant crewed presence in orbit.

After the Shenzhou-15 spaceship makes an automated docking with the Tianhe core modules’ front port, the station will be expanded to its maximum size, with three modules and three spaceships for a total mass of nearly 100 tons, Ji said.