ANKARA

China’s unmanned Shenzhou-22 spacecraft docked Tuesday with the Tiangong space station, after the country activated an emergency backup launch system for the first time, state media reported.

The spacecraft lifted off from the Jiuquan Satellite Launch Center in northwest China and successfully linked up with Tiangong, where three Chinese astronauts -- Zhang Lu, Wu Fei and Zhang Hongzhang -- are continuing their mission, according to the China Manned Space Agency.

The backup launch was triggered after the Shenzhou-20 return capsule, carrying a previous crew, was hit by suspected orbital debris, delaying its trip home last week. On Nov. 5, the agency said the debris impact meant the capsule “does not meet the requirements for the astronauts’ safe return,” prompting the crew to extend their stay in orbit.

Shenzhou-21, which delivered the current crew last month, is China’s sixth crewed mission and includes the country’s youngest-ever astronaut -- along with four mice that were sent to space for scientific experiments.

The mice returned last week with the Shenzhou-20 crew -- Chen Dong, Chen Zhongrui and Wang Jie -- who spent 204 days in orbit, setting a new record for the longest mission by Chinese astronauts.