Three Chinese astronauts returned from the Tiangong space station Friday after a nine-day delay caused by damage to their original Shenzhou-20 return capsule, likely from space debris.

They instead returned in the newly arrived Shenzhou-21, which had delivered a replacement crew, completing China’s longest space station stay at 204 days.

The capsule landed in the Gobi Desert, where the crew was safely recovered, along with four mice used in experiments on microgravity effects.

The delay did not impact the astronauts’ work on experiments or daily routines, and the mice adapted well to the space environment for further study, the AP has reported.

China’s Tiangong space program, managed by the military, continues to advance national space ambitions, including Mars exploration and a planned crewed moon landing by 2030.