The three astronauts stationed on China’s Tiangong space station will extend their stay by around a month, state broadcaster CCTV said on Friday.

The crew lifted off from the Jiuquan Satellite Launch Centre on October 31 on board the Shenzhou-21 vessel and were expected to return to Earth at the end of this month after a standard six-month mission.

In November, a crack was discovered in a window of the Shenzhou-20 spacecraft, forcing the space station’s previous crew to extend their stay for a further nine days before using their replacements’ Shenzhou-21 vessel to return to Earth.

As part of the rescue mission, the uncrewed Shenzhou-22 capsule was sent to the space station to help the current crew return to Earth safely.

“To further validate technologies related to long-term human habitation in orbit and to maximise the comprehensive benefits of using the Shenzhou-22 spacecraft as an emergency launch vehicle to resupply the space station, it has been decided, after careful evaluation and assessment, that the crew’s stay in orbit will be extended by approximately one month,” CCTV reported.

The Shenzhou-22 astronauts were originally going to blast off this month, but are now expected to travel to the space station in May on the Shenzhou-23 vessel.