The return of the Shenzhou XIX crew from the Tiangong space station, originally set for Tuesday, has been postponed due to weather concerns, according to the China Manned Space Agency.

The agency said in a short news release on Tuesday afternoon that the decision was made in consideration of the unfavorable weather conditions at the Dongfeng Landing Site in the Inner Mongolia autonomous region and is intended to ensure the astronauts' health and safety as well as the mission's success.

The crew's return will be determined and take place in due course in coming days, it noted.

The outgoing Shenzhou XIX astronauts — mission commander Senior Colonel Cai Xuzhe, Lieutenant Colonel Song Lingdong and Lieutenant Colonel Wang Haoze — were launched from the Jiuquan Satellite Launch Center in Inner Mongolia on Oct 30 and arrived at the Tiangong space station later that day.

After several days of handover work, Cai and his teammates, who are the eighth crew to inhabit the Chinese space station, took over the massive outpost in early November from their peers in the Shenzhou XVIII mission.

As of Tuesday, they had spent 181 days in a low-Earth orbit about 400 kilometers above ground and have completed a lot of scientific and technological tasks as well as three spacewalks.

Their successors — astronauts in the Shenzhou XX mission — arrived at the space station on Friday.

A space industry observer who wished not to be named said that the safety of astronauts is always the most important factor when mission planners decide their landing date and that there are a lot of unpredictable elements in the astronauts' return journey.

"For instance, if the wind is too strong, the parachute of the reentry capsule will not be capable of resisting and will lead to deviation from original trajectory. A sandstorm will also cause big problems for ground recovery personnel. Therefore, it is understandable and necessary to adjust the landing date to ensure the absolute safety of our crew members," he explained.

zhaolei@chinadaily.com.cn