The Shenzhou-21 astronauts returned to Earth on Friday after staying in Tiangong space station for more than 200 days, establishing the record for longest on-orbit stay by a Chinese crew.The trio touched down at the Dongfeng landing site in the Inner Mongolia autonomous region at around 8.11pm aboard the Shenzhou-22 spacecraft, according to state broadcaster CCTV.Their stay was extended by one month after their probe was used in an emergency mission for the previous crew to return home last year.The team was set to bring back samples of artificial embryos to be used to study whether humans could reproduce in zero gravity.01:31Hong Kong’s first astronaut Lai Ka-ying among Shenzhou-23 crew entering Tiangong space stationAccording to Cang Huaixing, a chief researcher for the space station’s experiments at the Technology and Engineering Centre for Space Utilisation of the Chinese Academy of Sciences, the experiment went off “successfully”, with the samples refrigerated and ready to be sent back.