Chinese astronauts have successfully completed the latest phase of construction work on the Tiangong space station by moving one of its laboratory modules into its final position. The Wentian lab module was first separated from the forward port of the core module Tianhe and slowly slotted into the side port using the space station’s robotic arm . The next phase of construction will be the launch later this month of the Mengtian lab module , which will eventually be placed on the other side port to form a T-shaped space station. The three astronauts on board the Tiangong and engineers at the ground command centre worked together to conduct the hour-long operation – a first for the country’s space programme, the China Manned Space Agency (CMSA) said. Wei Zhi, an engineer from the Shanghai Academy of Spaceflight Technology, told The Beijing News that it was safer to dock the modules at the front at first and move them to the side later to reduce the risk that the heavy modules would unbalance the space station and cause it to “roll out of control”. The Mengtian lab module and the Long March rocket that will carry it into space are already in place at the Wenchang Space Launch Site on the southern island of Hainan. A source familiar with the CMSA’s work said the launch was scheduled for the end of the month as all the assembly and testing were going “very smoothly”. After the launch and installation of the Mengtian module, the two space lab modules will provide a pressurised environment for astronauts and researchers to conduct experiments in free fall or zero gravity which are very difficult or impossible to carry out on Earth. They will also allow experiments to be conducted outside the module to see the effects of exposure to cosmic winds and solar rays on materials to be used in extreme working conditions. On September 1, two astronauts stationed on board the space station – mission commander Chen Dong and crew member Liu Yang – carried out a six-hour spacewalk to prepare the Wentian module for the operation and set up emergency procedures. The Earth satellite project bringing Chinese, US and Russian space scientists together It was the first time that the space crew had used the airlock cabin in the Wentian lab module to leave the space station. The pair and their teammate Cai Xuzhe arrived at the space station in early June and will spend six months in space. They will be joined by three more astronauts when the Shenzhou 15 mission blasts off later this year – the first time six crew members have been stationed on board at the same time.