The Tianzhou 3 cargo spacecraft departed from the Tiangong space station Sunday morning, according to the China Manned Space Agency.
The agency said in a brief release that the robotic craft undocked from the Tiangong at 10:59 am and will be guided by ground controllers to fall back to Earth in due course.
In an earlier statement, the agency said the Tianzhou 3 would undock to leave its docking hatch for the coming Wentian space lab.
Launched on Sept 20 from the Wenchang Space Launch Center in Hainan province, Tianzhou 3 docked with Tiangong in a low-Earth orbit of around 400 kilometers later that day.
Carrying nearly 6 metric tons of propellants and materials, the cargo ship was tasked with supporting the Shenzhou XIII mission, during which a three-member crew stayed for six months inside the Tiangong station from mid-October to mid-April.
Currently, Tiangong consists of the Tianhe core module, the Tianzhou 4 and the Shenzhou XIV spacecraft. Its current occupants – three astronauts of the Shenzhou XIV mission – arrived in the station in mid-June and are scheduled to fly with it until year's end.
Within this month, the Tiangong station's first lab component — Wentian, or Quest for the Heavens — will be launched from Wenchang to dock with the station, while the second lab named Mengtian, or Dreaming of the Heavens, will be sent in October. After they are connected with the Tiangong, the station will form a T-shaped structure.
After the space labs, the Tianzhou 5 cargo craft and the Shenzhou XV crew are scheduled to arrive at the massive orbiting outpost around the end of the year.
Each Tianzhou cargo spaceship has two parts, a cargo cabin and a propulsion section. Such vehicles are 10.6 meters long and 3.35 meters wide.
The cargo vehicle has a lift-off weight of 13.5 tons and can transport up to 6.9 tons of supplies to the space station.
When it comes to carrying capacity, Tianzhou is the world's best space cargo ship because it is the first of its kind to be able to transport as much as 6.9 tons of materials to space.