During that test, Tianzhou 2 departed from the Tianhe module in the first place and the robotic arm soon secured the cargo craft and moved it to a new position.

Then the arm reversed the maneuvers to bring it back to its original position. Tianzhou 2 re-docked with Tianhe, finishing the 47-minute test.

Upon its completion at the end of this year, Tiangong will consist of three main components -- a core module attached to two space labs -- and will have a combined weight of nearly metric 70 tons. The station is scheduled to operate for 15 years in a low-Earth orbit about 400 kilometers above the planet.

Six launches will be made this year to deploy the Shenzhou XIV and XV mission crews to Tiangong station, to transport Tianzhou 4 and 5 robotic cargo spaceships to the station for refueling and resupply operations, and to send two large space labs to dock with the station.

The first of the six to be launched will be Tianzhou 4, which will be followed by the Shenzhou XIV manned spacecraft. Then the two space labs — Wentian, or Quest for the Heavens, and Mengtian, or Dreaming of the Heavens — will be launched into space to complete the station. The fifth to be launched will be Tianzhou 5 and the final will be Shenzhou XV.