The Tianzhou 2 robotic cargo spacecraft changed a docking hatch with the Tiangong space station on Saturday, according to the China Manned Space Agency.

The agency said in a brief statement on Saturday afternoon that Tianzhou 2 departed from the station's rear hatch at 10:25 am and then spent about four hours moving to and docking with the front hatch.

The combination of the station's core module and the cargo spaceship had been in good condition, the agency said, noting the orbiting pair will soon welcome the Tianzhou 3 cargo ship and the Shenzhou XIII crewed spacecraft that will carry three astronauts.

Tianzhou 2 was launched by a Long March 7 carrier rocket at the Wenchang Space Launch Center in South China's Hainan province in late May and soon docked with Tiangong's core module.

A 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 craft, which has a liftoff weight of 13.5 metric tons, can transport up to 6.9 tons of supplies to the space station.

With a designed life of more than one year, Tianzhou 2, the country's second cargo spaceship, carried 6.8 tons of supplies for Tiangong, including 2 tons of propellants, more than 160 packages of living and experiment materials, and two roughly 100-kilogram spacesuits for the astronauts to perform extravehicular activities outside the core module.