The Wentian module was launched atop a Long March 5B rocket from Hainan Island at 2:22 p.m. local time on Sunday.
Wentian, China’s largest ever spacecraft weighing 23 metric tons, is equipped with four scientific cabinets to conduct ecological and biotechnological experiments under varying gravity conditions. It also features a robotic arm for external experiments and an additional airlock for spacewalks.
The docking marks the penultimate phase in the construction of China’s ambitious three-module Tiangong space station project, which is slated to finish construction by late 2022.
The Tiangong space station is the world’s second operational orbital outpost, alongside the International Space Station (ISS).
Chinese astronauts have long been excluded from the ISS, due to US political objections and legislative restrictions. Russia, a longtime contributor to the ISS, has also left the project.