China has successfully launched the second of three modules that will eventually make up its Tiangong space station. On Sunday at 2:22 PM local time (2:22 AM ET), the Wentian “Quest for the Heavens” module lifted off from the country’s Wenchang spaceport atop a Long March 5B rocket, Reuters reports. With the launch a “complete success,” Wentian is expected to rendezvous with the Tiangong space station later today.

At that point, the crew of China’s Shenzhou-14 mission will begin the work of linking Wentian with the Tianhe “Harmony of Heaves” module. The latter has been in space since orbital construction on Tiangong began in April 2021. Once Wentian is operational, it will serve as one of two laboratories that will form Tiangong’s eventual t-shaped structure. Once complete, the station will be about a fifth of the size of the International Space Station, with long-term accommodation for three astronauts.

In addition to including space and equipment for Chinese astronauts to carry out microgravity and life sciences research, Wentian features an airlock cabin that will serve as the main entry and exit point for future extravehicular activities out of Tiangong. The module also has temporary living quarters that will allow China to carry out crew handover missions. According to Space.com, the first such handover is planned for later this year. China plans to launch Tiangong’s final module in October. The country is exploring the possibility of allowing commercial space flights to visit Tiangong. It has also invited international space agencies to visit the station.