China successfully launched its second module, called Wentian, to the Tiangong space station early Sunday morning (via SpaceNews). Wentian took off aboard a Long March 5B rocket from the Wenchang Space Launch Site in Hainan, China at 2:22AM ET (2:22PM local), docking at the Tiangong space station about 13 hours later at 3:13PM ET (3:13AM local).

The Wentian module contains equipment that allows the Chinese astronauts, also known as taikonauts, to perform various scientific experiments during their time on the station. As noted by The New York Times, the additional module will also provide three extra spaces to sleep, as well as another airlock that crewmembers can use to conduct spacewalks.

In June, China sent the three-person Shenzhou 14 crew to Tiangong to prepare for Wentian’s arrival. Mengtian, the station’s third and final lab module, is set to launch on a Long March 5B in October. This will complete the Tiangong space station, forming a T-shaped structure once the final module has docked.

There are some concerns about where the massive Long March 5B rocket will end up now that it delivered Wentian, though. While most rockets safely drop their lower stages into the ocean below, this type of rocket does things differently. As SpaceNews notes, it delivers its payload by launching its entire first stage into low-Earth orbit, with no way to redirect or control its movement when it comes crashing down to Earth.

In 2020, the rocket was blamed for the metal debris that wound up in Côte d’Ivoire. It also made an uncontrolled descent into the Indian Ocean after it delivered the Tianhe core module to space last year.