China launches space station’s third and final module

China launched the third and final module of its space station Monday, a significant step as the country expands its extensive scientific research outside the Earth’s atmosphere.

State television broadcast the launch live, showing a rocket roaring into a gray layer of clouds above Hainan Island in southernmost China, with the module aboard. Deng Hongqin, the director of the launch command center, announced after 14 minutes that the module was in orbit.

Nearly 59 feet long and weighing 23 tons, the module, called Mengtian, was expected to dock with the Tiangong space station about 13 hours after launch. The module carries a wide range of experimental equipment, including extremely accurate atomic clocks and gear designed to create the coldest conditions ever achieved by humanity.

Yang Hong, the space station’s chief designer, said at a news conference in April that the Mengtian module would be equipped with a cargo airlock. Outside the airlock will be a platform on which experiments can be mounted, with robotic arms to help carry them out, he said. The module will supply the space station with racks of additional laboratory equipment and give the astronauts more room to operate.

Completing the space station is the latest step in Beijing’s broad effort to match and eventually surpass the United States in the exploration of space, and to build a broad base of knowledge for China’s large and ever-growing scientific community.

The station’s core module, called Tianhe, went into space last year. In July, China followed up by launching the first of two science modules, the Wentian, which then docked with the core. Once the Mengtian module docks, the completed space station will essentially have a “T” shape.

Like the first two modules, the Mengtian was launched on a Long March 5B rocket. These launches have prompted criticism from the United States, because China has not demonstrated the ability to control where the rocket’s 23-ton core booster stage, as tall as a 10-story building, will hit the Earth on reentry.

Typically, the core stages of similar rockets that reach orbit fire their engines again after releasing their payloads. That allows them to be aimed at unpopulated areas, like the middle of an ocean, when they fall from orbit. But so far, China has not shown that the Long March 5B can do this.

After a Long March 5B launch in 2020, the booster reentered over West Africa. Debris caused damage to villages in Ivory Coast, but no injuries. When another Long March 5B was used last year to launch the space station’s Tianhe core, the booster fell into the Indian Ocean near the Maldives.

And in July, after China launched the Wentian module, much of the booster burned up over the Sulu Sea, southeast of the Philippines.

The China Manned Space Agency said in an online statement that it had made adjustments to the Long March 5B used for the launch Monday. But those changes involved putting the Mengtian module into orbit more accurately, not guiding the booster back to earth.

The Mengtian module is designed to function in space for 10 years, state television said. One of its first experiments will involve testing how seeds grow after being exposed to microgravity and the radiation of space. Chinese scientists also plan to use it to study how spiders spin webs in free fall, an experiment that has also been performed aboard the International Space Station.