China's Shenzhou 20 astronauts return to Earth on different spacecraft after finding window cracks in their own (video)

The three astronauts of China's Shenzhou 20 mission safely touched down on the Dongfeng Landing Site in China's Inner Mongolia Autonomous Region shortly before 3.45 a.m. EST (0845 GMT) on Nov. 14, after spending over 6 months in low-Earth orbit aboard the Tiangong space station.

Commander Chen Dong, Chen Zhongrui and Wang Jie have since exited the return spacecraft and appear to be in good health, having made a final parachute-aided descent to Earth's surface.

The Shenzhou 20 trio were supposed to leave China's Tiangong space station on Nov. 5. But the departure was postponed after their Shenzhou 20 spacecraft absorbed an impact, apparently from a small piece of space debris.

The taikonauts finally left Tiangong on Thursday (Nov. 13) at 10:14 p.m. EDT (0314 GMT and 11:14 a.m. Beijing time on Nov. 14). But they left the Shenzhou 20 vehicle behind, traveling instead in the newly arrived Shenzhou 21 spacecraft.

"The Shenzhou-20 spacecraft does not meet the requirements for the astronauts' safe return and will remain in orbit to continue relevant experiments," the state-run Xinhua news outlet reported on Thursday, citing information from the China Manned Space Agency (CMSA).

"Tiny cracks have been found in the return capsule's viewport window, which are most probably caused by external impact from space debris, according to the CMSA," Xinhua added.

The Shenzhou 20 astronauts launched to Tiangong on April 24. Their mission is the third spaceflight for Dong and the first for both Zhongrui and Jie. The trio conducted a variety of scientific experiments and outreach activities during their time on the station. They also completed four spacewalks, installing (appropriately enough) debris shields and other equipment on Tiangong's exterior.

The three-astronaut Shenzhou 21 mission launched to Tiangong on Oct. 31 to relieve their predecessors and begin their own six-month stint aboard the orbiting outpost. But the newcomers' vehicle ended up having an unexpectedly brief space stay, thanks to the debris strike on Shenzhou 20.

When the time comes, the Shenzhou 21 astronauts will apparently ride home on the Shenzhou 22 vehicle, which will launch (presumably uncrewed) "at an appropriate time in the future," according to another Xinhua report.

Shenzhou 20 was the ninth crewed mission to Tiangong, a three-module space station that was fully assembled by October 2022. Tiangong is about 20% as massive as the International Space Station, but it may get bigger; Chinese space officials have mentioned the possibility of adding more modules to the outpost.