Damaged Shenzhou-20 Left at Tiangong — What Happened, the Risks, and China's Options

BEIJING — Three Chinese astronauts returned to Earth after an unusual crew swap at the Tiangong space station following debris damage to their original return capsule, Shenzhou-20. The incident left the station temporarily without an immediately available emergency return vehicle for the newly arrived crew and prompted questions about how China will restore a safe lifeboat capability.

What happened to Shenzhou-20?

The China Manned Space Agency (CMSA) determined that a crack found in one of Shenzhou-20’s windows made the spacecraft unsafe to fly. As a result, the three astronauts who had arrived in Shenzhou-20 — Chen Dong, Chen Zhongrui and Wang Jie — remained aboard Tiangong until they could return to Earth in the Shenzhou-21 capsule.

Shenzhou-21 had docked at Tiangong about two weeks earlier carrying the relief crew who were to replace the Shenzhou-20 team. Shenzhou-21 was originally scheduled to remain docked for roughly six more months before returning to Earth, but it was used instead to bring the Shenzhou-20 crew home.

What risks does this create for the current crew?

Because Shenzhou-20 has been left at the station and judged unfit for immediate flight, Tiangong temporarily lacks a serviceable spacecraft that could be used to evacuate the Shenzhou-21 crew in the event of an emergency. Among those now aboard Tiangong is 32‑year‑old Wu Fei, China’s youngest astronaut to fly to date.

Chinese state media focused on the safe return of the Shenzhou-20 crew and did not dwell on the station’s temporary vulnerability. Xinhua described the operation as "the first successful implementation of an alternative return procedure in the country's space station program history" and noted the returning crew set a new Chinese record for longest in-orbit stay.

How might China respond?

CMSA said Shenzhou-22 will be launched "at an appropriate time." That launch — originally planned for next April — could be brought forward to restore a docked return vehicle. Because Shenzhou spacecraft are based on Russia’s Soyuz design, Chinese engineers can draw on precedents from Soyuz operations when planning a response.

For example, in December 2022 a micrometeoroid damaged the thermal-radiator assembly on Soyuz MS-22 while it was docked to the International Space Station. Russia elected to send Soyuz MS-23 as a replacement return vehicle so the crew could come home safely. Igor Marinin of the Russian Academy of Cosmonautics said Chinese specialists were likely to have studied such "non-standard situations" when preparing contingencies.

Can Shenzhou-20 be removed from Tiangong?

China has rotated three-person crews on roughly six-month tours aboard Tiangong since 2021, but this is the first time a Shenzhou capsule has been intentionally left behind while its crew returned in another vehicle. Keeping a damaged spacecraft docked could block a port and impede future arrivals, so there are two basic options: repair the craft in orbit (if feasible) or undock and deorbit it.

Russian analysts say that if onboard damage is significant and irreparable, the likely course would be to undock Shenzhou-20 and send it to burn up on reentry — most likely targeted to a remote area of the Pacific Ocean.

Key facts: Shenzhou-20 left at Tiangong due to a cracked window; returning crew came back in Shenzhou-21; no immediate lifeboat is docked; CMSA may advance Shenzhou-22 or deorbit Shenzhou-20 if it cannot be fixed.

(Reporting by Eduardo Baptista and Maxim Shemetov in Beijing; Editing by Alison Williams.)