Damage to Shenzhou-20 Mission from Space Debris Worsens Than Initially Assessed, Causing Return Delay

China’s Shenzhou-20 spacecraft, which carried three astronauts to the Tiangong space station, suffered more severe damage from space debris than initially reported. The incident, which occurred in early November 2025, forced the mission’s crew to delay their return to Earth and ultimately return via an emergency spacecraft. Damage to the return capsule’s viewport window, including cracks penetrating through multiple layers, raised concerns about reentry safety and highlighted the growing risks posed by orbital debris.

The Incident and Initial Response

Chinese astronauts Chen Dong, Wang Jie, and Chen Zhongrui discovered small cracks in the Shenzhou-20 spacecraft’s viewport during a routine inspection on November 5, 2025, as they prepared to depart the Tiangong station. According to interviews with China Central Television (CCTV), Chen Dong initially suspected a fallen leaf might have caused the marks but quickly realized the damage was likely from space debris. The cracks, some of which penetrated through the viewport’s protective layers, prompted the China National Space Administration (CNSA) to delay the crew’s return.

To address the issue, CNSA launched a replacement spacecraft, Shenzhou-21, to the station. The Shenzhou-20 crew transferred to the Shenzhou-21 vehicle, which safely returned them to Earth on November 14, 2025, landing in Inner Mongolia. The original Shenzhou-20 capsule, left unmanned, was later recovered in Mongolia on January 19, 2026, after ground teams intervened to prevent it from being dragged by strong winds following a failed parachute deployment.

The Porthole Crack Repair Device

In response to the damage, CNSA expedited the development of a specialized “porthole crack repair device”, which was launched aboard the uncrewed Shenzhou-22 spacecraft in late 2025. The device, described as a ‘window crack repair tool,’ was installed inside the Shenzhou-20 capsule to enhance its heat protection and sealing capabilities during reentry. According to reports, the repair improved the capsule’s structural integrity, allowing it to land intact despite the damage.

Astronauts conducted a spacewalk on December 9, 2025, using a high-definition camera to inspect the porthole’s condition. The repair device’s exact mechanism remains undisclosed, but its deployment marked a critical step in addressing the risks of space debris. The Shenzhou-20 capsule’s 270-day orbital verification period, including its uncrewed return, provided valuable data for future spacecraft design.

The Broader Context: Space Debris as a Global Threat

The incident underscores the escalating dangers of space debris, a problem exacerbated by the proliferation of satellites in low Earth orbit (LEO). As of 2025, over 45,000 human-made objects orbit Earth, with more than 34,000 pieces larger than 10 centimeters tracked by NASA. The majority of this debris stems from launches by China, the U.S., and Russia, with historical events like China’s 2007 anti-satellite test contributing significantly to the problem.

Space debris poses a critical risk to both crewed and uncrewed missions. At speeds exceeding 27,000 km/h, even small fragments can cause catastrophic damage. The Shenzhou-20 incident aligns with warnings from experts about the potential for a ‘Kessler syndrome‘—a cascading chain of collisions that could render certain orbits unusable. The incident also highlights China’s growing vulnerability to debris, as its Tiangong station and satellites face increasing threats from both domestic and international sources.

Implications for International Collaboration

The Shenzhou-20 incident has sparked discussions about the need for international cooperation to mitigate space debris. While China and the U.S. have historically been reluctant to collaborate on such issues, the event may pressure both nations to share data on debris tracking and develop joint solutions. Proposals include satellite debris removal technologies, such as “tractor beams” or capture systems, though no large-scale solutions are currently operational.

China’s space program, a source of national pride, now faces heightened scrutiny. The Tiangong station, a cornerstone of China’s space ambitions, remains at risk from debris, with reports indicating that debris from Russia’s 2021 anti-satellite test came dangerously close to a Chinese satellite. The Shenzhou-20 incident, while not causing catastrophic damage, serves as a reminder of the fragility of human space operations in an increasingly crowded orbital environment.