Summary: A piece of orbital debris likely cracked a window on China’s Shenzhou-20 return capsule, forcing mission directors to delay its Nov. 5 reentry and ultimately return the crew aboard Shenzhou-21; the three landed safely after 204 days in space. The incident underscores a growing orbital debris crisis — researchers estimate more than 34,000 trackable objects over 10 cm and tens of millions of smaller, untracked fragments. Experts say prevention, stricter international disposal rules, and better operational safeguards are the most realistic near-term responses.
Debris Near-Miss: Shenzhou-20 Window Cracked, Crew Brought Home Safely — A Stark Warning on Space Junk
Summary: A piece of orbital debris likely cracked a window on China’s Shenzhou-20 return capsule, forcing mission directors to delay its Nov. 5 reentry and ultimately return the crew aboard Shenzhou-21; the three landed safely after 204 days in space. The incident underscores a growing orbital debris crisis — researchers estimate more than 34,000 trackable objects over 10 cm and tens of millions of smaller, untracked fragments. Experts say prevention, stricter international disposal rules, and better operational safeguards are the most realistic near-term responses.
02:58 AM, 11/15/2025Science
INNER MONGOLIA, CHINA — China’s Shenzhou-20 mission became an urgent reminder of a rising threat to human spaceflight when a small piece of orbital debris apparently cracked a window on its planned return capsule, forcing mission directors to delay the crew’s scheduled Nov. 5 reentry and ultimately bring them home in a different spacecraft.
What happened
The Shenzhou-20 crew — Chen Dong, Chen Zhongrui and Wang Jie — had boarded China’s Tiangong space station on April 24 and were due to return on Nov. 5, handing station command to the Shenzhou-21 crew that arrived Oct. 31. On Nov. 4 Chinese space authorities posted on Weibo that "the Shenzhou-20 manned spacecraft is suspected of being struck by small space debris, and impact analysis and risk assessment are underway," and postponed the return to ensure astronaut safety.
With repairs or replacement of the capsule not immediately feasible, mission controllers left the potentially compromised Shenzhou-20 docked to Tiangong and returned the crew aboard Shenzhou-21. The three astronauts landed safely at the Dongfeng recovery site in Inner Mongolia at 3:45 a.m. EST on Nov. 14 after 204 days in space. Commander Chen Dong told reporters, according to an Associated Press translation, "The path of human space exploration is not smooth. It's filled with difficulties and challenges. But that is exactly why we choose to walk this path."
Why a cracked window matters
A breach or crack in a spacecraft window is not a cosmetic issue: it threatens cabin integrity during microgravity operations and the extreme aerodynamic and thermal loads of atmospheric reentry. Without a guaranteed airtight return vehicle, crews have limited options for a safe evacuation in the event of an emergency.
Broader context — a growing debris crisis
The Shenzhou-20 incident highlights a problem decades in the making. Since Sputnik’s 1957 launch, spent rocket stages, defunct satellites, discarded hardware and tiny fragments have accumulated in orbit. A recent study from Georgetown University’s Center for Security and Emerging Technology, by Kathleen Curlee and Lauren Kahn, estimates more than 34,000 objects larger than 10 cm (about 4 inches) currently orbit Earth — plus tens of millions of smaller, untracked pieces that can still inflict lethal damage at orbital velocities.
“There are tens of millions of smaller, untraceable pieces that can still wreak havoc,” said Curlee, noting that active collision avoidance and a measure of good fortune have prevented even more incidents.
Some debris events were self-inflicted. In 2007, China’s anti-satellite test destroyed one of its own defunct weather satellites and generated more than 2,000 pieces larger than 10 cm and tens of thousands of smaller fragments — a cloud NASA called "the most severe artificial debris cloud in Earth orbit" at the time. Because orbital decay is slow at high altitudes, many of those fragments remain hazardous today.
Operational impacts and mitigation
Space agencies regularly maneuver satellites and the International Space Station to avoid predicted conjunctions; astronauts also shelter in docked return vehicles when a high-risk pass is predicted. But active avoidance has limits, and removal of existing debris remains experimental. "There is no cost-effective way to remove debris already in space," Curlee says. The near-term priority, experts say, is prevention: stricter international rules for end-of-life disposal, safer operational practices, and global coordination as the space economy — currently estimated at roughly $1.8 trillion — continues to expand.
What’s next
The Shenzhou-21 crew remains aboard Tiangong with limited immediate escape options; Xinhua reported that an empty Shenzhou-22 will be launched "at an appropriate time in the future" to restore normal return capability when the current crew’s rotation ends. The Shenzhou-20 episode was a warning shot — the astronauts survived this time, but the risks posed by orbital debris are rising and will demand stronger international action and better operational safeguards.