China’s Stranded Astronauts Show the Dangers of Space Junk
November 7, 2025
4 min reading
Stranded Chinese astronauts show dangers of space junk
Three Chinese astronauts likely to return to Earth safely after space debris strike. But incident highlights growing risk of orbital debris
Wang Jie, Chen Dong and Chen Zhongrui before their April 2025 launch on the Shenzhou-20 spacecraft.
This week, the China Human Space Mission Agency (CMSA) announced that the return of three of its astronauts had been delayed after a piece of space debris hit the ground. Shenzhou 20 spacecraft that was intended to bring them back to Earth from China’s Tiangong space station. As the agency continues to investigate the extent of the damage, independent experts say the incident is a clear sign that the danger of orbital debris proliferation will only grow.
Although this is the first time a return to Earth has been affected by debris, scientists have long warned that the growing amount of space debris makes such disruptions inevitable.
“It was only a matter of time before this happened,” says Lauren Kahn, a research analyst at Georgetown University.
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Space junk is basically any man-made object floating in space that is no longer useful. As orbital launches and other space activities have increased, fragments produced by collisions, accidental ruptures, spent rocket stages, etc. have become increasingly common. In Earth’s orbit, debris can drift in space for decades, gradually descending due to atmospheric drag before finally experiencing a fiery reentry. The result, Kahn says, is that parts of Earth’s orbital environment are teeming with dangerous objects that can collide with vital space infrastructure.
A recent analysis, co-authored by Kahn, tracked 34,000 pieces of space debris larger than 10 centimeters recorded between 1958 and mid-April 2025. Researchers found that 73% of all debris tracked in orbit today can be traced to just 20 major sources: launches by China, the United States and Russia.
According to NASA, there are more than 45,000 man-made objects orbiting Earth today. Some of them could cause serious damage to space stations and satellites, endangering the global space economy floating above our heads, currently valued at over $600 billion.
Although objects larger than 10 cm can be found and tracked, the real danger comes from harder-to-see debris, which can be as small as a bullet and traveling at more than 27,000 kilometers per hour. “These are the ones that are scary,” says Jonathan McDowell, astronomer at the Center for Astrophysics | Harvard and Smithsonian. “They are time bombs in orbit.”
Although the CMSA did not reveal further details about the object that may have hit the Shenzhou 20 spacecraft, McDowell says even a small piece could be dangerous if it hit a key system.
Still, the astronauts should be safe, McDowell says, because China has another spacecraft docked at the space station and ready to pick them up if they can’t get back to the space station. Shenzhou 20 craftsmanship.
A cascade of collisions
The biggest fear among space scientists is that the debris could trigger a chain reaction of satellite collisions, creating even more junk, a nightmare scenario known as Kessler syndrome.
In recent years, astronomers tracking space debris have focused on low Earth orbit (LEO), where manned space missions operate alongside communications and observation satellites. According to the analysis Kahn co-authored, most space debris – more than 83% of objects tracked in April 2025 – is in LEO.
Currently, there are about 13,000 active satellites orbiting Earth, about 10 times more than there were a decade ago. For this reason, McDowell explains, satellites often have to move apart to avoid crashing into other satellites or debris. These movements, called evasive maneuvers, already occur tens of thousands of times each year. The number of maneuvers increases much faster than the number of satellites, because more satellites means more chances of crossing paths. If the number of satellites were increased 10-fold, maneuvers could be increased 100-fold, making orbital traffic much more difficult to manage safely.
Even as that risk increases rapidly, there are still plans to launch mega-constellations of tiny satellites similar to those already in orbit as part of SpaceX’s Starlink system, as well as a new emerging push for orbital data centers such as Nvidia’s Starcloud. “There is currently no limit to the number of satellites you can launch,” says McDowell.
Two issues are of particular concern, says Victoria Samson, chief director of space security and stability at the Secure World Foundation, a Colorado-based nonprofit: There is currently no way to clean up space debris, and there is very little international coordination to prevent further debris-generating collisions, particularly between the United States and China.
This is not the first time that China’s human spaceflight program has encountered dangerous debris. In March 2024, CMSA said in a statement that a fragment struck one of the Tiangong space station’s solar panels, damaging it and causing a loss of power that required astronauts to conduct spacewalks to make repairs.
But the potential damage caused by the increasing number of collisions cannot always be repaired during a spacewalk. Beyond the risk to space infrastructure, the biggest concern is the growing number of astronauts in orbit. “There are a lot of people up there,” Samson said.
