A hairline crack in orbit shows how tiny space debris can trigger major safety risks

Space.com reports on a recent incident involving China’s space programme that has renewed attention on the issue of space debris.

A Shenzhou crew capsule returning from the Tiangong space station was found to have a cracked window during routine checks. The damage was traced to a piece of debris smaller than one millimetre.

Although tests showed a low chance of failure during re-entry, Chinese officials decided not to risk a crewed return. A separate rescue mission was launched instead.

The case shows how small objects in orbit can cause serious disruptions. According to international estimates, millions of fragments now circle Earth at high speed.

Even objects too small to track can damage spacecraft, satellites, or stations. Each collision also risks creating more debris, increasing long-term pressure on space operations.

The article places this event in a wider context. Space activity is increasing, involving governments, militaries, and private companies. Existing treaties do not fully address debris management or enforcement.

Technical ideas for debris removal exist, but they are limited in scale. Without shared rules and cooperation, debris levels are expected to rise, affecting all users of Earth orbit.
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A debris strike and an emergency response

In November, the crew of a Chinese spacecraft spotted a crack that one of the windows of the Shenzhou 20 unit had developed during their inspection before the departure of the Tiangong space station.

A few hours later, the ground support team decided that the harm was due to a sub-millimetre particle which was travelling at a very high speed in orbit.

At such a speed, which is about 7.6 kilometres per second in the low Earth orbit, very small pieces of debris can easily poke their way through tough materials.

Computer models indicated that the window would not break under the conditions of a re-entry through the atmosphere. However, the mission planners considered the risk too high to be taken.

Therefore, the return of the capsule with no crew on board was the next step, and a different vehicle, Shenzhou 22, was sent to bring the astronauts back.

A later report described the event by stating, “A tiny crack in a spacecraft window triggered China’s first-ever emergency launch to Tiangong space station.”

Experts say the incident reflects a broader pattern. Tracking systems can monitor large objects, but debris under one centimetre is mostly invisible from the ground.

When such debris hits a spacecraft, it can also create new fragments. Each impact adds to the total number of objects in orbit, increasing future collision risks for all space missions.

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Debris growth, rules, and proposed solutions

International agencies estimate that more than 15,000 tonnes of human-made material are currently in orbit. This includes inactive satellites, rocket stages, and fragments from collisions and tests.

The European Space Agency reports around 140 million debris objects between one millimetre and one centimetre in size. These pieces cannot be tracked individually.

Global rules exist, but are limited. The 1967 Outer Space Treaty sets broad principles but does not cover modern debris levels or private launches.

Current guidelines recommend that spacecraft be “de-orbited within 25 years” after the end of their missions, but enforcement is weak. Some small satellites do not yet have proven ways to meet this standard.

Several removal ideas have been tested or proposed, including nets, harpoons, and ground-based lasers. Each approach has technical limits and risks. Past anti-satellite tests show how quickly debris can multiply.

One such test in 2007 created about 3,500 fragments. Another collision in 2009 added roughly 2,400 more. These cases show that without shared action, debris creation continues faster than cleanup.

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