Space Debris Threat: Growing Risk for Aircraft as Reentries Increase

Researchers have warned that the increasing amount of space debris falling back to Earth could pose a growing threat to aircraft. A new study, led by researchers at Canada's University of British Columbia, highlights the rising risk due to an increase in both space debris reentries and flights.

While the probability of a collision between space debris and an airplane remains small, the consequences of such an event could be catastrophic, according to the study published in Scientific Reports. The research focuses on rocket bodies, which present a greater risk due to their size and mass.

The Risk of Space Debris Reentry

The study authors analyzed the odds of a rocket body reentering within airspace. They found that high-density regions immediately surrounding major airports have an 0.8% chance per year of being affected by an uncontrolled reentry. However, in larger but still busy airspace areas, such as those found in the northeastern United States or around major cities in Asia, the risk rises to 26%.

Although the probability of debris striking an aircraft is low, a collision between a commercial plane and space debris could lead to mass casualties, the researchers warned. The amount of debris in low Earth orbit has significantly increased, putting satellites and the International Space Station at risk of colliding with even the tiniest fragments of space junk.

Growing Concern and Future Challenges

The study emphasizes that the risk will only escalate as space debris continues to orbit Earth. Trackable objects in orbit have doubled in the last decade, while the number of daily flights has nearly doubled since 2000. Large reentries occur almost weekly, according to the authors.

"Over 2,300 rocket bodies are already in orbit and will eventually reenter in an uncontrolled manner," the study noted. "Airspace authorities will face the challenge of uncontrolled reentries for decades to come."

Airspace Closures and the Need for Controlled Reentries

The researchers highlighted an incident in 2022, when a 20-ton rocket body was set to reenter the atmosphere. Predictions the night before the reentry indicated it might land over southern Europe. European space and air traffic industries issued a safety bulletin recommending that authorities implement airspace restrictions.

Spanish and French authorities ultimately closed part of their airspace, marking the first instance of airspace closure for an uncontrolled reentry. The closures delayed 645 aircraft for approximately 29 minutes, including diverting some planes already in the air. Airspace in Italy, Portugal, and Greece, which remained open, experienced an "unexpected increase in air traffic" from diverted flights, creating "different, operational risks" compared to those posed by the falling space debris.

"The incident highlighted, among other things, a lack of preparation for this eventuality and a lack of harmonization of responses among states," the study authors noted. The rocket body eventually fell in the Pacific Ocean.

The study authors argued that, rather than closing airspace, it would be more effective if all rocket missions required controlled reentries with charted flight paths and scheduled landings. Currently, fewer than 35% of launches incorporate controlled reentries, according to the authors. "Uncontrolled rocket body reentries are a design choice, not a necessity," the study stated. "If controlled reentries were used by all operators, the risks to people and aircraft would be greatly reduced".