You know the feeling of annoyance when, on the highway, a pebble splashes against the windshield? Multiply that feeling by a million, add the risk of an air disaster and you have an idea of the risk of falling space debris: an increasingly serious problem, highlighted by a recent study.
With air traffic increasing and Earth's orbit increasingly filled with space junk, the possibility of a collision between an airplane and debris from space is no longer a remote possibility, but a real threat to flight safety. And maybe it's time we started getting seriously worried.
Keep your eyes peeled for the risk of falling debris
A recent study conducted by researchers from the University of British Columbia in Canada has sounded a disturbing alarm: the risk of falling space debris impacting aircraft is increasing. The probability of such an event remains relatively low, but the exponential growth of debris in orbit and air traffic is rapidly raising the stakes. According to the authors of the study, this threat, although underestimated, could have catastrophic consequences.
The research, published on Scientific Reports (I link it to you here), focuses in particular on rocket bodies, the largest and therefore most dangerous debris. These objects, once re-entered the atmosphere in an uncontrolled manner, are a real stray projectile that could cross the path of an airliner. Imagine the scene: a Boeing 747 flying at cruising speed, unaware of the impending danger, and a fragment of a rocket weighing several tons falling from the sky at supersonic speed.
Impact probability: airports and traffic areas at risk
Canadian researchers have set out to quantify the risk of space debris falling in the busiest airspace areas. The results are far from reassuring, considering the worsening trend. In areas with high air traffic density, immediately surrounding large airports, the probability of space debris re-entering the atmosphere is 0,8% per year, but in larger, albeit still very busy, air areas, such as those in the north-east of the United States or large Asian cities, the risk jumps to 26%.
These data translate into a concrete possibility that, every year, significant portions of airspace are crossed by uncontrolled space debris. And although the probability of a debris directly hitting an airplane is still low (I repeat again, because I do not want to alarm but to inform), scientists warn that a collision between a commercial aircraft and a space debris could "lead to mass casualties". Why do we need to think about it now? Because the problem is destined to get worse if we do not act on it.
Earth's orbit increasingly crowded, risk increasingly concrete
The amount of debris in low Earth orbit has increased dramatically, putting not only aircraft at risk, but also satellites and the International Space Station. Trackable objects in orbit have doubled in the last decade, and the number of daily flights has almost doubled since 2000. As if that were not enough, uncontrolled re-entries of large debris occur almost weekly, underline the authors of the study.
Over 2.300 rocket bodies are already in orbit and will eventually re-enter uncontrolled. Airspace authorities will have to deal with the challenge of uncontrolled re-entries for decades to come.
The situation is clear: Earth's orbit has become a space dump, and this garbage, sooner or later, is destined to fall back to Earth. The risk of falling, therefore, is not only theoretical, but a concrete challenge that aerospace authorities will have to urgently address in the coming years.
Space debris risk as France and Spain close airspace
The study cites an emblematic episode that occurred in 2022, when the 20-ton Chinese Long Marche rocket was about to re-enter the atmosphere. Predictions the day before indicated a possible impact zone over southern Europe. European space and air traffic authorities immediately issued a safety bulletin, recommending airspace restrictions. Spain and France they decided to close part of their airspace. It was the first time that such a decision had been made for an uncontrolled re-entry.
The closure of the airspace, although dictated by prudence, had significant consequences. As many as 645 flights were delayed, averaging 29 minutes, and some planes in flight were even hijacked. The airspaces of Italy, Portugal and Greece, which had not adopted restrictions, experienced an “unexpected increase in air traffic” due to diverted flights, creating “different operational risks” than those posed by falling space debris. A real chaos in the skies, precisely to manage a risk of falling into space.
The incident highlighted, among other things, a lack of preparedness for this eventuality and a lack of harmonization of responses among states.
Controlled re-entries: the definitive solution to reduce the risk of falling
Fortunately, in that case, the old rocket ended its run in the Pacific Ocean. But the episode demonstrated the fragility of the system and the need to find more effective solutions than simply closing the airspace. According to the authors of the study, the real solution would be to make controlled reentries mandatory for all space missions, with planned flight paths and scheduled landings. Currently, less than 35% of launches involve controlled reentries.
Uncontrolled reentries of rocket bodies are a design choice, not a necessity. If controlled reentries were used by all operators, the risks to people and aircraft would be greatly reduced.
The technology for controlled re-entries It exists and is not particularly complex. It is therefore, as often happens, a political, economic and industrial choice. Abandoning uncontrolled reentries would mean drastically reducing the risk of falling space debris, ensuring greater safety for flights and for people on Earth.
We have already seen recently What happens when you focus only on costs and revenues?: maybe it's time to stop considering space as a landfill and start designing more responsible and sustainable space missions.
