Scientists have found that there is a 26% annual chance that rocket or spacecraft debris will enter an active air traffic zone somewhere. This doesn’t mean that every 4 years there should be an aviation accident caused by spacecraft, but the trend is alarming.
Danger to air traffic
There is a 26% annual chance of space rocket debris re-entering the atmosphere and passing through a busy flight zone, according to a University of British Columbia (UBC) study. The study is published in the journal Scientific Reports.
While the probability of debris hitting an aircraft is very low, the study highlights that uncontrolled space debris can interrupt flights and create additional costs for airlines and passengers.
Space debris disrupting air traffic is far from unusual. In 2022, a 20-tonne rocket fragment re-entered the atmosphere, forcing aviation authorities in Spain and France to close parts of their airspace.
UBC researchers say with the increase in rocket launches and flights, politicians need to take action.
When objects such as satellites are launched by rockets into space, large parts of the rockets often remain in orbit. If these remnants of rocket stages have a low enough orbit, they could enter the atmosphere uncontrollably. Most of the material will burn up in the atmosphere, but a lot of the debris will still fly towards the ground.
Rocket launches and flights are on the rise
The researchers used the number of aircraft on the busiest day in 2023 and compared it to the probability of rocket debris re-entry over different levels of air traffic, calculated from ten years of data. Denver, Colorado, had the highest density of air traffic that day, with about one aircraft per 18 km2.
Using this peak, they calculated the probability of rocket debris re-entering the atmosphere at different air traffic density thresholds. When they looked at regions with 10% of peak air traffic density or higher, such as the type of activity seen in the airspace over Vancouver-Seattle, they found a 26% probability per year of rocket debris re-entering that space.
In 2024, there were 258 successful rocket launches and a record 120 uncontrolled re-entries of rocket debris, with more than 2,300 rocket debris still in orbit. According to the International Air Transport Association, the number of air passengers will grow by almost 7 % in 2025.
Export risk of the space industry
The researchers also calculated the annual probability of space rocket debris colliding with an aircraft — one in 430,000.
When space rocket debris enters busy airspace, aviation authorities either roll the dice and allow flights or act by diverting flights or closing airspace.
“But why should authorities have to make these decisions in the first place? Uncontrolled rocket body re-entries are a design choice, not a necessity,” said study co-author Dr Aaron Boley, associate professor of physics and astronomy. “The space industry is effectively exporting its risk to airlines and passengers.”
Instead, industry could use rockets that re-enter the atmosphere in a controlled manner after use, falling safely into the ocean. Such a solution requires collective international action, says study co-author Dr Michael Byers, a professor of political science at the University of British Columbia (UBC).
“Countries and companies that launch satellites won’t spend the money to improve their rockets’ designs unless all of them are required to do so,” said Dr. Byers. “So, we need governments to come together and adopt some new standards here.”
According to phys.org
