Could a small piece of metal from space one day strike an airliner?
This question is becoming more relevant. Man-made objects are falling back to Earth more and more often, and some debris manages to pass through the atmosphere without burning up completely. This situation introduces a new form of air risk, small but real, which is drawing the attention of specialists.
On average each week, a rocket stage or an old satellite ends its journey in the Earth's atmosphere. The vast majority of these objects disintegrate due to heat and friction. However, some fragments survive and continue their fall towards the ground. Statistical studies, including one published in 2025 in
Space Safety Engineering, assess the existence of a low but measurable probability that one of these pieces of debris could hit an aircraft. The models mention a one in a thousand chance of a commercial flight being struck during the year 2030.
Debris from Starship 7 seen from the cockpit of an airliner, January 2025. However, these figures should be viewed in the context of the immense density of global air traffic. An engineer from the European Space Agency points out that an aircraft can be affected by very small particles, similar to the danger volcanic ash poses to engines. Thus, attention focuses not only on the probability of an impact but also on the potential severity of such an event, considering the number of passengers on board and the vulnerability of the aircraft.
The incident related to the uncontrolled reentry of a Chinese Long March 5B rocket stage in 2022 illustrates this problem well. It led to the closure of airspace over Spain, disrupting more than three hundred flights. This episode revealed the difficulty of predicting the final trajectory of a falling object with exactitude. The margins of error remain significant, potentially covering several hours of flight and thousands of miles (kilometers), which greatly complicates the decision to close a portion of the sky.
Improving forecasts requires a deeper understanding of the upper layers of the atmosphere. This is the goal of missions like DRACO, planned by the European Space Agency for 2027. This instrumented capsule is designed to disintegrate in a controlled manner during its reentry, thereby gathering valuable information on this phenomenon. Simultaneously, an international committee bringing together several space agencies regularly organizes simulation exercises to refine predictive models.
Close coordination between air traffic managers and space agencies constitutes another part of the response. It involves developing common protocols to determine from what risk threshold an air sector should be temporarily prohibited. Organizations such as the International Civil Aviation Organization are already collaborating with the space industry on these topics, aiming to establish standards and procedures applicable uniformly worldwide.
Travelers can be reassured: the probability for an individual to be affected by this phenomenon remains infinitesimal. The ongoing work aims to make this risk even more marginal by improving the prediction of reentries and air traffic management. The ambition is to anticipate these events to allow aircraft to avoid them smoothly, without passengers even noticing, thereby ensuring fluidity and safety of travel.
Satellite Atmospheric Reentry
When a satellite or rocket stage runs out of fuel, its orbit around the Earth begins to gradually lower. This descent results from friction, however minute, with the outermost layers of the atmosphere. This region, located between 60 and 120 miles (100 and 200 kilometers) in altitude, is extremely tenuous but sufficient to slow objects down.
The more massive or dense the object, the longer it takes to burn up. Its shape and the materials it is made of also play a decisive role. Solar panels or aluminum tanks generally melt faster than parts made of titanium or ceramic. This is why some fragments can reach much lower altitudes.
Calculating the final trajectory proves very difficult. The air density at these altitudes constantly changes with solar activity. An intense solar cycle can heat and swell the atmosphere, increasing drag and accelerating the fall of debris. These unpredictable variations explain the wide margins of error in forecasts.
To track large objects, space agencies use radars and telescopes. For smaller fragments, they rely on computer models that simulate disintegration. These models are constantly being refined thanks to data collected during observed reentries, which allows for a better understanding of the fate of each component.