A recent incident involving a Boeing 737 has raised concerns about the growing risk of aircraft being struck by space debris. In mid-October, a mysterious object cracked the windshield of the aircraft while it was flying at 36,000 feet over Utah, leading to an emergency landing. While initial speculation suggested a piece of space debris may have been responsible, later analysis indicated it was likely a remnant of a weather balloon. Nonetheless, this incident highlights a serious issue: the risk of flights being impacted by debris from space is increasing.
According to the European Space Agency, approximately three pieces of old space equipment, such as defunct satellites and used rockets, re-enter Earth’s atmosphere every day. With the projected increase in satellite numbers—currently around 12,900 active satellites, which could grow to 100,000 in the next decade—experts anticipate a rise in the frequency of potential space debris encounters.
To mitigate the risk of collisions, satellite operators are encouraged to guide old satellites to burn up in Earth’s atmosphere. However, the physics of this reentry process is complex and not entirely understood. As Richard Ocaya, a professor of physics at the University of Free State in South Africa, notes, “The number of such landfall events is increasing. We expect it may be increasing exponentially in the next few years.” Despite no reported injuries from space debris strikes, several close calls have occurred.
In March 2022, a 0.7-kilogram metal piece struck a house in Florida, confirmed as a remnant from the International Space Station. The incident occurred while the homeowner’s son was resting in an adjacent room. Earlier this year, a 1.5-meter fragment from a SpaceX Falcon 9 rocket crashed near Poznan, Poland. Additionally, a 2.5-kilogram piece from a Starlink satellite fell on a farm in Saskatchewan, Canada.
Experts warn that many incidents may go unnoticed. James Beck, director of the UK-based space engineering research firm Belstead Research, emphasizes that the risk associated with space debris might be underestimated. SpaceX claims that its satellites are designed to burn up entirely during reentry; however, Beck’s wind tunnel tests suggest that some components made of durable materials, like titanium, may survive the intense heat.
The International Civil Aviation Organization (ICAO) acknowledges the challenges posed by the rapid growth of satellite deployments, indicating that the risk to aviation safety cannot be quantified as precisely as established hazards. The Federal Aviation Administration (FAA) recently estimated that by 2035, the likelihood of an aircraft experiencing a space debris strike could reach roughly 7 in 10,000. Such a collision could either destroy the aircraft or lead to a rapid loss of cabin pressure, endangering everyone on board.
The risk for individuals on the ground is even higher. Aaron Boley, an associate professor at the University of British Columbia, suggests that if megaconstellation satellites do not burn up completely, the chance of a human injury or fatality from falling debris could rise to around 10% per year by 2035. The FAA’s report predicts an even more alarming statistic, estimating that one person could be injured or killed every two years due to falling space debris.
Given these rising risks, efforts are underway to adjust air traffic safety protocols to account for space debris. The German company Okapi Orbits, in collaboration with the German Aerospace Center and the European Organization for the Safety of Air Navigation (Eurocontrol), is investigating how to improve air traffic control systems to provide real-time alerts about potential space debris threats.
Despite advancements in artificial intelligence aimed at improving predictions of space object trajectories, accurately forecasting the descent of debris remains a challenge. The unpredictability of reentry paths can lead to last-minute alerts that may disrupt air travel. For instance, when a 21-metric-ton Chinese Long March rocket was falling in 2022, predictions indicated it could scatter debris across southern Europe, prompting a temporary airspace closure that ultimately proved unnecessary as the rocket fell into the Pacific Ocean.
The FAA’s research indicates that regions with heavy air traffic, like northern Europe and the northeastern United States, already face a 26% yearly chance of experiencing disruptions due to space debris reentry. As satellite constellations continue to expand, airspace closures may become increasingly common, potentially rivaling delays caused by severe weather.
International regulators are urging satellite operators to deorbit large satellites and rocket bodies in a controlled manner. Currently, only about half of rocket bodies reentering Earth’s atmosphere do so under controlled conditions. Approximately 2,300 old and uncontrollable rocket bodies still orbit the Earth, posing an ongoing threat.
As Aaron Boley succinctly puts it, “Although the probability of space debris hitting an aircraft is small, the probability that the debris will spread and fall over busy airspace is not small.” The implications for aviation safety, as well as for individuals on the ground, are becoming increasingly significant as the number of satellites continues to rise.
