Every day, we see around three large pieces of space debris—like old satellites and rocket parts—return to Earth. Unfortunately, we don’t know exactly where they land or what happens as they fall through the atmosphere. However, researchers have come up with a promising new method that uses seismic sensors—commonly used to detect earthquakes—to track these pieces in real-time.
In November 2022, air traffic over parts of Spain and France was halted for about 40 minutes because a big piece of a Chinese rocket was expected to crash in southern Europe. This caused major flight delays and significant financial losses. In the end, the rocket piece fell in the Pacific Ocean, far from where people feared it would land.
This incident highlighted the lack of accurate information we have about falling space debris. The new method developed by folks at Johns Hopkins University and Imperial College London could change that. By using existing seismic networks, researchers aim to get a clearer picture of where debris will land.
The current process of predicting where space debris will reenter relies mainly on radars and telescopes, which are effective in space but less reliable as objects approach Earth. Benjamin Fernando, a researcher involved in the study, emphasized this point: “Once you’re below a couple of hundred kilometers, it gets chaotic, making predictions tricky.” Ground-based radars are not evenly spread out, leading to gaps in where we can track falling debris.
On the other hand, seismic sensors are much more common. They’re designed to pick up vibrations caused by earthquakes, explosions, and even songs from whales. In their study, Fernando and colleagues analyzed data from these sensors to reconstruct the path of a piece of debris that fell in April 2024. They found that their predictions of where it would land were incorrect, illustrating the uncertainty still present in space debris tracking.
Fernando pointed out that potential crash sites can be densely populated. “There are 50 million people living under that flight path,” he said, reminding us of the risks involved. While they didn’t find any debris after the event, the possibility remains that hazardous materials could be released.
One of the goals of this new method is to reduce the time it takes to locate any debris once it falls, shifting the timeframe from days or weeks to just minutes or hours. Historical incidents, such as a 1978 event where a Russian satellite broke apart over Canada and left behind radioactive materials, underline the need for better tracking systems.
This method might also help settle a debate in the space community regarding reentry safety. For instance, SpaceX claims that its Starlink satellites completely burn up upon reentry. Yet, many experts are skeptical. Some parts, like batteries and fuel tanks, are likely to survive the fall. Tracking these pieces more accurately could change how we assess risks to people and property below.
In future studies, researchers hope to employ acoustic sensors that can extend the reach of their tracking system even further. These sensors can pick up sounds from thousands of miles away, making them particularly useful for monitoring events over oceans, where other data is sparse. As the conversation around space debris grows, collecting accurate data will be vital for ensuring public safety and understanding the true impact of these space objects.
For more detailed insights on space debris, including latest research findings, you can check out NASA’s page on space debris.
