Every year, Earth is bombarded with objects from space—some natural, like meteoroids, and others manmade, like space junk.
Most burn up harmlessly in the atmosphere, but tracking where and how they fall is becoming increasingly important as the skies grow more crowded.
New research presented at the European Geosciences Union General Assembly (EGU25) shows how scientists are using sound—specifically, infrasound—to detect and track these falling objects. Infrasound is a type of low-frequency sound that humans can’t hear, but which travels great distances through the air.
When meteoroids or space debris streak through the sky at high speeds and break apart, they produce powerful shock waves.
These show up as infrasound, creating what scientists call “bolides”—bright flashes and loud booms in the sky.
Elizabeth Silber, a scientist at Sandia National Laboratories, has been studying how these infrasound signals can reveal the paths of objects entering Earth’s atmosphere. But tracking these objects isn’t always simple.
Unlike a single explosion that happens in one spot, a bolide moves quickly across the sky, producing sound along its path. This makes it tricky to determine its exact flight path, especially when it enters at a shallow angle, almost skimming across the atmosphere.
To better understand this challenge, Silber used global data from infrasound stations operated by the Comprehensive Test Ban Treaty Organization (CTBTO). These stations were originally set up to listen for illegal nuclear tests, but they also pick up natural and human-made events—like meteors, thunderstorms, and even rocket re-entries.
Silber found that when a meteoroid or piece of space junk enters the atmosphere steeply—at an angle greater than 60 degrees—the sound data can reliably tell scientists where it came from and where it might land.
But when an object enters more horizontally, the results become less accurate. In those cases, different listening stations may pick up parts of the sound from different directions, making it harder to piece together the full path.
“Infrasound from a bolide is more like a sonic boom stretched across the sky than a single bang,” Silber explains. This means that scientists need to consider the object’s full movement to make accurate predictions.
As space junk continues to build up in Earth’s orbit, tracking these falling objects becomes more urgent. Studies like this one help scientists improve how we listen to the sky—so we can better predict where space debris might land and prepare for it.
Source: KSR.
