Meteoroid shockwaves offer clues for tracking space junk returns

Meteoroid shockwaves offer clues for tracking space junk returns
by Erica Marchand
Paris, France (SPX) May 05, 2025

Every year, Earth gains mass from the constant bombardment of space debris and meteoritic material. Roughly 50 metric tons of meteorites reach the surface annually, accompanied by even more fine space dust. Since the dawn of the space age, human-made objects have joined this influx, with derelict satellites, discarded rocket parts, and even tools dropped by astronauts periodically plunging back into the atmosphere.

These objects travel through low Earth orbit at blistering speeds of up to 18,000 miles per hour. Once they reenter, scientists strive to trace their trajectories to forecast potential impact zones. Determining whether debris will descend vertically or streak at an angle is critical to preparing for any consequences.

At next week's General Assembly of the European Geosciences Union, Sandia National Laboratories researcher Elizabeth Silber will present new findings that could enhance such tracking. Her study focuses on how infrasound sensors detect bolides-luminous meteors that explode in the atmosphere. These dramatic events release intense energy, producing infrasound waves that propagate across continents.

However, unlike stationary explosions, bolides travel as they generate sound, complicating efforts to triangulate their path. This issue is particularly pronounced when objects enter the atmosphere at shallow angles, causing infrasound readings from different stations to suggest varying directions.

To investigate this, Silber analyzed global infrasound data from sensors managed by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). Although designed to monitor illegal detonations, these instruments also capture natural and anthropogenic atmospheric events. Silber's research isolated the geometric influence of bolide motion on infrasound signals.

Her results indicate that for steep-angle entries exceeding 60 degrees, trajectory estimates from infrasound remain accurate. But for lower-angle entries, uncertainty grows due to the spread of the acoustic source over the sky.

"Infrasound from a bolide is more like a sonic boom stretched across the sky than a single bang," Silber explains. "You must account for the fact that the sound is being generated along the flight path."

The study emphasizes the necessity of incorporating motion geometry into data interpretation, especially when applying these techniques to human-made space debris. As Silber notes, infrasound is a key tool for planetary defense, but its effectiveness depends on understanding the trajectory of incoming objects.

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