Scientists Develop Way to Track Dangerous Space Debris Using Sonic Booms
Objects in orbit that fall to Earth can pose a risk to life and infrastructure. Research outlines a new method to follow their paths.
- Scientists propose using seismometers to track space debris re-entry, analyzing sonic booms to determine trajectory and fallout zones.
- The method was demonstrated using data from the Chinese Shenzhou-15 spacecraft’s re-entry in April 2024 over the southwestern U.S.
- This technique aids in locating fallen debris and assessing its characteristics, as the volume of re-entering space objects increases exponentially.
Tens of thousands of human-made objects orbiting the Earth could pose a risk to life, infrastructure and the environment when they fall through the atmosphere.
Typically the space debris is tracked using ground-based or orbital radar and optical instruments. But these methods struggle to monitor objects when they begin burning up in the atmosphere, hurtling toward the ground at speeds of 17,000 miles an hour. Sometimes, re-entry predictions can be off by thousands of miles.
In a new study, two scientists have outlined a way to track space-debris crash sites and fallout zones using the sonic booms that occur when such objects streak through the atmosphere. Vibrations from the booms—the shock waves produced by something traveling faster than the speed of sound—can be picked up by ground-based stations typically used to monitor for earthquakes, helping researchers calculate an object’s speed, trajectory and potential fallout zone. The approach offers additional clues about whether an object might have broken up during its fall.
“It’s rapid re-entry forensics,” said Constantinos Charalambous, a planetary seismologist at Imperial College London and co-author of a study detailing the method published Thursday in the journal Science.
Though space debris usually breaks up during re-entry, pieces can survive—and these potentially toxic, flammable, or even radioactive fragments might need to be tracked down and disposed of, said Benjamin Fernando, a seismologist at Johns Hopkins University and study co-author.
To demonstrate their idea, the scientists looked at data from more than 100 earthquake-monitoring seismometers on the ground across the southwestern U.S. to study the sonic boom from debris of the Chinese Shenzhou-15 spacecraft as it re-entered Earth’s atmosphere in April 2024. When that shock wave hit, it shook the ground. Monitoring stations closer to the debris’ path recorded the vibrations more quickly, while stations farther afield recorded a delay. The pattern of the recordings helped the scientists estimate the craft’s re-entry path, which passed over tens of millions of Americans between the Southern California coast and Las Vegas.
Tracking a Sonic Boom
In 2024, seismometers across Southern California and Nevada picked up a sonic boom, or shock wave, from an orbital module as it re-entered the atmosphere. Stations closer to the point of entry recorded the shock wave first, while those farther along the path recorded a delay.
The new method doesn’t offer people on the ground advance warning of debris falling, Fernando said. “This object is always going to outrun its own sonic boom, meaning you’ll see it and it will hit you before you hear it,” he said.
Rather, he said, it could help researchers quickly find where the debris has landed, how big it is, or confirm whether it has burned up in the atmosphere.
Over the last decade, the number of spacecraft—such as dead satellites or used rocket stages—that re-enter Earth’s atmosphere from orbit has grown exponentially. As re-entries become more frequent, tracking the objects becomes more important.
“We are at a point now where this problem is getting worse and worse, but the tracking and response aspect that we’re working on here has not actually caught up with reality,” he said.