- Scientists track space debris falling to Earth using earthquake sensors detecting sonic booms
- Traditional radar struggles to track debris descent due to atmospheric disturbances
- New method tracked a 1.5-ton Chinese module's fall, correcting previous location estimates
Every day, at least three large pieces of space debris, such as old satellites and spent rocket stages, fall back to Earth. But scientists have very limited knowledge of where these dangerous fragments land and what happens to them in the atmosphere. A new method may help track these debris fragments in real time using data from earthquake sensors. In November 2022, some airspace in Spain and France was closed for approximately 40 minutes. Officials feared that a large part of a Chinese rocket could fall over southern Europe. This resulted in the rerouting or delay of hundreds of flights and millions of dollars in losses. However, the main part of the rocket ultimately landed in the Pacific Ocean, far from the predicted area, reported Space.com.
This incident demonstrated the limited knowledge we have about the behaviour of debris returning from space.
Researchers at Johns Hopkins University and Imperial College London have developed a new method for tracking space debris. This technology uses seismic sensors that can detect the sonic boom of debris as it falls into the atmosphere.
Benjamin Fernando, lead author of the study and a postdoctoral fellow at Johns Hopkins University, said, "When an object is in orbit, radar and optical tracking are very helpful. But once it descends a few hundred kilometers, the effects of the atmosphere make its path erratic, making it difficult to determine where the debris might fall."
He also pointed out that ground radars are not available everywhere and often cannot track the breakup of returning debris. Furthermore, the data from these radars is not immediately available to everyone.
Earthquake sensors are already installed in many parts of the world. These sensors can also detect things like explosions, road vibrations, and whale sounds in the ocean.
In their study, Fernando and his team used these sensors to track a 1.5-ton module that separated from China's Shenzhou 17 crew capsule and fell to Earth in April 2024.
This module was expected to fall in the South Pacific or North Atlantic. But Fernando said, "Both assumptions proved completely wrong."
Researchers analysed data from 127 earthquake sensors spread across California and tracked the module's sonic boom, which travelled through the atmosphere at 30 times the speed of sound. They found that it travelled about 25 miles (40 kilometers) north of the US Space Command's estimate. Some fragments could have fallen between Bakersfield, California, and Las Vegas, Nevada
This new method could provide real-time data on falling space debris, increasing safety and allowing authorities to take faster action.
