A blazing trail of fireballs was seen over Los Angeles and parts of central and Southern California on April 2, sparking speculation among onlookers. This phenomenon was later attributed to the reentry and subsequent disintegration of debris from the Shenzhou-15 spacecraft, originally launched by China in November 2022. The incident, which caused a sonic boom detected by ground-based seismic sensors, has prompted concerns about space debris while opening new avenues for its detection and tracking.

Trajectory Tracked Through Seismic Signals

According to findings presented at the American Geophysical Union’s Annual Meeting in Washington, D.C., the spacecraft’s reentry provided a unique opportunity for seismic researchers to map its path through the atmosphere. Dr. Benjamin Fernando, a planetary scientist at Johns Hopkins University, explained to Live Science that seismic measurements from stations across the Los Angeles basin were analysed to reconstruct the debris’ trajectory. The data revealed the speed, size, and eventual fragmentation of the object as it moved inland from the Pacific coast.

The Role of Seismometers in Space Debris Tracking

Reports indicate that this marks one of the first instances where seismometers have been utilised to track space debris without prior notification. Dr. Fernando highlighted the advantages of seismometers in picking up subtle vibrations, particularly in regions where visual observations or radar systems might be unavailable. The technology could potentially predict whether debris poses risks to populated areas.

Challenges in Predicting Reentry Paths

Kathleen McKee, a volcano geophysicist at Vanderbilt University, commented on the difficulties of using seismic data for tracking objects moving in three dimensions through a dynamic atmosphere while speaking to Live Science. She noted that factors such as wind and weather conditions can complicate efforts to pinpoint the exact trajectory and potential impact zones. Despite these challenges, the method offers promising applications for improving public safety and monitoring space debris.

Growing Concerns Over Space Debris

The event underscores the increasing hazards posed by space missions and the resulting debris returning to Earth. Researchers stress the importance of innovative detection techniques to mitigate risks to lives and property as the frequency of such occurrences rises. This case demonstrates the potential of seismic technology to enhance global monitoring capabilities.