Earthquake detectors can track falling space junk

Researchers used networks of seismometers to record sonic shock waves from the Shenzhou-15 orbital module's 2024 reentry and reconstructed its path, finding the seismic trajectory about 40 kilometres north of the official prediction.

Networks of seismometers designed for earthquakes can also pick up shock waves from objects reentering Earth's atmosphere. Researchers led by Benjamin Fernando and Constantinos Charalambous tested this idea on China's Shenzhou-15 orbital module when it reentered on 2 April 2024. Seismic stations across southern California registered the reentry and produced a series of signals along the module's track. Comparing those readings with radar-based predictions revealed a notable difference in the module's actual path. What researchers found: - Seismometer networks recorded shock waves from the Shenzhou-15 reentry. - Analysis of timing and intensity reconstructed the module's trajectory, speed, altitude, and where it fragmented. - The seismic-derived path lay about 40 kilometres north of the trajectory predicted by U.S. Space Command. - The seismic method provides near real-time, independent information that complements radar tracking. Summary: The study shows seismic monitoring can help locate where large debris pieces actually fall and identify fragmentation points that matter for tracking possible contaminants and recovery. Undetermined at this time.