Space junk falling out of orbit and crashing toward Earth is a growing threat. Indeed, old satellites and spacecraft parts reenter our planet’s atmosphere more than three times a day.When these objects burn through the atmosphere, they can release harmful substances, and if they reach Earth’s surface, they can contaminate the environment as well as collide with buildings, other infrastructure and possibly even people.However, tracking falling debris in an effort to mitigate its impact is complicated because space junk can deorbit suddenly as it travels at speeds up to 18,000 miles per hour. Current methods to monitor falling space junk use radar and optical tracking but they struggle to accurately predict where most objects could land, especially if the debris breaks up during reentry into Earth’s atmosphere. This lack of precise location data can delay or prevent the recovery of dangerous toxic space residue.AdvertisementAdvertisementAdvertisementAdvertisementNow, researchers from the Johns Hopkins University and Imperial College London say they’ve found a new way to help spot space junk during reentry. Their approach uses seismometers, the instruments that normally detect earthquakes in the ground.The trick is to look for data indicating a sonic boom — the shock wave produced when an object exceeds the speed of sound — which the falling debris generates as it tumbles through the atmosphere.“We’ve known for a long time that space debris reentering the atmosphere produces sonic booms, exactly the same way as natural meteoroids or supersonic aircraft produce sonic booms,” said Benjamin Fernando, a postdoctoral research fellow at Johns Hopkins, who studies earthquakes on Mars, Earth and other planets in our solar system.“I did a lot of work on a NASA mission called InSight, where we tried to use meteoroids as seismic sources on Mars, with a single seismometer,” added Fernando, who coauthored a paper with Constantinos Charalambous, a research fellow at Imperial College London, on the new method that published Thursday in the journal Science.AdvertisementAdvertisementAdvertisementAdvertisementThe InSight lander, which touched down on Mars in 2018, has detected more than 1,300 marsquakes, a handful of which were produced by meteoroids striking the surface, rather than by the movement of rocks within the planet. InSight was able to “hear” the shock waves that the meteoroids produced as they entered Mars’ thin atmosphere and then pinpoint the location of the impact. NASA’s Mars Reconnaissance Orbiter was subsequently flown over these craters to study and photograph them, revealing important insights about the red planet’ …
