Researchers with the U.S. military's Defense Advanced Research Projects Agency (DARPA) have successfully used Earth's atmosphere as a sensor to detect a distant disturbance.

DARPA accidentally detects SpaceX Falcon 9 rocket reentry by listening to Earth's atmosphere

Source: space
Source Link: https://www.space.com/space-exploration/tech/darpa-accidentally-detects-spacex-falcon-9-rocket-reentry-by-listening-to-earths-atmosphere