NASA deliberately smashed Apollo 12’s empty lunar lander into the Moon at about 3,750 mph in 1969, and a seismometer the crew had set up on 19 November before leaving recorded the Moon ringing like a bell for nearly an hour.
NASA used Apollo 12’s uncrewed lunar module ascent stage as a controlled seismic source on November 20, 1969, allowing scientists to compare a known impact with the Moon’s response. The signal built for about seven minutes before slowly fading for nearly an hour, exposing an unusual style of seismic propagation that researchers are still using to investigate the Moon’s impact-shattered outer layers.
