Scientific researchers has been able to record the inaudible sounds of the human ear of the missiles when they leave the Earth, as they generate low-frequency sound waves without hearing that need special tools to detect them.
Infrasound waves are sound waves with a frequency of less than 20 hertz, which the human ear cannot perceive.
According to (Science Alert), scientists have detected these waves. A new scientific study details what is known as "infrasound" after the launch of 1001 missiles, including the Space Shuttle, Falcon 9, Soyuz, Ariane 5, Russian Proton, and Chinese Long March rockets.
These recordings were made using the International Monitoring System (IMS), a network of monitoring stations around the world after the 1996 Comprehensive Nuclear-Test-Ban Treaty.
The network has been designed to detect nuclear explosions, and also works well for detecting missile launches.
The sound of the launch of the space shuttle Atlantis can be heard from the Kennedy Space Center in Florida, on November 16, 2009, after the sound waves were accelerated by 250 times to reach the human ear, through this audio clip.
The instruments used by the IMS are finely tuned enough to pinpoint the launch stages of the missile in some cases. In the example above, boosters can be heard in the ocean before the roar of takeoff.
The researchers hope that such recordings will enable them to assess the success of individual missile launches, and to identify any problems that may have occurred along the way.
In missile launches that don't go as planned, infrasound waves can help scientists figure out why.
These infrasound waves can travel very long distances, and the IMS network can detect them up to 9,000 km away.
The 1001 missile launches were recorded as part of 7,637 infrasound waves captured and analyzed between 2009 and 2020 at IMS stations.