Infrasound at long range from saturn v, 1967

Area of Science:

• Acoustics
• Atmospheric Science
• Aerospace Engineering

Background:

• Infrasonic waves generated by large rocket launches can travel long distances.
• Understanding the propagation and characteristics of these waves provides insights into atmospheric conditions and launch vehicle acoustics.

Purpose of the Study:

• To analyze the distinct groups of infrasonic waves recorded from the Saturn V rocket launch in 1967.
• To determine the origin and characteristics of the recorded infrasonic signals.
• To investigate the phenomenon of signal reversal and the separation of wave groups.

Main Methods:

• Recording infrasonic waves at a distance of 1485 km from the launch site.
• Analyzing the trajectory data of the Saturn V rocket.
• Applying Fourier analysis to the recorded infrasonic data.

Main Results:

• Two distinct groups of infrasonic waves were identified, differing in amplitude and duration.
• The first group (10-minute duration) was attributed to the first stage reentry or second stage at high altitude (>120 km).
• The second, more intense group (9-minute duration) was identified as sound from the powered first stage, with signal reversal observed.

Conclusions:

• The separation into two distinct signal groups is likely due to the rocket outrunning its sound.
• Trapping of sound within the upper atmospheric sound channel may explain the observed signal separation.
• Fourier analysis revealed energy extending to long periods (7-10 seconds), characteristic of rocket-generated infrasound.