It is confirmed that the speed of sound of Mars is slower than that of the earth, and it is also found that the speed varies depending on the pitch of the sound

It is known that the speed of sound is not always constant, and that the speed changes depending on the substance and temperature transmitted. A new experiment using the Mars explorer ' Perseverance ' has revealed 'the speed of sound on Mars' and 'the difference in speed depending on the pitch'.

Sound Speed on Mars measured by the SuperCam microphone on Perseverance.
(PDF file) https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf

On the earth, the speed of sound traveling in the air at 0 degrees is 331.5 m / s, but the speed of sound increases by 0.6 m / s for each temperature rise. In addition, the speed changes when the transmitted substance changes, and the speed at which sound travels in water at 0 degrees is 1500 m / s.

It is known that the atmosphere of Mars is less dense than the Earth and the temperature is very low. For this reason, it has been expected that the speed of sound on Mars will be slower than that on Earth. In this experiment, the speed of sound on Mars was actually measured using the experimental equipment installed in Perseverance.

The method of the experiment is like this. First, the perseverance irradiates the surface of Mars with a laser to generate plasma, and the sound emitted at that time is recorded by a microphone mounted at an altitude of 2.1 m, and the time when the laser is emitted and the microphone make a sound. The speed of sound is calculated from the difference in the time picked up.

As a result of the above experiment, it was found that the speed of sound in the air of Mars is about 240 m / s. It was also found that the low atmospheric pressure on Mars caused the phenomenon that 'high frequencies above 240 hertz are 10 m / s faster than low frequencies'. The research team said, 'Mars is the only planet in the solar system where the speed of sound changes in the human audible range (20 to 20,000 hertz).' There is a possibility. '

The research team plans to continue measuring the speed of sound on Mars and to find the relationship between daily and seasonal atmospheric fluctuations and the speed of sound.