Scientists have discovered that the speed of sound on Mars is very different from that recorded here on Earth. The discovery was announced by planetary scientist Baptiste Chide, from Los Alamos National Laboratory, at the 53rd Lunar and Planetary Science Conference that took place from March 7-11.
Apparently, on the red planet, higher frequency (treble) waves travel faster than lower frequency (bass) waves – that is, if we could live there without special suits, we would hear the loudest sounds before the quietest.
This is because the speed of sound can change depending on the density and temperature of the medium through which it passes. Thus, the denser the medium, the faster the sound travels through it.
The Earth’s atmosphere has a density of about 1.2 kg/m. In it, sound travels about 343 meters per second at 20 degrees Celsius, 1,480 meters per second in water and 5,100 meters per second in steel. The atmosphere of Mars is much less dense, with about 0.020 kg/m. By itself, this fact would already make the sound propagate differently on the two planets.
But there are other factors that can affect the speed of Martian sound waves. Among them is the heating of the Planetary Boundary Layer – a band of the atmosphere just above the surface, which generates convective updrafts, generating strong turbulence.
How was the speed of sound measured on Mars?
Measurements of the speed of sound on Mars were only possible thanks to instruments on NASA’s Perseverance rover: a microphone, installed on the SuperCam, and a laser that can trigger perfectly timed noise.
Supercam is the head of the jeep robot Perseverance
Image: NASA
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To calculate the sound dissipation on the neighboring planet, the scientists measured the time elapsed between the laser firing and the moment when the sound reached the microphone, at 2.1m altitude. The results show that it propagates at about 240 meters per second near the surface.
Scientists also explain that the unique properties of carbon dioxide molecules at low pressure on Mars cause a change in the speed of sound, right in the middle of the audible bandwidth for humans.
At frequencies above 240 Hertz, the vibrational modes activated by the collision of carbon dioxide molecules do not have enough time to relax or return to their original state, resulting in sound that travels over 10 meters per second faster at higher frequencies. than on lows.
This is what scientists call the “unique listening experience” on Mars: the higher-pitched sounds reach the listener before the lower ones.
The research team also used SuperCam sensors to measure large and rapid temperature changes on the planet’s surface, as the speed of sound is also altered by temperature fluctuations. These data can help scientists understand our reddish neighbor even better.
* With information from Science Alert
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