May 28, 2024

I, Science

The science magazine of Imperial College

John Bader
5th May, 2022

If Mariah Carey and Frank Sinatra are harmonizing on Mars, you’ll be able to hear Mariah’s high notes a few seconds before Frank’s deep vocals. Why is that? It’s because of the unique Martian atmosphere properties. 

Nasa’s Perseverance rover, which landed on Mars in February 2021, captured sound recordings on the red planet, revealing a unique acoustic phenomenon. Recordings suggest that high-pitched sounds travel at a higher speed than bass ones, creating a “trippy” listening experience for humans.

Perseverance is the first ever mission to capture sound recordings of the Martian soundscape. Two earlier ventures to capture such recordings, the Mars Polar Lander and the Phoenix lander, had failed due to technical issues. Perseverance was equipped with two cameras, each with a separate microphone that would be able to capture recordings from two different locations on the rover. This maximized the chance to capture and retain recordings and allow scientists to study sound properties of Mars.    

These findings were announced at the 53rd Lunar and Planetary Science Conference by planetary scientists from the Los Alamos National Laboratory. Scientists at the conference attributed the phenomenon to the unique properties of the Martian atmosphere. Both the density of the atmosphere just above the surface of the planet, also known as the Planetary boundary layer, and temperature fluctuations play a role in the delay between high- and low-pitched sounds. 

Sound travels at a slower speed in a lower density medium than a higher density one. For instance, sound travels at about 343 m/s in our atmosphere, and at 1,480 m/s in water, a denser medium than air. Likewise, sound on Mars travels at a slower speed than on Earth as the density of the red planet atmosphere is lower than ours.  

On top of that, the high temperature fluctuations and the irregular CO2 molecules behaviour on the planet cause a speed gap between sounds of different frequencies. As a result, high-pitched sounds with a high frequency are allowed to travel at a higher speed through the medium than lower-pitched low-frequency sounds. 

“Due to the unique properties of the carbon dioxide molecules at low pressure, Mars is the only terrestrial-planet atmosphere in the Solar System experiencing a change in speed of sound right in the middle of the audible bandwidth (20 Hz – 20 kHz),” said scientists who studied the phenomenon, explaining the eerie listening experience humans would have on Mars… one day. 

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We might not know much about life on  Mars, but there’s one thing we know for sure: “No harmonizing on Mars!”

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John Bader is the News Editor for I,Science and is studying an MSc in Science Media Production at Imperial College London