May 26, 2022

The microphones aboard the Perseverance rover have picked up some interesting sounds during their surveys, but for the most part there is a “profound silence” on the Red Planet. In this collection of expedition sounds, you can still hear the “chug, swirl, thump” of the rover’s instruments, the hum of the Ingenuity helicopter, and a gentle breeze over Mars.

We previously indirectly heard the sound of Mars when researchers reused some of the InSight Mars lander’s sensors, but this is a much more targeted recording. You can learn more about the atmosphere and other factors that influence it by comparing the sound of an action or event on Mars with how it would sound on Earth.

“This is a new kind of research that we’ve never used before on Mars,” said astrophysicist Sylvester Maurice of the University of Toulouse, lead author of the study, published today in the journal Nature. As the summary says:

Prior to the landing of the Persistence rover, the acoustic environment of Mars was unknown…theoretical models were uncertain due to the lack of experimental data at low pressures and the difficulty of describing turbulence or humidity in a closed atmosphere. Here, using persistent microphone recordings, we present the first characterization of pressure fluctuations in the acoustic environment of Mars both outside and beyond the audible range… These results provide the basis for modeling acoustic processes, which is important for research in the atmosphere. And Venus.

In essence, the conclusion is that on Mars, sound travels slowly and at the same time decays or decays rapidly.

The speed of sound at sea level on Earth is about 767 miles per hour. On Mars, it has been measured at 537 miles per hour, although it varied with the seasons as barometric pressure rose and fell. And while a medium-sized sound stops after about 200 feet on Earth, that same sound only travels 26 feet before becoming inaudible.

This is good practical wisdom for designing systems to work and live on Mars – we now know that there is no point in yelling at anyone or perhaps sounding an alarm.

Sounds picked up by the rover’s microphone include the popping of a tunneling laser, the explosion of a dust-sweeping fan, and the steady hum of Ingenuity’s rotors as it takes off, even if it’s at a distance. Hear the sounds of Mars in the compilation below:

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