The microphone aboard Mars Rover Perseverance has captured a number of interesting noises in its explorations, but for the most part, “a deep silence prevails” on the red planet. You can still hear the “puff, whir, zap” of the rover’s tools, the hum of the Ingenuity helicopter and the woosh of a gentle Martian breeze in this collection of sounds from the expedition.
We previously heard the sound of Mars indirectly when researchers repurposed some sensors on the InSight Mars Lander, but this is a much more purposeful recording. By comparing how an action or event sounds on Mars to how it would sound on Earth, you can learn about the atmosphere and other factors that affect it.
“It’s a new sense of investigation we’ve never used before on Mars,” said astrophysicist Sylvestre Maurice of the University of Toulouse, lead author on a study published today in Nature. As the abstract puts it:
Prior to the Perseverance rover landing, the acoustic environment of Mars was unknown… theoretical models were uncertain because of a lack of experimental data at low pressure, and the difficulty to characterize turbulence or attenuation in a closed environment. Here using Perseverance microphone recordings, we present the first characterization of Mars’ acoustic environment and pressure fluctuations in the audible range and beyond… These results establish a ground truth for modelling of acoustic processes, which is critical for studies in atmospheres like Mars and Venus.
The findings are essentially that sound on Mars is both slow to move and quick to attenuate, or fade out.
The speed of sound at sea level on Earth is about 767 miles per hour. On Mars, it was measured at 537 MPH, though that will change with the seasons as the air pressure rises and falls. And while a medium-size sound like a voice drops off after perhaps 200 feet on Earth, that same sound will travel only 26 feet before becoming inaudible.
That’s good practical knowledge for designing systems for work and life on Mars — now we know there’s no sense yelling to someone, or perhaps even having audible alarms.
Among the sounds the rover’s microphone picked up are the snap of a tunneling laser, the puff of a blower that clears away dust and the steady hum of Ingenuity’s rotors when it takes off — even though it was some distance away. Listen to the sounds of Mars in the compilation below: