NASA’s Perseverance rover, which landed on Mars in February 2021, has two microphones that are recording hours of audio every day. As the rover explores Mars, it’s almost unsettling to imagine its world where the wind is gentle, and the air is silent. For the first year of recording, scientists wondered if they were even collecting any viable data.
“It is so quiet that, at some point, we thought the microphone was broken!” says Dr Baptiste Chide, from Los Alamos National Laboratory, in a statement.
(So if you want to get away from it all and get some peace and quiet, you should consider going on a trip to Mars!)
Once scientists started listening to the audio for signs of sound, they realized they could hear a lot — the inner workings of the rover’s instruments whirled to life while Martian wind brushed against the microphone.
From the rover’s wheels crunching over the Jezero Crater terrain to its SuperCam instrument firing a laser at Martian rock, Perseverance seems to have a lot to say. Scientists are operating the loudest thing that exists on Mars.
The audio clips can sound slightly unsettling, but to scientists and space enthusiasts, they show that Perseverance is alive and performing its experiments nominally. When scientists listen to Perseverance’s instruments, they can monitor whether or not they’re working.
The mission team is using the audio recordings to study various environments on Mars and the behavior of the hardware being used. After a year of collecting data, the Perseverance playlist features more than 5 hours of martian sounds. Scientists cut it down to 16 minutes of raw, unedited audio.
On Mars you have three notably main distinctive differences compared to Earth:
The speed of sound is reduced. While you may not notice closer to the emitter of the sound, you may notice the further you get from the emission source. Sound travels at about 540 MPH on Mars compared to 760 MPH on Earth.
The atmosphere as aforementioned is 100 times less dense. 96% of the Martian atmosphere contains carbon dioxide, which absorbs higher-pitched sounds.
Quality of sound
Mars is made up of 96% carbon dioxide meaning that higher pitched frequencies, like bird trills, babies crying, and high-pitched screaming would be more muffled and less likely to travel. Lower-toned and deeper notes carry easier on this world. This effect is called “attenuation” — when signals weaken at certain frequencies. (Imagine hearing a low-wailing siren on this dusty landscape.)
Oxygen isn’t necessarily a requirement for sound to travel. Sound can travel through a number of mediums; liquid, air (even without oxygen), and even solids (otherwise you wouldn’t hear those noisy neighbors if sound waves didn’t pass through solids.)
The fact we can even hear anything on another planet has an exhilarating impact on the scientific community. We can hear the eerie call of Mars from the gentle winds and the near-silent trudge of Perseverance. This will give us excitement from generation to generation as we capture literal wonder and splendor from the Martian star.