A NASA rover ambling over the red desert planet for the past four years has been recording audio of Mars.
In this alien world 156 million miles away in space, even the everyday whispers of wind and mechanical parts are exotic to human ears. Scientists say that's because the Martian atmosphere is about 1 percent as dense as Earth's, which alters the volume, speed, and characteristics of sound.
How to describe what Perseverance has heard at Jezero crater?
Well, it doesn't not sound like the eerie ambient noise of Stanley Kubrick's 2001: A Space Odyssey, but you can listen for yourself.
Like an aspiring DJ or singer-songwriter, Perseverance has a Soundcloud account, where people can experience the latest Martian tracks. NASA shared this week some of the strange audio the rover has captured. You can find a sampling further down in this story.
When the rover touched down on Mars in 2021, it didn’t just bring cameras, drills, and tubes for rock samples. It also carried two microphones — nothing special, just a couple of off-the-shelf devices anyone could buy online. The only modification NASA made was to attach little grids at the end of the mics to protect them from Martian dust.
One of the microphones, mounted on the rover’s head, is known as the SuperCam and has recorded most of the audio; another is attached to the body. What they’ve picked up is changing the way scientists think about the Red Planet.
This is the first time humanity has ever been able to listen to the din of another world.
"We've all seen these beautiful images that we get from Mars," said Nina Lanza, a Los Alamos National Laboratory scientist, in a NASA video, "but having sound to be able to add to those images, it makes me feel like I'm almost right there on the surface."
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NASA shared Martian audio in the above post on X.
Researchers published the first study of acoustics on Mars in the journal Nature, based on Perseverance's recordings, in 2022. Apparently, the Red Planet is a much quieter place than originally thought, and not just because it's unpopulated.
It’s so silent, in fact, there was a time the rover team believed the mics had stopped working. But Perseverance just wasn't getting much material from its surroundings. That's largely due to Mars' low-atmospheric pressure, though the pressure can vary with the seasons.
The team studying these sounds found that Mars' thin air, composed mostly of carbon dioxide, makes sound waves behave differently. On Earth, sound travels at roughly 767 mph. On Mars, deeper pitches move at about 537 mph, with higher ones traveling a bit faster, at 559 mph.
The thin atmosphere also causes sound to drop off quickly. A sound that could be heard from 200 feet away on Earth falls silent after 30 feet on Mars. Higher-pitched tones have an even shorter range.
"Sounds on Earth have very rich harmonics. You can hear multiple frequencies. It gets a really nice depth to the sound," said Justin Maki, a NASA scientist, in a video. "On Mars, the atmosphere attenuates a lot of those higher frequencies. So you tend to hear the lower frequencies, and it's a much more isolated sound, a little more muted than the sounds we hear on Earth."
With this data, scientists have learned that some of their earlier models for how they thought sound should move on Mars missed the mark.
"The Martian atmosphere can propagate sound a lot further than we thought it could," Lanza said.
Translation: The Red Planet can literally carry a tune.
