The Perseverance rover carries two microphones. One is part of a special camera on the rover's mast called SuperCam that examines rocks and soils with a camera, laser and spectrometer. A powerful infrared laser zaps a rock, heating it to 18,000° F (10,000° C), hot enough to turn it into vapor. The spectrometer analyses the vapor to determine the chemical makeup of the rock. The microphone will record the popping sound of each laser zap to get more information on the mass, hardness and type of rock.
The other microphone is mounted on the side of the rover and recorded the sounds of the entry, descent and landing. When synched with the video made at the same time, we'll soon be able to experience both the sights and sounds of the landing in a very visceral way. Can't wait!
Despite the fact that Mars's atmosphere is 100 times less dense than that on Earth and composed primarily of carbon dioxide, it's nice to know you'd still sound pretty much like yourself if you could carry on a conversation there. But there are fascinating differences. For instance, you'd have to wait slightly longer for sounds to arrive in your ear, and voices would be quieter and more muffled. Probably the biggest difference is that high-pitch sounds like birdsong, bells and squeaky doors would be nearly inaudible.
Sounds are made when air molecules vibrate and generate waves in the air much like a stone tossed in a pond creates a series of expanding waves. The whistle of a tea kettle makes the air vibrate, and those vibrations are transmitted to your eardrum. Tiny hairs on the eardrum's surface quiver in response and send signals to your brain that help you identify the source of the sound.
Most familiar sounds travel through air but sound also travels through liquids and solids. And it does it faster and better. The next time you're at the beach put your head against the sand and listen to the footfalls of people walking. You'll be surprised at how far away you can hear them coming.
What makes Mars sound different?
Three things affect sound quality and speed on Mars — temperature, density of the air and its composition. In cold temperatures sound takes slightly longer to reach your ear. With an average temperature around -81° F (-63° C), sound on Mars travels more slowly, around 540 mph (870 kph) compared to 760 mph (1220 kph) on the Earth. Up close you wouldn't notice the delay but you would over a distance.
Say you hollered to someone about 300 feet (100 m) away. On Mars it would take the sound of your voice about a second longer to reach their ears compared to Earth. Heat makes air molecules move around faster, so they're pre-primed to carry a pressure wave compared to colder air.
The fact that there's so little air on Mars also affects how sounds waves travel from a source to your ears. Sounds are a lot softer in thin air, so you'd have to be much closer to the source to hear that sound with the same volume as you would on Earth. In other words, you'd have to whisper louder.
Finally, the atmosphere of Mars is 95.3 percent carbon dioxide, very different from the air we breathe, which is rich in nitrogen and oxygen. Martian oxygen and nitrogen long ago combined with its surface rocks, leaving CO2 as the primary atmospheric gas. Carbon dioxide absorbs a lot of higher-pitch sounds, so only low-pitched sounds would travel longer distances. The effect would be increasingly noticeable the farther you got from the source.
Knowing that sounds are different at the Red Planet, NASA created a fun way to compare them using familiar examples like birds and backup beepers. But the best part is hearing your own voice. Go to the Sounds of Mars Experience. There you have three choices: listen to a variety of Earth sounds as you'd hear them on Mars, listen to a short list of sounds from Mars or record your voice through a Mars "filter".
On Mars we'd all sound pretty muffled, as if talking from under a blanket... or, dare I say, a mask?
"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.