Thanks to scientists, years of research, and space exploration, we continuously discover new facts about the cosmic space and planets beyond Earth. For example, in 2013, NASA’s Curiosity Rover found evidence of an ancient streambed on Mars. The following year, rock material collected from the red planet revealed organic chemistry on the planet.
Fast forward to April 2022 and scientists have another discovery regarding the solar system’s red planet, and this time, it’s about sound. NASA’s Perseverance Rover landed on Mars in February 2021. During its exploration, the planetary rover collected audio recordings using two microphones. The first microphone was placed on the head of the rover’s mast, while the second mic was located on its chassis.
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A team of international scientists led by University of Toulouse astrophysicist Sylvestre Maurice, the study’s primary author, evaluated the red planet’s acoustics for the first time.
What kind of sound is there on Mars?
The study, published in the international journal Nature, reveals that Mars is a planet of silence, with the occasional sound of light gusts of wind. “At some point, we thought the microphone was broken; it was so quiet,” Maurice expresses.
However, the team also noticed that in the five-hour audio recording, the sounds of the rover’s mini helicopter blades could also be heard.
Despite the prevalence of silence on the red planet, the minimal sounds the rover captured prove a new groundbreaking characteristic of the Martian atmosphere: that there are two speeds of sound on Mars.
Contrary to the Earth, where sound travels at 767 mph (343 meters per second), low-pitched sounds such as the whirring of helicopter rotors travel on Mars at 537 mph (240 meters per second), whereas high-pitched sounds like lasers travel at 559 mph (250 meters per second).
Based on these findings, sound travels slower on the red planet, but the speed varies depending on pitch or frequency. The slower sound speed is possible on Mars because the planet’s atmosphere is 95 percent carbon dioxide.
It’s also thanks to the low atmospheric pressure that the planet is practically noiseless, according to co-author of the study, Baptiste Chide of Los Alamos National Laboratory. However, as the seasons on the red planet change, so does the pressure. So there is a chance that the acoustics on the planet could be different as the season progresses.
the red planet’s thin, cold atmosphere also affects how far the sound is carried. Sound on Mars can only carry a short distance, already faltering at around 8 meters (26 feet), whereas high-pitched sounds are already gone. Sound on Earth usually wavers at 65 meters (213 feet.)
Before the mission, scientists had expectations about the planet’s atmosphere affecting acoustics. However, these recordings are the first evidence and observation that backs up the phenomenon.
How do the two different sound speeds make an impact compared to Earth’s usual sound speed? To visualize its effect, two people on Mars who are only 5 meters apart would have a hard time trying to have a conversation.
Earth sounds on Mars
NASA’s 2020 Perseverance Mission is focused on exploring the red planet’s astrobiology. With the help of the rover, scientists can characterize and study the red planet’s geology with the hope of future human exploration.
With the efforts of NASA’s mission, they’ve compiled the sounds captured on the Mars Perseverance rover into the official Mars Playlist. Here, you can listen to the first sounds of Mars’ wind, laser zaps, and more.
For further understanding of the acoustic differences between Earth and Mars, NASA also provides an Earth Playlist, which showcases what the usual sounds on Earth would sound like on Mars with the differences in sound speeds.