Interplanetary spacecraft have taken hundreds of stunning pictures of the Martian surface over the past 50 years, but not a single sound. All of that has changed thanks to NASA’s Persistence navigator.
A new study, based on recordings made by the Perseverance detector and published in the journal Nature, has found that the speed of sound is slower on Mars than on Earth and the planet. mostly silent.
The team behind the Franco-American Perseverance SuperCam2 instrument is convinced that studying Mars’ sonic landscape can help us better understand the planet. So, the team in Toulouse, France, designed a microphone specifically for Mars exploration to deal with this scientific challenge.
The first sounds from Mars were recorded by Perseverance on February 19, 2021, the day after its arrival. Between 20 Hz and 20 kHz, these sounds fall within the range of human hearing. They demonstrate that Mars is quiet, so quiet that scientists mistakenly believe the microphone is broken on many occasions.
Research shows that other than wind, natural sound sources are rare. In addition, the scientists studied the sounds produced by the rover itself, such as the shock waves caused by the impact of the SuperCam laser on rocks and the flights of Ingenuity helicopters.
They were able to accurately characterize the acoustics of the Martian atmosphere by investigating the Martian propagation of these sounds. Their behavior is well understood on Earth.
The researchers found that the speed of sound on Mars is slower than it is on Earth: 240 m/s compared to 340 m/s on our planet. The most striking discovery is that there are two different speeds of sound on Mars, one for high-pitched noises and one for low frequencies.
On Mars, sound attenuation is stronger than on Earth, especially for high frequencies, unlike low frequencies, which attenuate rapidly even over short distances, the study said.
All these factors will make it difficult for two people standing only 5 meters apart to talk and hear each other.
This is due to the composition of Mars’ atmosphere (96% CO2, compared with 0.04% on Earth) and the extremely low atmospheric surface pressure (170 times that of Earth).
After a year on the mission, a total of five hours of auditory environment recordings were collected.
The sound produced by the turbulence of the Martian atmosphere has become perceptible thanks to an in-depth analysis. Studying this turbulence, on a scale 1,000 times smaller than anything previously known, could help us better understand how Mars’ atmosphere interacts with its surface.
Other robots with microphones could be used in the future to help us better understand the atmospheres of planets.
