The atmosphere of Mars influences sound, causing the high and low frequencies to travel at different speeds.
The first audio recordings from Mars reveal a quiet planet, where sound circulates slowly and at two different speeds.
According to an article published in Nature, the surprising acoustic landscape of the red planet is gradually being revealed by the microphones of the Perseverance robot , which has been circulating for just over a year on its surface.
The first sounds were recorded as soon as the rover started walking. Beneath the raucous sound of the vehicle, a gust of wind could be clearly perceived.
The main author of the study, Sylvestre Maurice, co-responsible for the SuperCam installed on the robot, assures that the analyzes show turbulence that was unknown until now.
But the red planet had more important surprises in store, such as the fact that the frequency of high-pitched sounds and that of low-pitched sounds travel at different speeds.
Maurice’s team used records from the small Ingenuity helicopter , which accompanies the Perseverance , and aural results from laser fire at rocks to probe their chemical composition.
With this particular instrument, which emits a kind of “clack clack”, “we had a very localized sound source, between two and five meters away from its target, and we knew exactly when it was going to fire,” explained the researcher.
The results confirmed for the first time that the speed of sound is slower on Mars , at 240 m per second, compared to 340 m on Earth.
It was predictable, since the atmosphere of Mars contains 95% carbon dioxide, compared to 0.04% on Earth. Mars ‘ atmosphere causes sound to be muffled, on the order of about 20 decibels, relative to our planet, the study said.
But the surprise came when measuring the sound of the laser: 250 m per second.
‘Panic’
“I panicked a bit,” the expert explained. “I told myself: one of the two measurements is false, because on Earth, near the surface, sound only has one speed.”
But the results were confirmed over and over again: the treble of the laser has one speed, the bass of the helicopter blades another.
“The treble is lost very quickly, even at close range,” explained Maurice. That implies that “a conversation between two people would be difficult, even five meters away,” explained the French National Center for Scientific Research in commenting on the article.
“On Earth, the sounds of an orchestra come to you at the same time, whether they’re low or high. On Mars, if you’re a bit far from the scene…the gap can be phenomenal.”
The analysis of the sounds of turbulence, such as vertical winds known as “convection plumes” will in particular allow “fine tuning our digital models for climate and meteorology prediction”, explained Thierry Fouchet, from the Paris Observatory, another of the authors. of the studio.
Venus and Titan could be the next candidates for sound investigations using microphones like those used on Mars .