Mars comes out of its silence

the first Martian audio recordings They reveal a quiet planet, where sound rotates slowly and at two different speeds, according to a paper published in Nature on Friday.

surprise Acoustic landscape of the red planet Little by little they are revealed by the microphones of the perseverance robot, which has been circling for just over a year on its surface.

The first sounds were recorded as soon as the rover started moving. Under the loud sound of the vehicle, a gust of wind could be clearly seen.

The lead author of the study published in Nature, Sylvester Morris, co-author of the SuperCam installed on the robot, confirmed that analyzes show a hitherto unknown disorder.

But the red planet had more significant surprises in store, such as the fact that the frequency of high-pitched sounds and the frequency of low-pitched sounds travel at different speeds.

Morris’ team used recordings from a small creativity chopper, which accompanies perseverance, and acoustic results from laser fire on the rocks to examine their chemical composition.

With this special instrument, which emits a kind of “clack clack,” “we had a very local sound source, two and five meters from its target, and we knew exactly when it was going to fire,” the researcher explained.

The results confirmed for the first time that the speed of sound is slower on Mars, at 240 meters per second, compared to 340 meters on Earth.

As expected, Mars’ atmosphere contains 95% of carbon dioxide, compared to 0.04% on Earth. The study said that the Martian atmosphere causes a muted sound of about 20 decibels relative to our planet.

But the surprise came when measuring the sound of the laser: 250 meters per second.

– ‘Panic’ –

“I panicked a little,” the expert explained. “I said to myself: One of those two measurements is wrong, because on Earth, near the surface, sound has only one velocity.”

But the results have been repeatedly confirmed: three times the speed of a laser has one speed, and the bass of a helicopter has another.

Commenting on the article, Morris explained that the treble gets lost very quickly, even at close range. This means that “a conversation between two people will be difficult, even from five meters away.”

On the floor, the sounds of the orchestra reach you at the same time, both low and high. On Mars, if you are a little further from the scene (…) the delay can be enormous.”

In particular, the analysis of turbulence sounds, such as vertical winds known as “convective plumes”, explained Thierry Foucher, from the Paris Observatory, would allow “in particular to fine-tune our digital models for climate prediction and meteorology”. studio.

Venus and Titan could be the next candidates for sound examinations using microphones such as those used on Mars.

*** mjpr ***