Good news for Martian weather forecasts: the Perseverance rover has managed to record the sound of a huge dust devil, a great first that will help to better understand the climate of the red planet, according to a study published on Tuesday.
Comparable to the whirlwinds of sand sweeping certain deserts on Earth, the whirlwinds of dust called “convective vortices” are a meteorological phenomenon characteristic of Mars, an arid planet with a very sparse atmosphere.
They form when there is a strong temperature difference between the ground and the air, and often cross paths with robotic exploration missions sent by humans. The Jezero crater, where the Perseverance rover has been operating since February 2021, is full of it, but the NASA robot had so far been unable to capture its sound directly.
Luckily, on September 27, a whirlwind 118 meters high passed just above the head of the robot and its SuperCam instrument, equipped with a microphone – the one that had recorded the very first audio from Mars just following its landing. .
The data reaches Earth a few days later. “When we realized that we not only had the images from the camera, the weather sensors and the sound measurement in situ, we said to ourselves that we had hit the jackpot!”, tells AFP Naomi Murdoch, lead author of the study published in Nature Communications.
“We hear the wind associated with the vortex, the moment it arrives, then nothing because we are in the eye of the vortex, then once more when the microphone passes through the second wall”describes this planetary scientist from Isae-Supaéro in Toulouse, where the microphone was designed.
dust storms
And above all, the precise “tac tac tac” of the impacts of the grains, which makes it possible to “count the number of particles” to be able to study the structure of dust and its behavior.
“On Mars, the dust cycle on the surface and in the sky plays a very important role for the climate, much like the water cycle on Earth”underlines Naomi Murdoch.
Analyzing the dust makes it possible to “explore the interactions” between the ground and this extremely fine atmosphere, which was much denser billions of years ago, which allowed the presence of liquid water on the surface, notes Sylvestre Maurice, chief scientist of SuperCam who participated in the study.
This new data might explain how dust is lifted from the Martian surface, something scientists don’t know so far.
“In some regions, whirlpools pass by sucking up the dust, cleaning the solar panels of the robots on the way, details Naomi Murdoch. In others, and we don’t know why, they pass without raising dust: it’s just moving air”. As on the site where the American Insight probe operates, whose solar panels are “covered with dust” for lack of having been able to take advantage of these natural vacuum cleaners.
Clarifying this mechanism may help to model dust devils to better predict them. And, on a larger scale, the great dust storms that can cover the entire planet like that of the science fiction film “Alone on Mars” (2015) whose violence is nevertheless “unrealistic”, according to the scientist.
“We are in the process of refining our weather model. It is important for the maintenance of our vehicles, and for future human exploration missions”, welcomes Sylvestre Maurice.
And the search for extra-terrestrial life? “You might think that studying the Martian climate today is unrelated to the search for traces of life from billions of years ago. But it’s a whole because the history of Mars is is that of an extreme climate change which has made it go from a humid, hot planet (and therefore conducive to the appearance of life, editor’s note) to a completely arid and cold planet”, concludes this astrophysicist.
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