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Milton Keynes (UK), 15 December (talk) Dust storms look a bit like tornadoes, but are weaker and rarely last more than a minute.
It’s a twisting column of warm air racing across the sun-heated ground, visible in the dust it kicks up. While usually benign, occasionally dust storms can be deadly.
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Dust devils have been known to occur on Mars since the 1970s. They can be observed both from the ground and from orbit.
The more dust there is in the Martian atmosphere, the warmer and more agitated it will become, which could escalate into a global dust storm.
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When the dust settles, it can cover and disable the solar panels that are essential to many of the instruments we land on Earth.
There’s still a lot we don’t know about how these demons work. But new research, published this week in the journal Nature Communications, has documented the sound of dust storms — shedding new light on how they operate.
But it also raises questions about how future astronauts will detect and interpret sounds on the Red Planet.
Since the last rivers and lakes disappeared, there has been a lot of erosion on Mars, including the current landing sites for NASA’s Curiosity and Perseverance rovers.
While individual dust storms are minimally erosive, billion-year dust storms can wear away kilometers of rock.
So there are many reasons to want to better understand how dust storms work.
Thanks to a new study led by Naomi Murdoch of the University of Toulouse in France, we now know what Martian dust storms sound like.
Cameras on Mars landers and rovers have captured many dust storms passing by, but Murdoch and her team report that on September 27, 2021, one luckily passed just above the Perseverance rover, which The car is at the bottom of the Jezero crater.
The rover’s masthead camera, called SuperCam, includes a microphone that records the sound of wind heaving as the dust storm passes.
In detail, the wind noise rises when the front wall of the vortex arrives, followed by a calm representing calm air in the eye of the vortex, and then a second wind noise occurs as the trailing wall of the vortex passes.
This took less than ten seconds and you can hear the recording below (volume turned up to maximum).
Other sensors also provide information. They showed that the pressure was minimized between bursts of wind noise—which to me is consistent with sucking rather than blowing—and also documented the effect of individual dust particles on the rover.
The dust storm was about 25 meters in diameter, at least 118 meters high, and moved across the ground at a speed of about 5 meters per second.
The maximum wind speed in the swirling vortex is likely to be just under 11 meters per second, which corresponds to a “fresh” to “strong” breeze on Earth.
Does it really sound like that? Listening to a recording that purports to be Martian wind sounds is all very well, but if we were in it, would we really hear such sounds?
The first thing to note is that this does originate from “real sound”, unlike other data such as images or radio signals turned into sound (a process called sonification), such as the so-called sound of two black holes colliding or from Venus Atmospheric radio noise.
The dust storm audio file contains actual sound waves picked up by microphones on Mars.
The atmosphere there is much thinner than on Earth (the surface pressure on Mars is less than one percent that of ours), so the high-frequency components of sound are barely carried (scientists call this “attenuation”).
The result is a wind that sounds much lower-pitched than similar winds on Earth.
The only other planetary body for which we have actual recordings is Venus, and in 1982 two Soviet “Venera” landers recorded wind and lander operating noises.
However, if you were on Mars, you would never be able to hear the wind directly with your own ears.
If you were stupid enough to expose your ears to the Martian atmosphere, the low external pressure would cause your eardrums to burst, and you would be instantly deaf and unable to breathe air.
If you go outside in a pressurized space suit (a far more sensible idea), what you hear will depend on how well sound waves are transmitted through the helmet’s solid shell, and then on how those sound waves are converted into sound waves in the air inside the helmet .
In other words, you hear a distorted version of what the external microphone picks up. Just imagine walking around the globe and putting your head in a goldfish bowl and you’ll understand part of the idea.
If future human explorers on Mars want to hear what’s going on in the external environment, I suspect they’ll rely on spacesuit-mounted microphones feeding wireless earbuds, although I can’t find any evidence that this has been taken into account on Mars Set design.
It all boils down to the fact that recordings from external microphones are the best way to present sound on Mars or any other planet with an atmosphere.
If you want to hear more from Mars, NASA has a collection of recordings for you to listen to. (conversation)
(This is an unedited and auto-generated story from a Syndicated News feed, the content body may not have been modified or edited by LatestLY staff)
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