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A towering dust whirlwind passed over the Perseverance rover as it explored the site of an ancient lake on Mars — and the rover recorded the first sounds of this Martian dust devil using his microphone.
Dust devils, or dust whirlwinds, are common on Mars, and are part of the weather patterns on the Red Planet.
Other missions have collected images, weather data, and dust measurements of these events, and the NASA InSight probe has recorded seismic and magnetic signals created by dust devils. But sound has been the missing ingredient – until now.
When the Perseverance rover touched down on Mars in February 2021, it became the first mission carrying microphones on a trip to the Red Planet.
The robotic explorer’s SuperCam microphone happened to be turned on and recorded on Sept. 27, 2021, when a dust devil passed directly over the rover, according to a new study published Tuesday in the journal Nature. Nature Communications.
During the 11-second clip captured by the microphone, there are two periods of low-frequency winds as the front and back walls of the dust devil pass over the rover, said lead study author Dr. Naomi Murdoch, a researcher at the University of Toulouse. Institute of Aeronautics and Space.
Murdoch said that between the walls of the whirlwind there was a lull when the rover was in the eye of the whirlpool.
Crackling and hissing can be heard during the event, which have been identified as dust grains hitting the rover.
Murdoch said the researchers were able to count the particles in the dust devil when it hit the rover, leading to an entirely new kind of measurement on the Red Planet. It is the first time that an instrument has been able to quantify the amount of dust rising on the surface of Mars.
Images and other data sent back by the rover also confirmed what happened. When the researchers put all the items the rover had collected together, they determined that the dust devil reached more than 387 feet (118 meters) long and 82 feet long (25 meters wide) — about 10 times larger than the rover itself. Murdoch said that while this looks like an enormous whirlwind, it’s about the average size of a Martian dust devil.
The researchers were surprised to discover that dust accumulated inside the dust devil, rather than just being carried inside the outer walls – this is possible because the dust devil may have still been forming as it moved over the perseverance.
Dust devils act as indicators of turbulence in the Martian atmosphere and play an important role in the Martian dust cycle.
Learning more about how dust rises and moves on the Red Planet—a key feature of its weather and climate since dust is the main feature—could help scientists better understand the formation and evolution of dust storms.
What is the dust storm that surrounds the planet? Completed the 15-year rover mission in 2018.
“Global dust storms are important for understanding the Martian climate,” Murdoch said. Thus, acoustic measurements of dust effects and dust uplift will improve our understanding of dust devils and will also help improve Martian climate models. Understanding dust lifting is also critical to space missions due to the damage that can be caused to instrumentation.”
Murdoch said Perseverance’s wind sensors were already being damaged by rising dust particles likely carried by the wind or a dust devil.
Dust devils are known to be both beneficial and harmful on Mars.
The The InSight mission is expected to end this month After spending four years studying earthquakes and other phenomena on the Red Planet. Layers of dust had accumulated on its solar panels and prevented the spacecraft from gathering enough power to continue powering its instruments.
Dust devils occur frequently at Jezero Crater, where Perseverance landed, but appear to be absent at InSight’s home on the flat plain of Elysium Planitia — and the researchers aren’t sure why.
In the case of InSight, dust from the atmosphere has settled onto the solar panels. However, since there are no whirlwinds capable of raising dust in the InSight region, whirlwinds are unable to “clean” the solar panels.”
Other Mars missions have, in fact, benefited from regular cleanings by dust devils, which acted like vacuum cleaners for dust collected on the solar-powered Spirit and Opportunity rover and provided them with a longer-than-expected lifespan.
Higher Institute of Aeronautics and Space of the University of Toulouse, better known as ISAE-SUPAERO, the microphone that sits on the perseverance. Every month, Murdoch and her team gather Eight recordings of 167 seconds each.
“We estimate that observing a single mic in the middle of the day (the time of day when the dust devil is most active) has only a 1 in 200 chance of recording a dust devil like the one we encountered,” Murdoch said. “We definitely got lucky, but we also carefully targeted the tool’s feedback to increase the chances of success.”
More microphone recordings can pick up additional dust devils, and Murdoch’s team is using the audio recordings to measure atmospheric turbulence to determine their extent on Mars.
The SuperCam microphone was originally included for listening as instruments on the rover rocks to characterize them, but its acoustic data also sheds light on the possibilities for atmospheric science on the Red Planet, Murdoch said.
“All of these measurements and analyzes highlight how valuable acoustic data is in planetary exploration. Therefore, in parallel with ISAE-SUPAERO, we are developing the next generation of acoustic sensors that will be transmitted to other planetary bodies in the atmosphere in the future.