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A giant dust whirlwind passed just above 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 vortices, are common on Mars and part of weather patterns on the red planet.
Other missions have collected images, weather data, and dust measurements of these events, and NASA’s InSight lander has even recorded seismic and magnetic signals created by the dust devils. But sound has been the missing element, until now.
When the Perseverance rover landed on Mars in February 2021, it became the first mission to carry microphones on a journey to the red planet.
The robotic explorer’s SuperCam microphone just fired up and recorded on Sept. 27, 2021, when a heck of dust passed directly over the rover, according to a new study published Tuesday in the journal Nature Communications.
During an 11-second clip captured by the microphone, there are two periods of low-frequency wind as the front and rear walls of the dust devil pass over the rover, said lead study author Dr Naomi Murdoch. researcher at the University of Toulouse’s Higher Institute of Aeronautics and Space.
There is a quiet period between the vortex walls when the rover was in the eye of the vortex, Murdoch said.
Crackles and hisses can be heard during the event, determined to be specks of dust hitting the rover.
The researchers were able to count the particles in the dust devil as they hit the rover, leading to an entirely new type of measurement on the red planet, Murdoch said. It is the first time that an instrument has been able to quantify the dust stacked on Mars.
Images and other data sent by the rover also confirmed what happened. When the researchers put together all the items collected by the rover, they determined that the dust devil reached more than 118 meters in height and spanned 25 meters in width, about 10 times larger than the rover itself. While this sounds like a massive whirlwind, it’s the average size of Martian dust devils, Murdoch said.
The researchers were surprised to find that the dust accumulated inside the dust devil, rather than simply being transported inside the outer walls, possible because the dust devil may still be forming as it moved about Perseverance.
Dust devils serve as indicators of turbulence in the atmosphere on Mars and play an important role in the Martian dust cycle.
Learning more about how dust kicks up and moves on the Red Planet — a key feature of its climate and climate since dust is its primary feature — may help scientists better understand storm formation and evolution. of sand.
A planet-encircling dust storm is what ended the Opportunity rover’s 15-year mission in 2018.
“Global dust storms are important to understanding the Martian climate,” Murdoch said. “Acoustic measurements of impacts and dust uplift will therefore improve our understanding of dust devils and also help improve Martian climate models. Understanding dust lift is also critical for space missions due to the damage it can cause to hardware.”
Perseverance’s wind sensors have already been damaged by airborne dust particles possibly carried by the wind or a dust devil, Murdoch said.
Dust devils have a reputation for being both helpful and harmful on Mars.
The InSight lander’s mission is expected to conclude this month after spending four years studying earthquakes and other phenomena on the red planet. Layers of dust built up on its solar panels and prevented the spacecraft from gathering enough energy to continue operating its instruments.
Dust devils occur frequently in Jezero Crater, where Perseverance landed, but they appear to be absent at InSight’s home on the flat plain of Elysium Planitia and researchers aren’t sure why.
“In the case of InSight, the dust settled from the atmosphere onto the solar panels. However, since there are no tornadoes capable of kicking up dust in the InSight region, the tornadoes are unable to “clean” the solar arrays.”
Other missions to Mars have actually benefited from regular cleanings by dust devils, which acted as a vacuum cleaner for the dust collected on the solar-powered Spirit and Opportunity rovers and provided them with longer-than-expected lifespans.
The Higher Institute of Aeronautics and Space of the University of Toulouse, known as ISAE-SUPAERO, built the microphone that sits on Perseverance. Every month, Murdoch and his team collect eight recordings of approximately 167 seconds each.
“We estimate that a single microphone observation in the midday period (the time of day when there is most dust devil activity) has only a 1 in 200 chance of registering a dust devil like the one we encountered,” he said Murdoch. “We were definitely lucky, but we also carefully targeted the instrument observations to increase the chances of success.”
More microphone recordings could catch more dust devils, and Murdoch’s team is using acoustic recordings to measure atmospheric turbulence to determine its extent to Mars.
The SuperCam microphone was originally included to listen to how instruments on the rover zap rocks to determine their properties, but its acoustic data is also shedding light on the possibilities of 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, at ISAE-SUPAERO, we are developing the next generation of acoustic sensors that will be sent to other planetary bodies with an atmosphere in the future,” she said.
