For years, we’ve seen images from various Mars rovers and landers of dust devils churning across the dusty landscape of the Red Planet. But now, thanks to a microphone on the Perseverance rover and a whirling dust storm that passed directly over the rover, we know what a dust devil on Mars sounds like, too.
Perseverance is equipped with a microphone on the SuperCam laser-zapping science instrument. When SuperCam blasts a rock, the resulting sounds give scientists clues about the rock’s composition. But one of the most anticipated uses of the microphone was the ability to hear the sounds of Mars itself.
“We can learn a lot more using sound than we can with some of the other tools,” said Roger Wiens, the principal investigator of SuperCam, from Purdue University. “The microphone lets us sample, not quite at the speed of sound, but nearly 100,000 times a second. It helps us get a stronger sense of what Mars is like.”
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Dust devils are by no means a rare event, as it appears the Perseverance rover sees dust devils several times a day. A paper from earlier this year detailed the first 216 days of Perseverance’s mission in Jezero Crater and reported how the newest rover on Mars appears to be located in a “dust storm track” that runs north to south across the planet. Jezero Crater has particularly high levels of dust and wind activity. However, this is the first time the microphone was on when a dust devil passed over the rover.
To save data and power, the microphone is not always on. It records for about three minutes every couple of days. By chance, the SuperCam mic was turned back on September 27, 2021 just as a dust devil hoovered over Perseverance. The audio has about 10 seconds gusty winds – which the researchers estimate at about 40 kph (25 mph) — as well as the pinging of hundreds of dust particles hitting the rover.
Planetary scientist Naomi Murdoch and a team of researchers at the National Higher French Institute of Aeronautics and Space and NASA published their dust devil finding in Nature Communications. They said the dust devil encounter was also simultaneously imaged by the Perseverance rover’s Navigation Camera and observed by several sensors in the Mars Environmental Dynamics Analyzer instrument.
“Combining these unique multi-sensorial data with modelling, we show that the dust devil was around 25?meters large, at least 118?meters tall, and passed directly over the rover traveling at approximately 5?meters per second,” they reported. ?
The sound recording of the dust devil, taken together with air pressure readings and time-lapse photography, help scientists understand the Martian atmosphere and weather.
“We could watch the pressure drop, listen to the wind, then have a little bit of silence that is the eye of the tiny storm, and then hear the wind again and watch the pressure rise,” Wiens said in a press release.
It all happened in a few seconds.
“The wind is fast—about 25 miles per hour, but about what you would see in a dust devil on Earth,” Weins said. “The difference is that the air pressure on Mars is so much lower that the winds, while just as fast, push with about 1% of the pressure the same speed of wind would have back on Earth. It’s not a powerful wind, but clearly enough to loft particles of grit into the air to make a dust devil.”
Since Perseverance is nuclear-powered, the rover team doesn’t have to worry about dust collecting on any solar panels and impacting the mission, like previous rovers such as Spirit and Opportunity. But it appears there is more dust lifting into the air in Jezero Crater.
Meanwhile, about 3,452 km (2,145 miles) away the Mars InSight mission will be shut down soon because dust has covered the solar panels. Researchers have reported a of wind and dust devils in the Elysium Planitia where the InSight lander sits.
“Just like Earth, there is different weather in different areas on Mars,” Wiens said. “Using all of our instruments and tools, especially the microphone, helps us get a concrete sense of what it would be like to be on Mars.”