Thanks to a bit of good luck, the Mars rover Perseverance has captured the first-ever sound of a Martian dust devil.

The NASA rover has witnessed dusty whirlwinds before. But when this one swept right over Perseverance, the rover’s microphone happened to be turned on. So the first-of-its-kind data include the sounds of dust grains either pinging off the microphone or being transmitted to the mic through the rover’s structure, researchers report December 13 in Nature Communications.

Because the rover’s microphone is turned on only occasionally, the team estimates that such events, when they occur, might be recorded just around 0.5 percent of the time.

On September 27, 2021, Perseverance’s navigation camera spotted a dust devil (purplish cloud in the images at top, which were processed to reveal the dust) whirling toward it from 50 to 60 meters away. As the whirlwind swept across the rover, Perseverance’s microphone recorded the sound it made, capturing the first-ever audio of a Martian dust devil (middle), and the rover’s instruments detected a slight drop in atmospheric pressure (bottom). These data may someday help researchers better understand dust dynamics on Mars.

Wind speeds in the walls of the dust devil reached nearly 40 kilometers per hour, planetary scientist Naomi Murdoch of the Institut Supérieur de l’Aéronautique et de l’Espace in Toulouse, France, and colleagues report. As with previous whirlwinds detected by other instruments, this late-morning dust devil caused a slight drop in atmospheric pressure and rise in temperature as it swept over the rover on September 27, 2021. It was 25 meters in diameter, at least 118 meters tall and ambled by at about 20 kilometers per hour.

One big surprise, Murdoch says, is that a prodigious amount of dust was airborne in the calm center of the whirlwind as well as in the brisk winds that formed its walls. Data from this event, as well as from other whirlwinds measured by the rover’s instruments, will help researchers better understand how dust gets lifted off the Martian surface (SN: 10/24/06). As of yet, Murdoch says, that remains a mystery to planetary scientists (SN: 7/14/20).

from Science News https://ift.tt/ghS0e7T
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