by The treasure trove of data from the meeting has thrilled the scientists, who are acutely aware of the enormous influence Martian dust has on the planet’s climate. The fine-grained particles can also damage scientific instruments on Martian landers and rovers and potentially cover solar arrays to the point of rendering them useless. Studying the rover’s gritty recordings may provide insight into how the dust could affect ongoing Mars missions and perhaps even future human exploration.
The sound of the dust devil, released Tuesday to accompany an article in the journal Nature Communications, is subtle. It’s crackling and percussive, like radio static, though one might more generously imagine a breeze ruffling some distant palm fronds.
Then comes a few seconds of silence as the eye of the dust devil passes over the rover. The sound comes back for a couple more seconds as the dust devil drag wall spins on the rover again. Then it’s all over and Mars is quiet again.
This wasn’t exactly an “extreme weather” event. Mars has a bland atmosphere, about 1 percent denser than Earth’s, so storms there don’t howl. The rover suffered no damage.
However, there is a lot of signal in this short dose of noise and in the visual images taken by the SuperCam instrument atop the rover. Researchers estimate the dust devil was about 25 meters (82 feet) wide and 118 meters (387 feet) tall. It is taller than the Statue of Liberty, including the pedestal.
“As the dust devil passed over Perseverance, we could actually feel the individual impacts of the grains on the rover,” said Naomi Murdoch, a planetary scientist at ISAE-SUPAERO, an aerospace engineering institute in Toulouse, France, and an author of the new report. . “We could actually count them.”
A dust devil is a bit like a miniature storm cell. It usually opens during the middle of the day as warm air spirals up from the surface. A scientist who wanted to speak more technically could call it a dust-laden convective vortex. The dust is not the cause of the vortex, but that’s just for the ride.
Murdoch said the team’s success in capturing the sound of a dust devil reflected both luck and preparation. The rover’s microphone records recordings that last just under three minutes, and it does so only eight times a month. But the recordings are timed for when the dust devils are most likely to occur, and the rover’s cameras are pointed in the direction they are most likely to be seen.
“Then we just have to cross our fingers,” he said.
This clearly worked, because Perseverance managed to capture the dust devil through multiple instruments, recording the drop in air pressure, the changes in temperature, the sound of the specks hitting, all peppered with images showing the size and the shape of the vortex.
“I can’t think of a previous case where so much data from so many instruments helped characterize a single dust devil,” John Edward Moores, a planetary scientist at York University, said in an email. reviewed the new article. He said the team was lucky to have all the observations overlapping.
“I had the [camera] pointed in a different direction or the microphone observation was scheduled just seconds later, key pieces of the story would be missing. Sometimes it helps to be lucky in science!”
While the Perseverance team encourages their windy encounter, the calm weather has become a problem for another NASA robotic vehicle on Mars. The InSight lander, which landed more than 2,000 miles away in November 2018, has tools for exploring seismicity and the planet’s interior.
InSight lasted a couple of years past the timeline of its primary mission, but is now in the final weeks of its science life because its solar arrays are 90 percent covered in dust. What he needs is a direct hit from a dust devil, because such vortices are capable of cleaning solar panels.
“A dust devil is like a little vacuum cleaner that glides across the surface,” said Bruce Banerdt, a planetary geophysicist at NASA’s Jet Propulsion Laboratory and InSight principal investigator.
But InSight didn’t get a visit from a devil capable of cleaning its arrays. Banerdt said there is currently enough power to run a seismometer for eight hours, but then it has to rest for three days while the batteries recharge.
“We’re still limping at this point,” he said.
Murdoch said this scattered pattern of dust devils appearing on Mars remains mysterious. Furthermore, planetary scientists cannot predict when the Red Planet will experience a global dust storm, he said, citing “our poor understanding of how and when dust will be kicked up from the surface of Mars.”
But things are changing, she hopes, as the microphone her team developed continues to hear the sounds of that distant desert planet.
