The wealth of data that emerged from the encounter has excited scientists, who are well aware of the outsized influence that Martian dust has on the planet’s climate. The fine-grained particles can also damage scientific instruments on Mars landers and rovers, potentially rendering solar panels unusable. Studying the rover’s gritty footage could provide insight into how dust could affect ongoing Mars missions, and perhaps even future human exploration.
The sound of the dust devil, published Tuesday with a paper in the journal Nature Communications, is subtle. It’s creaky and percussive, like radio noise, though you can more generously imagine a breeze blowing some palm fronds in the distance.
Then there’s a few seconds of silence as the dust devil’s eye sweeps over the rover. The sound returns for a few more seconds as the back wall of the dust devil rotates over the rover again. Then it’s all over and Mars is quiet again.
This wasn’t exactly an “extreme weather” event. Mars has an insignificant atmosphere, about 1 percent as dense as Earth’s, so the storms there do not Cry. The rover was not damaged.
Still, there’s a lot of signal in this short dose of noise and in the visual images captured by the SuperCam instrument on top of the rover. Researchers estimate that the dust devil was about 25 meters wide and 118 meters high. That is higher than the Statue of Liberty, including the plinth.
“As the dust devil passed Perseverance, we could hear the individual grain impacts on the rover,” said Naomi Murdoch, a planetary scientist at ISAE-SUPAERO, an aerospace engineering institute in Toulouse, France, and the author of the new paper. report. “We could actually count them.”
A dust devil looks a bit like a miniature storm cell. It usually pops up in the middle of the day as hot air spirals up from the surface. A scientist who wants to speak more technically might call this a convective vortex full of dust. The dust is not the cause of the vortex, but just goes with it.
Murdoch said the team’s success in capturing the sound of a dust devil reflected both luck and preparation. The rover’s microphone records just under three minutes, and it does so only eight times a month. But the shots are timed for when dust devils are most likely to be seen, and the rover’s cameras are pointed in the direction where they’re most likely to be seen.
“Then we just have to keep our fingers crossed,” she said.
It clearly worked, as Perseverance managed to capture the dust devil with multiple instruments, recording the drop in air pressure, changes in temperature, the sound of impacting grains, all topped off with images showing the size and shape of the vortex. .
“I can’t think of any 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 after reading the new paper. . He said the team was lucky that all the observations overlapped.
“Had the [camera] pointed in any other direction or the microphone observation was scheduled just a few seconds later, important bits of the story would be missing. Sometimes it helps to be lucky in science!”
Mars rover unearths intriguing clues in the hunt for life beyond Earth
As the Perseverance team cheers on their windy encounter, calm is another problem for another NASA robotic craft on Mars. The InSight lander, which landed more than 2,000 miles away in November 2018, has instruments to explore seismicity and the planet’s interior.
InSight has lasted a few years beyond the primary mission timeline, but is now in the final weeks of its science life as its solar arrays are 90 percent covered in dust. What it needs is a direct hit from a dust devil, because such vortices are able to clean solar panels.
“A dust devil is like a little vacuum cleaner that walks across the surface,” said Bruce Banerdt, a planetary geophysicist at the NASA Jet Propulsion Laboratory and principal investigator of InSight.
But InSight hasn’t had 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 along at this point,” he said.
Murdoch said this scattered pattern of dust devils appearing on Mars remains mysterious. Planetary scientists also can’t predict when the Red Planet will have a global dust storm, she said, citing “our poor knowledge of exactly how and when dust is lifted off the surface of Mars.”
But that’s changing, she hopes, as the microphone her team developed continues to listen for the sounds of that distant desert planet.