The Perseverance rover has recorded the sound of a sand devil 100 meters high on Mars. Perseverance is the first spacecraft to take a microphone to another planet.
We have heard the sound of a dust devil on Mars for the first time. The rover Perseverance has a whirlwind moving over the rover. These images could help us predict future dust storms on Mars.
On twice a week
Sand devils are whirlwinds that toss the Martian soil into the air for a few minutes before dissipating again. Millions of them move across the planet’s surface every day. Several landers have already noticed them.
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Perseverance itself has so far encountered hundreds of sand devils on the Martian surface. They detected the rover because they let the local atmospheric pressure drop. Although Perseverance has a microphone on board – the first ever sent to another planet – the rover had not yet recorded any sound from the sand devils. That’s because the microphone is only on for a few seconds about twice a week. However, on September 27, 2021, the rover did record the sound of dust particles thrown at it by a devil of sand.
At least 118 meters high
“If you were standing on the surface of Mars, you might see the dust moving towards you, but you probably wouldn’t feel much and hear nothing because of the thin atmosphere,” says Naomi Murdoch, planetary scientist at the University of Toulouse in France. “Sound doesn’t travel very far on Mars, so we know these particles must have landed very close to the microphone.”
By combining the audio recordings made with data from Perseverance’s other sensors, Murdoch and her team were able to calculate that the sand devil was about 25 meters in diameter. It must have been at least 118 meters high.
Unexpected dust cloud
The researchers measured an average of sixty impacts of dust particles per second. That is similar to what other teams have measured in terrestrial sand deluges.
Oddly enough, those impacts did come in three short bursts. You would expect the dust particles to be mainly in the walls of the whirlwind. Then a passing hail would trigger two outbursts. Images of the sand devil showed an unexpected cloud of dust in the middle of the whirlwind. The researchers do not yet know what caused it.
Predict bigger storms
“One of the biggest problems scientists have with modeling the Martian climate is predicting major dust storms,” says Murdoch. “One of the reasons we fail to model it is that we don’t fully understand when, why and how dust is thrown into the atmosphere.” Sand devils lift dust into the air on a smaller scale, so studying them can help us understand and even predict larger storms on Mars.