A dust storm that covered the Mars Perseverance rover in September 2021 was a massive 119 meters tall, according to an audio recording of the event. This is the first time a dust devil has been recorded on the surface of Mars. The recording also reveals new information about how these short-lived events move dust around on the planet. The new study published in the journal Nature Communications reveals new information about how dust is moved around on Mars. The study was based on a recording of the planet.
According to the lead author of the study, Naomi Murdoch, who is a physicist at the National Higher French Institute of Aeronautics and Space (ISAE-SUPAERO) at the University of Toulouse in France, the recording of the Martian dust devil allows us to hear the noise of particles impacting the rover.
This sound allows researchers to determine how many particles were in the vortex. Murdoch also stated that this is the first time such a measurement has ever been made on Mars. Dust is a common presence on the surface and in the air of Mars. Its movement has a significant impact on the weather and climate of the planet and is in turn influenced by these factors.
Dust Presence in Martian Environment
Understanding the movement of dust is crucial for modeling the Martian climate and for planning missions to the planet. For instance, the wind sensors on the Perseverance rover have been damaged by dust, and the InSight Lander is ending operations because dust has accumulated on its solar panels, reducing the amount of power available for scientific monitoring.
Dust devils are created when warm air near the ground rises and rotates, carrying dust with it. The Jezero crater, where the Perseverance rover is currently exploring, is an area with a high incidence of dust devils. The Mars Environmental Dynamics Analyzer (MEDA) on the rover has recorded at least 91 dust devils near the rover.
However, on September 27, 2021, a dust devil passed directly over the rover, providing an opportunity for MEDA's instruments to gather data during the encounter, as well as for Perseverance's navigation cameras to capture imagery and its SuperCam mic to record the sound of the event. This is the first time that such a measurement has been made on Mars.
Dust Devils and Storms
Using the data from the three different sources, Naomi Murdoch and her team were able to determine that the dust devil was 82 feet (25 m) in diameter, nearly ten times wider than the rover. It was also 390.4 feet tall, about the height of a 40-story building. The storm moved at a speed of 11.8 mph (19 km/h) and had peak winds of 24.8 mph (40 km/h). These measurements provide new insights into the size and strength of Martian dust devils.
However, the Martian atmosphere is much thinner than Earth's, so even though the wind speed may be high, the force of the wind is much smaller due to the low number of particles in the Martian atmosphere. In a typical dust devil, most of the dust is concentrated in the walls of the vortex. Furthermore, in this case, the dust hit the rover in three distinct bursts, consisting of two walls and a cloud of dust in the center of the dust devil. This accumulation of dust in the center of the dust devil is an unusual finding, according to Murdoch.
Currently, researchers do not fully understand how dust is lifted from the surface of Mars, but this is a crucial aspect of modeling both dust devils and dust storms. Murdoch stated that their research has demonstrated that the microphone on the rover can be used to directly observe the process of dust lifting and to determine the conditions under which such lifting occurs. This new information will help improve our understanding of dust movement on Mars.
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