Throughout the year on Mars, an equally colorful and ephemeral phenomenon occurs: immense swirls of dust that form around low-pressure airbags, which measure about a kilometer high and have such a large diameter that they are visible From space. They are known as “dust devils,” one of the greatest dangers for missions operating on the surface of the red planet. Although they are not very fast – their speed is between 30 and 50 kilometers per hour – they are able to inject that dust from the soil into the Martian atmosphere and modify their behavior.
Despite being quite common, they barely extend in time, which makes it very difficult to take a snapshot of the moment. However, the HiRISE camera, on board the Mars Reconnaissance Orbiter, has succeeded. An amazing image of a devil of Martian dust that formed on the volcanic plains of Amazonis Planitia. The bright tornado is approximately 50 meters wide and its shadow can be seen behind. Based on these parameters, astronomers calculate that the column of rotating dust rises to about 650 meters in the atmosphere.
It is not the first time that HiRISE manages to capture one of these devils from the dust. In fact, in 2012 he was able to capture in the same place another column of dust that rose up to 20 kilometers high.
How do these dust devils form?
Dust devils on Mars are formed similarly to their counterparts on Earth: as sunlight warms the soil of the red planet during the day, the hot air rises, creating a rising current.
Under certain conditions, this updraft begins to spin, causing a vertical vortex. The differences in atmospheric pressure create a suction effect, lifting any loose material from the surface. On Mars, this loose material is dust. When a dust devil moves over the Martian surface, it raises a thin layer of light-colored sand from the ground, exposing the darkest underlying material. These narrow dark tracks mark the paths taken by the dust devils.
In their wake, these eddies leave trails on the Martian surface that can be several hundred meters wide and several kilometers long. They tend to form in the afternoon on warm spring and summer days, when the surface is illuminated by sunlight for longer and, therefore, heats up more. However, dust devils have also been observed during the winter months. .