Strong winds on Mars can kick up huge columns of dust that are visible in satellite images. Analyzes of such recordings now show that wind speeds on our neighboring planet can reach up to 160 kilometers per hour and are therefore significantly faster than previously assumed. The results can help create more accurate climate and weather models of Mars and tailor future Mars missions accordingly.
Although Mars only has a very thin atmosphere consisting primarily of carbon dioxide, temperature differences cause strong winds to arise in this gas envelope. While these winds remain invisible even on satellite images, the dust they stir up can be clearly seen. These also include so-called dust devils, i.e. rotating columns of dust and CO2 that whirl across the surface of Mars at high speed.
Seasonal and daily fluctuations
A team led by Valentin Bickel from the University of Bern has now tracked such dust devils using satellite images of the surface of Mars and thereby gained new insights into the atmospheric dynamics of our neighboring planet. The researchers used images from the Mars camera CaSSIS (Colour and Stereo Surface Imaging System) on the Mars probe Trace Gas Orbiter and HRSC (High Resolution Stereo Camera) on board the Mars Express probe. They analyzed the recordings from 2004 to 2024 using machine learning.
In this way, Bickel and his colleagues identified over 1,000 dust devils. “Our data suggests that dust devils form on both flat and rugged terrain, for example in the flat plains of the northern hemisphere of Mars and in the mountains of the southern hemisphere,” the authors report. About two-thirds of all observed dust devils occurred in the northern hemisphere. The dusty gusts of wind most often developed at midday, when the temperature differences were greatest. During the year they occurred most frequently in spring and summer.
Stormier than expected
The research team also used stereo images to analyze the direction and speed at which 373 dust devils moved. “Stereo images are images of the same place on the surface of Mars, but taken a few seconds apart,” explains Bickel’s colleague Nicolas Thomas. “These images can therefore be used to measure the movement of dust devils.”
It was shown that the fastest dust devils race across the Red Planet at a speed of up to 44 meters per second, or around 160 kilometers per hour. Previous measurements came to a maximum of 100 kilometers per hour. “Our observations show that strong near-surface winds are common on Mars and play an important role in the formation of atmospheric dust, which has a direct impact on more accurate models of the Martian atmosphere, weather and climate,” the researchers report.
Important for future Mars missions
Due to the low gravity of our neighboring planet, mini-tornadoes can reach heights of several kilometers. In addition, it takes much longer for the particles thrown into the air to sink back to the ground. Once in the atmosphere, these swirled dust particles can influence the climate: During the day, they block the sun, so that the Martian surface heats up less. At night, however, they act like a blanket and prevent heat from escaping into space. The findings are therefore important for refining climate models of Mars.
The results can also help in planning future Mars missions: “Information about wind speeds and directions is very important for planning the arrival of future landers and rovers on Mars,” says Bickel. “Our measurements could help scientists develop an understanding of wind conditions at a landing site before a probe touches down.” This makes it possible, among other things, to estimate how much dust could be deposited on a rover’s solar panels – important information for energy supply. In addition, the landings can be planned so that they do not take place during the peak hurricane season.
Source: Valentin Bickel (University of Bern, Switzerland) et al., Science Advances, doi: 10.1126/sciadv.adw5170