Dozens of tornado-like whirlwinds have been caught moving across the surface of Mars, all at once, in a single set of images from the European Space Agency's Mars Express orbiter. The spacecraft photographed more than 30 active dust devils in a valley system called Mamers Valles, each one appearing as a small yellow dot with a pinkish trailing shadow. These are not rare events on Mars, but seeing so many together in one frame is unusual.
A camera that catches moving targets
Mars Express uses a High Resolution Stereo Camera that combines views from up to nine separate channels, each looking at Mars in a different color or from a different angle. When the surface is still, those views align perfectly. But when something moves, like a dust devil, it stands out clearly against the background. That is how the orbiter spotted these whirlwinds. The same technique also lets scientists calculate the direction and speed of each dust devil. Researchers have used data from Mars Express and ESA's ExoMars Trace Gas Orbiter to track more than 1,000 of these storms and map how winds sweep around the planet.
A vast and broken landscape
Mamers Valles is a labyrinth of canyons and valleys etched into the Martian surface. The name comes from the ancient Oscan language of pre-Roman Italy, where Mamers means Mars and Valles means valley. The channels stretch about 1,000 kilometers, crossing from the planet's ancient southern highlands into the northern lowlands. In some places they measure 25 kilometers wide and 1.2 kilometers deep. Surrounding the channels are steep flat hills called mesas, sheer cliffs, and debris covered glaciers. Those glaciers contain water ice buried beneath rock and dust, and they can be seen building up at the base of steep slopes. All of these features create what scientists call fretted terrain.
Why dust devils matter on Mars
Dust devils form when parts of Mars warm in the Sun, causing air just above the surface to swirl upward and carry dust with it. They are similar to dust devils on Earth but far larger. On Mars they can tower up to eight kilometers high, travel for kilometers at a time, and reach speeds of 45 meters per second. These whirlwinds play a key role in moving dust across the entire planet. Patches of dark material also line some of the valleys in Mamers Valles, likely deposited by these same winds. The images from Mars Express offer a rare look at how dust moves through one of the most rugged regions on Mars.
