Scientists have tracked 1,039 dust devils - tornado-like whirlwinds that skitter across the Red Planet. To do this, the team stitched together two decades of images from the European Space Agency's (ESA's) Mars Express and ExoMars Trace Gas Orbiter.
By following how these twisting columns move, the team produced the first catalog that records both where and how fast dust devils travel. The new dataset offers a fresh, planet-wide view of Martian winds and how dust takes flight.
On Mars, dust is the climate. Airborne particles dim sunlight by day, trap heat by night, seed clouds, and - even in regional or global storms - can loft water vapor high enough to escape into space.
Because there's no rain to scrub the air, dust lingers and circulates around the globe. Understanding when, where, and how dust is lifted from the surface is key to decoding Martian weather.
It's also essential for planning missions, since solar panels, cameras, and radiators all suffer when dust settles.
Led by Valentin Bickel at the University of Bern, the team trained a neural network to spot dust devils in vast archives of orbital images.
They used Mars Express data dating back to 2004 and ExoMars TGO images captured since 2016.
The resulting public catalog pinpoints 1,039 dust devil events and measures direction and speed for 373 of them.
The map shows that dust devils can form almost anywhere - from crater floors to the flanks of giant volcanoes.
But they're especially common in certain "source regions," such as the fine-grained plains of Amazonis Planitia.
By tracking how far each whirlwind drifted between successive image channels, the researchers clocked surface winds up to 44 meters per second (about 158 miles per hour).
That's swifter than in situ rover measurements and, in many places, faster than current Mars weather models predict.
The thin Martian air means those gale-force numbers don't pack the same punch they would on Earth - but they do matter for dust lifting.
Stronger than expected winds hint that more material may be getting lofted into the atmosphere than models currently account for.
Just like on Earth, dust devils on Mars keep a seasonal and daily schedule. They're most common in spring and summer in each hemisphere, when surface heating is strongest.
Activity tends to peak from late morning to early afternoon - roughly 11:00 to 14:00 local solar time.
Most whirlwinds last only minutes, but their collective effect adds up, constantly feeding the atmosphere with fresh, fine dust.
Neither Mars Express nor TGO was built to measure wind. The clever trick here exploits how their cameras build images. Each picture is assembled from multiple narrow "channels" taken in quick succession - different colors and, in some cases, slightly different viewing angles.
If the ground is still, the channels line up perfectly. If something moves - say, a dust devil or cloud - tiny offsets appear between channels. Those offsets, usually a nuisance, become a ruler.
On Mars Express, the delay between channels is 7 to 19 seconds, enough to watch a dust devil creep across the terrain and even detect small wobbles in its path.
On TGO, paired views taken one second apart for color and 46 seconds apart for stereo let scientists track longer displacements, trading fine detail for reach.
Folding these wind measurements into global circulation models should sharpen forecasts of when and where dust is likely to lift - and how it moves once airborne.
That's not just academic. Knowing the prevailing winds at candidate landing sites helps engineers plan for local conditions.
The research shows how often solar-powered rovers may need to self-clean, how dust could abrade optics and radiators, and how parachutes and backshells will perform in the thin, gusty air.
ESA's Rosalind Franklin rover, slated to land in 2030, is already being scheduled to avoid the peak global dust storm season.
The catalog is public and growing as both orbiters continue to image the surface. Now that researchers know the hotspots and the hours when dust devils favor certain terrains, they can aim more observations exactly when and where they're likely to appear.
Coordinated campaigns - capturing the same dust devil at the same time with different instruments - will give scientists powerful new comparisons. They'll be able to cross-check speeds, validate methods, and study how these whirlwinds change with terrain, season, and time of day.
"Dust devils make the normally invisible wind visible," Bickel said. With this work, scientists have turned those fleeting signatures from curiosities in rover albums into data points woven into a global tapestry.
From climate models to landing plans, from solar-panel maintenance to cloud formation, Mars' smallest storms are telling us how the whole system breathes.
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