Dozens of dust devils hidden in plain sight

The European Space Agency’s Mars Express has captured part of Mars’s Mamers Valles: a fascinating valley system speckled with brief, tornado-like whirlwinds known as dust devils. The institutional report frames the development in practical terms and ties it to the broader mission or observing effort.

That matters because astronomy does not advance on single detections. The field builds confidence by accumulating independent observations across different wavelengths, instruments and epochs until isolated signals become defensible conclusions. What looks convincing in one dataset can dissolve when a second instrument looks at the same target, and what looks marginal can solidify when follow-up campaigns confirm the original reading. The current standard requires that a result survive this triangulation before the community treats it as settled. Dust devils form as parts of Mars warm in the Sun, causing the air just above the surface to swirl upwards and carry dust with it as it goes. To form a single image using its High Resolution Stereo Camera, the instrument responsible for these new snapshots, the spacecraft combines sequential views from up to nine.

In this new set of images, Mars Express captures not one but dozens of active dust devils. Click on the image below to see more than 30 circled, each visible as a small yellow dot with a pinkish trailing ‘shadow’.

The alignment and combination of Mars Express’s various camera channels also allows us to figure out the direction and speed of Mars’s dust devils. This is something that scientists have done using data from both Mars Express and ESA’s ExoMars Trace Gas Orbiter, revealing how more than 1000 of these tornado-like storms move.

The feature was named in 1976 based on the ancient Oscan language of pre-Roman Italy, with ‘Mamers’ meaning ‘Mars’ and ‘Valles’ meaning ‘Valley’. Although water ice isn't stable on Mars's surface today, it has managed to survive here because it was covered by rocky material, which has stopped it from escaping to the martian.

What gives the story weight is not just the object itself, but the way the measurement trims the range of plausible physical explanations. Astronomy has accumulated enough cases to know that the most interesting results are rarely the ones that confirm expectations cleanly; they are the ones that confirm some expectations while complicating others, or that open a parameter space that previous instruments could not reach. The scientific community evaluates these contributions by asking whether the new data constrain a model in a way that older data could not, and whether those constraints survive systematic review.

Mars Express has visited this region of Mars before, imaging the areas surrounding both Mamers Valles (2008) and the neighbouring Deuteronilus Mensae (2019). This era is a significant one, as it marks when Mars began to transition from a warmer, wetter, more geologically active world to the cold, arid one we see today.

Because the account originates with ESA Space Science, it functions best as a primary institutional report that is close to the data and operations, not as independent scientific validation. Institutional communications are produced by organizations with legitimate interests in presenting their work in a favorable light, which does not make them unreliable but does make them partial. Details that complicate the narrative, including instrument limitations, unexpected failures and results below projections, tend to be minimized relative to progress messages. Technical documentation and peer-reviewed publications, where they exist, provide the complementary layer that institutional releases cannot substitute.

The next step is to see whether other instruments and other wavelengths tell the same story. Campaigns with JWST, the VLT, the forthcoming Extremely Large Telescopes and radio arrays will provide the spectral coverage and spatial resolution needed to move from detection to physical characterization. The timeline for that kind of confirmation is typically measured in years, not months, which is worth keeping in mind when reading the current result.

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