On Christmas Eve 2023, the European Space Agency (ESA) captured an intriguing image of Mars. This photo, taken by the ExoMars Trace Gas Orbiter, showcases what looks like a series of dark, stripe-like trails on the slopes of Apollinaris Mons, a giant, dormant volcano near Mars’ equator. These stripes mark the paths of dust avalanches triggered by meteoroid impacts.
Although these slope streaks cover less than 0.1% of Mars, they significantly influence the planet’s dust cycle. According to ESA, they collectively move enough dust every Martian year to rival two global dust storms, making them key to understanding the Martian climate.
A recent study led by Valentin Bickel from the University of Bern offers a fresh perspective. It found that fewer than one in a thousand of these streaks are caused by meteoroid impacts. Most are instead the result of seasonal changes in wind and dust activity. Bickel said, “Meteoroid impacts and quakes seem to be locally distinct, yet globally relatively insignificant drivers.”
To reach this conclusion, Bickel analyzed over 2 million slope streaks from around 90,000 images taken by NASA’s Mars Reconnaissance Orbiter (MRO). Utilizing an advanced deep-learning algorithm, he was able to track the formation and movement of these streaks, revealing their connection to seasonal patterns.
The study indicates that the most active streak formations occur during the southern summer and autumn, when strong winds can lift sand-sized particles. Bickel estimates that these streaks contribute to about a quarter of all the dust transferred between Mars’ surface and its atmosphere each year—a figure comparable to what massive dust storms achieve.
Interestingly, the optimal conditions for forming these streaks often happen at sunrise and sunset. However, since Mars orbiters seldom capture images during these times, the real-time creation of streaks remains undocumented.
Bickel’s research also identifies five significant “hotspots” for slope streaks: Amazonis, Olympus Mons aureole, Tharsis, Arabia, and Elysium. These areas have steep slopes, loose dust, and adequate winds—perfect for generating dust movement.
Colin Wilson, the project scientist for the ExoMars Trace Gas Orbiter, noted that these findings could enhance our understanding of Martian processes today. This research adds depth to our knowledge about how Mars is changing now, as opposed to when earlier missions were active.
For a deeper dive into the study and its implications, you can read the detailed findings published in Nature Communications here.
