Mars Orbiter Captures Unique Avalanche Patterns on Red Planet

On December 24, 2023, the European Space Agency's ExoMars Trace Gas Orbiter captured an extraordinary geological phenomenon on Mars, revealing dark, finger-like trails on the slopes of Apollinaris Mons.

These streaks, reminiscent of a barcode, are the result of dust avalanches triggered by a meteoroid impact, which shook loose fine grains of dust that cascaded down the volcano's flanks. According to ESA, while these features cover less than 0.1% of the Martian surface, they significantly contribute to the planet's dust cycle.

Researchers indicate that collectively, these slope streaks transport as much dust each Martian year as at least two global dust storms, making them crucial to understanding Mars' climate system. A study led by Valentin Bickel from the University of Bern analyzed over two million slope streaks captured in 90,000 images from Mars orbiters, predominantly NASA's Mars Reconnaissance Orbiter, taken between 2006 and 2024.

This analysis revealed that fewer than one in a thousand slope streaks form as a direct result of meteoroid impacts, with most being initiated by seasonal changes in wind and dust activity. Bickel emphasized that meteoroid impacts and quakes are relatively insignificant drivers on a global scale but can have distinct local effects.

His research utilized an improved deep-learning algorithm to examine the full archive of images from the Context Camera on the Mars Reconnaissance Orbiter, allowing for the mapping of global patterns in slope streak formation.

The findings indicate that these streaks predominantly form during the planet's dustiest seasons, particularly southern summer and autumn, when conditions are ripe for moving sand-sized particles. Notably, the most favorable conditions for the formation of these streaks tend to occur at sunrise and sunset, periods during which orbiters rarely capture images.

Bickel's study identified five global hotspots for slope streaks: Amazonis, the Olympus Mons aureole, Tharsis, Arabia, and Elysium, where steep slopes, loose dust, and sufficient wind combine to trigger movement.

Colin Wilson, project scientist for the ExoMars Trace Gas Orbiter, stated that these observations could enhance our understanding of current geological processes on Mars, shedding light on the planet's dynamic surface.