The immense dusty expanse of Mars preserves the scars of exceptional space events.
A recent study published in
Nature Communications reveals how falling meteors can trigger spectacular landslides, drawing long dark streaks on the sides of volcanoes. These observations, made possible by the ExoMars probe, are changing our perception of the surface dynamics of the red planet.
The rarity of these events provides a comparison element against the classic surface weathering mechanisms of Mars. While wind constantly sculpts Martian landscapes, a meteor impact represents a sudden and localized disturbance. The analysis of millions of these streaks reveals that less than 0.1% of them result from these cosmic collisions, making each occurrence valuable data for planetary scientists.
A) New cluster of craters in Elysium that triggered more than 100 dark streaks, observed by CaSSIS (higher resolution than CTX).
B) Impact-triggered streaks in Amazonis, seen by CTX.
C) Similar case in Arabia.
D) Impact and streaks observed in Tharsis; crater marked with white dot, downward slope with white arrow.
E) Evolution of the number of streaks in zone D between 2010 and 2022; decrease after the impact, linked to fading and less favorable imaging conditions. The mechanism of a geological transformation
The collision of a meteoroid with the Martian surface generates a shock wave capable of destabilizing the upper dust layers. This released energy causes material detachment on slopes sometimes very distant from the impact point. Images from the ExoMars probe thus show hundreds of streaks radiating from an impact crater cluster identified near Apollinaris Mons.
The event documented during the Christmas period of 2023 perfectly illustrates this process. The discolored area covers approximately nine square kilometers (about 3.5 square miles), forming a pattern of dark striations. Researchers determined that the impact occurred between 2013 and 2017, demonstrating the persistence of these geological signatures over several Martian years.
Mars' thin atmosphere explains the relative frequency of these impacts. With a density less than 1% of Earth's, it offers little protection against cosmic projectiles. This particularity makes the red planet a natural laboratory for studying impact craters and their secondary effects on the environment.
Mapping a planetary phenomenon
Valentin Bickel's team developed an innovative methodology to inventory these ephemeral formations. Algorithmic analysis of more than two million images enabled the creation of a comprehensive catalog of Martian streaks. This monumental work identified five main areas where these phenomena are concentrated between 2006 and 2024.
The distribution of these streaks follows precise seasonal and geographical patterns. Researchers confirm that wind and dust dynamics remain the main drivers in the overwhelming majority of cases. In
Nature Communications, they emphasize that meteor impacts and seismic activity represent marginal triggers on a global scale.
The ExoMars Trace Gas Orbiter mission plays a crucial role in this continuous monitoring. Its CaSSIS instrument provides stereoscopic images that allow reconstruction of the topography of affected sites. These systematic observations are part of the broader goal of understanding Mars' recent geological evolution.
Article author: Cédric DEPOND