A single asteroid impact may explain the appearance of Mars' moon Deimos

A single asteroid impact may explain the appearance of Mars' moon Deimos. The study, led by Dr. Sabina Raducan, used high-resolution computer simulations to show that the distinctive depression near Deimos's south pole was most likely formed by a single, non-destructive asteroid impact. The impact is also believed to have created the regolith layer present on Deimos. The research team used the Bern SPH code, which simulates collisions between asteroids, comets or planets, to model the impact. The simulation showed that a 320-meter diameter asteroid striking at a 45-degree angle caused the observed depression and surface structure. The impact also redistributed material globally, covering many surface features to a depth of more than 200 meters. The study is the first scientific publication to use data from the flyby of Deimos by the ESA space probe Hera.

• The study used the Bern SPH code, developed at the University of Bern over two decades.
• The code simulates collisions between asteroids, comets or planets.
• The researchers varied the size, velocity and impact angle of the potential impactor, as well as the internal structure of Deimos.
• The simulation showed that a single impact was sufficient to decisively shape the current landscape of Deimos.
• The impact was violent enough to redistribute material globally, but not so strong that it would have shattered the moon.
• The comparison between the model and observations shows that the uppermost layers of Deimos are exceptionally weak and that its internal structure is highly porous.

The study provides important predictions for the Japanese space mission, such as the thickness and distribution of the regolith layer and the mechanical properties of Deimos's material. These predictions can be tested by future space missions, including the Japanese Martian Moons eXploration (MMX) mission, which is scheduled to launch in 2026. The MMX mission's goal is to observe the two Martian moons in detail and bring samples from Phobos back to Earth. The study offers a unified explanation for both features of Deimos and provides practical predictions that can be tested by future space missions.

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