Deimos may have been reshaped by a single massive asteroid impact

New research published in Nature Astronomy suggests that a single massive asteroid impact may have reshaped Deimos, one of Mars’ two small moons. Computer simulations led by researchers at the University of Bern indicate that an asteroid approximately 320 meters wide striking at a 45-degree angle could explain both the moon's unusually smooth surface and its large south-polar depression.

The impact likely released enough debris to create a thick layer of regolith, burying ancient craters under as much as 120 to 200 meters of dust and rubble. While the collision was powerful enough to reshape the moon and create a 10-kilometer-wide depression, it was not strong enough to destroy Deimos, potentially due to a fractured, porous interior that absorbed the energy.

These findings contribute to the ongoing scientific debate regarding whether Mars' moons are captured asteroids or debris from ancient Martian impacts. Future space missions, such as JAXA’s Martian Moons eXploration (MMX) mission scheduled to reach the moons in 2027, may provide the necessary data to test these impact theories.