Martian moon Deimos resembles a potato. A big asteroid strike may have shaped it
New research suggests that the Martian moon Deimos was likely reshaped by a single, massive asteroid impact. This event explains the moon's unique potato-like shape, its polar crater, and the layer of dust covering its surface.
Why it matters
Understanding the origins of Martian moons provides critical data for upcoming space exploration missions, including the JAXA MMX mission.
Animation shows how an asteroid strike may have reshaped Deimos and cloaked it in dusty material. - S. D. Raducan/ESA Mars has two tiny moons that lack a confirmed origin story for how they came to orbit the red planet — but new research may explain some of the mysteries surrounding outermost satellite Deimos.
Named for the son of the Greek god Ares, Deimos, which means dread in ancient Greek, is a small, lumpy rock shaped like a potato. Ares is also known as Mars in Roman mythology.
The moon is about 14,913 miles (24,000 kilometers) from the Martian surface, and orbiters have observed it since the 1970s — including a recent flyby of the European Space Agency's Hera mission in March 2025. Hera is en route to study the aftermath of NASA's DART mission that intentionally crashed a spacecraft into a small moon orbiting a larger asteroid.
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