# Asteroid impact theory for Mars moon Deimos > Live situation record from CLSTR: https://clstr.news/situations/asteroid-impact-theory-for-mars-moon-deimos > Updated: 2026-08-21T14:30:00.000Z. Sources: 12. Developments: 2. Research published in Nature Astronomy suggests that a single, massive asteroid impact significantly reshaped Deimos, one of the moons of Mars. Scientists, including researchers from the University of Bern, utilized high-resolution imagery from the European Space Agency’s Hera mission flyby and computer simulations to model the event. The findings indicate that a roughly 320-meter-wide asteroid striking at a 45-degree angle likely created the large impact basin observed at the moon’s southern pole. This oblique collision is proposed as the cause for Deimos’ unusually smooth surface, as the impact ejected enough material to create a global layer of regolith—consisting of dust and rubble—that may be between 120 and 200 meters deep. Researchers suggest that Deimos’ porous and fractured internal structure may have allowed it to absorb the impact energy without being destroyed. These conclusions contribute to the scientific debate over whether Martian moons are captured asteroids or debris from ancient impacts and provide predictions for the upcoming Japan Aerospace Exploration Agency (JAXA) Martian Moons eXploration (MMX) mission. ## Timeline ### 2026-08-21: Deimos may have been reshaped by a single massive asteroid impact Simulations suggest a single asteroid impact reshaped the Martian moon Deimos, creating its smooth surface and south-polar depression by spreading debris across the moon. 3 sources. https://clstr.news/cluster/deimos-may-have-been-reshaped-by-a-single-massive-asteroid-impact ### 2026-08-19: Deimos reshaping: Asteroid impact explains Mars moon features New research suggests a single asteroid impact reshaped Mars' moon Deimos, creating its southern polar basin and a thick layer of surface dust, according to data from the ESA Hera mission. 9 sources. https://clstr.news/cluster/deimos-moon-of-mars-reshaped-by-single-asteroid-impact --- Cite as: Asteroid impact theory for Mars moon Deimos. CLSTR, https://clstr.news/situations/asteroid-impact-theory-for-mars-moon-deimos