Mars's Funky Moon Deimos was Shaped by an Impact

A new study suggests that Deimos, Mars's larger moon, was shaped by a single large impact. The research, published in Nature Astronomy, uses simulations to show that a 320-meter-wide asteroid struck Deimos at 45 degrees, creating a 10-km-wide crater and covering the moon in regolith. The impact, which occurred around 4 billion years ago, explains the moon's smooth surface and the presence of buried craters. The simulations, conducted using the Bern Smoothed Particle Hydrodynamics (SPH) code, show that the impactor was small and the moon's interior is a rubble pile, not a solid body.

• Deimos's south polar crater, 10 km wide, is attributed to a single impact.
• The impact created a thick layer of regolith that obscures many of Deimos's craters.
• The simulation shows that the impactor was a small asteroid, and the moon's interior is not solid but made of loose, fragmented material.

This research supports the idea that Deimos was shaped by an impact, but it also highlights the moon's fragile interior. The findings suggest that Deimos may have formed from material kicked up by surface impacts on Mars, rather than being a captured asteroid. The study also notes that Hera's observations helped improve the accuracy of the simulations, and the results are a significant step in understanding the formation of small planetary bodies.

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