Such a low surface strength was also found for the last two near-Earth asteroids visited by space probes, Bennu and Ryugu by NASA's OSIRIS-REx and JAXA's Hayabusa2 mission, respectively. That poses the question whether low surface strength is a common characteristic of small asteroids. Ultimately other missions would be needed to interact with them to determine whether they in fact have diverse mechanical properties or else actually share this common weakness. Answering this question has strong implications for planetary defence.

Colas Robin and Alexia Duchene, two PhD students from ISAE-SUPAERO also supervised by researcher Naomi Murdoch, and co-authors analysed the detailed shapes of surface boulders on Dimorphos, comparing them with those on other small rubble pile asteroids surveyed by spacecraft: Itokawa, Ryugu and Bennu. The researchers found the boulders shared similar characteristics, suggesting all these types of asteroids formed and evolved in a similar fashion. The team also noted that “the elongated nature of the boulders around the DART impact site implies that they were likely formed through impact processing”.

DART and Hera team member Naomi Murdoch explains: ““Planetary defense efforts heavily rely on understanding the physical properties of asteroids. In these five papers, we have used images from the DART mission, combined with various methodologies, to provide vital information about the surface material and strength of these asteroids, enhancing our ability to protect Earth from potential threats while simultaneously unravelling the history and evolution of Didymos and Dimorphos.”