SPH Simulations of Boulder Disruptions: from Laboratory Scale Impacts to Asteroids

The detailed observations of the boulder populations on rubble-pile asteroid surfaces such as Ryugu, Bennu or Dimorphos provide insights into their physical properties and the evolution of their host asteroids [1]. Asteroid surfaces evolve through impacts and thermal processing – both mechanisms that may lead to boulder fragmentation (Figure 1). Figure 1: a) - c) Images acquired by the DART spacecraft approaching the surface of Dimorphos. Boulders which may have originated as a result of an impact event on the asteroid surface are highlighted in red (NASA/Johns Hopkins APL). Here, we present numerical simulations using the Bern SPH code [2] to study the impact fragmentation of boulders on asteroid surfaces. Before applying our models to asteroid scales, we successfully validated them by comparing the results with boulder disruptions observed in laboratory impact experiments [3].In scenarios of impacts on rubble-pile asteroids, our Bern SPH simulations include the displacement and late-stage evolution of the boulder fragments, using a recently developed approach [4,5]. This allows us to determine their final position on the asteroid surface or if they are ejected from the asteroid. Our initial results suggest that only for boulders with a relatively low bulk tensile strength (