Binary asteroid systems make up roughly 15% of objects occupying near-Earth space, the Main Belt, and trans-Neptunian space. The impact history of asteroids in binary systems represents an interesting aspect of the general problem pertaining to the nature and evolution of surfaces for such objects. Specifically, the post-impact dynamics of ejecta and its relation to surface modification is a challenging question owing, in part, to the unusual gravitational field in a binary system and the subsequent capture and emplacement of debris on either binary component. Observable differences or similarities between the two bodies in the color, reflectance, thermal properties, and grain properties of their respective regoliths could give insight into the system's past and the circumstances of recent impacts. Here we present simulations of impact scenarios in a wide variety of binary systems in order to generate a large family of prediction models for resurfacing and ejecta covering outcomes due to impacts. In this way, we can address our main science question of how specific binary system parameters influence the evolution of their surfaces. To create a library of ejecta outcomes, we first developed the Rebound Ejecta Dynamics (RED) package (Larson and Sarid 2021), an N-body integrator designed to model post-impact debris dynamics that builds on the existing Rebound software (Rein and Tamayo 2015). This package allows us to vary the many of the important parameters of a binary system, including primary-secondary separation, rotation periods, and mass ratios, as well as impact-related parameters, such as impact surface location, ejecta size and velocity distribution, and ejecta compositions. Our simulations generally use 10,000 particles and cover one week of simulation time. From our simulations, we calculate the percentage of the system that is resurfaced, the distance that particles travel from the impact site, and the percentage of particles that impact the surface. These regions of resurfacing can often be observed with different colors or spectral properties than the original surface. We find that there are trends in ejecta end-states as a function of binary system properties (i.e., primary rotation period and system mass ratio) for several common impact scenarios. We analyzed the dominant effect that influences the outcome of each impact event.


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Graduation Date





Fernandez, Yan


Doctor of Philosophy (Ph.D.)


College of Sciences



Degree Program

Physics; Planetary Sciences Track




CFE0009556; DP0027565





Release Date

May 2023

Length of Campus-only Access


Access Status

Doctoral Dissertation (Open Access)