Hyper-Velocity Impacts on Rubble Pile Asteroids
The thesis presents a tool to create rubble pile asteroid simulants for use in numerical impact experiments, and provides evidence that the asteroid disruption threshold and the resultant fragment size distribution are sensitive to the distribution of internal voids. This thesis represents an important step towards a deeper understanding of fragmentation processes in the asteroid belt, and provides a tool to infer the interior structure of rubble pile asteroids. Most small asteroids are 'rubble piles' – re-accumulated fragments of debris from earlier disruptive collisions. The study of fragmentation processes for rubble pile asteroids plays an essential part in understanding their collisional evolution. An important unanswered question is “what is the distribution of void space inside rubble pile asteroids?” As a result from this thesis, numerical impact experiments can now be used to link surface features to the internal structure and therefore help to answer this question. Applying this model to asteroid Šteins, which was imaged from close range by the Rosetta spacecraft, a large hill-like structure is shown to be most likely primordial, while a catena of pits can be interpreted as evidence for the existence of fracturing of pre-existing internal voids.
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angle Asphaug asteroid belt asteroid families asteroid Itokawa asteroid simulant asteroid Šteins Astronomy and Astrophysics Autodyn Benz calculated catastrophic disruption catena cell collisional collisions comets crater Diamond cratering event density diameter discussed in Sect disruption threshold distribution dynamic E-type asteroid energy equation evolution Figure flyby formation fractures gravitational aggregate gravitational forces Holsapple Icarus images impact crater impact events impact simulations impactor radius interior internal structure Jorda Jutzi k-D tree larger largest remnant fragment LS-DYNA macroporosity main belt mass monolithic observed orbit parameters pebbles Planetary Science planetesimals planets porosity porous power law Pravec regime regolith Rimp ¼ Rmax Rmin Rosetta Rosetta spacecraft rotation Rozitis rubble pile asteroids rubble pile simulant scale shape model shock physics code slope small asteroids Smoothed Particle Hydrodynamics solar system spacecraft SPH solver spherical spin-up Šteins simulant strength surface features target velocity vimp void fraction void space Vokrouhlicky Yarkovsky Yarkovsky effect YORP effect