When Rubble Piles Collide...

Here you will find movies and data related to our paper on simulations of rubble pile collisions: Leinhardt et al. (2000).


We performed a series of simulations to investigate what happens when two rubble piles collide. We used a hard-sphere model for our rubble piles so we were restricted to the low-speed regime where impacts are gentle enough not to actually crush the rock. This may be appropriate for the early stages of planet formation, for example. Follow the links below to see stills and animations from our experiments. The simulations were carried out on a 16-node cluster of Intel Pentium IIs using pkdgrav.

Model A Equal size, no spins
Model B1 Equal size, opposite spins
Model B1x Bonus B1 results
Model B2 Equal size, same spins (retrograde)
Model B3 Equal size, same spins (prograde)
Model C Unequal size, no spins
These experiments involved impactors of 1 km radius and 2 g/cc bulk density (except Model C where one impactor was 0.5 km in radius). The dissipation parameter (coefficient of restitution) was fixed at 0.8, i.e. 20% dissipation. The impact parameter b is measured in units of the sum of the impactor radii, so b = 0 means a head-on collision and b = 1 means a grazing collision. The encounter speed v is in units that depend on the binding energy. For Models A and B the unit is 2.1 m/s; for Model C it's 2.9 m/s. Remember to click on the thumbnails for animations!

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