That last bit needs some explaining. For numerical reasons I stopped using a single large particle for my moonlet a while back. Instead, I use a lattice of spheres with an enhanced density so the total mass matches that of a single sphere. In my other simulations this has worked great and the lattice holds together. In this one, it got knocked to pieces in just one orbit. We haven't worked out all the implications of this, but here are a few possibilities.
- The internal density of constituent parts of moonlets has to be high enough so this doesn't happen.
- The moonlets can't be loose rubble piles. They have to have physical strength.
- The constituent pieces of a moonlet have to be significantly larger than the top end of the surrounding size distribution.