Tides and Elastic Bodies, the Dynamics of Moons, Impacts on Gravel, and some Space Science and Geophysics

Mass spring models are simple and fast, can accurately track very small body deformations, and they accurately conserve angular momentum. We are creating a new field we call `astro-elastodynamics' or 'soft astronomy'. Our recent papers 1) proposing that tidal encounters can cause crustal failure (and a new geophysical process!); 2) showing that we can accurately measure tidal spin down for spherical bodies directly tying simulated rheology to tidal evolution; 3) measuring and understanding spin down rates of ellipsoids (and moving into an area with no prior analytical predictions). 4) Explaining the high obliquity of Pluto and Charon's satellites with a new type of spin resonance. 5) Studying propagation of impact excited seismic waves and normal mode excitation on an asteroid. 6) Measuring the distribution of tidally generated heat, including a proposed trigger for the lopsided near/far side growth of the lunar crust. 7) Measuring the rate that wobbling asteroids damp into principal axis rotation. 8) Exploring the tidal evolution of Phobos and Deimos. 9) Exploring accretion of ornamental ridges on Saturn's moons. 10) We resolve two problems in binary asteroids with non-principal axis rotation and predict that binary asteroid secondaries are in complex rotation states. The two problems are accounting for their lifetime and a discrepancy in estimates of their viscoelastic material properties.

Recently we have become interested in how planetesimals interact with particles and gas in the protostellar disk in which they form.

For a talk on simulating tidal dynamics with mass-spring models see Astro-Elastodynamics (soft astronomy!) Spin dynamics and Cracking Charon!

I worked on the Uranian satellite system to try and better understand the chaotic dynamics of closely packed orbiting systems. It's the setting in the Solar system that is closest dynamically to the recently discovered (from the Kepler mission) tightly packed compact planetary systems.

Brief forays into space science and geophysics are tagged below.