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.
-
Arrokoth's smooth undulating terrain suggests that it was sandblasted by the snowstorm in which
it coalesced.
Wind erosion and transport on planetesimals (on arxiv) or
ADS/Icarus
-
We predict that the secondaries of binary asteroids are in complex rotation states.
Non-principal axis rotation in binary asteroid systems and how it weakens the BYORP effect,
arxiv
, ADS/Icarus
- Habitat Bennu: With solar energy, you
can build a habitat from an asteroid and spin it up by tossing off pieces of rubble.
Habitat Bennu:
Design Concepts for Spinning Habitats Constructed From Rubble Pile Near-Earth Asteroids
-
Dannielle's MS thesis
Rearrangement of Granular Surfaces on Asteroids due to Thermal Cycling (on arxiv)
- Ways to make a ravioli shaped moon within Saturn's rings
Accretion of Ornamental Equatorial Ridges on Pan, Atlas and Daphnis (in Icarus, ADS),
(arxiv)
- Excitation of Tumbling and Tidal Evolution in Phobos and Deimos. We propose
that near-catastrophic impacts can cause Phobos and Deimos to tumble and
damp their orbital eccentricities.
arxiv ,
Icarus
- We use the mass spring model to measure the energy dissipation rate of wobbling spinning
asteroids (asteroids in non-principal axis rotation states). The simulations match the analytical
predictions really well!
Simulations of wobble damping in viscoelastic rotators ,
arxiv
- A way to trigger uneven lunar crustal growth,
arxiv ,
Near/Far Side Asymmetry in the Tidal Heated Moon
- A seismic study of asteroid Bennu using a Bennu shape model
and using our mass/spring model simulations:
arxiv ,
Impact Excitation of a Seismic Pulse and Vibrational Normal Modes on Asteroid Bennu and Associated Slumping of Regolith
- Tilting Styx, Nix, Kerberos and Hydra;
Obliquity evolution of the minor satellites of Pluto and Charon ,
arxiv
There are unidentified spin resonances in these simulations. Proposed
is a new spin-resonant mechanism for tilting the satellites.
- A new spin resonance model for the spin-secular/mean-motion resonance:
Tilting Styx and Nix but not Uranus with a Spin-Precession-Mean-motion resonance ,
arxiv
- Tidal spin down and drift rates for triaxial ellipsoids like Haumea,
(with Andrea!)
Tidal spin down rates of homogenous triaxial viscoelastic bodies ,
arxiv
- We propose that rare past strong tidal encounters can account for formation
of chasmata and graben complexes on icy moons, Charon (and maybe even Mars). With
David, John and Cindy!
Crustal Failure in Icy
Moons and Satellites from a Strong Tidal Encounter ,
(arxiv)
A movie on You-tube:
More elastic body movies at elastic movies
- Simulating tidal spin up and spin down with a mass spring model. With Julien!
The quality function k2/Q is
dependent on viscoelastic relaxation timescale! More importantly mass-spring model
s
can accurately simulate tidal evolution (and that means we can do many more things
with them ....).
Damped Mass-spring model Simulations of Tidal Spin down in a Kelvin-Voigt viscoelastic sphere ,
arxiv
Movie: Click here:
-
Improved estimates of three-body resonance strengths and resonance overlap parameters
for Uranian moons in chains of mean motions resonances.
Resonant Chains and Three-body Resonances in the Closely-Packed Inner Uranian Satellite System ,
arxiv
Geophysics