Physics of Planetary Interiors

This course focuses on the different aspects of numerical modelling of planetary interiors. The interior of a planet or moon can be studied via observations of its gravity field, shape, surface features, rotation, tidal deformations and orbital evolution. To interpret these observations, the response of the bodies to forcings (thermal and mechanical) need to be modelled. As a student you will get hands-on experience in modelling planetary bodies with various numerical code packages. Different problems will be discussed, including solving the Stokes equation for internal mantle convection, static and time-variable gravity forward modelling as well as orbital evolution and relation to interior dynamics. You will be able to study a range of internal solid and fluid processes, consider their role in planetary evolution and link them to existing and planned observations.

Lecture topics include:

1. Observations related to planetary interiors: Gravity field, rotation, tides, shape (topography, faults)

- Example bodies and learn about different internal processes. You will learn how to calculate the internal gravity, density, and pressure of these bodies.

2. How to model fluid-solid mechanics of a planet?

- Stokes equations in planetary science in spherical coordinates, rheology

- Heat-transport: state equation exercise with different heat regimes

- Mantle convection applications: dynamics and ocean flows

3. How to perform gravity field modelling

- non-uniqueness, advanced isostasy/flexure models, density anomalies

- Forward modelling density anomalies: spectral vs. volumetric methods

- Inversion of lithosphere structure

- Effect of mantle convection on the gravity field

- Lessons learned from seismology on Earth

4. Tidal and loading deformation

- Tidal and surface loads

- Forward modelling of time-variable gravity field and deformation

- Love numbers and they connection with interior properties.

- Use of observations to constrain interior properties (e.g., detection of subsurface oceans, tidal heating in Io, etc)

5. Rotational dynamics

- Rotational dynamics basics.

- Main drivers of rotational dynamics

- Effect of surface loads in the spin of a planet (Polar Wander)

- Effects of tides in the spin of a planet (tidal de-spinning, spin-orbital resonances, librations)

- Using observations of the rotation of a body to constrain its interior (e.g., librations and subsurface oceans)

6. Interior and orbit evolution

- Perturbations to Keplerian orbits

- Effect of tides in the orbital evolution of planets and moon

- Third body perturbation effects, including secular and mean motion resonances

- Feedback between interior and orbital evolution

- Use of orbital observations to constrain the interior of planets.