Descrizione del progetto
Nuovi modelli per comprendere i flussi dei nuclei planetari
Numerosi pianeti e le loro lune possiedono nuclei parzialmente o completamente liquidi. Tutto questo sciabordare di liquido sotterraneo esercita un importante impatto sul comportamento e sulle caratteristiche dei pianeti e delle relative lune, tra cui i campi magnetici e le rotazioni. Il progetto THEIA, finanziato dall’UE, sta utilizzando un sistema modello sperimentale, una struttura gigante simile a un giradischi per studiare i moti vorticosi in varie condizioni. Ricalibrando i modelli numerici risultanti alle dimensioni dei pianeti, gli scienziati sperano di chiarire il ruolo delle topografie non sferiche nella modulazione degli effetti del flusso fluido su campi magnetici e rotazione. Il progetto sta sviluppando un approccio teorico innovativo e simulazioni numeriche attraverso il codice Dynamo più veloce. Il progetto è ancorato a tre osservazioni geofisiche ben documentate all’interno del sistema Terra-Luna: la dissipazione dell’energia nel nucleo terrestre liquido, la dissipazione dell’energia nel nucleo lunare liquido e il campo magnetico della giovane Luna.
Obiettivo
Understanding planetary core flows is crucial as they generate planetary magnetic fields and modify planetary rotation. However, their study is an outstanding challenge involving geomagnetism, geodesy and fluid mechanics. Notably, present models fail to explain two puzzling observations. First, geodesy constrains the Earth and Moon core dissipations to values exceeding those of current theoretical models. Second, lunar paleomagnetism gives an early Moon magnetic field too intense for the current planetary dynamo paradigm, based on convection.
My project tackles these issues by going beyond the present planetary core simulations, performed in exact spheres. Planetary core boundaries are actually not spherical, being affected by large-scale and small-scale deformations. This topography, although advocated for a long time to play a role for the core dynamics, has been largely overlooked in core flow models.
I propose to investigate topographic effects in planetary fluid cores by combining theory, numerics and experiments. Using the largest turntable worldwide, I will build an experiment to study the dissipation of turbulent flows in the presence of rotation, density variations and topography. Building upon my recent advances in applied mathematics, I will develop new numerical models keeping only the relevant topographic effects. Using efficient spectral methods, I will reach unprecedented parameters, closer to planetary ones. Developing scaling laws, I will assess how planetary core dissipations and magnetic fields are modified by topographic effects. Beyond the Earth-Moon system, my models will also apply to fluid layers of other bodies, such as the subsurface oceans of the Jupiter icy moons, studied by future spatial missions (JUICE, Europa Clipper). This project is especially timely as the liquid core of Mars is studied by the on-going spatial mission InSight.
Programma(i)
Argomento(i)
Meccanismo di finanziamento
ERC-STG - Starting GrantIstituzione ospitante
75794 Paris
Francia