Reconstruction of Mercury's internal magnetic field beyond the octupole

Simon Toepfer,Ida Oertel,Vanita Schiron,Daniel Heyner,Uwe Motschmann,Patrick Kolhey,Karl-Heinz Glassmeier,Yasuhito Narita

doi:10.5194/angeo-40-91-2022

Abstract

Abstract. The reconstruction of Mercury's internal magnetic field enables us to take a look into the inner heart of Mercury. In view of the BepiColombo mission, Mercury's magnetosphere is simulated using a hybrid plasma code, and the multipoles of the internal magnetic field are estimated from the virtual spacecraft data using three distinct reconstruction methods: the truncated singular value decomposition, the Tikhonov regularization and Capon's minimum variance projection. The study shows that a precise determination of Mercury's internal field beyond the octupole up to the dotriacontapole is possible and that Capon's method provides the same high performance as the Tikhonov regularization, which is superior to the performance of the truncated singular value decomposition.

Highlights

The in-depth analysis of planetary magnetic fields is a key element to understand the structure and dynamics of planetary interiors (Glassmeier and Heyner, 2021)
Due to the plasma physical interaction with the solar wind, the magnetic field around Mercury is composed of the planetary internal field, and of the external component resulting from currents flowing within the magnetosphere (e.g., Glassmeier and Heyner, 2021; Wang et al, 2021)
In preparation for the analysis of the magnetic field measurements provided by the magnetometer on board the Mercury Planetary Orbiter (MPO), the plasma interaction of Mercury with the solar wind is simulated numerically

Summary

Introduction

The in-depth analysis of planetary magnetic fields is a key element to understand the structure and dynamics of planetary interiors (Glassmeier and Heyner, 2021). Revealing the nature of Mercury’s markedly weak internal magnetic field is one of the primary goals of the BepiColombo mission (Benkhoff et al, 2010, 2021). Thereby, the detailed reconstruction of Mercury’s internal field from the total measured magnetic field is of major importance for modeling Mercury’s internal dynamo process. Due to the plasma physical interaction with the solar wind, the magnetic field around Mercury is composed of the planetary internal field (such as the dynamo-generated field and the crustal remanent field), and of the external component resulting from currents flowing within the magnetosphere (e.g., Glassmeier and Heyner, 2021; Wang et al, 2021). For the reconstruction of Mercury’s internal magnetic field, each part of the field has to be parametrized properly

Objectives

Methods

Conclusion