Electrodynamic interactions with the planet Mercury – ESA/JAXA BepiColombo exploration begins

ESA’s cornerstone project BepiColombo is a spacecraft mission to the planet Mercury in co-operation between ESA and JAXA.

It consists of the Mercury Magnetospheric Orbiter (MMO), and the Mercury Planetary Orbiter (MPO), which are transported together as one spacecraft during the cruise phase.

We (IRF Uppsala, and space physics group at KTH), have since 2004 developed, manufactured, implemented, and now operate the electric field instrument (MEFISTO) onboard the MMO, as part of the Plasma Wave Instrument (PWI) led by Tohoku University. The launch in 2018 became a welcome success. In December 2025 it will arrive at Mercury!

Our instrument will deploy its wire booms immediately after MMO separation, and with MEFISTO we will carry out the first ever low frequency electric field measurements around Mercury.

We have a proprietary period of 6 months to do science with the sampled data before the calibrated data must be released to the worldwide science community.

Several science objectives are to be addressed and we would like to be well supported to fulfil them immediately at the commencement of the measurements.

We therefore apply here for funding support for a PhD student to work with us from 2025 to 2028 here at IRF Uppsala when these unique data arrive from Mercury.

The overall scientific goal of our MEFISTO team (at IRF-Uppsala and KTH) is to identify, map and understand the main processes in the space plasma around Mercury and its role in the interaction with the surface.The science task for the PhD student applied for here, is to study the electrodynamic interactions with the planet Mercury.

This involvesInfer the electrodynamics related to the “auroral” acceleration regions, e.g., electrostatic potential structures and/or Alfvén wave cascade processes.

This is related to the electric current systems, whether they couple to field-aligned currents closing near the planet surface and how they are involved in momentum transfer/stress balance between the magnetosphere and the planet.Map the locations and conditions where Alfvén waves can be generated (e.g., Kelvin-Helmholtz instabilities near the magnetopause, other ULF wave sources, shears in the magnetotail etc), and follow their propagation through the observed Poynting flux direction toward the planet.Infer the energization and momentum transfer of other wave-particle interaction processes that may play a role in the magnetosphere of Mercury, e.g., lower hybrid, Whistler, and Chorus wave processes.