The goal of our team is to resolve key open questions in the solar wind interaction with Mercury’s dynamic magnetosphere by exploiting the synergies between different numerical approaches and in situ observations. Identifying and characterising the fundamental physical processes that drive the global and local plasma environments is needed to optimally prepare for the BepiColombo mission and maximise its science return.
Mercury has one of the most dynamic magnetospheres in the solar system. MESSENGER observations showed that the system can completely reconfigure itself on the order of minutes. This can be caused by external events such as variations in the solar wind and interplanetary magnetic field, or it can be “self-triggered” when the system surpasses its own threshold for instabilities to develop. BepiColombo, currently en-route to Mercury, carries a sophisticated suite of instruments that will provide new data with unprecedented spatial and temporal resolutions. The first and second Mercury flybys are foreseen for Oct. 2021 and Jun. 2022. To correctly interpret and analyse BepiColombo’s local measurements, however, a substantial complementary modelling effort is required to provide a global context.
The proposed team will bring together an international team of experts from (a) the modelling community, focussing on the plasma interaction with Mercury using extended MHD, hybrid and fully kinetic approaches; and (b) key personnel from the plasma instruments’ team on board the BepiColombo and MESSENGER missions. We will focus on two essential elements:
- We will model and characterise the [global] structure and evolution of the Hermean magnetosphere in response to changes in the upstream plasma conditions, steered by measurements and models derived from the plasma instruments onboard the MESSENGER spacecraft and the preliminary data from BepiColombo’s first Mercury flybys. Using simulations with different physical models allows us to determine precisely when and where electron- and ion-dynamic processes dominate the interaction and how to use computational resources most efficiently. In particular, the shape and location of the magnetospheric boundaries, and the relative importance of the different current systems will be of prime interest to interpret future coordinated science observations from BepiColombo’s Magnetospheric (Mio) and Planetary Orbiter (MPO).
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Our team will identify kinetic interactions in the Hermean plasma environment, such as particle acceleration, heating, and wave generation. For example, the nonlinear evolution of Kelvin-Helmholtz waves, which are [local] fluid-to-kinetic scale instabilities that were frequently observed near Mercury’s magnetopause, may play an important role in governing the energy transfer mechanisms between the solar wind and the inner magnetosphere. Disentangling the details of the energy budget of Mercury’s magnetosphere also provides important clues to understand better the magnetospheres of other bodies in the solar system.
The Mariner and MESSENGER missions left the scientific community with many intriguing enigmas to be explored further. In anticipation of BepiColombo’s arrival at Mercury in late 2025, modelling the planet’s magnetised environment and assessing the role of microphysics in the global dynamics of the system is of high priority. It will help the instrument and science consortia to prepare better for the conditions to expect at various stages of the mission and provide vital support for the rapid analysis and interpretation of BepiColombo’s observations.