Structure and dynamics of the hermean magnetosphere revealed by electron observationsafter the first three Mercury flybys of BepiColombo, 50 years after Mariner 10.
- 1Institut de Recherche en Astrophysique et Planétologie (IRAP), CNRS-UPS-CNES, Toulouse, France.
- 2Institut Supérieur de l’Aéronautique et de l’Espace (ISAE-SUPAERO), Université de Toulouse, Toulouse, France
- 3Laboratoire de Physique des Plasmas (LPP), CNRS-Observatoire de Paris Sorbonne Université - Université Paris Saclay-Ecole Polytechnique - Institut Polytechnique de Paris, Palaiseau, France.
- 4Department of Geophysics, Graduate school of Science, Kyoto University, Kyoto Japan
- 5Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
- 6AKKODIS, Blagnac, France
- 7Swedish Institute of Space Physics, Uppsala, Sweden
- 8Department of Earth and Space Science, Graduate School of Science, Osaka University, Japan
- 9Max Planck Institute for Solar System Research, Göttingen, Germany
The Mercury Electron Analyzer (MEA) obtained new electron observations during the first three
Mercury swingbys (MSBs) by BepiColombo on 01 October 2021 (MSB1), 23 June 2022 (MSB2),
and 19 June 2023 (MSB3). We identify the magnetospheric boundaries and describe the structure and dynamics of the electron populations observed in the various regions explored along the swingby trajectories. We compare and contrast our new BepiColombo electron observations with those obtained from the Mariner 10 Scanning Electron Spectrometer (SES) 50 years ago.
A comparison to the averaged magnetospheric boundary crossings by MESSENGER indicates
that the magnetosphere of Mercury was compressed during MSB1, close to its average state
during MSB2, and highly compressed during MSB3. Our new MEA observations revealed a
significant dusk-dawn asymmetry in electron fluxes on the nightside magnetosphere, and of
strongly fluctuating electrons with energies above 100s eV on the dawnside magnetosphere.
Magnetospheric electron densities and temperatures were in the range of 10-30 cm⁻³ and above a few 100s eV in the pre-midnight-sector, and in the range of 1-100 cm ⁻³ and well below 100 eV in the post-midnight sector, respectively.
MEA electron observations of different solar wind properties encountered during the first three
MSBs revealed the highly dynamic response of the solar wind-magnetosphere interactions at
Mercury. A good match is found between the electron plasma parameters derived by MEA in the various regions of the Hermean environment with similar ones derived for a few cases from other instruments on board BepiColombo.
How to cite: Rojo, M., André, N., Aizawa, S., Sauvaud, J.-A., Harada, Y., Saito, Y., Fedorov, A., Penou, E., Barthe, A., Persson, M., Yokota, S., Mazelle, C., Hadid, L., Delcourt, D., Fränz, M., Katra, B., Krupp, N., and Murakami, G.: Structure and dynamics of the hermean magnetosphere revealed by electron observationsafter the first three Mercury flybys of BepiColombo, 50 years after Mariner 10., Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-1243, https://doi.org/10.5194/epsc2024-1243, 2024.
