EGU21-11897, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Ion properties of Mercury’s northern cusp under extreme solar wind observed by MESSENGER

Sae Aizawa1,2, Nicolas André1, and Jim Raines3
Sae Aizawa et al.
  • 1IRAP, Toulouse, France (
  • 2Graduate School of Science, Tohoku University, Sendai, Japan
  • 3Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI USA

Mercury’s magnetic cusp allows solar wind plasma to precipitate into the magnetosphere, exosphere, and directly to the surface. This precipitation of solar wind leads to the production of neutrals in the exosphere and/or ions in the magnetosphere and thus it has an important role in shaping Mercury’s space environment. Characterizing the ion properties in the cusp region is important for obtaining a better understanding of the Sun-planet interactions and assessing the solar wind penetration in Mercury’s magnetosphere.

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has observed the northern cusp regularly during its orbital phase. We have analyzed plasma data obtained by the Fast Imaging Plasma Spectrometer (FIPS) onboard MESSENGER under extreme solar wind events and compared the resulting ion properties in the northern cusp with those under non-extreme solar wind events for the first time. We found that (1) flux enhancement is confirmed under the extreme solar wind, and (2) the ion distribution in the cusp has a smaller kappa value than in the magnetosheath, suggesting ion acceleration occurs in the magnetosphere.

How to cite: Aizawa, S., André, N., and Raines, J.: Ion properties of Mercury’s northern cusp under extreme solar wind observed by MESSENGER, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11897,, 2021.


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