EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Mirror mode-like structures around unmagnetised planets: 1. Mars as observed by the MAVEN spacecraft

Cyril Simon Wedlund1, Martin Volwerk1, Christian Mazelle2, Sebastián Rojas Mata3, Gabriella Stenberg Wieser3, Yoshifumi Futaana3, Jasper Halekas4, Diana Rojas-Castillo5, César Bertucci6, and Jared Espley7
Cyril Simon Wedlund et al.
  • 1Space Research Institute (IWF), Austrian Academy of Sciences, Graz, Austria (
  • 2Institut de Recherche en Astrophysique et Planétologie (IRAP), Université de Toulouse, CNRS/UPS/CNES, Toulouse, France
  • 3Swedish Institute of Space Physics, Kiruna, Sweden
  • 4Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
  • 5Instituto de Geofísica, Universidad Nacional Autónoma de México, Coyoacán, Mexico
  • 6CONICET/University of Buenos Aires, Buenos Aires, Argentina
  • 7NASA Goddard Space Flight Center, Laboratory for Planetary Magnetospheres, Greenbelt, MD, USA

Temperature anisotropy-driven instabilities such as the mirror mode and ion cyclotron instabilities are responsible for the generation of waves in the turbulent magnetosheath of planets. We present two statistical studies of mirror mode-like structures in the magnetosheaths of (mostly) unmagnetised planets such as Mars and Venus, characterised in the same way and with the same tools with the help of on-board magnetometers. In this presentation, we discuss observations by the MAVEN spacecraft. As in our companion Venus study (see poster by Volwerk et al. in the same session), we use magnetic field-only measurements to constrain and identify these quasi-linear compressive structures and discuss ways to mitigate false positive detections based on one instrument only. After calculating the residence time of the spacecraft in the Martian magnetoenvironment, we show two-dimensional statistical maps of mirror mode-like occurrence rates with respect to EUV solar flux levels, Mars Year, and atmospheric seasons. We find detection probabilities of about 1% at most, with two main regions of occurrence, one behind the collisionless shock, the other close to the induced magnetospheric boundary, with the clearest modulation of the probability due to EUV solar flux conditions. Finally, we qualitatively compare our results with past studies at Mars.

How to cite: Simon Wedlund, C., Volwerk, M., Mazelle, C., Rojas Mata, S., Stenberg Wieser, G., Futaana, Y., Halekas, J., Rojas-Castillo, D., Bertucci, C., and Espley, J.: Mirror mode-like structures around unmagnetised planets: 1. Mars as observed by the MAVEN spacecraft, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-1305,, 2023.