Field‐Aligned Proton Beams Upstream of the Martian Bow Shock: First Observations

K. Meziane; Christian Mazelle; C. Simon-Wedlund; J. Halekas; A. Hamza; C. Bertucci; D. Mitchell; J. Espley

doi:10.1029/2025GL115483

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Field‐Aligned Proton Beams Upstream of the Martian Bow Shock: First Observations

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Field‐Aligned Proton Beams Upstream of the Martian Bow Shock: First Observations

K. Meziane, Christian Mazelle, C. Simon-Wedlund, J. Halekas, A. Hamza, C. Bertucci, D. Mitchell and J. Espley

Geophysical research letters, Vol.52(11), p.9

05/30/2025

DOI: 10.1029/2025GL115483

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Abstract

Abstract We report fast sunward‐propagating energetic proton field‐aligned beams (FABs) observed about one Mars radius upstream of the Martian bow shock, recorded by the Solar Wind Ion Analyzer instrument on the MAVEN spacecraft. The velocity distributions show that all the beams have a bulk parallel speed , exceeding the shock speed . Several FABs are observed in the field‐aligned region, linked to the quasi‐parallel shock. The nearly synchronous variations of shock values and beam speeds rule out specular reflection, suggesting a non‐specular reflection mechanism. However, the slower Martian foreshock beam speeds remain unexplained compared to their terrestrial counterparts.

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Details

Title: Subtitle: Field‐Aligned Proton Beams Upstream of the Martian Bow Shock: First Observations
Creators: K. Meziane - University of New Brunswick
Christian Mazelle - Université Toulouse III - Paul Sabatier
C. Simon-Wedlund - Austrian Academy of Sciences
J. Halekas - University of Iowa
A. Hamza - University of New Brunswick
C. Bertucci - Institute of Astronomy and Space Physics
D. Mitchell - University of California, Berkeley
J. Espley - Goddard Space Flight Center
Resource Type: Journal article
Publication Details: Geophysical research letters, Vol.52(11), p.9
DOI: 10.1029/2025GL115483
ISSN: 0094-8276
eISSN: 1944-8007
Publisher: American Geophysical Union
Grant note: CNESFrench space agency CNES (National Centre for Space Studies)
K.M. thanks Emmanual Penou for his devotion in providing his valuable help in CL software development tool. Parts of this work for the observations obtained with the SWEA instrument are supported by the French space agency CNES (National Centre for Space Studies).
Language: English
Date published: 05/30/2025
Academic Unit: Physics and Astronomy
Record Identifier: 9984826347302771

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