The Largest Electron Differential Energy Flux Observed at Mars by the Mars Express Spacecraft, 2004–2016. Issue 8 (22nd August 2018)

• Record Type: Journal Article
• Authors: Frahm, R. A.; Winningham, J. D.; Coates, A. J.; Gérard, J.‐C.; Holmström, M.; Barabash, S.
• Is Part Of: Journal of geophysical research. Volume 123:Issue 8(2018)
• Page Start: 6576
• Page End: 6590
• Publication Date: 2018-08-22
• Subjects: Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2018JA025311
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: The goal of this paper is to understand the processes by which solar wind electrons are energized in the Martian magnetosphere and how this compares to processes at Venus and Earth. Each is unique in the source of its magnetic field topology and how this influences electron energization. To achieve this goal, 24 million spectra spanning 13 years have been examined using the electron spectrometer from the Mars Express spacecraft between about 12, 000 km and about 250 km altitude, and from all latitudes and local times. The top 10 largest differential energy flux at energies above the differential energy flux peak have been found: seven spectra from the magnetosheath near noon, three from the dark tail (the largest two from the middle and ionospheric edge of the magnetosheath). Spectral comparisons show a decade range in the peak of the electron distributions; however, all distributions show a similar energy maximum dictated by solar wind/planet interaction. Similarly derived, the largest Venus spectrum occurred near the magnetosheath bow shock and had the same shape as the most intense Mars inner magnetosheath spectrum. The Mars and Venus dayside spectra compared to the Mars nightside spectrum that included an enhanced optical signal attributed to discrete "auroral" precipitation show a similar shape. These spectra are also compared to a selected auroral zone electron spectra from the Earth. The Mars and Venus results suggest that there is no more energy needed to generate electrons forming the nightside precipitation than is gained during the solar wind/planet interaction. Key Points: Top 10 orbit‐selected electron energy spectra from Mars are identified from MEx ASPERA‐3 ELS between 2004 and 2016 The Mars and Venus dayside electron spectra are similar, and a discrete "auroral" spectrum from the nightside tail of Mars is also similar No more energy than that supplied by the solar wind‐planet interaction is required to produce discrete auroral spectrum from the nightside tail of Mars