Observations and Modeling of Martian Auroras

Abstract

Observations of planetary auroras form a new area of planetary exploration from space, especially for nonmagnetic planets since various kinds of auroras like Discrete, Proton and Diffuse auroras have been observed at Mars. We review the latest results of Martian auroras obtained by the instruments (1) SPICAM (Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) aboard Mars Express (MEX) and ( 2) IUVS (the Imaging Ultraviolet Spectrograph) on MAVEN (the Mars Atmosphere and Volatile Evolution mission). The MARSIS instrument (the Mars Advanced Radar for the Subsurface and Ionosphere Sounding) on MEX, in addition, exhibited strong ionizations in some electron density profiles, thus providing further evidence for the existence of Martian auroras. We review these MARSIS observations as well. In addition, we review various models of Martian auroras.

Impact of Mars GDS 2018 on the Chemistry of Water, Nitrogenated and Deuterated Cluster Ions: NOMAD Observations

“…Therefore, the photoelectron impact ionization rates are higher than the photoionization rates by ∼1 order of magnitude (Shah et al., 2021). The production rates of H 2 O + , HDO + , and D 2 O + depend on the modeling parameters: the mixing ratios of H 2 O, HDO, and D 2 O, air density, photo ionization/photo electron impact cross sections, photon flux, GCR flux, and yield spectrum method (Haider et al., 2016, 2022; Shah et al., 2021; Vandaele et al., 2019).…”

“…The red star represents the production rate caused by photoelectrons resulting from model 1 due to the impact of hard X-rays, while the black star shows the production rate caused by photoelectrons resulting from model 2 due to the impact of hard X-rays. HDO, and D 2 O, air density, photo ionization/photo electron impact cross sections, photon flux, GCR flux, and yield spectrum method (Haider et al, 2016(Haider et al, , 2022Shah et al, 2021;Vandaele et al, 2019).…”

“…The function was fitted analytically later (cf. Haider et al, 2009Haider et al, , 2010Haider et al, , 2016Haider et al, , 2022Shah et al, 2021). These ion production rates have been used in the calculation of the densities of cluster ions.…”

EMM EMUS Observations of FUV Aurora on Mars: Dependence on Magnetic Topology, Local Time, and Season

“…electron discrete aurora), first identified by the SPICAM (SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) ultraviolet spectrometer on Mars Express (Bertaux et al, 2005(Bertaux et al, , 2006Leblanc et al, 2006;Soret et al, 2016), are spatially confined photon emissions in Mars' nightside upper atmosphere, generated by the decay of electronic states in atoms and molecules primarily excited by suprathermal electrons (energies greater than ∼9 eV; Soret et al (2024)). These discrete aurorae (a total of 19 detections by SPICAM: 16 in nadir mode and 3 in limb mode), distinguishable by their small spatial scales and association with strong vertical crustal magnetic fields, differ significantly from other Mars auroral types (González-Galindo et al, 2024;Haider et al, 2022): diffuse aurora, caused by the global precipitation of solar energetic particles (Gérard et al, 2017;Nakamura et al, 2022;Schneider et al, 2015Schneider et al, , 2018, and proton aurora, resulting from solar wind protons directly entering the upper atmosphere after charge exchange with neutral hydrogen in the corona (Chaffin et al, 2022;Deighan et al, 2018;Gérard et al, 2019;Hughes et al, 2019;Ritter et al, 2018).…”

“…As mentioned previously, dependence of aurora on upstream solar wind parameters and IMF parameters also needs to be examined in detail (Girazian et al, 2022;Schneider et al, 2021). Furthermore, the mechanisms for particle precipitation and aurora formation require detailed exploration (Bowers et al, 2023;Brain & Halekas, 2012;Haider et al, 2022). The consequences of aurora, such as enhanced ionization (creating a "patchy" ionosphere), Joule heating of the upper atmosphere, changes in chemical composition, and enhanced ion escape via auroral flux tubes, need further investigation (Brain & Halekas, 2012;Fillingim et al, 2007;Harada et al, 2024;Shematovich et al, 2017).…”