ENA diagnostics of auroral activity at Mars

One prominent feature of solar wind—Mars interaction has to do with the presence of strong crustal magnetic fields, especially, in the southern hemisphere. This physical property has set Mars apart from Venus as far as the kinetic effect in detail. In this paper, we review briefly the recent particles-and-fields measurements at Mars in connection to the auroral activity driven by magnetic field reconnection between the crustal magnetic fields and the interplanetary fields. It is suggested that the subsolar ENA (energetic neutral atoms) jets discovered by the NPD instrument of Mars Express could be resulting from charge exchange effect of the shocked solar wind protons at the magnetopause-like regions of the Martian mini-magnetospheres and at the cusp regions of the crustal magnetic fields. It also means that ENA and LENA (low energy neutral atom) detectors could be important experiments for diagnostics of the auroral process unique to Mars, which might contribute to the overall atmospheric loss budget.

► Consider the heating and acceleration of ionospheric ions in the auroral zones of Mars.
► Charge exchange of the ion conics will lead to production of suprathermal ions.
► Energetic neutral atoms of solar wind origin could be trapped and re-neutralized in the mini-magnetospheres.
► Diagnosis of such new effects can be facilitated by neutral atoms imaging detectors.