Electrodynamic currents in near-Mars space

The solar wind interaction with Mars, lacking a global magnetic field, directly impacts its ionosphere, inducing currents to deflect the interplanetary magnetic field (IMF). These currents ultimately drive part of the atmospheric ion loss to space. This study estimates and characterizes these currents using MAVEN data over a long period, examining the influence of crustal magnetism and solar wind activity. Spherical polar magnetic field maps and Ampère's law are used to calculate current densities. Our analysis also considers both the absence of the south pole's crustal fields in order to obtain the “pure” ionospheric current system.  Separately, we also study the effects of varying solar wind dynamic pressure. Results show current structures at the induced magnetosphere boundaries, closing in the ionosphere with hemispheric and dawn-dusk asymmetries, as in previous related studies. In areas where crustal magnetic fields are weaker, the IMF generally penetrates deeper. For the first time, we estimate variations in the induced current system due to solar wind pressure changes, showing that when the dynamic pressure rises the magnetosphere contracts and intensifies the currents closer to Mars. Finally, we comment on these results in the context of the potential future exploration of Mars.