The global current systems of the Martian induced magnetosphere

Abstract:

Nearly 5 years of magnetic field measurements by NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has enabled us to map the near-Mars global quasi-steady-state (DC) current systems without the need for multiple formation-flying spacecraft. The measurements are combined to make global maps of the average magnetic field configuration of the Martian induced magnetosphere in the Mars-Sun-Electric field (MSE) reference frame, from which we derive the average DC currents using Maxwell-Ampere’s law. These are the first global empirical and quantified maps of the DC current systems in an induced magnetosphere, revealing an electrodynamic interaction between the solar wind and the Martian ionosphere that leads to the formation of the induced magnetosphere, as well as significant unexpected asymmetries in the system. We show how the interaction induces a magnetospheric convective electric field powered by generator currents at the Induced Magnetosphere Boundary and at the Bow Shock, electrodynamically coupling the solar wind to the Martian ionosphere, driving heating and atmospheric escape.