The Current Systems Formed Around Mars as a Result of a Solar Wind Driven Convective Electric Field

Unlike the Earth, Mars lacks a global magnetic dipole. Because its upper atmosphere is ionized by solar X-rays and extreme ultraviolet (EUV) radiations, the ionosphere of Mars presents a highly conductive obstacle to the flow of the magnetized solar wind plasma. The resulting interaction induces electric currents in the ionosphere which, in turn, create sufficient magnetic pressure to slow and deflect the solar wind around the bulk of the ionosphere, forming an induced magnetosphere.

NASA scientists used magnetic field measurements from the Mars Atmosphere and Volatiles EvolutioN (MAVEN) orbiter to make the first quantitative global map of the induced currents that shape the Martian induced magnetosphere. In doing so they found strong asymmetries between the north-south electric-polar hemispheres, particularly in the concentration of sunward currents, an electric connection between the planet’s ionosphere and its bow shock, as well as a twist in the global near-Mars current system. Mapping the currents reveals how the solar wind’s energy transfers into the induced magnetosphere where it powers escape of the Martian atmosphere.

Here we show visualizations of the actual and the idealized current systems that are formed as a result of a solar wind driven convective electric field. In addition, a sequence of calculated magnetic fields measured by MAVEN shown here illustrates that magnetic fields are forced to wrap around the planet by currents induced in Mars’ ionosphere.