Overview of the plasma environment of Mars as seen by the radar sounder on Mars Express Spacecraft

The Mars Express Spacecraft carries a radar sounder that is in its 6^th year of operation in orbit around Mars. The sounder provides both local and remote measurements of electron densities and in some cases the magnitude of the magnetic field in the Martian ionosphere. Here, we give an overview of the plasma environment of Mars as seen by the radar. Both local and remote electron density profiles are reported, including density fluctuations and gradients, magnetically controlled structures, interaction between the ionosphere and the solar wind, and holes and other structures in the nightside ionosphere.