Space Science Seminar: Electron density bulges and solar wind intrusions: the variable Martian ionosphere

Dr Catherine Dieval, Department of Physics, Lancaster University

Wednesday 04 November 2015, 1400-1500
Cavendish Colloquium Room

At Earth and at Mars, ionospheres exist due to the ionization of the upper atmospheres by impacting radiation, primarily from solar ultraviolet photons. However, due to the different nature of the magnetic field at these two planets, their topside atmospheres interact differently with the stream of ionized particles (plasma) flowing from the Sun, the solar wind. The Earth has a global magnetic dipole (like a magnet) which protects its upper atmosphere rather well, forming a magnetic bubble often excluding the solar wind: the magnetosphere. In contrast, Mars does not have a global magnetic dipole, thus its topside atmosphere is not protected from erosion by the solar wind. However, the direct interaction of the solar wind with the Martian ionosphere leads to the formation of an (induced) magnetosphere as well. In addition, localized magnetic fields formed in the planetary crust also help to withstand the incoming solar wind. The Martian ionosphere is affected in various ways by both the solar wind mass/energy inputs and by the crustal magnetic fields. In particular, Catherine will present her work on a few of these phenomena, i.e. electron density bulges and solar wind plasma intrusions in the ionosphere. These processes are part of the present state, dry and tenuous, of the Martian atmosphere, whose fate may have been driven by solar wind erosion over billions of years.