Planetary Ionospheres -Sources and Dynamic Drivers

Joseph M. Grebowsky

NASA Goddard Space Flight Center, USA

External energy inputs into all planetary upper atmospheres include combinations of solar EUV, soft x-rays, solar energetic particles, solar wind charged particles, magnetospherically accelerated particles, solar wind electric field, interplanetary dust particles as well as propagating lower atmosphere disturbances. Each input has analogous physical interactions with all planetary ionospheres and upper atmospheres but the integrated consequences of the multiple energy inputs vary from planet to planet. The Earth forms the framework for most fundamental processes because of its extensive measurements of the effects of each of the inputs. However the conditions at Earth are far different from those at the carbon dioxide atmosphere of magnetic field-free, slow-rotating Venus, the carbon dioxide atmosphere of Mars with patchy remnant magnetic fields, and the fast rotating giant outer planets with intrinsic magnetic fields, satellites within their magnetospheres and hydrocarbon atmospheres. The commonness, the differences and the still unresolved aspects of the physics of the various ionospheres (and their inseparable upper atmospheres) will be described.