Towards a Generalized Understanding of Ion Escape: Lessons from Measurements in the Solar System and Expectations Beyond

Over the course of the past 3 decades, a number of orbiters have been sent to and used to investigate atmospheric ion escape from the terrestrial planets of the solar system, revealing widely varying effects of upstream drivers (solar wind, EUV, IMF), depending on the planet. These diverging behaviors are likely a consequence of the varying intrinsic properties of each body, e.g. gravity, size, atmospheric profile and magnetization. We review and compare the investigations undertaken with missions such as Phobos-2, Cluster, Mars Express, Venus Express and MAVEN to show how the results from these missions can inform our understanding of ion escape as a general phenomenon affecting the evolution of planets orbiting stars.