Ionospheres are an integral part of planetary atmospheres, coupling the neutral atmosphere to the exosphere, possessing rich compositional, density, and temperature structures, and affecting neutral dynamics via Joule heating and ion drag. The ionospheres of unmagnetized bodies with substantial atmospheres are controlled not only by solar photons but also directly impacted by the surrounding plasma environment (e.g. the solar wind for Mars, Venus and comets, and the Kronian magnetosphere for Titan). This interaction affects atmospheric loss, neutral winds, photochemistry, and energy balance. This session focuses on the ionospheres of Mars, Venus, Titan, and comets such as 67P/CG, and solicits abstracts concerning remote and in situ data analysis, modeling studies, instrumentation and mission concepts. Topics may include, but are not limited to, day and night side ionospheric variability, sources and influences of ionization, ion-neutral coupling, current systems, comparative ionospheric studies, and solar wind-ionosphere interactions. Abstracts on general plasma processes and escape are also welcome.