Whitepaper #351 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: basic research. Additional topics: planetary ionospheres / upper atmospheres; space-based missions/projects.
There is a need to advance our understanding of the Lower Thermosphere-Ionosphere and of the neutral-plasma interactions that shape it. A mission that provides comprehensive in situ measurements down to altitudes where ion-neutral interactions maximize (120 km or lower) is feasible and mature, and will explore, for the first time, the dominant processes in the atmosphere-space transition region.