Due to launch on December 7th, the mission will aim to cover the area where the Earth's atmosphere thins into space: NASA’s ICON Explores the Boundary Between Earth and Space
While possibly not a mission most people will get excited about, the NASA piece goes into some detail about the problem of defining where the atmosphere ends, and where space begins - and how little we actually know about the ionosphere.
While possibly not a mission most people will get excited about, the NASA piece goes into some detail about the problem of defining where the atmosphere ends, and where space begins - and how little we actually know about the ionosphere.