Exploring Earth`s Atmospheric Escape with Small Satellites

Planetary atmospheres are subject to losses due to thermal (Jeans) escape, induced by solar radiation, but also due to non­thermal loss mechanisms. Energetic processes in the Earth’s upper atmosphere due to solar plasma activity, such as geomagnetic storms and the solar wind, produce the ring current and energetic ions that escape Earth’s gravity due to energization mediated by plasma instabilities. These processes result in heated magnetized plasma in Earths’ ionosphere, leading to preferential energization of ions such as O+, and their eventual escape from the Earth’s gravity. I will provide an overview of planetary atmospheric loss mechanisms, and present the results of theoretical models of O+ and other ion instabilities, and their thermalization, using hybrid numerical simulation method (kinetic ions and fluid electrons) of the ion ring distribution, formed in the auroral ionosphere, with a range of ring velocities and thermal to magnetic pressure ratios. The model demonstrates the development of plasma instabilities that could lead to ion heating and escape. I will present a brief overview of the new NASA mission study on Mechanisms of Energetic Mass Ejection – eXplorer (MEME­-X) a small explorer dual satellite mission aimed at probing Earth’s atmospheric escape processes.