In this splinter, we discuss what should be measured to fully understand the atmospheric escape from the Earth, as a preparation for future space mission proposals such as ESA M5.

What ion species should we and can we measure at different energy?
What kind of field measurement should we need?
What is expected isotope ratio for different escape mechanisms or for different source altitude?
What kind of exospheric and upper ionospheric parameters should we measure?
What kind of simulation should we need for the above diagnosis?

There are many observations on the atmospheric escape from the Earth, e.g., total amount of non-thermal ion escape and correlation studies with local geomagnetic field and limited magnetospheric and solar parameters. However, these studies are mainly limited to proton and oxygen, and more importantly the exact source conditions and acceleration profiles for such non-thermal escape is not well understood. Recent Mars studies proved that exosphere plays important role. This indicates that energization of ions for escape can be started at both low and high altitude, and that we need to understand exosphere to fully understand the exosphere even for ion escape. Everybody is welcome.