SMILE is a space  mission which aims to measure Earth's global system responses to solar wind and geomagnetic variations.

SMILE will investigate the dynamic reponse of the Earth's magnetosphere to the impact of the solar wind in a unique manner, never attempted before: it will combinne soft X-ray imaging of the Earth's magnetopause and magnetospheric cusps with simultaneous UV imaging of the Northern aurora. For the first time we will be able to trace and link the processes of solar wind injection in the magnetosphere with those acting on the charged particles precipitating into the cusps and eventually the aurora. SMILE will also carry in-situ instrumentation to monitor the solar wind and magnetosheath plasma conditions, so that the simultaneous X-ray and UV images can be compared and contrasted directly, and self-sufficiently, with the upstream and local driving conditions. With its unparallelled payload SMILE will provide answers to many of the open questions in solar-terrestrial relationships in a thoroughly novel way. 

SMILE was put forward in March 2015 in response to the European Space Agency and Chinese Academic of Sciences joint call for a small-size space mission. Out of 13 missions originally proposed,SMILE was the one chosen for an initial study phase during the summer of 2015. An initial study of the whole mission was carried out by ESA and CAS at their Concurrent Design Facilites during October 2015, and the conclusion was that the mission is feasible, with no show stoppers. In early November 2015 SMILE was formally selected by the ESA Science Programme Committee. Launch is expected to take place in 2025.

Scientists and engineers from the UK,China, Canada, several European countries and the US are collaborating in order to make SMILE a reality.