The Solar wind Magnetosphere Ionosphere Link Explorer, or SMILE, is a joint mission between the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS). SMILE aims to build a more complete understanding of the Sun-Earth connection by measuring the solar wind and its dynamic interaction with the magnetosphere.

Although there are many spacecraft, such as Cluster, MMS, and STEREO, that constantly observe the Sun and its effect on the Earth's environment, no single mission is able to view the full Sun-Earth connection – instead they study localised processes and individual weather events. SMILE fills this gap; it will study our magnetosphere on a global scale, building a more complete understanding of the Sun-Earth connection by measuring the solar wind and its dynamic interaction with the magnetosphere.

SMILE is scheduled for launch in 2025. After launch, it will enter a highly-inclined elliptical orbit that will take it nearly a third of the way to the Moon at apogee. This orbit will allow SMILE to make clear and quasi-continuous observations of key regions in near-Earth space with both remote-sensing and in situ instruments.

IWF participates in the Soft X-ray Imager (SXI) and is Co-Investigator for the magnetometer (MAG).

Further information on SMILE is found at ESA.