ملف:Smile spacecraft during a test of the magnetometer boom deployment ESA25354924 (cropped).jpg

English: Smile will study Earth’s magnetic environment (its magnetosphere) on a global scale, building a more complete understanding of the Sun-Earth connection. It will do this by observing the flow of charged particles streaming out from the Sun into interplanetary space (the solar wind) and exploring how these interact with the space around our planet.
Smile's magnetometer boom is the long black protrusion on the left of the spacecraft. To counteract gravity, it is being held up by balloons - a solution that won't be necessary in the zero-gravity environment in space!
The boom will be folded up during launch, before deploying in space to a total length of 3 m. The magnetometer instrument will measure the strength and direction of magnetic fields around the Smile spacecraft to help us understand how the solar wind affects Earth’s magnetosphere and therefore our planet as a whole.
Smile is a joint mission between ESA and the Chinese Academy of Sciences. ESA is providing Smile’s payload module, which carries the scientific instruments, the payload module equipment control unit and the communication channel that downlinks all the science data to the ground.