In the late 1990s and early 2000s, X-ray astronomers came to realise that geospace, and the wider heliosphere, emit X-rays. This was a source of frustration, as the astronomical targets of interest for these astronomers tended to be much more distant stars and galaxies. The foreground X-ray emission required quantification and characterising, in particular to aid the understanding of observations taken by large telescopes such as XMM-Newton and Chandra. This problem, however, could be turned on its head. Perhaps the X-rays emitted in the exosphere could be used to image large areas of the Earth's magnetosheath, complimenting and enhancing our current views obtained through in situ measurements? Can we track the motion of the magnetopause using this technique?
In this talk we will explore the various ideas that have led to the joint European Space Agency and Chinese Academy of Sciences SMILE mission, which is due for launch in 2023, and how both the X-ray astronomer and solar-terrestrial communities are preparing for the mission.