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No early than January 2026
In testing
Highly elliptical orbit around Earth
Heliophysics observatory
Thanks to its wide-field X-ray and ultraviolet vision, Smile will be the first mission to get a truly global picture of the interaction between the Sun and Earth. Although several spacecraft have observed the effects of the solar wind and coronal mass ejections on Earth's magnetic shield, they have mostly studied local processes and individual space weather events – making them ‘detail-oriented’ missions. In contrast, Smile will take a holistic view on those phenomena, and be the first mission to build a truly global picture of the interaction between the Sun and Earth.
Animation of the Smile spacecraft deployed in space. Credit: ESA/Lightcurve Films.
We want to unveil the Earth’ magnetic field by addressing the following key questions:
Examine solar wind-magnetosphere interaction:
What happens where the solar wind meets Earth’s magnetic shield?
Investigate magnetospheric dynamics:
What causes magnetic glitches on the dark side of Earth?
Forecast space weather:
How can we predict the most dangerous space weather threats in advance?
Smile will use X-ray imaging, ultraviolet observations, and in-situ plasma measurements to study the interactions between the solar wind and Earth's magnetosphere. Equipped with four instruments, it will make clear and near-continuous observations of key regions in near-Earth space. By combining remote sensing and in situ data, Smile will reveal how space weather affects Earth's magnetic environment.
Credit: ESA. Instruments list: In-situ – Light Ion Analyser (LIA), Magnetometer (MAG) and Remote sensing – Soft X-ray Imager (SXI), UltraViolet Imager (UVI)
Smile builds on the legacy of ESA’s Cluster and Double Star missions, which pioneered in-situ studies of Earth’s magnetosphere, and ESA's XMM-Newton which observed astronomical objects in x-rays. Cluster provided 3D views of magnetospheric structures, while Double Star, a collaboration with China, focused on solar wind interactions. Smile will take this further by delivering the first global X-ray and UV images of the magnetosphere simultaneously.
Smile during electromagnetic compatibility testing in the Maxwell Test Chamber at ESTEC. Credit: ESA–M.Roos.
Smile is a joint mission between ESA, which provides the payload module and the launcher, and the Chinese Academy of Sciences (CAS), which provides the platform. European and Chinese scientific institutions are collaborating on instrument development and will collaborate on data analysis. ESA selected Airbus as prime contractor for the construction of the satellite.
The scientific idea behind Smile’s ability to image Earth’s magnetosphere traces back to the work of Professor Lisse. In the early 1990s, while working on the X-ray astronomy mission ROSAT, he proposed an unexpected experiment. A newly discovered comet, Hyakutake, was predicted to pass very close to Earth in 1996 and become one of the brightest comets seen from our planet. Prof. Lisse suggested pointing ROSAT at the comet to check whether its coma or tail might emit X-rays. Surprisingly, ROSAT detected X-rays, but not where they were expected. Instead of trailing the comet, the emission appeared in a bow shape ahead of it. A year later, this was explained by a process called solar wind charge exchange – the very same principle Smile will use to image Earth's magnetosphere.
Explore a subset of the ESA Science Programme missions here. Additional mission pages are in progress.
The currently available mission pages are ESA's flagship missions launched from 2013 and to be launched (L-class), and the ones in development (M- and F-class).
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