The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE), a collaborative mission between the Chinese Academy of Sciences (CAS) and the European Space Agency (ESA), was launched by a Vega-C rocket from Europe's Spaceport in French Guiana on Tuesday.

The satellite has entered the preset orbit with its solar panels deployed, marking a success for the launch mission.

The SMILE mission is China's first mission-level, comprehensive deep cooperation space science exploration mission with the European Space Agency, and also serves as the culminating mission of the Chinese Academy of Sciences' Strategic Priority Program on Space Science (Phase II).

The core mission of the satellite is to perform comprehensive soft X-ray imaging of Earth's outermost magnetosphere, revealing the processes and physical mechanisms of solar wind interactions with Earth.

Solar wind, a high-speed plasma flow from the sun, can trigger space weather events such as geomagnetic storms and substorms during intense solar activity. Such space weather events can directly threaten the safety of orbiting satellites, the accuracy of navigation systems, the stability of communication links and the operation of power grids in high-latitude regions. Earth's magnetosphere acts as a natural shield against the solar wind, protecting the planet like an outer shell. Understanding the coupling mechanisms between the solar wind and the magnetosphere is essential to mitigating these adverse effects.

The SMILE satellite carries four scientific instruments. The soft X-ray imager and ultraviolet imager are the two core imaging devices. They can capture global soft X-ray images of the Earth's magnetopause and cusps, while also monitoring auroral activity to show the dynamics of magnetospheric boundaries and auroral evolution. The other two instruments – the magnetometer and light ion analyzer – conduct in-situ measurements, which will monitor in real time the solar wind ion properties, magnetic field variations, and the ion and magnetic environment at the magnetospheres boundaries. They can precisely capture dynamic changes in matter and energy in the space environment.

The CAS and ESA have carried out in-depth collaboration in development, launch and mission monitoring, and data sharing, setting a model for China-Europe space cooperation and a new benchmark for international collaboration in space science.

As planned, after reaching orbit, the satellite will arrive at its observation orbit after about 42 days of orbital maneuvers, followed by in-orbit testing for two months. It will then enter a three-year regular science observation period.

The satellite's long-term, stable data is expected to fundamentally advance the understanding of solar wind-magnetosphere interactions and the mechanisms of space weather, providing critical support for improving space weather forecasting accuracy and ensuring near-Earth space safety.