ESA and China's SMILE Spacecraft Arrives at Launch Site for April Liftoff to Map Earth's Magnetic Shield in X-Rays

The Solar Wind Magnetosphere Ionosphere Link Explorer, known as SMILE, arrived at Europe’s Spaceport in Kourou, French Guiana on February 26 after a two-week voyage aboard the Maritime Nantaise Colibri cargo ship. The 2,300-kilogram spacecraft is now undergoing final health checks and propellant loading ahead of a launch window that opens on April 8 and closes on May 7.

SMILE is a joint mission between the European Space Agency and the Chinese Academy of Sciences, the first to be jointly designed, built, launched, and operated by the two agencies. It will ride to orbit atop a Vega-C rocket, the four-stage European launcher whose third stage, the Zefiro-9 with 10 tonnes of solid propellant, was prepared for stacking at the launch pad on March 2.

First X-Ray View of the Magnetosphere

The mission’s central scientific contribution is its Soft X-ray Imager, or SXI, which will capture the first-ever images of Earth’s magnetosphere in soft X-rays. When the solar wind, a continuous stream of charged particles from the Sun, collides with Earth’s magnetic field, the interaction produces faint X-ray emissions through a process called solar wind charge exchange. Until now, the magnetosphere’s large-scale structure has been mapped only by constellations of point-measurement satellites. SMILE will produce wide-field images that show the entire boundary in a single frame.

The spacecraft carries four instruments totaling 70 kilograms. In addition to the SXI, it is equipped with an Ultraviolet Aurora Imager that will continuously photograph the northern and southern aurorae, a Light Ion Analyser with two sensors for measuring solar wind particles, and a Magnetometer mounted on a deployable three-meter boom.

Orbit and Operations

SMILE will enter a highly elliptical, highly inclined orbit that takes it to an apogee of 121,000 kilometers above the North Pole, roughly one-third of the distance to the Moon, and a perigee of 5,000 kilometers above the South Pole. This geometry will allow the spacecraft to image the magnetosphere’s dayside boundary for up to 40 continuous hours per orbit, far longer than any previous mission.

The nominal mission duration is three years, during which SMILE will address three questions identified in ESA’s Cosmic Vision programme: what happens at the boundary where the solar wind meets Earth’s magnetic shield, what triggers magnetic disturbances on the planet’s nightside, and how dangerous magnetic storms can be predicted earlier.

“Building on the 24-year legacy of our Cluster mission, which ended science operations last year, SMILE is the next big step in revealing how our planet’s magnetic shield protects us from the solar wind,” said ESA Director of Science Carole Mundell when the mission passed its qualification and flight acceptance review in November 2025.

Timing Aligned with Solar Maximum

The launch window coincides with the current solar maximum, a period of heightened solar activity that produces more frequent and intense solar storms. Mundell noted that the timing offers ideal scientific conditions, as more energetic solar wind events will produce stronger X-ray signals and more dynamic magnetospheric responses for SMILE to observe.

The mission builds on decades of European magnetospheric research. ESA’s Cluster mission, a constellation of four spacecraft launched in 2000, spent 24 years making in-situ measurements of the magnetosphere before ending science operations in 2024. Where Cluster provided detailed point measurements along the spacecraft trajectories, SMILE will deliver global images that capture the magnetosphere’s behavior as a whole system, a perspective that has long eluded space physicists.

SMILE’s remaining preparation steps in Kourou include a comprehensive health check to confirm the spacecraft was not damaged during its ocean crossing, the loading of 1,500 kilograms of hydrazine propellant, and integration with the Vega-C launch vehicle. If the April 8 target is met, first science data could arrive within months of launch.