The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission, a collaborative effort between the European Space Agency (ESA) and China, successfully launched into orbit. The Vega C rocket lifted off at 11:52 p.m. Eastern on May 18 (0352 UTC, May 19) from Kourou, French Guiana. The spacecraft separated from its launch vehicle approximately 57 minutes after liftoff, followed by the successful deployment of its solar arrays.
The SMILE mission is designed for a planned three-year duration to study the interaction between Earth’s magnetosphere and solar storms. This research aims to improve the prediction of space weather impacts. The 2,200-kilogram spacecraft, which includes 1,500 kg of propellant, was initially launched into a 706-kilometer orbit inclined at 70 degrees. Over the next month, SMILE will utilize about 90 percent of its propellant to reach its highly elliptical science orbit.
Mission Objectives and Technology
SMILE will achieve an apogee of approximately 121,000 kilometers above the North Pole, offering a unique global perspective of Earth’s magnetosphere.
This view will be captured using its wide-angle X-ray SXI and UVI ultraviolet cameras. Data will be downlinked to DLR’s O’Higgins Antarctic ground station during passes over the South Pole, at a perigee of about 5,000 km. The highly elliptical orbit will also enable SMILE to conduct 45 hours of continuous aurora observations during each 51-hour orbital period.
Wang Chi, director general of the National Space Science Center (NSSC), stated that SMILE will provide the first images of the magnetopause, a magnetic field acting as a shell for Earth. Previous missions offered only local measurements of these dynamics. Wang noted that imaging the magnetopause as solar activity varies will allow scientists to study its movement and how mass and energy are transported from the solar wind, which is crucial for space weather prediction.
International Collaboration and Instruments
The SXI, developed by the UK’s Leicester University, incorporates lobster-eye optics and some of the largest CCDs ever used in space, cooled to minus 120 degrees Celsius.
The SMILE mission was jointly developed by the European Space Agency and the Chinese Academy of Sciences (CAS). It was selected in 2015 from 13 proposals submitted by joint ESA-CAS teams. The spacecraft carries four scientific instruments: the soft X-ray imager (SXI), the ultraviolet imager (UVI), an in-situ ion analyzer, and magnetometer instruments.
The SXI, developed by the UK’s Leicester University, incorporates lobster-eye optics and some of the largest CCDs ever used in space, cooled to minus 120 degrees Celsius.
This instrument focuses on solar wind charge exchange emission, which occurs when highly charged solar wind ions interact with neutral atoms. The combination of imagers and in-situ payloads will provide both global response views and simultaneous measurements of the particles driving these phenomena. ESA science director Carole Mundell emphasized the mission's importance for understanding cause and effect, particularly given modern life's reliance on space infrastructure.
The mission experienced delays due to component changes following an export control assessment in 2020 and disruptions from the COVID-19 pandemic. Despite these challenges, both agencies highlighted the success of their partnership. Mundell commented on the collaborative learning process, stating, “Not only have we learned to speak one another's languages, we've also learned to speak different languages of engineering, different ways of doing science, and we've learned from one another along the way.” This launch marked the seventh flight for the Vega C rocket and the first instance where Italian company Avio assumed the role of launch operator.
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