China-Europe joint SMILE mission begins science operations

The landmark China-Europe joint mission, the Solar wind Magnetosphere Ionosphere Link Explorer (SMILE), has officially entered science operations following a comprehensive in-orbit commissioning review. This marks a significant milestone in humanity's efforts to understand the dynamic interactions between the Sun and Earth's magnetic environment.

Jointly developed by the Chinese Academy of Sciences and the European Space Agency, the mission also unveiled on Wednesday its first batch of observation images and geophysical data collected by the satellite's four onboard scientific instruments.

The Earth's magnetosphere is a vast, invisible "umbrella" that shields the planet from high-speed charged particles known as the solar wind. Their interaction at the dynamic magnetospheric boundary — the very first gateway for solar wind energy to enter near-Earth space — can trigger severe space weather events, threatening satellites, navigation systems, communication links and power grids, especially in high-latitude regions. Understanding this boundary's behavior is central to reliable space weather forecasting, with the SMILE mission designed to achieve the first-ever global imaging of this critical frontier.

Launched on May 19 from Europe's Spaceport in Kourou, French Guiana, aboard a Vega-C rocket, the satellite reached its science orbit on June 20 after about a month of orbital maneuvers. Since then, the payload module and all scientific instruments have been activated in turn, completing in-orbit checkout and calibration, and have started delivering valid scientific data as expected.

The satellite is operating normally, with all functions and performance targets verified. The CAS team independently carried out payload module operations, paving the way for the first-ever global imaging of solar wind-magnetosphere interactions and real-time observation of the coupling process. Both parties commended the collaboration and expressed full satisfaction with the commissioning results.

Among the first batch of released data, the Ultraviolet Auroral Imager (UVI) stands out as one of the mission's most anticipated achievements. Unlike previous aurora-monitoring payloads that were limited by narrow fields of view or short observation windows, SMILE's UVI can operate continuously for up to 44 hours with a temporal resolution of 5 seconds.

Switched on July 16, the instrument has already produced the world's first uninterrupted panoramic view of the northern aurora, capturing not just broad auroral oval structures but also the fine, fast-changing features that reveal how energy from the solar wind cascades down into Earth's upper atmosphere.

For the Soft X-ray Imager (SXI), the first instrument of its kind ever built for dedicated Earth observation from orbit powered on June 27, the first test image of a supernova remnant in the Large Magellanic Cloud about 160,000 light-years away demonstrated the well functioning of the instrument. Initial data indicate some stray light effects, which the joint team is actively addressing through instrument tuning and software updates.

The other two in-situ payloads have returned unprecedented high-resolution measurements at these extreme orbital altitudes. The Magnetometer (MAG) was activated on June 27 to measure magnetic fields in the solar wind and magnetosphere, a key parameter linking the solar wind, magnetosphere, and ionosphere. After completing its critical boom deployment, the MAG experienced a dramatic reduction in instrumental noise and achieved a final resolution better than 0.1 nT, enabling it to detect subtle solar wind variations.

The Light Ion Analyzer (LIA), activated on June 30, has delivered three-dimensional ion distribution maps across the energy range of 10 eV to 25 keV. These data are consistent with typical ion beam distributions, providing critical input for understanding the ion environment along SMILE's orbit and assisting in the interpretation of SXI and UVI images.

Both sides said the successful entry into science operations marks a new chapter in China-Europe space science cooperation and promises major advances in understanding solar wind-magnetosphere interactions and improving space weather prediction.