SMILE Mission

SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) is a joint ESA (European Space Agency) and Chinese Academy of Sciences (CAS) mission to study the interaction of the solar wind with the Earth’s magnetosphere and ionosphere. The SMILE S/C (Spacecraft) payload consists of four instruments; SXI (Soft X-ray Imager), UVI (Ultraviolet Imager), LIA (Light Ion Analyser) and MAG (Magnetometer).

The University of Leicester is the PI (Principal Investigator) institution for the SXI instrument. SXI is a collaboration between three UK institutions (University of Leicester, Mullard Space Science Laboratory and the Open University) funded by the United Kingdom Space Agency (UKSA) and several European and international organisations.

SXI will investigate the dynamic interaction of the solar wind with the Earth’s magnetosphere by the detection of X-rays produced when heavy ions in the solar wind collide with neutral particles within the Earth’s exosphere. This mechanism allows the position of the boundary between the outer solar wind and the inner Earth’s magnetosphere to be tracked using global X-ray imaging. Simultaneous to the SXI measurements will be observations of the aurorae at the North Pole taken with the UVI Instrument. The LIA and MAG instruments complement these measurements by monitoring the in-situ plasma and magnetic field environments. The mission science is intended to assist the understanding of the structures and dynamics of the magnetosphere and ionosphere on a global scale, with many downstream benefits and terrestrial applications. The S/C has a highly elliptical Earth orbit, travelling from about 5,000km at perigee to 120,000km at apogee. Approximately 80% of the 52-hour orbital period is spent obtaining high altitude observations.

The design of SXI utilises years of heritage in novel light-weight micropore X-ray optics to focus X-rays on to a pair of CCD (Charge-coupled Device) detectors within a compact telescope. Notable engineering challenges for the Instrument include the sole use of European parts for all systems, cryogenic TCS (Thermal Control System) and the inclusion of a radiation shutter mechanism which is opened and closed to protect the CCDs as the S/C traverses the Van Allen Belts.

The University of Leicester delivered the Proto-flight Model (PFM) SXI to ESA in June 2024 and supported integration on to the PLM (Payload Module) at Airbus Madrid. The team will support SMILE S/C vibration and thermal test activities at ESTEC (The European Space Research and Technology Centre) in 2025, prior to shipment and launch from Kourou, which is anticipated late 2025. Post launch, we will work directly with ESA and CAS via a dedicated SXI Ground Segment Operations Centre located on our Main Campus, and will manage science observations tasking and downlink and process science data.