SMILE's payload consists of two imaging instruments – the wide field of view soft X-ray imager (SXI) and an auroral ultraviolet imager (UVI) – and an in situ measurement package working in conjunction with the imagers to explore the properties of the solar wind. This package, built using knowledge and experience gleaned from past missions including ESA's Cluster and ESA-CNSA Double Star fleets, contains a light ion analyser (LIA) and a magnetometer (MAG).


SXI – Soft X-ray Imager
The SXI is a wide-field lobster-eye telescope using micropore optics to spectrally map the location, shape, and motion of Earth's magnetospheric boundaries, including the bow shock, magnetopause, and cusps, by observing emission from the solar wind charge exchange (SWCX) process. The SXI is equipped with two large X-ray-sensitive CCD detectors covering the 0.2 keV to 5 keV energy band, and has an optic field of view spanning 16° × 27°.
Contributions: Developed, built, and calibrated at the University of Leicester, UK, and other institutions throughout Europe. Specific software developed in partnership with NSSC. CCDs procured from e2v, UK by ESA.
UVI – UltraViolet Imager
The UVI is an ultraviolet camera to image Earth's northern auroral regions. It will study the connection between the processes taking place in the magnetospheric boundaries – as seen by the SXI – and those acting on the charged particles precipitating into our ionosphere. The UVI is a CMOS-based camera centred on the 155-175 nm waveband, with a 10° × 10° field of view. It will have a spatial image resolution at apogee of 100 km, and will use four thin film-coated mirrors to guide light into its detector.
Contributions: A joint venture between the University of Calgary (Canada), the Chinese National Space Science Centre, CAS, the Polar Research Institute of China (PRIC), and Centre Spatial de Liège (CSL), Belgium.
LIA – Light Ion Analyser
The LIA will determine the properties and behaviour of the solar wind under various conditions by measuring the three-dimensional velocity distribution of solar wind ions. It is a top-hat-type electrostatic analyser. It is capable of sampling the three-dimensional distribution of the solar wind, and can measure ions in the energy range 0.2 to 20 keV with a field-of-view of 360° in azimuth, and +/- 45° in elevation.
Contributions: A joint venture between the Chinese National Space Science Centre, CAS, and University College London's Mullard Space Science Laboratory (UCL-MSSL), UK.
MAG – Magnetometer
The MAG will be used to determine the orientation and magnitude of the solar wind's magnetic field, and to detect any solar wind shocks or discontinuities passing over the spacecraft. Two tri-axial sensors will be mounted away from the spacecraft on a 2.5-m-long boom some 80 cm apart, with a corresponding electronics unit mounted on SMILE's main body. This configuration will let the MAG act as a gradiometer, and allow SMILE's background magnetic field to be accurately determined and subtracted from any measurements. MAG will measure the three components of the magnetic field in the range +/- 9600 nT.
Contributions: A joint venture between the Chinese National Space Science Centre, CAS, and the Space Research Institute, Austrian Academy of Sciences.