Solar wind-Magnetosphere-Ionosphere Link Explorer



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 2.5 keV energy band, and has an optic field of view spanning 15.5° × 26°.


Contributions: Developed, built, and calibrated at the University of Leicester, UK, and other institutions throughout Europe. 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 (top figure) centred on the 160-180 nm UV waveband, with a 10° × 10° field of view. It will have a spatial image resolution at apogee of 150 km, and will use four thin film-coated mirrors to guide light into its detector. Temporal resolution will be up to 60 s. The UVI electronics box is shown in the bottom picture on the right side.

Contributions: A joint venture between the Chinese National Space Science Centre, CAS, the Centre Spatial de Liège (CSL), Belgium, ESA , the University of Calgary (Canada) and the Polar Research Institute of China.
LIA – Light Ion Analyser

The LIA will determine the properties and behaviour of the solar wind and magnetosheath ions under various conditions by measuring the three-dimensional velocity distribution of protons and alpha particles. It is made of two top-hat-type electrostatic analysers, each mounted mounted on opposite side of the platform. It is capable of sampling the full 4 π three-dimensional distribution of the solar wind, and can measure ions in the energy range 0.2 to 20 keV at up 0.5 second time resolution.


Contributions: A joint venture between the Chinese National Space Science Centre, CAS, and University College London's Mullard Space Science Laboratory (UCL-MSSL), UK, and LPP/CNRS/Ecole Polytechnique, France.

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 3-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 +/- 12800 nT.


Contributions: A joint venture between the Chinese National Space Science Centre, CAS, and the Space Research Institute, Austrian Academy of Sciences.