The Soft X-ray Imager (SXI), part of the Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission, is a wide-field X-ray telescope designed to spectrally map Earth's magnetospheric boundaries using micropore optics. Led by the University of Leicester, the project involves collaboration with the Mullard Space Science Laboratory (MSSL), the Open University, and several European institutions. UK engineers provided key components, including the main telescope assembly, X-ray optics module, and advanced X-ray detector system.

The SXI is the first instrument to be completed at Space Park Leicester, where the Assembly, Integration, and Test (AIT) Team assembled it in a purpose-built cleanroom. Following extensive testing to withstand the harsh space environment, the final flight model was delivered to Airbus Defence and Space in Madrid for integration onto the European Space Agency (ESA) platform.

The SMILE mission, a collaboration between ESA and the Chinese Academy of Sciences (CAS), aims to study the interaction between the solar wind and Earth's magnetic field. Scheduled for a September 2025 launch on an ESA Vega-C rocket from Kourou, French Guiana, the mission will undergo system tests at the European Space Technology Centre (ESTEC) in the Netherlands before the final spacecraft integration.

Dr. Steven Sembay, SMILE SXI Principal Investigator at the University of Leicester, stated, "SXI is a powerful but compact X-ray telescope that has been challenging to design within the constraints on size and mass and the space environment imposed by the SMILE mission. It has been a real team effort to meet and get past all these challenges and is a testament to both the technical skill of our University-based engineers here in the UK and the great collaborative atmosphere all across our international consortium."

Dr. Jennifer Carter from the University of Leicester School of Physics and Astronomy added, "Our Earth is protected from the solar wind by its magnetic field, which acts like a shield. SMILE will transform our understanding of this highly dynamic magnetosphere. SXI will image this magnetic shield, whilst a different camera will take ultraviolet pictures of aurora in the Northern Hemisphere. For the first time ever, we will see how changes to this shield cause effects in the upper atmosphere at the same time."

Dr. Colin Forsyth from Mullard Space Science Laboratory, the SMILE Co-Principal Investigator at the Mission level, emphasized, "SXI is crucial to the innovative observations that SMILE will provide, enabling us to reveal the invisible structures and processes around Earth, so it is very exciting to see this key instrument ready to go."

Dr. Caroline Harper, Head of Space Science at the UK Space Agency, noted, "This is a major milestone for Space Park Leicester and a huge achievement for the University of Leicester who led this international team to develop the cutting-edge instrumentation for SMILE, that will help us to understand more about the solar wind and how space weather can impact Earth. Space weather was responsible for the beautiful auroras that got the whole of the UK staying up, and looking up, in May 2024. It also brings potential risks such as radio blackouts, disruptions to satellites, and power grid failures. So it is vital we build our understanding and gain new insights into the solar winds that bombard our planet's magnetosphere."

The UK Space Agency has supported this instrument's development with approximately Pounds 13 million in funding, furthering its mission to invest in advanced technologies and world-class science for the benefit of Earth's citizens.

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