Recent progress of the Solar Wind Magnetosphere Ionosphere Link Explorer (SMILE) mission

SMILE is a single spacecraft mission consists of two main elements: a 3-axis stabilized Platform (PF), consisting of a Service Module (SVM) and a Propulsion Module (PM) that provides the spacecraft resources, will raise the orbit from the Launcher insertion orbit to the scientific Highly Elliptical Orbit (HEO). It also hosts the two LIA sensors to enable them to far a combined full-sky field of view.  The Payload Module (PLM) hosts the other three science instruments, SXI, UVI and MAG, the equipment and instrument control unit, and the X-band science downlink subsystem.

 

A New mechanism for driving planetary magnetosphere convection: Plasma convection induced by the interaction between planetary magnetic fields and the impinging solar wind is a fundamental and prominent feature of planetary magnetosphere dynamics. A global-scale pattern of magnetospheric convection in Earth’s magnetosphere, known as the Dungey cycle, provides basic understanding of solar-wind-magnetosphere coupling and has been used to explain day-to-day convection processes. In the Dungey cycle, reconnection between the IMF and the magnetosphere drives the convection of open magnetic field-lines through the polar cap and magnetotail lobes, whereas nightside reconnection closes this open flux and drives the convection of closed field-lines through the magnetosphere and back to the dayside. The dynamics of magnetosphere convection are crucial in the occurrence of geomagnetic storms and substorms. Differing from Dungey cycle, Dai et al provide direct evidence supporting a scenario whereby reconnection on the dayside enhances the Region 1 and Region 2 current systems, resulting in enhanced convection within the closed magnetosphere towards the dayside as well as the expected convection of open field-lines towards the nightside. This new finding was published in Nature communications with the title of “Global-scale magnetosphere convection driven by dayside magnetic reconnection”, and was featured on the homepage and cover of the Nature Communications official website. This important finding provides valuable insights into the mechanisms driving planetary magnetosphere convection, which may be tested by the observation of the upcoming SMILE mission.

 

The SMILE Modelling Working Group (MWG) provides modeling supports for the SMILE mission, such as Magneto-Hydro-Dynamical (MHD) model comparison, validation of the SXI requirements and goals, boundary tracing from simulated SXI data, and the development of techniques to reconstruct the 3D magnetopause from X-ray images. The main progress of MWG has been published recently in the journal Earth and Planetary Physics (EPP) as a special issue

 

The PF structure is a stacked structure, combining the PM structure, comprising a large Carbon Fiber Reinforced Polymer (CFRP) primary structure and four propellant tanks, and the cubical-shaped SVM structure, featuring several honeycomb panels and CFRP frames. There are two solar arrays mounted on the SVM +Y and -Y lateral panels. The assembly of SVM and PM flight models has now been completed.

 

 

SXI will use novel soft X-ray imaging technology to obtain global images of the large-scale structures of the magnetosheath for the first time. This is critical to understand the key features of magnetospheric global dynamics. SXI consists of a main telescope, an SXI electronics box and the front-end electronics. The telescope uses a Lobster-eye technique based on micropore optics to focus the X-rays onto the two very large CCD arrays located on the focal plane. The focal plane is protected from potential radiation damage by a shutter mechanism. Fig. 5 shows the SXI Telescope Proto-Flight Model (PFM) during vibration Test conducted at Rutherford Appleton Laboratory (RAL) Space. SXI is now going through its PFM Qualification and Acceptance Review (QAR) and will be delivered to Airbus shortly thereafter.

 

UVI will capture global images of the northern hemisphere auroras with high spatial resolution. UVI consists of two key sub-assemblies: the optical module (UVI Camera, UVI-C), which is the heart of the instrument; and the electrical control unit (UVI-E). Following programmatic difficulties in 2021, the responsibilities for the development of this instrument, originally led by the Canadian Space Agency, was taken on by CAS with contributions by ESA. This caused a delay in the development of UVI, however, CAS and ESA are doing their utmost to minimize the schedule impact. The UVI-C Qualification Model (QM) has completed delivery acceptance testing, and QM Pre-Shipment Review (PSR) will follow. The FM of UVI will be tested at acceptance levels, calibrated, and delivered to ESA by September 2024.

 

The MAG instrument will measure the in-situ magnetic field using a digital fluxgate magnetometer system consisting of two individual tri-axial fluxgate sensor heads mounted on a 3-meter-long deployable boom. In March 2024, MAG FM passed the QAR and PSR organized by CAS and ESA. It has now been delivered to Airbus, which is the first instrument of SMILE that has been delivered to ESA.

 

Two identical LIA sensors are designed on the basis of a top-cap electrostatic analyser for large dynamic flux range, wide Field of View (FOV) and high-resolution ion measurement. Since each LIA has 2π FOV, a large 4π FOV for the ion measurement can be achieved overall by the two LIAs. The FMs of LIA have been calibrated at the National Space Science Center (NSSC) and further calibration will take place at the Mullard Space Science Laboratory (MSSL) in August 2024. LIA has now completed its QAR.

 

The Ground Segment (GS) of the SMILE mission will be jointly established by CAS and ESA. The ground segment responsibilities and operation principles for CAS are: Science Operations, Mission Operations, Telemetry, S-band Tracking and Command (TT&C) ground stations, X-band payload data communication station. The ground segment responsibilities and operation principles for ESA are: Science Operations, S-band TT&C ground stations, X-band payload data communication station.

 

SMILE will be launched by a Vega-C rocket provided by ArianeSpace. The fit check with the satellite and the Launch vehicle adapter has been conducted at the beginning of 2023 in ESTEC. The mechanical interface with the satellite has been confirmed. In April 2023, ESA signed a launch agreement with ArianeSpace, with a launch window now expected between September 2025 to September 2026.

 

Based on the status of the instruments, PLM and PF CDRs, the joint Mission CDR was completed successfully in June 2023 in Shanghai, which is the fourth joint review of the SMILE mission, marking the kick-off of Phase D activities. Currently, the SMILE mission is going through Phase-D, the final Flight Model (FM) assembly and testing phase. FMs of MAG, LIA, SXI and QM of UVI have been completed and will be integrated on the PLM. The FM of PF is under Assembly, Integration and Tests (AIT) and will be shipped to ESA for integration with the PLM in September 2024. The schedule remains challenging, but all work progresses smoothly. It is expected that the SMILE mission will be launched in the last quarter of 2025.

 

 

 

See the article：

Recent Progress of the Solar Wind Magnetosphere Ionosphere Link Explorer (SMILE) Mission

https://doi.org/10.11728/cjss2024.04.2024-yg18

https://www.cjss.ac.cn/cn/article/doi/10.11728/cjss2024.04.2024-yg18

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