Spacecraft and Instruments

The SMILE mission carries a suite of state-of-the-art scientific instruments enabling novel investigations. Key payloads are:

the Soft X-ray Imager (SXI) :which will spectrally map the Earth's magnetopause, magnetosheath and magnetospheric cusps;

the Ultraviolet Imager (UVI) :dedicated to imaging the auroral regions;

the Light Ion Analyser (LIA) : establish the solar wind properties (plasma parameters) simultaneously with the imaging instruments.

the MAGnetometer (MAG): establish the solar wind properties  (magnetic field parameters) simultaneously with the imaging instruments.

the Soft X-ray Imager:

SXI (Soft X-ray Imager) is a lobster-eye telescope that employs CCD detectors to image X-rays with energies from 0.2-5 keV within a wide 27 x 16 degree field-of-view (FOV).

The SXI uses micro pore optics (MPOs) in a Lobster-eye configuration. MPOs are essentially square pore microchannel plates heat slumped to a hemispherical radius of curvature.

The SXI MPOs are 4 cm x 4 cm plates with a 600 mm radius of curvature. Each plate is 1.2 mm thick with channels of width 40 μm. The channel walls are coated with iridium to enhance the reflectivity and a film of aluminium is applied to the top surface of the MPO to block optical and UV photons.

The SXI detector plane consists of two CCD devices. The CCDs are optimised for X-ray detection and enhanced radiation hardness. The CCDs expected energy resolution is ~50 eV (FWHM) at 0.5 keV and are expected to be able to detect X-ray photons between an effective energy range of ~0.15 to 2.5 keV. Above this energy the expected induced particle background will dominate the signal.

  Figure 1: CAD model of the SXI Telescope and Front End Electronics

the Ultraviolet Imager :

UVI (the Ultraviolet Imager ) is a four mirror telescope imaging ultraviolet emissions with wavelengths from 155 to175 nm using a CMOS detector. It is broken into three logical partitions: UVI-Camera (UVI-C) and UVI-Electronics (UVI-E) connected via a harness (UVI-H). The UVI optical design philosophy is based on an on-axis, 4-mirror system, optimized for the SMILE orbit and the required cadence and spatial resolution. UV filter technology coupled with the 4-mirror design provides orders of magnitude greater visible light suppression than previous auroral missions and is an enabling factor for the UVI science objectives. The detector module comprises a micro-channel plate (MCP) based image intensifier optically coupled to a CMOS detector.

Figure 2: CAD model of the UVI camera (UVI-C).

the Light Ion Analyser (LIA) :

The LIA (the Light Ion Analyser) is a top-hat analyser for detection of protons and alphas. Energy range 50 eV-20 keV. Charged particles entering the analyser will be deflected in the electric field and follow the curvature of the hemispheres to hit a position sensitive detector system comprising an annular microchannel plate (MCP) with a system of 48 radial anode segments. The ion-optical system thus acts as monochromatic detector which is sensitive to ions entering the analyser from a pre-determined direction and have an energy/charge ratio set by the applied voltage.

Figure 3:  Left panel: 3D rendition of LIA highlighting the main sub-systems. Right panel: cut-away view of the LIA electro-optical sensor. A typical path of a detected ion is shown as a red line.

the MAGnetometer (MAG):

The MAG (the MAGnetometer) employs a digital fluxgate magnetometer system consisting of two individual tri-axial fluxgate sensor heads mounted on a deployable 3 m boom. The deployable boom is mounted on the PLM on a set of PLM owned mounting brackets. The sensor heads are connected by harness to an electronics box mounted on the PLM. The electronics unit consists of a FPGA based digital processing unit, a DC/DC converter and dedicated front-end electronics for each of the magnetometer sensors.

Figure4: The MAG sensor head. Left panel: 3D rendition from CAD model. Right panel: Finished engineering model.