Solar Polar-orbit Observatory

Solar magnetic fields and related solar magnetic activities dominate the heliospheric environments from the near-Earth space, to the interplanetary space, and up to the interstellar boundary. The polar magnetic fields of the Sun and its dynamic processes are especially vital in the aspects of manifesting the internal dynamo of the Sun, and shaping magnetic fields in the heliosphere. But so far, almost all the solar satellites have been limited in the vicinity of the ecliptic plane. Due to the serious projection effect, the polar regions remain as the least-known mysterious territory of the Sun. The spacecraft of "Solar Polar-orbit Observatory (SPO)" has been designed to directly image the solar polar regions in an unprecedented way by traveling in a large solar inclination angle (>= 80 degrees) and a small ellipticity. Based on multi-band remote-sensing and in-situ measurements, the SPO will make breakthrough on the following top-level scientific objectives: (1) Provide decisive observations for solving the problem of the century-How the solar magnetic activity cycle originates that shapes the living environment of human beings; (2) provide direct observational supports for unveiling the origin, mechanism, and effect of the "primitive" high-speed solar wind that connects the Sun and celestial bodies in the solar system; (3) provide the necessary, complete, and self-consistent initial and boundary conditions for creating a data-driven global heliospheric numerical model that serves as the foundation for space weather prediction. To achieve these scientific objectives, the SPO will be equipped with six remote-sensing instruments and one in-situ instrument package. The remote-sensing instruments are Magnetic and Helioseismic Imager (MHI; FOV: 34' (full disk)/17' (high resolution); pixel resolution: 1"/0.5"; sensitivity: 10 G (longitudinal), 200 G (transverse); cadence: 15 min; sensitivity of Doppler velocity: 30 m/s; Cadence: 1 min), Extreme Ultraviolet Solar Telescope (EUST; FOV: 51'; spatial resolution: 3.5"; imaging band: 19.3, 17.1, 13.1 and 30.4 nm; cadence: 1 min), Visible-light Coronagraph (VISCO; FOV: 0.69 degrees-2.67 degrees annular; pixel resolution: 4.8"; wave band: 700 +/- 40 nm; cadence: 2 min), Very Large Angle Coronagraph (VLACOR; FOV: 2.67 degrees-24 degrees annular; pixel resolution: 45"; wave band: 600-750 nm; cadence: 10 min (white light), 60 min (polarization)), X-ray Imaging Telescope (XIT; FOV: 48'; angular resolution: 10"; energy range: Energy spectrum 0.5-10 keV; spectral resolution: 1 keV@6 keV; time resolution: 5 s (common), 1 s (burst)), and Low Frequency Radio Spectrometer (LFRS; frequency range: 10 kHz-2.0 MHz and 1.0-50 MHz; spectral resolution: <= 5 kHz@2.0 MHz and <= 0.1 MHz@50 MHz; time resolution: 1 s; dynamic range: >72 dB). The in-situ instrument package includes Solar Wind Ion Analyzer (SWIA), Solar Energetic Particles Analyzer (SEPA), and Magnetometer (MAG).