The Solar Polar Constellation (SPOC) Mission: Combining Operational Full-Sun Magnetic Field Measurements with Polar Exploration

One of the fundamental gaps in our ability to accurately model the solar coronal magnetic field and solar wind acceleration is the lack of magnetic field "boundary conditions" over the full Sun. Current observing platforms can only measure the solar magnetic field over a portion of the Earth-facing hemisphere, forcing us to rely on solar rotation to build up fictional ``synoptic maps'' of the full-Sun field over 27-days. In addition, views restricted to the Ecliptic plane cannot accurately measure the crucial polar regions that control coronal hole formation. The resulting errors in background solar wind predictions contribute directly to our inability to accurately forecast G1—G3 geomagnetic storms from coronal hole High-Speed Stream (HSS) events and Co-rotating Interaction Regions (CIRs). In addition, background solar wind speed errors are a significant contributor to errors in arrival time forecasts for Coronal Mass Ejections (CMEs) that can cause the most severe G4—G5 geomagnetic storms. To improve operational solar wind and CME forecasting, we need to measure the magnetic field of the entire Sun on time-scales on the order of one day. We propose a novel constellation of small satellites called the Solar Polar Constellation (SPOC) that will rapidly obtain magnetic field and doppler velocity measurements over the entire solar photosphere, including direct overhead measurements of the polar regions. The SPOC constellation will consist of four identical satellites placed into 90-degree inclination circularized heliocentric orbits using Jupiter gravitational assist trajectories. The SPOC magnetograph is a compact doppler imaging magnetograph instrument based on the Solar Dynamics Observatory (SDO) Helioseismic and Magnetic Imager (HMI) instrument. The 3-axis stabilized platform will also be suitable for coronagraph, heliospheric imager, or EUV imagers and photometer instrumentation, as well as in-situ magnetic field and solar wind plasma instruments. Optical communications will ensure a high data rate with low-latency to satisfy operational requirements. The SPOC mission follows the model of "hybrid operational-research" missions developed by the CU Space Weather Technology, Research, and Education (SWx-TREC) to enhance utility and collaboration by developing critical operational data sources for space weather forecasting that can also produce high-quality scientific research.