Solar Polar Diamond Explorer (SPDEx): Understanding the Origins of Solar Activity Using a New Perspective

Our knowledge of the Sun, its atmosphere, long term activity and space weather potential is severely limited by the lack of good observations of the polar and far-side regions. Observations from a polar vantage point would revolutionize our understanding of the mechanism of solar activity cycles, polar magnetic field reversals, the internal structure and dynamics of the Sun and its atmosphere. Only with extended (many day) observations of the polar regions can the polar flows be determined down to the tachocline where the dynamo is thought to originate. Rapid short period polar orbits, using in situ and remote sensing instrumentation, distributed over a small number of spacecraft, will provide continuous 360o coverage of the solar surface and atmosphere in both longitude and latitude for years on end. This unprecedented full coverage will enable breakthrough studies of the physical connection between the solar interior, the solar atmosphere, the solar wind, solar energetic particles and the inner heliosphere at large. A potential implementation, the Solar Polar Diamond Explorer (SPDEx) built upon the Solar Polar Imager mission design, involves up to four small spacecraft in a 0.48-AU orbit with an inclination of 75o. The orbit is achieved using solar sails or ion engines, both technologies already demonstrated in space.