Firefly: The Case for a Holistic Understanding of the Global Structure and Dynamics of the Sun and the Heliosphere

Critical knowledge gaps exist in our understanding of how magnetic fields control solar (and, by extension, stellar) activity in timescales from minutes to years; filling these gaps will require a transformative observational approach. We know that solar activity drives space weather as the result of dynamic magnetic fields that form in the solar interior and evolve continuously until reaching levels of complexity in the atmosphere that trigger eruptions. However, we do not fully understand how solar and, more generally, stellar magnetic fields are generated, or how they evolve through the eruptive states. The major obstacle is our reliance on observations from a single viewpoint – particularly from within the ecliptic plane. This vantage point can only provide limited information. To fill our critical knowledge gaps, we must (i) understand the generation of solar magnetic fields deep in the convection zone; (ii) determine the origin of the solar cycle and predict its timing and strength; (iii) explain the causes of solar activity and their triggers; (iv) reliably predict when and how coronal mass ejections (CMEs) will impact Earth and other planets; (v) fathom the structure and dynamics of the corona as it creates the heliosphere; and (vi) understand the energization and transport of energetic particles; etc. Firefly will revolutionize solar and heliospheric research by implementing a holistic observational philosophy from the Sun’s interior, through the photosphere, to the corona, and into the solar wind. This approach will provide simultaneous observations from multiple vantage points, enabling a continual and global 4π-steradian coverage of the Sun over much of a solar cycle. Firefly focuses on the global structure and dynamics of the Sun’s interior, the generation of solar magnetic fields, the deciphering of the solar cycle, the conditions leading to the explosive activity, and the structure and dynamics of the corona as it drives the heliosphere. Firefly provides diverse and complementary observations across multiple disciplines, bringing together a diverse group of scientists and engineers to deliver a unified 4π-steradian view of the heliosphere.