Authors: M. Akhavan-Tafti (University of Michigan), L. Johnson (MSFC), R. Sood (University of Alabama), J. A. Slavin (University of Michigan), T. Pulkkinen (University of Michigan), S. Lepri (University of Michigan), E. Kilpua (University of Helsinki, Finland), D. Fontaine (Ecole Polytechnique, France), A. Szabo (GSFC), L. Wilson (GSFC), G. Le (GSFC), T. Y. Atilaw (University of Michigan), M. Ala-Lahti (University of Michigan), S. L. Soni (University of Michigan), D. Biesecker (Alcyon Technical Services LLC), L. K. Jian (GSFC), D. Lario (GSFC)

The Space Weather Investigation Frontier (SWIFT) mission will aim at making major discoveries on the three-dimensional structure and temporal evolution of heliospheric structures that drive space weather. Existing remote-sensing and in-situ observatories are not suited for resolving multi-scale heliospheric structures and evolutionary processes. Here, we propose a groundbreaking mission concept, utilizing flight-ready solar sail propulsion to enable continuous, in-situ, multi-point observations along the Sun-Earth line at and inside the Lagrange point L1 (sub-L1). One sailcraft hub at sub-L1 and three identical nodes at L1 will fly in an optimized tetrahedron constellation, covering distances between 10 to 100’s of Earth radii. SWIFT’s science objective is to distinguish between local and global processes that drive space weather by revealing the spatial characteristics, temporal evolution, and geo-effectiveness of small-to-mesoscale solar wind structures as well as the substructures of macro-scale structures, such as interplanetary coronal mass ejections (ICMEs) and stream interaction regions (SIRs). In addition, real-time measurements of earth-bound heliospheric structures will improve our current forecasting lead-times by up to 35%.