Mission to the Sun‐Earth L 5 Lagrangian Point: An Optimal Platform for Space Weather Research

The Sun‐Earth Lagrangian L 5 point is a uniquely advantageous location for space weather research and monitoring. It covers the “birth‐to‐impact” travel of solar transients; it enables imaging of solar activity at least 3 days prior to a terrestrial viewpoint and measures the solar wind conditions 4–5 days ahead of Earth impact. These observations, especially behind east limb magnetograms, will be a boon for background solar wind models, which are essential for coronal mass ejection (CME) and shock propagation forecasting. From an operational perspective, the L 5 orbit is the space weather equivalent to the geosynchronous orbit for weather satellites. Optimal for both research and monitoring, an L 5 mission is ideal for developing a Research‐to‐Operations capability in Heliophysics.