PILOT: Using a Small Satellite Constellation to Understand Cold Plasma in the Inner Magnetosphere

Magnetospheric physics has a massive problem: we have not yet determined the fundamental processes that govern plasma mass and energy flow through the terrestrial magnetosphere, nor the degree to which these flows regulate key magnetospheric subsystems. The Plasma Imaging LOcal and Tomographic experiment (PILOT) mission concept leverages a small satellite constellation to provide the transformational multi-scale observations needed to resolve critical heliophysics problems related to mass and energy flow through a planetary magnetosphere, enabling previously infeasible magnetospheric science. The PILOT mission concept, developed as a NASA-funded Heliophysics Mission Concept Study, is a potential Flagship-class NASA Heliophysics mission to be considered by the 2024–2033 Solar and Space Physics Decadal Survey. PILOT uses a constellation of 30 microsat spacecraft and 4 smallsat spacecraft in two highly-elliptical, equatorial Earth orbits to make high-resolution radio tomographic density maps of total plasma density in the equatorial plane, augmented by EUV imaging of ion plasma density and flows in the meridional plane, and in-situ measurements of electric and magnetic fields, plasma density, energetic particles, and ion composition. The comprehensive suite of measurements made by the PILOT constellation fully captures plasma mass dynamics and its impact on magnetospheric systems over an unprecedented range of spatial and temporal scales. Here we discuss the PILOT mission architecture, including instrument heritage, manufacturing strategy, concept of operations, and required technology development.