The ESA M7 candidate mission Plasma Observatory: unveiling plasma energization and energy transport in the Magnetospheric System with multiscale observations

Plasma energization and transport of energy are key open problems of space plasma physics. Their comprehension is a grand challenge of plasma physics that has implications on research fields that span from space weather to the understanding of the farthest astrophysical plasmas. The Earth’s Magnetospheric System is a  complex and highly dynamic plasma environment where strong energization and energy transport occurs and it is the best natural laboratory to study these processes through in situ measurements. Theory, numerical simulations and previous multi-point observations from missions such as ESA/Cluster and NASA/MMS evidenced that cross-scale coupling has a fundamental role in plasma energization and energy transport. Therefore, in order to ultimately understand these key processes, simultaneous in situ measurements at both large, fluid and small, kinetic scales are required. Such measurements are currently not available. Here we present the Plasma Observatory (PO) multi-scale mission concept tailored to study plasma energization and energy transport in the Earth’s Magnetospheric System through simultaneous measurements at both fluid and ion scales. These are the scales at which the largest amount of electromagnetic energy is converted into energized particles and energy is transported. PO has an HEO 7.2x17 RE orbit, covering all the key regions of the Magnetospheric System including the foreshock, the bow shock, the magnetosheath, the magnetopause, the transition region and the magnetotail current sheet. PO baseline mission includes seven identical smallsat Sister Space Craft (SSC) in two nested tetrahedra formation. The tetrahedra separation scales cover all typical ion and fluid scales of interest in the Key Science Regions  and vary between about 50 km and 5000 km. The SSC payload provides a complete characterization of electromagnetic fields and particles simultaneously at multiple locations with measurements tailored to ion and fluid scales. PO is the next logical step after Cluster and MMS and will allow us to resolve for the first time scale coupling in the Earth’s Magnetospheric System, leading to transformative advances in the field of space plasma physics. Plasma Observatory is one of the three ESA M7 candidates, which have been selected in November 2023 for a competitive Phase A with a mission selection planned in June 2026 and launch in 2037.