Description
The comprehension of particle energization and energy transport 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, where strong energization and energy transport occurs, 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, NASA/MMS and THEMIS evidenced that cross-scale coupling has a fundamental role in plasma energization and energy transport. Therefore, 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 tailored to study plasma energization and energy transport in the Earth’s Magnetospheric System through simultaneous measurements at both fluid and ion scales. PO baseline mission employs seven identical smallsat Sister Space Craft (SSC) in two nested tetrahedral formation in an HEO 7.2x17 RE orbit, enabling observations in 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. The nominal mission duration is 3.5 years with 3 Nominal Science Phases during which the scale of the inner/outer tetrahedra are increased in three steps: 30-60/150-300 km, 100-200/500-1000 km, and 3500-6500 km, covering all typical ion and fluid scales of interest in the magnetospheric key regions. 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 PO has been recently recommended by ESA as the Medium-class mission M7 of the ESA scientific
program. The ESA Science Program Committee will make the formal decision at its next meeting in November 2026. The launch of PO is expected in 2037.