Comprehensive Observations of Magnetospheric Particle Acceleration, Sources, and Sinks (COMPASS): A Mission Concept to Explore the Extremes of Jupiter’s Magnetosphere

Since the dawn of the space age in 1957, humanity has achieved the remarkable feat of exploring all the planets in our Solar System with robotic spacecraft. This glimpse into the diversity of space environments that make up our Solar System has revealed that no two planetary systems are identical; however, each planet harbors key clues in working toward a more unified and predictive understanding of the basic structure and dynamics of all planetary, and even exosolar, magnetospheres. A common feature found in all strongly magnetized planets are regions of trapped, high-energy charged particles called radiation belts. Dedicated missions studying the radiation belts encompassing Earth have led to major space physics discoveries over the past several decades, but Earth's magnetosphere exists in a relatively small swath of the parameter space found in our Solar System. To expand that parameter space, we present a mission concept that was reported in the recent National Academies of Sciences, Engineering, and Medicine (NASEM) Decadal Survey to expand the frontiers of Heliophysics in the 2024-2033 decade. The mission concept is called COMPASS, short for Comprehensive Observations of Magnetospheric Particle Acceleration, Sources, and Sinks. COMPASS is a mission dedicated to the exploration of Jupiter's radiation belts, with an unprecedented suite of instruments covering i) particle species from thermal plasma to 10 tens of MeV electrons and relativistic protons and heavy ions; ii) comprehensive magnetic and electric fields and waves; and iii) dedicated X-ray imaging. COMPASS will enable the scientific community to test existing hypotheses and make new discoveries of how Jupiter's radiation belts are sourced, accelerated, and lost within such a complex system.