The Energetic Particle Experiment on the Plasma Observatory Mother Spacecraft

Plasma Observatory is a candidate mission of the European Space Agency (ESA) with a possible selection foreseen in 2026 and a launch in 2037. It aims to investigate the plasma coupling across different scales. To achieve this aim, Plasma Observatory will investigate different regions in the Earth’s magnetosphere which is rich in many interesting plasma phenomena. It consists of a mother and six daughter spacecraft. This allows to configure the spacecraft in two nested tetrahedra to investigate cross-scale coupling.

Energetic particles are sensitive tracers of processes which can alter the energy (or velocity) of ions and electrons. It is thus of high importance to measure them in situ at high cadence. They are bound to magnetic field lines but can be scattered onto others by various processes.

Energetic electrons and ions will be measured by the Energetic Particle Experiments (EPE) on the main (M) and six daughter (D) spacecraft. Here we present different instrument concepts for EPE-M, all of which which cover the energy range from 30 keV – 600 keV for electrons and up to 8 MeV for ions. The current (baseline) design utilizes the foil-magnet technique to separate electrons from ions. The experiment consists of two sensors each with two bidirectional telescopes and thus has eight viewing directions. Together with the spacecraft spin (2 rpm) EPE-M covers a field of view of nearly 4π steradians. Higher time resolution is possible at reduced angular resolution. Alternative design concepts have been derived and are presented as well.