Particle Environment Package (PEP) for the Juice Mission: Current Status

The Particle Environment Package (PEP) onboard ESA’s Jupiter Icy Moons Explorer (JUICE) provides particle measurements to address three overarching science questions:How does Jupiter’s co-rotating magnetosphere interact with Ganymede, Callisto, Europa, and Io? How do internal and solar wind drivers generate energetic, time-variable, and multi-scale phenomena in Jupiter’s steadily rotating giant magnetosphere? What are the structure and composition of the icy moons’ exospheres, and how do they respond to external conditions? PEP measures positive and negative ions, electrons, exospheric neutral gas, thermal plasma, and energetic neutral atoms (ENAs) across all domains of the Jupiter system—covering nine decades of energy, from < 0.001 eV to > 1 MeV, with full angular coverage.The six PEP sensors are:Jovian Plasma Dynamics and Composition Analyzer (JDC) Jovian Electrons and Ions Analyzer (JEI) Jovian Energetic Electrons (JoEE) Jovian Energetic Neutrals and Ions Sensors (JENI) Jovian Neutrals Analyzer (JNA) Neutral Gas and Ion Mass Spectrometer (NIM) These sensors are grouped into two subsystems:PEP-Lo: JDC, JEI, JNA, NIM (covering low energies up to tens of keV) PEP-Hi: JENI, JoEE (covering up to 1 MeV) For the first time at Jupiter, PEP combines magnetospheric ENA imaging with in-situ measurements, enabling remote sensing of the Europa and Io tori via ENAs. Using low-energy ENAs produced by particle–surface interactions, PEP investigates space weathering of the icy moons caused by particle precipitation.PEP directly samples the exospheres of Europa, Ganymede, and Callisto with unprecedented mass resolution (>700).PEP-Hi (JENI and JoEE), JEI, and JDC are fully commissioned and collected excellent data during the Moon–Earth flyby on 19–20 August 2024.This presentation overviews the status of the package, collected data so far, sensor performance, and science operations in the Jovian system and during the cruise phase.