PEP (Particle Environment Package) will study the interaction between space and Jupiter’s icy moons.
The instrument with its six sensors will investigate how neutral and charged particles, such as ions, electrons and atoms,
behave in the magnetosphere and the electrical fields contained in the Jupiter system.

  APL built two state-of-the-art instruments for the European Space Agency’s Jupiter Icy Moons Explorer, or JUICE, mission to 
  explore the Jupiter system: the Jovian Energetic Neutrals and Ions (JENI) instrument and the Jovian Energetic Electrons (JoEE) instrument. 
  JENI will use a technique pioneered at APL to image neutral atoms that form from interactions between the plasma and neutral gases from 
  the moons with Jupiter’s intense radiation environment.