Particle Environment Package (PEP)


On this page you will be able to access the science data aquired by PEP / NIM once they are available. First science results are expected by earliest 2030.

The six main goals of the JUICE Mission are described under the "Mission" page. PEP will contribute to the two JUICE science goals 4 and 5.

  • JUICE Science Goal 4: Compare the atmospheres, plasma environments, and magnetospheric interactions.
  • JUICE Science Goal 5: Determine global surface compositions and chemistry, especially as related to habitability.

The JUICE science goals are addressed as five overarching PEP science questions. 

  • PEP Science Question 1 – Ganymede: How does the co-rotating magnetosphere of Jupiter interact with the complex and diverse magnetic environment of Ganymede?
  • PEP Science Question 2 – Callisto: How does the rapidly rotating magnetosphere of Jupiter interact with the seemingly inert Callisto?
  • PEP Science Question 3 – Europa and Io: What are the governing mechanisms and their global impacts of release of material into the Jovian magnetosphere from seemingly inert Europa and active Io?
  • PEP Science Question 4 – Magnetosphere: How do internal and solar wind drivers cause such energetic, time variable and multi-scale phenomena in the steadily rotating giant magnetosphere of Jupiter?
  • PEP Science Question 5 – Origin: What is the chemical composition of the volatile and rocky inventory of the icy moons?


Artists concept of JUICE, the Jupiter moons orbiter mission (credit ESA)
Artists concept of JUICE, the Jupiter moons orbiter mission (credit ESA)


The NIM instrument main scientfic goal is the determination of the chemical composition of the extended atmospheres of the three Gallilean Moons, in particular the neutral and the ionised components, i.e. measuring and characterising the

  • Atmospheres of the three moons, being the result of evaporation and sublimation and exogenic processes (sputtering)
  • Chemical composition of volatiles
  • Contribution from non-ice material on the surface
  • Isotopic composition of major species

The NIM instrument will perform first-ever neutral gas mass spectroscopy of the atmospheres of the icy moons Europa, Ganymede and Callisto.

Given the limited knowledge of species in Europa’s exosphere and the chemical and mineralogical composition of Europa’s surface (non-ice regions), many additional species are expected to be detected in the mass spectra of the exosphere if they are present at the surface with an abundance of 1 permil or more. The present knowledge of the composition of Ganymede’s and Callisto’s atmospheres and surfaces is even more limited than of Europa, and these measurements are urgently needed to study the formation of the jovian satellites.

Therefore, NIM will pursue in the identification of the chemical nature of various surface elements. In particular, deriving the chemistry of the non-ice material on Europa’s surface (which turned out to be impossible from orbit with infra-red spectroscopy on the Galileo mission), possibly even finding traces in the chemical composition indicative of present or former biological activity. There is strong evidence that this non-ice material originates from below the ice surface and it might give clues to the chemical composition of the ocean underneath (Spencer et al., 2006).

Publication - Science