  Remote sensing observations indicate that Europa is surrounded by a tenuous
atmosphere. Furthermore, recent observations and historic data from Galileo
hint at the occurrence of water vapour eruptions originating from the interior
that create 200 km high plumes. Due to the lack of adequate measurements large
uncertainties exist in the properties of Europa's atmosphere (e.g. loss rate
and structure) and plumes (e.g. structure, source location, duration), of the
latter one the existence is not even confirmed. Unexploited opportunities to
constrain properties of the atmosphere or plumes remain in the in-situ data
collected by the Galileo mission, the only mission that has surveyed Europa
from close by. In this thesis, I investigate how to constrain the properties
(density, scale height) of Europa's tenuous atmosphere and plumes, using data
from the Galileo in-situ particle detector instruments (PLS, EPD). I simulate
the depletion of energetic protons and oxygen ions measured during the E12
flyby. A Monte Carlo particle tracing method is used to simulate the particle
trajectories and determine where they are depleted: at the surface or in the
atmosphere. The simulations show that the depletions of energetic ions observed
in the range 80 to 540 keV can be explained by charge exchange with neutral
atmospheric particles, but not by impact on the surface alone. This suggests
that an atmosphere must have been present during the E12 flyby. The simulations
best represent the sublimated component of the atmosphere and favour higher
surface densities than the literature, but are not sensitive to the scale
height. Furthermore, an additional depletion is visible very briefly in the
energetic protons with energies from 540 to 1040 keV. This feature could be
consistent with localized losses from a Europa plume, although such a solution
is not unique.
