  We investigate the feasibility of detecting water molecules (H2O) and water
ions (H20+) from the Europa plumes from a flyby mission. A Monte Carlo particle
tracing method is used to simulate the trajectories of neutral particles under
the influence of Europa's gravity field and ionized particles under the
influence of Jupiter's magnetic field and the convectional electric field. As
an example mission case we investigate the detection of neutral and ionized
molecules using the Particle Environment Package (PEP), which is part of the
scientific payload of the future JUpiter ICy moon Explorer mission (JUICE). We
consider plumes that have a mass flux that is three orders of magnitude lower
than what has been inferred from recent Hubble observations (Roth et al.,
2014a). We demonstrate that the in-situ detection of H2O and H2O+ from these
low mass flux plumes is possible by the instruments with large margins with
respect to background and instrument noise. The signal to noise ratio for
neutrals is up to ~5700 and ~33 for ions. We also show that the geometry of the
plume source, either a point source or 1000 km-long crack, does not influence
the density distributions, and thus, their detectability. Furthermore, we
discuss how to separate the plume-originating H2O and H2O+ from exospheric H2O
and H2O+ . The separation depends strongly on knowledge of the density
distribution of Europa's exosphere.
