The search for life in other celestial bodies has always been a topic of great interest within the scientific community. The curiosity to know if we are the only ones in the universe or not has driven the development of many engineering projects. This Master Thesis is meant to do its bit in this research field. Europa, a moon of Jupiter, is thought to have an ocean made of water underneath its icy surface. This ocean could be the perfect environment to find life. The hypotheses of the existence of an ocean gained more strength with the discovery of a water vapour plume in the southern hemisphere of Europa. This plume could be expelling particles from the underneath ocean. The main idea of the project is to design a mission of a pseudo-orbiter (a spacecraft orbiting Jupiter and doing flybys of Europa) which could collect particles from this plume during its flyby trajectory.

The objective of this thesis is to determine the maximum number of particles that can be collected with a pseudo-orbiter strategy. To achieve this, first, a plume particle model has been simulated. The outcome of this simulation is a 3D density profile of the water vapour molecules of the plume. The results of this part are needed in order to be able to determine the number of particles that the spacecraft can collect when crossing the plume. After this, the trajectory of the pseudo-orbiter has been designed. The Graphical Method for Same-body Transfers has been used in order to select potential trajectories that could lead to a maximum number of collected particles. This method allows the engineers to identify resonant orbits such that the ground-track of the flyby crosses regions of potential interest. Finally, coupling the two parts of the project has led to the determination of the number of collected particles for the selected trajectories.