Plasma environment around comet 67P

Unlike previous cometary missions which flew by a comet in a few hours, the European Space Agency Rosetta mission escorted comet 67P over a two-year journey, from a distance distance of 3.6 au from the Sun to perihelion at 1.2 au and to the end of mission at 3.8 au.

As a result, it harvested a rich and unprecedented dataset of the neutral and plasma environment over a large range of heliocentric distance, season, latitude, longitude, outgassing and solar activity.

The aim of the thesis will be to explore how the plasma environment around the comet evolved over the escort phase and to link it to remote-sensing observations.

Measurements from the ion and neutral mass spectrometer will be exploited, taking advantage of the high mass resolution offered by the instrument. The evolution of ion composition over time in different interaction regions will be assessed.

The findings will be compared with modelled outputs in order to infer the relative importance of chemistry versus transport and address a very puzzling question on ion dynamics.

The role of collisions versus transport will also be assessed for auroral emissions, including the red line whose brightness decreases at high outgassing activity.