Rosetta is a solar-powered spacecraft of the European Space Agency on a mission to comet 67P/Churyumov-Gerasimenko. It consists of two main elements: the Rosetta orbiter and the Philea lander. The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA), one out of ten scientific instruments on board, consists of three sensors: a cometary pressure sensor (COPS), a double focusing mass spectrometer (DFMS) and a reflectron-type time-of-flight mass spectrometer (RT0F). Even prior to launch, fluorine was detected, while chlorine appeared only in space. It is clear that some of the fluorine is due to remnants from brazing, but part of it is certainly due to fluorocarbons contained in structures and tapes. Although contamination control and outgassing restrictions have been considered for a long time during the design and construction of spacecraft, the phenomenon and the associated timescales still seem to be highly underestimated.