Evolution of H 2 O related species in the neutral coma of 67P

The ROSINA-DFMS mass spectrometer has been probing the coma of 67P since the spacecraft arrived at the comet in August 2014. The acquired data set covers a large range of viewing geometries for the ever changing conditions of 67P along its journey to pericenter. With the high temporal resolution of ROSINA-DFMS we are able to examine diurnal and seasonal changes of different species in the gaseous coma. Large scale heterogeneities in the coma have been reported since the very first measurements of the neutral inventory at 67P. Many of the minor species are seen to follow one of the major compounds, H 2 O, CO or CO 2 . In this paper we will present the latest results on H 2 O related species. We will discuss the possible trapping/building mechanisms responsible for these species and why it is different from other species such as CO, N 2 or CO 2 .