The European Space Agency’s Rosetta spacecraft accompanied comet 67P/Churyumov-Gerasimenko for over 2 years from when it was more than 3 AU from the Sun to perihelion at 1.24 AU and then out again. Rosetta carried out an in-depth investigation of the comet’s nucleus and surrounding coma. The ROSINA instrument suite, a part of the Rosetta payload, was dedicated to measuring the neutral gas and low energy plasma ions in the coma of the comet. ROSINA consisted of two mass spectrometers and a pressure sensor to derive the composition and total abundance of the gases set free from the comet.<br/>Due to the high sensitivity of the mass spectrometers, the isotopologues of different species could be analyzed and molecules have been identified that were not previously known to be present in comets. It is particularly noteworthy that parts of the ice seem to have survived the formation of the solar system as their isotopic signature bears a closer resemblance to interstellar material than to the average composition of the Solar System. Examples are the elevated D/H ratio in the comet’s water and the very short-lived sulfur molecule S<sub>2</sub> found in the comet. These results together with a host of more complex organic molecules are clearly linked to the low-temperature ice-grain-surface chemistry that occurred in the dark molecular cloud from which our Solar System emerged. In this presentation, we discuss some of the major findings of the ROSINA instrument suite with regard to the origin of at least part of the matter incorporated into the comet.

Links between the ices of comet 67P/Churyumov-Gerasimenko and the interstellar medium from Rosetta/ROSINA observations

253rd National Meeting (2017)

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