Inventory of the volatiles on comet 67P/Churyumov-Gerasimenko from Rosetta/ROSINA

¹ Center for Space and Habitability, University of Bern, 3012 Bern, Switzerland
e-mail: lena.leroy@csh.unibe.ch
² Physikalisches Institut, University of Bern, 3012 Bern, Switzerland
³ LATMOS/IPSL-CNRS-UPMC-UVSQ, 4 avenue de Neptune, 94100 Saint-Maur, France
⁴ Department of Atmospheric, Oceanic and Space Science, University of Michigan, Ann Arbor, MI, USA
⁵ Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, LPC2E, CNRS 7328/Université d’Orléans, 3A av. de la Recherche Scientifique, 45071 Orléans, France
⁶ BIRA-IASB, Belgian Institute for Space Aeronomy, Ringlaan 3, 1180 Brussels, Belgium
⁷ Institute of Computer and Network Engineering (IDA), TU Braunschweig, Hans-Sommer-Straße 66, 38106 Braunschweig, Germany
⁸ Space Science Division, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238, USA
⁹ Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78238, USA

Received: 1 May 2015
Accepted: 30 July 2015

Abstract

Context. The ESA Rosetta spacecraft (S/C) is tracking comet 67P/Churyumov-Gerasimenko in close vicinity. This prolonged encounter enables studying the evolution of the volatile coma composition.

Aims. Our work aims at comparing the diversity of the coma of 67P/Churyumov-Gerasimenko at large heliocentric distance to study the evolution of the comet during its passage around the Sun and at trying to classify it relative to other comets.

Methods. We used the Double Focussing Mass Spectrometer (DFMS) of the ROSINA experiment on ESA’s Rosetta mission to determine relative abundances of major and minor volatile species. This study is restricted to species that have previously been detected elsewhere.

Results. We detect almost all species currently known to be present in cometary coma with ROSINA DFMS. As DFMS measured the composition locally, we cannot derive a global abundance, but we compare measurements from the summer and the winter hemisphere with known abundances from other comets. Differences between relative abundances between summer and winter hemispheres are large, which points to a possible evolution of the cometary surface. This comet appears to be very rich in CO₂ and ethane. Heavy oxygenated compounds such as ethylene glycol are underabundant at 3 AU, probably due to their high sublimation temperatures, but nevertheless, their presence proves that Kuiper belt comets also contain complex organic molecules.