Organics in comet 67P – a first comparative analysis of mass spectra from ROSINA–DFMS, COSAC and Ptolemy

Kathrin Altwegg (1, 2) , Hans Balsiger (1) , Jean-Jacques Berthelier (3) , André Bieler (1) , Ursina Calmonte (1) , Stephen A. Fuselier (4, 5) , Fred Goesmann (6) , Sébastien Gasc (1) , Tamas I. Gombosi (7) , Léna Le Roy (1) , Johan de Keyser (8) , Andrew Morse (9) , Martin Rubin (1) , Marc Schuhmann (1) , Matt G. G. T Taylor (10) , Chia-Yu Tzou (1) , Ian Wright (9)

1 Physikalisches Institut [Bern]
2 CSH - Center for Space and Habitability
3 PLANETO - LATMOS
4 Space Science and Engineering Division [San Antonio]
5 UTSA - The University of Texas at San Antonio
6 MPS - Max-Planck-Institut für Sonnensystemforschung
7 AOSS - Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor]
8 BIRA-IASB - Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique
9 School of Physical Sciences [Milton Keynes]
10 ESTEC - European Space Research and Technology Centre

The ESA Rosetta spacecraft followed comet 67P at a close distance for more than 2 yr. In addition, it deployed the lander Philae on to the surface of the comet. The (surface) composition of the comet is of great interest to understand the origin and evolution of comets. By combining measurements made on the comet itself and in the coma, we probe the nature of this surface material and compare it to remote sensing observations. We compare data from the double focusing mass spectrometer (DFMS) of the ROSINA experiment on ESA's Rosetta mission and previously published data from the two mass spectrometers COSAC (COmetary Sampling And Composition) and Ptolemy on the lander. The mass spectra of all three instruments show very similar patterns of mainly CHO-bearing molecules that sublimate at temperatures of 275 K. The DFMS data also show a great variety of CH-, CHN-, CHS-, CHO₂- and CHNO-bearing saturated and unsaturated species. Methyl isocyanate, propanal and glycol aldehyde suggested by the earlier analysis of the measured COSAC spectrum could not be confirmed. The presence of polyoxymethylene in the Ptolemy spectrum was found to be unlikely. However, the signature of the aromatic compound toluene was identified in DFMS and Ptolemy data. Comparison with remote sensing instruments confirms the complex nature of the organics on the surface of 67P, which is much more diverse than anticipated.

Domains: Earth and Planetary Astrophysics [astro-ph.EP]; Solar and Stellar Astrophysics [astro-ph.SR]

Kathrin Altwegg, Hans Balsiger, Jean-Jacques Berthelier, André Bieler, Ursina Calmonte, et al.. Organics in comet 67P – a first comparative analysis of mass spectra from ROSINA–DFMS, COSAC and Ptolemy. Monthly Notices of the Royal Astronomical Society, 2017, 469 (Suppl_2), pp.S130 - S141. ⟨10.1093/mnras/stx1415⟩. ⟨insu-01574263⟩