The organic-rich surface of comet 67P/Churyumov-Gerasimenko as seen by VIRTIS/Rosetta
Langevin, Y.; Bellucci, G.; Jaumann, R.; Stephan, K.; Mottola, S.; Barucci, M. A.; Fornasier, S.; Encrenaz, T.; Erard, S.; Crovisier, J.; Ip, W. H.; Drossart, P.; Piccioni, G.; Mennella, V.; Colangeli, L.; Biver, N.; Capaccioni, F.; Arnold, G.; Peter, G.; Orosei, R.; Palumbo, P.; Grassi, D.; Combi, M.; Cerroni, P.; Coradini, A.; Filacchione, G.; Ciarniello, M.; Henry, F.; Cartacci, M.; Cicchetti, A.; Noschese, R.; Raponi, A.; Tosi, F.; De Sanctis, M. C.; Capria, M. T.; Longobardo, A.; Palomba, E.; Quirico, E.; Rinaldi, G.; Bockelee-Morvan, D.; Leyrat, C.; Schmitt, B.; Tozzi, G. P.; Fink, U.; Combes, M.; Blecka, M.; Jacquinod, S.; Semery, A.; Tiphene, D.; Fonti, S.; Combe, J. -Ph.; Flamini, E.; Blanco, A.; Orofino, V.; Taylor, F.; Benkhoff, J.; Magni, G.; Carsenty, U.; Beck, P.; Ammannito, E.; Bibring, J. P.; Giuppi, S.; Politi, R.; Merlin, F.; Hello, Y.; Irwin, P.; McCord, T.; Kuehrt, E.; Carlson, R.; Federico, C.; Despan, D.; Bonal, L.; Markus, K.; Schade, U.; Reess, J. M.; Moroz, L.; Frigeri, A.; Gudipati, M.
Italy, France, Germany, United States, Netherlands, Poland, Taiwan, United Kingdom
Abstract
The VIRTIS (Visible, Infrared and Thermal Imaging Spectrometer) instrument on board the Rosetta spacecraft has provided evidence of carbon-bearing compounds on the nucleus of the comet 67P/Churyumov-Gerasimenko. The very low reflectance of the nucleus (normal albedo of 0.060 ± 0.003 at 0.55 micrometers), the spectral slopes in visible and infrared ranges (5 to 25 and 1.5 to 5% kÅ-1), and the broad absorption feature in the 2.9-to-3.6-micrometer range present across the entire illuminated surface are compatible with opaque minerals associated with nonvolatile organic macromolecular materials: a complex mixture of various types of carbon-hydrogen and/or oxygen-hydrogen chemical groups, with little contribution of nitrogen-hydrogen groups. In active areas, the changes in spectral slope and absorption feature width may suggest small amounts of water-ice. However, no ice-rich patches are observed, indicating a generally dehydrated nature for the surface currently illuminated by the Sun.