ESA’s Philae Lander Discovers Organic Molecules On Comet 67P

Highlights of the initial observations from the Philae lander are reported in seven papers recently published in the journal Science. The papers reveal that Comet 67P is porous, with a relatively homogeneous interior. It also has a varied surface that feature many different carbon-containing organic molecules, the scientists report.

The data comes from the 60 hours of observations Philae conducted immediately after landing on Comet 67P/Churyumov-Gerasimenko when it was dropped off there by the European Space Agency’s Rosetta orbiter.

Nicolas Altobelli, Rosetta project scientist, said to Space.com in an email:

“What really blows my mind is to have this combination of complementary results, allowing us at the same time to ‘feel’ the surface of the comet, very locally, as if we were there, while also getting the bigger picture through the sounding of the cometary interior structure.

The implications of these measurements, and in particular the fairly homogeneous, very porous structure of the interior, will help constrain the formation models of planetesimals in the solar nebula, by a better understanding of the accretion processes.”

Before landing Philae, said Stephan Ulamec, from the German Aerospace Centre, scientists had thought that cometary surfaces might actually be much more soft, being a loose regolith under a low gravity. Some even feared the lander could sink into the surface when it touched down on the comet’s surface.

“Although we were aware of our limited knowledge, the fact that some of the material is so hard, and that the surface is so heterogeneous, was indeed a bit surprising,” he notes.

The structure of the regolith on 67P/Churyumov-Gerasimenko from ROLIS descent imaging
S. Mottola, G. Arnold, H.-G. Grothues, R. Jaumann, H. Michaelis, G. Neukum, J.-P. Bibring, S. E. Schröder, M. Hamm, K. A. Otto, I. Pelivan, G. Proffe, F. Scholten, D. Tirsch, M. Kreslavsky, E. Remetean, F. Souvannavong, and B. Dolives
Science 31 July 2015: aab0232

Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko
T. Spohn, J. Knollenberg, A. J. Ball, M. Banaszkiewicz, J. Benkhoff, M. Grott, J. Grygorczuk, C. Hüttig, A. Hagermann, G. Kargl, E. Kaufmann, N. Kömle, E. Kührt, K. J. Kossacki, W. Marczewski, I. Pelivan, R. Schrödter, and K. Seiferlin
Science 31 July 2015: aab0464

Organic compounds on comet 67P/Churyumov-Gerasimenko revealed by COSAC mass spectrometry
Fred Goesmann, Helmut Rosenbauer, Jan Hendrik Bredehöft, Michel Cabane, Pascale Ehrenfreund, Thomas Gautier, Chaitanya Giri, Harald Krüger, Léna Le Roy, Alexandra J. MacDermott, Susan McKenna-Lawlor, Uwe J. Meierhenrich, Guillermo M. Muñoz Caro, Francois Raulin, Reinhard Roll, Andrew Steele, Harald Steininger, Robert Sternberg, Cyril Szopa, Wolfram Thiemann, and Stephan Ulamec
Science 31 July 2015: aab0689

The nonmagnetic nucleus of comet 67P/Churyumov-Gerasimenko
Hans-Ulrich Auster, Istvan Apathy, Gerhard Berghofer, Karl-Heinz Fornacon, Anatoli Remizov, Chris Carr, Carsten Güttler, Gerhard Haerendel, Philip Heinisch, David Hercik, Martin Hilchenbach, Ekkehard Kührt, Werner Magnes, Uwe Motschmann, Ingo Richter, Christopher T. Russell, Anita Przyklenk, Konrad Schwingenschuh, Holger Sierks, and Karl-Heinz Glassmeier
Science 31 July 2015: aaa5102 Published online 14 April 2015 [DOI:10.1126/science.aaa5102]

Properties of the 67P/Churyumov-Gerasimenko interior revealed by CONSERT radar
Wlodek Kofman, Alain Herique, Yves Barbin, Jean-Pierre Barriot, Valérie Ciarletti, Stephen Clifford, Peter Edenhofer, Charles Elachi, Christelle Eyraud, Jean-Pierre Goutail, Essam Heggy, Laurent Jorda, Jérémie Lasue, Anny-Chantal Levasseur-Regourd, Erling Nielsen, Pierre Pasquero, Frank Preusker, Pascal Puget, Dirk Plettemeier, Yves Rogez, Holger Sierks, Christoph Statz, Hakan Svedhem, Iwan Williams, Sonia Zine, and Jakob Van Zyl
Science 31 July 2015: aab0639

Illustration: DLR German Aerospace Center/flickr