Comets give spectacular shows in the sky that have been noticed by human civilizations for thousands of years. These icy bodies, which originate from the Kuiper Belt and Oort Cloud, are known to be the left-over remnants from the formation of our solar system. Thus, comets are thought to preserve the composition of interstellar ice and dust particles that gravitationally collapsed to give rise to protoplanetary disks and subsequently planetary systems. Further, one of the working postulates of the Origin of Life on Earth is that comets and asteroids triggered the emergence of life during the early stages of the formation of our solar system (about four billion years ago) through the Late Heavy Bombardment (LHB) that delivered water and organic matter to Earth.
Thus, comets have a profound impact on our understanding of the birth-and-death cycles of stars, as well as on the evolution of planetary systems and the origin of life itself. Extensive ground-based observations so far have given valuable information on cometary outgassing, coma, and tail composition. The cometary nucleus, however, is still a puzzle – one that is being slowly put together through several in-situ observations carried out by NASA's Deep Impact and ESA's Rosetta missions.
Science results from the Rosetta spacecraft and its lander Philae on Comet 67/P Churyumov-Gerasimenko (67P-CG) have been groundbreaking, with significant insight into the physics and chemistry of this comet (and hence most likely other short-period comets). Various instruments that focus on different aspects of the comet have made unprecedented observations, some of which have been recently published. A few of these highlights are: the detection of a hard surface shell by Philae, which came as a surprise; thick layers of organic dust on the surface, which is yet to be fully understood; the first confirmed detection of nitrogen and oxygen in a cometary outgassing has been made, suggesting a very primitive interstellar-like inner composition.
In the light of these recent advances in our understanding of comets, in particular through the recent missions Rosetta, Deep-Impact, and Epoxi, this Wilhelm und Else Heraeus-Stiftung-supported "615th WE-Heraeus-Seminar: How Primitive are Comets?" will focus on the interior composition of cometary nuclei. All of the talks, posters, and discussion will focus on how recent scientific advancements and future comet missions could enable a better understanding of the cometary nucleus, its structure, and composition, from the deep interior to the surface, as well as of the formation of the first solid bodies in the young solar system.