1. Could you explain the significance of your article to the non-specialist? (50-100 words)

Cometary chemistry (or in other words, the study of cometary molecules) is crucial for our understanding of the formation of comets, and therefore, of the formation of the Solar System.  By colliding with the Earth in its early history, comets also played a role in the chemistry of the early Earth, which should be known to precise the initial conditions for the emergence of life.  Last but not least, comets are a natural laboratory and a unique chemical factory, allowing us to study molecular processes in physical conditions which are difficult to reproduce in a terrestrial laboratory.

2. What has motivated you to conduct this work?

Understanding the nature of comets has been a long process which was initiated several centuries ago.  Regarding the chemical composition of these bodies, the first results --and first questions -- date back from the beginning of astronomical spectroscopy in the second half of the 19th century.  Our team in Observatoire de Meudon made decisive progresses by extending the field of cometary spectroscopy to the radio and infrared domains, leading to the systematic identification of several molecules of increasing complexity.

3. Where do you see this work developing in the future?

The chemical study of comets is progressively shifting from remote sensing using spectroscopic techniques to in situ investigations by space probes (Stardust, Deep Impact, Rosetta).  Ultimate answers will be provided by sample return missions.  Already, the Stardust mission brought back samples of cometary dust.  In a remote future, we expect to obtain samples of cometary ices if a specific space mission could be designed and funded.

4. Are there any particular challenges facing future research in this area?

According to their orbits and presumed orbital evolutions, comets belong to different classes, possibly resulting to different formation scenarios.  A current challenge is to relate this dynamical diversity to a possible chemical diversity.  No significant trend has yet been obtained on this topic.  This study must be pursued by investigating a large sample of comets. This can be difficultly done by space exploration.  Remote sensing and traditional spectroscopy are still welcome.