D-A-CH: International Comet Experiments

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Over the past few decades, very successful space missions have significantly improved our knowledge of the origin and activity of comets. These space missions have been supported by a variety of different theoretical models and intensive observational campaigns. However, the support from ground-based laboratory experiments has been limited, although they can provide deeper insights into the physics of comets. The laboratory experiments performed so far were very useful to understand the nature of ice-dust samples under cometary-like conditions. However, since we have now data from several fly-by missions and more than two years of escorting a comet from the onset of activity throughout the perihelion (activity maximum) and beyond, the picture of gas and dust production has changed. These new insights have impact on the requirements needed to carry out state-of-the art comet simulation experiments with realistic sample materials. Thus, a new generation of ground-based laboratory experiments is mandatory to interpret the data gathered by previous space missions (especially by the Rosetta mission) and to support future space missions to comets, or to other icy bodies in the Solar System. These experiments require a broad spectrum of facilities and expertise to characterize the thermal, physical and optical properties of the analogue samples and their behavior during simulated cometary activity. As such they can only be addressed by a multi-national effort with contributions from several laboratories.The objective of this proposal is to better understand the fundamentals of cometary activity by performing state-of-the art laboratory experiments, accompanied by theoretical modeling, in an international framework. This will be done by designing, performing and evaluating a series of experiments to study the physical properties and activity behavior of comet analogue materials. The goal of these experiments is to design scientifically relevant and realistic test scenarios, which can be used to investigate the physical processes associated with comet activity (this project is not an attempt to perfectly reproduce a cometary nucleus in the laboratory). Additionally, this project aims at providing a guideline for state-of-the art cometary analogue sample preparation, which will be based on the expert knowledge of the proposers, extended in the framework of this project.In order to achieve these goals, scientists from Germany (D), Austria (A) and Switzerland (CH) will closely collaborate by joining together their expertise and laboratory equipment (D-A-CH group). This collaboration provides the possibility to perform a large variety of scientifically important, but small-scaled, experiments with the ultimate goal to construct a well-equipped simulation chamber (by bringing together the already available scientific equipment of the D-A-CH group), which will allow studying various aspects of comet activity.