Tracing the origins of the solar system

All contemporary objects of our Solar System emerged from a solar nebula which existed 4.5 billion years ago, and whose dynamical and thermo-chemical evolution led to the condensation of solids, then to the emergence of different types of planetesimals, and finally to the accretion of solid cores and to the formation of our planets. Space exploration makes it possible today to visit the different classes of solar system objects and retrieve key information which can help us to trace back the evolutionary path of the solar system, from its origins in the Solar Nebula to its present configuration and the likely development of habitats in planetary objects. We propose three un-ordered priorities for the space programme in this perspective: 1 - access to remaining pristine material in the solar system (interplanetary dust and small bodies); 2 - in-depth exploration of the systems of giant planets; 3 - in-situ analysis of some of the physical mechanisms relevant to planetary formation in the contemporary rings and plasma environments of giant planets. This research subject, which strongly connects our solar system and its objects to exoplanets and other planetary systems, is a very promising contribution to the progressive build-up of a synthetic view of their formation and evolution scenarios. It is a central element in the build-up of a "Cosmic Vision" of our own solar system. We show how the major scientific questions related to this broad theme can be translated into specific mission targets and measurement objectives, and grouped into a "short list" of key space missions. This short list forms an ideal basis to elaborate a multi-decadal endeavour to explore the outer solar system. Most of these missions, while addressing the specific question of solar system origin, also are of major interest for comparative planetology and exo-astrobiology. While a few can be implemented in a purely European context, most of these missions can be accomplished only in the framework of a strong international collaboration. In the spirit of the successful Cassini-Huygens mission, we trust that ESA will take advantage of the Cosmic Vision programme to develop with its international partners a long-term vision of the search for solar system origins, from the Solar Nebula to the emergence of potential habitats.