J. L. Bada.J. Gomez-Elvira.E. Javaux.M. Rosing. F. Selsis.R. Summons.R. M. Bonnet.O. Botta Originally published in the journal Space Science Reviews, Volume 135, Nos 1 4. DOI: 10. 1007/s11214-008-9328-1 (c) Springer Science+Business Media B. V. 2008 Twooftheoverarchingquestionsaskedinthepursuitofscienti c knowledgeare: (1)Isthere life outside the Earth? and (2) How did life originate on the Earth? Not coincidently, these questions are major milestones on the roadmap of the new interdisciplinary science eld of Astrobiology. A signi cant part in the quest for answers to these questions requires...