Introduction: Comets and the Origin of Life

Extraterrestrial objects such as comets and asteroids (and their associated dust) played a significant dual role in the early history of the Earth’s biosphere: they were both deliverers of organic material and volatiles, and also destroyers of organic material, by the heat and shock of violent impact. The study of the origins of life on Earth attempts to uncover the physical processes operating during this earliest, very turbulent era in the history of our planet. There is still much to learn, despite recent progress in our knowledge of such fundamental issues as the nature of organic chemical processes in space, the chemistry of comets and asteroids and the nature of the early terrestrial environment.