Prestellar formation of prebiotic molecules

Understanding how complex organic molecules (COMs) form and survive in space throughout the process of star and planet formation is a key step to unraveling the origin of life on Earth. Complex organic species are expected to be formed in a variety of interstellar environments at the surface of ice grains that act both as a molecular reservoir and as sites for catalysis. For decades, surface complex molecule formation has been thought to be triggered largely by energetic processing, e.g. photon, electron and cosmic ray bombardment of ice dust grains. The overall outcome of such formation mechanisms is mostly linked to late stages of star formation, when a protostar is already formed. As a result, the observation of COMs in dense dark clouds remained unexplained for many years. Only recently it has been shown that 'non-energetic' processing of ice material initiated by atom bombardment can potentially explain the presence of COMs in cold dense regions of the interstellar medium that are shielded from external radiation. In this talk I will present new laboratory and theoretical evidence that biologically relevant species can be efficiently formed at early stages of star formation through 'non-energetic' processing of interstellar ices. A prestellar formation of large COMs on ice grains suggests a more complex and ubiquitous prebiotic chemistry in space than previously assumed that effectively enriches the chemical content of planet-forming material.