The Catalytic Potential of Cosmic Dust: Implications for Prebiotic Chemistry in the Solar Nebula and Other Protoplanetary Systems

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Abstract
The synthesis of important prebiotic molecules is fundamentally reliant on basic starting ingredients: water, organic species [e.g., methane (CH4)], and reduced nitrogen compounds [e.g., ammonia (NH3), methyl cyanide (CH3CN) etc.]. However, modern studies conclude that the primordial Earth's atmosphere was too rich in CO, CO2, and water to permit efficient synthesis of such reduced molecules as envisioned by the classic Miller-Urey experiment. Other proposed sources of terrestrial nitrogen reduction, like those within submarine vent systems, also seem to be inadequate sources of chemically reduced C-H-O-N compounds. Here, we demonstrate that nebular dust analogs have impressive catalytic properties for synthesizing prebiotic molecules. Using a catalyst analogous to nebular iron silicate condensate, at temperatures ranging from 500K to 900K, we catalyzed both the Fischer-Tropsch conversion of CO and H2 to methane and water, and the corresponding Haber-Bosch synthesis of ammonia from N2 and H2. Remarkably, when CO, N2, and H2 were allowed to react simultaneously, these syntheses also yielded nitrogen-containing organics such as methyl amine (CH3NH2), acetonitrile (CH3CN), and N-methyl methylene imine (H3CNCH2). A fundamental consequence of this work for astrobiology is the potential for a natural chemical pathway to produce complex chemical building blocks of life throughout our own Solar System and beyond.