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

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.