Exobiology and Evolutionary Biology

Trapping Planetary Noble Gases during the Fischer-Tropsch-Type Synthesis of Organic Materials in the Primitive Solar Nebula

PI: Joseph Nuth

When hydrogen, nitrogen and CO are exposed to amorphous iron silicate surfaces at temperatures between 500 – 900K, a carbonaceous coating forms via Fischer-Tropsch type reactions. Under normal circumstances such a catalytic coating would impede or stop further reaction. However, we find that this coating is a better catalyst than the amorphous iron silicates that initiate these reactions. The formation of a self-perpetuating catalytic coating on grain surfaces could explain the rich deposits of macromolecular carbon found in primitive meteorites and would imply that protostellar nebulae should be rich in organic material. Many more experiments are needed to understand this system and its application to protostellar systems. We propose to carry out experiments that incorporate a noble gas mixture (49% Ne, 49% Ar, 1% Kr, 1% Xe) into the CO, N2 and H2 mixture we have been using to perform the synthesis of organic species for the past several years and measure the fraction of this mixture trapped in the organic coating as a function of temperature.
We propose to build multiple experimental systems in order to carry out several catalytic reaction, gas trapping experiments simultaneously. This is especially important for experiments below 473K where times for individual experimental runs on non-ideal catalysts will exceed 2 months, potentially by a wide margin, and at least 20 experimental runs are typically required to produce sufficient grain coating thickness for easy analysis. This request is submitted as a PME proposal.