Understanding the Surface Induced Phosphorylation of Prebiotic Molecules by Schreibersite

The study of the surface of a meteoritic mineral, schreibersite (Fe,Ni)3P, was investigated to provide insight into the role of the mineral’s surface in aqueous-phase phosphorylation reactions. The optimization of a custom-designed ultrahigh vacuum (UHV) apparatus and Fe2NiP (schreibersite) surface was performed to permit surface science analysis. The bare surface was characterized by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), which showed some oxidation and segregation of phosphorous within the near-surface region. The interaction and/or reaction of water (H2O), methanol (CH3OH), formic acid (HCO2H) and other molecules with the schreibersite surface at varying surface temperatures was probed by reflection absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD). At surface temperatures of approximately 130 K, H2O interacts with Fe-P bridge sites while CH3OH does not appear to interact with surficial phosphorus. The interaction between HCO2H and surficial phosphorus is still under investigation. At 295 K, it is demonstrated that H2O dissociatively chemisorbs as OH- and lattice phosphorus undergoes oxidation. An increase in the surface temperature to about 500 K results in the recombinative desorption of OH- as H2O. Adsorption of other probe molecules such as H2 and CO were not detected in the RAIRS experiments, and low dosages of pyridine (C5H5N) on the Fe2NiP surface showed the presence of both Lewis and Brønsted acid sites

The Evolution of the Surface of the Mineral Schreibersite in Prebiotic Chemistry

We present a study of the reactions of the meteoritic mineral schreibersite (Fe,Ni)3P, focusing primarily on surface chemistry and prebiotic phosphorylation. In this work, a synthetic analogue of the mineral was synthesized by mixing stoichiometric proportions of elemental iron, nickel and phosphorus and heating in a tube furnace at 820 °C for approximately 235 hours under argon or under vacuum, a modification of the method of Skála and Drábek (2002). Once synthesized, the schreibersite was characterized to confirm the identity of the product as well as to elucidate the oxidation processes affecting the surface. In addition to characterization of the solid product, this schreibersite was reacted with water or with organic solutes in a choline chloride–urea deep eutectic mixture, to constrain potential prebiotic products. Major inorganic solutes produced by reaction of water include orthophosphate, phosphite, pyrophosphate and hypophosphate consistent with prior work on Fe3P corrosion. Additionally, schreibersite corrodes in water and dries down to form a deep eutectic solution, generating phosphorylated products, in this case phosphocholine, using this synthesized schreibersite

Comprehensive Study of the Chemical Composition and Spatial Outgassing Behavior of Hyperactive Comet 46P/Wirtanen Using Near-IR Spectroscopy during its Historic 2018 Apparition

We present a comprehensive analysis of the chemical composition of the Jupiter-family comet and potential spacecraft target 46P/Wirtanen, in the near-IR wavelength range. We used iSHELL at the NASA Infrared Telescope Facility to observe the comet on 11 pre-, near-, and postperihelion dates in 2018 December and 2019 January and February during its historic apparition. We report rotational temperatures, production rates, and mixing ratios with respect to H _2 O and C _2 H _6 or 3 σ upper limits of the primary volatiles H _2 O, HCN, CH _4 , C _2 H _6 , CH _3 OH, H _2 CO, NH _3 , CO, C _2 H _2 , and HC _3 N. We also discuss the spatial outgassing of the primary volatiles, to understand their sources and the spatial associations between them. The spatial profiles of H _2 O in 46P/Wirtanen suggest the presence of extended H _2 O outgassing sources in the coma, similar to the EPOXI target comet 103P/Hartley 2. 46P/Wirtanen is among the few known hyperactive comets, and we note that its composition and outgassing behavior are similar to those of other hyperactive comets in many ways. We note that the analyzed parent volatiles showed different variations (relative mixing ratios) during the apparition. We compared the chemical composition of 46P/Wirtanen with the mean abundances in Jupiter-family comets and the comet population as measured with ground-based near-IR facilities to date. The molecular abundances in 46P/Wirtanen suggest that although they were changing, the variations were small compared to the range in the comet population, with CH _3 OH showing notably more variation as compared to the other molecules