Abstract
Context.How simple organic matter appeared on Earth and the processes by which it transformed into more evolved organic compounds, which ultimately led to the emergence of life, is still an open topic. Different scenarios have been proposed, the main one assumes that simple organic compounds were synthesized, either in the gas phase or on the surfaces of dust grains, during the process of star formation and they were incorporated into larger bodies in the protoplanetary disk. The transformation of these simple organic compounds in more complex forms is still a matter of debate. Recent discoveries have pointed to catalytic properties of dust grains present in the early stellar envelope, which can nowadays be found in the form of chondrites. The significant infall of chondritic meteorites during the early periods of Earth suggests that the same reactions could have taken place in certain environments on the Earth’s surface, with conditions more favorable for organic synthesis.Aims.This work attempts to synthesize simple organic molecules, such as hydrocarbons and alcohols via Fischer–Tropsch-type reactions supported by different chondritic materials under early-Earth conditions, to investigate if organic synthesis can likely occur in this environment and to determine what the differences are in selectivity when using different types of chondrites.Methods.Fischer–Tropsch-type reactions are investigated from mixtures of CO and H2at 1 atm of pressure on the surfaces of different chondritic samples. The different products obtained are analyzed in situ by gas chromatography.Results.Different Fischer–Tropsch reaction products are obtained in quantitative amounts. The formation of alkanes and alkenes being the main processes. The formation of alcohols also takes place in a smaller amount. Other secondary products were obtained in a qualitative way.Conclusions.Chondritic material surfaces have been proven as good supports for the occurrence of organic synthesis. Under certain circumstances during the formation of Earth, they could have produced a suitable environment for these reactions to occur.
Highlights
Life on Earth likely arose from a series of particular conditions, which have yet to be unambiguously determined
We note other reasons that support that reactions are taking place in the reactor: (i) The progressive decrease in the amount of CO detected in the gas chromatography (GC) with respect to the initial CO introduced in the reactor suggests that the products are formed from the reactants and that they do not come from the meteorites themselves; (ii) the agreement of the distribution of products with the one expected from FTT reactions, the fact that no other species are detected, and the consecutive formation of products indicate that the reactions are taking place on the surface of the meteorites; and (iii) if the products were coming from the samples, their production would not be detected over the extended time of the experiments
Summary In this work, FTT reactions have been investigated in the presence of different meteoritical samples and under conditions resembling those of the early Earth
Summary
Life on Earth likely arose from a series of particular conditions, which have yet to be unambiguously determined. It has been envisioned that the early Earth was exposed to different sources of energy, such as light, heat, and reduction–oxidation (redox) potentials. Such an environment received a large flux of extraterrestrial material, at least until the end of the late heavy bombardment (LHB, Bottke et al 2012). The conditions in the atmosphere and surface of our planet might have promoted an increase in molecular complexity (Rotelli et al 2016) which, later on, allowed the recombination of organic molecules to form more complex, interacting and self-replicating systems (Walde 2005; Shulze-Makuch & Irwin 2008). The synthesis of interstellar complex organic molecules (iCOMs) in the solar nebula and during the process of star formation has been extensively studied during recent years (Herbst 2017). Robust pieces of evidence indicate that the formation of iCOMs takes place on the surface of interstellar grains (Kress & Tielens 2001; Sekine et al 2006; Linnartz et al 2015; Oberg 2016, Enrique-Romero et al 2019; Zamirri et al 2019; MartínDoménech et al 2020), which with time will coagulate and form the embryos of rocky planets and minor bodies
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