Meteorite Parent Body Aqueous Alteration Simulations of Interstellar Residue Analogs

Abstract

Some families of carbonaceous chondrites are rich in prebiotic organics that may have contributed to the origin of life on Earth and elsewhere. However, the formation and chemical evolution of complex soluble organic molecules from interstellar precursors under relevant parent body conditions has not been thoroughly investigated. In this study, we approach this topic by simulating meteorite parent body aqueous alteration of interstellar residue analogs. The distributions of amines and amino acids are qualitatively and quantitatively investigated and linked to closing the gap between interstellar and meteoritic prebiotic organic abundances. We find that the abundance trend of methylamine > ethylamine> glycine > serine > alanine > β-alanine does not change from pre-to post-aqueous alteration, suggesting that certain parental cloud conditions have an influential role on the distributions of interstellar-inherited meteoritic organics. However, the abundances for most of the amines and amino acids studied here varied by about 2-fold when aqueously processed for 7 days at 125 °C, and the changes in the αto β-alanine ratio were consistent with those of aqueously altered carbonaceous chondrites, pointing to an influential role of meteorite parent body processing on the distributions of interstellar-inherited meteoritic organics. We detected higher abundances of αover β-alanine, which is opposite to what is typically observed in aqueously altered carbonaceous chondrites; these results may be explained by at least the lack of minerals, inorganic species, and insoluble organic matter-relevant materials in the experiments. The high abundance of volatile amines in the non-aqueously altered samples suggests that these types of interstellar volatiles can be efficiently transferred to asteroids and comets, supporting the idea of the presence of interstellar organics in solar system objects.

Molecular Diversity and Amino Acid Evolution in Simulated Carbonaceous Chondrite Parent Bodies

“…For instance, higher β-alanine/glycine is observed at a lower degree of alteration of preaccretional analogues (Table ). This finding is corroborated by similar aqueous alteration experiments performed by Qasim et al on a similar preaccretional material. On the contrary, in meteorites, it is proposed that a lower degree of aqueous alteration favors the presence of α-amino acids via the Strecker synthesis, while a higher degree of alteration enhances the presence of β-amino acids compared to α-amino acids. ,, Therefore, higher β-alanine/glycine ratios are observed for more aqueous altered meteorites.…”

“…It may occur through ice processing via the transformation of methyl carbamate, formed from the condensation in the ice between methylamine and carbon dioxide, 35,36 into glycinate salt under UV irradiation (Figure 3A), 35,36 as supported by the detection of methylamine in preaccretional analogues. 37 No investigation has been conducted on the formation of the other three amino acids, making it difficult to propose hypotheses about their formation mechanisms in such ice. The Strecker synthesis has been shown to occur partially during photoprocessing and heating of ice, since its last step, which consists of the hydrolysis of the amino nitrile, is not possible in these conditions due to a high energy barrier, 38−40 which prevents the formation of glycine.…”

“…Other targeted analyses on amino acids on similar analogues altered at 125 °C showed also weak evolution of several amino acids. 37 The concentration of α-amino acids (glycine, alanine, and serine) tends to increase with time, while the concentration of β-alanine decreases. Trends observed in Qasim et al are less pronounced than in our experiment, probably because of the differences in experimental conditions compared to our conditions, since they use lower temperatures (125 vs 150 °C), lower duration experiments (30 vs 100 days), and maybe different compositions in their preaccretional analogue.…”

“…The formation of glycine in the ice analogue can occur following different pathways. It may occur through ice processing via the transformation of methyl carbamate, formed from the condensation in the ice between methylamine and carbon dioxide, , into glycinate salt under UV irradiation (Figure A), , as supported by the detection of methylamine in preaccretional analogues . No investigation has been conducted on the formation of the other three amino acids, making it difficult to propose hypotheses about their formation mechanisms in such ice.…”

Molecular distribution and 13C isotope composition of volatile organic compounds in the Murchison and Sutter's Mill carbonaceous chondrites

“…Volatile organic compounds (VOCs) and nonvolatile soluble organic compounds (also referred to here as soluble organic matter or SOM) trapped in meteoritic matrixes are part of the molecular inventory of our primitive solar system that have remained unaltered by biological and geological processes since their formation early in solar system history (Öberg, 2016; Qasim et al., 2023; Sandford et al., 2020). VOCs are capable of evaporating or sublimating at modest temperatures (typically below room temperature).…”