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Organic hazes as a source of life’s building blocks to warm little ponds on the Hadean Earth

Presentation #108.01 in the session Astrobiology and Origins of Life (Oral Presentation)

Published onOct 23, 2023
Organic hazes as a source of life’s building blocks to warm little ponds on the Hadean Earth

Over 4 billion years ago, the Earth may have had a thick haze in its atmosphere, similar to Saturn’s moon Titan. This haze contained a large number of the basic building blocks of life, and may have played a role in creating suitable environments for life to begin. In this study, we recreated these organic hazes in the lab by simulating high (5%) and low (0.5%) methane levels in an early reducing Hadean atmosphere. Then, we analyzed the solid haze particles for nucleobases, amino acids, and other organic compounds using GC/MS/MS techniques to obtain their concentrations. We also heated the high methane haze particles to mimic the hazes settling on a surface that is too hot for liquid water. Using this experimental data and estimates of haze production, we developed a sophisticated sources and sinks computer model to calculate the concentrations of nucleobases in warm little ponds, which were potentially sites for the emergence of life during that time. The results showed that organic hazes typically provided concentrations of nucleobases ranging from 0.2 to 6.5µM in these ponds. However, if the nucleobases did not leak out of pores at the base of the pond, the concentrations of uracil and thymine—two key nucleobases in RNA and DNA—could reach up to 100µM, which is the current lower experimental limit required for the formation of nucleotides. When the samples were heated, the biomolecules partially or completely degraded, suggesting that the stockpiling of biomolecules on a hot surface is unlikely to have occurred.

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