Towards RNA life on Early Earth: From atmospheric HCN to biomolecule production in warm little ponds

Abstract

The origin of life on Earth involves the early appearance of an information-containing molecule such as RNA. The basic building blocks of RNA could have been delivered by carbon-rich meteorites, or produced in situ by processes beginning with the synthesis of hydrogen cyanide (HCN) in the early Earth's atmosphere. Here, we construct a robust physical and non-equilibrium chemical model of the early Earth atmosphere. The atmosphere is supplied with hydrogen from impact degassing of meteorites, sourced with water evaporated from the oceans, carbon dioxide from volcanoes, and methane from undersea hydrothermal vents, and in which lightning and external UV-driven chemistry produce HCN. This allows us to calculate the rain-out of HCN into warm little ponds (WLPs). We then use a comprehensive sources and sinks numerical model to compute the resulting abundances of nucleobases, ribose, and nucleotide precursors such as 2-aminooxazole resulting from aqueous and UV-driven chemistry within them. We find that at 4.4 bya (billion years ago) the limits of adenine concentrations in ponds for habitable surfaces is 0.05$\mu$M in the absence of seepage. These concentrations can be maintained for over 100 Myr. Meteorite delivery of adenine to WLPs can provide boosts in concentration by 2-3 orders of magnitude, but these boosts deplete within months by UV photodissociation, seepage, and hydrolysis. The early evolution of the atmosphere is dominated by the decrease of hydrogen due to falling impact rates and atmospheric escape, and the rise of oxygenated species such as OH from H2O photolysis. Our work points to an early origin of RNA on Earth within ~200 Myr of the Moon-forming impact.

Manuscript revised and resubmit to ApJ, 28 pages (14 main text), 13 figures, 8 tables

References in corpus (20)

• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• petitRADTRANS: a Python radiative transfer package for exoplanet characterization and retrieval
• On the radiative equilibrium of irradiated planetary atmospheres
• Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e
• Origin of the RNA World: The Fate of Nucleobases in Warm Little Ponds
• Disequilibrium biosignatures over Earth history and implications for detecting exoplanet life
• Hydrogen Cyanide in Nitrogen-Rich Atmospheres of Rocky Exoplanets
• The terrestrial late veneer from core disruption of a lunar-sized impactor
• Photochemistry of Anoxic Abiotic Habitable Planet Atmospheres: Impact of New H${}_2$O Cross-Sections
• Is the faint young Sun problem for Earth solved?
• Seeding the Pregenetic Earth: Meteoritic Abundances of Nucleobases and Potential Reaction Pathways
• On the Chemical Abundance of HR 8799 and the Planet c
• Lightning climatology of exoplanets and brown dwarfs guided by Solar System data
• The role of clouds on the depletion of methane and water dominance in the transmission spectra of irradiated exoplanets
• A Consistent Reduced Network for HCN Chemistry in Early Earth and Titan Atmospheres: Quantum Calculations of Reaction Rate Coefficients
• HCN production in Titan's Atmosphere: Coupling quantum chemistry and disequilibrium atmospheric modeling
• Understanding the atmospheric properties and chemical composition of the ultra-hot Jupiter HAT-P-7b II. Mapping the effects of gas kinetics
• Habitability of the early Earth: Liquid water under a faint young Sun facilitated by strong tidal heating due to a closer Moon
• Meteorites and the RNA World: A Thermodynamic Model of Nucleobase Synthesis within Planetesimals
• CRAHCN-O: A Consistent Reduced Atmospheric Hybrid Chemical Network Oxygen Extension for Hydrogen Cyanide and Formaldehyde Chemistry in CO2-, N2-, H2O-, CH4-, and H2-Dominated Atmospheres

Cited by in corpus (11)

• Hubble WFC3 Spectroscopy of the Rocky Planet L 98-59 b: No Evidence for a Cloud-Free Primordial Atmosphere
• An experimental and theoretical investigation of HCN production in the Hadean Earth atmosphere
• Formation of extraterrestrial peptides and their derivatives
• Organic hazes as a source of life's building blocks to warm little ponds on the Hadean Earth
• Eta-Earth Revisited II: Deriving a Maximum Number of Earth-like Habitats in the Galactic Disk
• Self-Shielding Enhanced Organics Synthesis in an Early Reduced Earth's Atmosphere
• A high-resolution spectroscopic analysis of aminoacrylonitrile and an interstellar search towards G+0.693
• Rovibrational Overtone and Combination Bands of the HCNH+ Ion
• Lightning activity on a tidally locked terrestrial exoplanet in storm-resolving simulations for a range of surface pressures
• Hydrocarbon complexity and photochemical shielding of prebiotic feedstock molecules in exoplanet atmospheres
• Deep Mantle-Atmosphere Coupling and Carbonaceous Bombardment: Options for Biomolecule Formation on an Oxidized Early Earth