Two recent Earth science studies by Barrett et al. and Bermingham et al. explore the origins of Earth’s water and indirectly, organic matter, key prerequisites for the development of intelligent life. Their findings support the early delivery of needed chemicals to form water and carbon molecules by inner and outer solar system planetesimals such as asteroids and comets.
Barrett et al. shows that an inner solar system sourced enstatite chondrite (EC) asteroid found in Antarctica is isotopically similar to Earth material, (not surprisingly, this supports the 270-year-old Nebular Hypothesis) capable of delivering substantial hydrogen during Earth’s accretionary phase (~4.56–4.5 billion years ago). The ECs contain hydrogen as H2S in silicate glass, linked to pyrrhotite, sufficient to account for up to 14 times Earth’s ocean mass. This hydrogen was systematically incorporated in the hot inner solar system via nebular processes, suggesting water was an inherent outcome of Earth’s formation, not a later addition. ECs also contain trace organic matter contributing modestly to Earth’s carbon inventory. Despite the chaotic “billiard table” trajectories of early solar system collisions, the stability of H2S in glass ensured survival during violent accretion. This early delivery of water and organics established a foundational habitable environment, priming the Earth’s prebiotic chemistry for the creation and evolution of intelligent life.
Bermingham et al., taking a different investigative track, analyze molybdenum isotopes in meteorites and Earth’s crust, concluding that water was delivered during the Late Heavy Bombardment (LHB: 4.1–3.8 billion years ago) by planetesimals, including inner solar system asteroids and outer solar system comets, as hydrous minerals or brine. This late accretion, post-Moon-forming event (4.5 billion years ago), suggests a stochastic bombardment enriched Earth’s surface volatiles. Comets and carbonaceous chondrites, rich in organic matter, likely delivered significant carbon compounds, enhancing the prebiotic chemical environment. The chaotic early solar system facilitated this influx of outer solar system organics, complementing earlier inputs.
Both studies align with life’s prerequisites by ensuring water and organic delivery to the planet. Barrett et al. provide the bulk water budget and trace organics via ECs, creating an early aqueous environment, while Bermingham et al.’s LHB bombardment added more water and substantial organics, boosting conditions for life’s emergence. They agree on asteroids’ role, possibly including ECs, but differ in timing (early accretion vs. LHB) and outer solar system delivery contributions (minor in Barrett, significant via comets in Bermingham). Barrett et al.’s early delivery of water and organics can be viewed as foundational and Bermingham et al.’s LHB as a surface-enriching supplement, together enabling the chemical and evolutionary path to intelligent life.
Source: Barrett et al, 2025, Icarus. Bermingham et al, 2025, Rutgers. Graphic: Comet Cometh, Grok3.
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