Bulk Silicate Earth Archives - Astrobiology

The changing mantle FeO and SiO2 of 8 Earth analogues as they grow through the simulation. The black dashed line and the grey band show the BSE concentrations of FeO and SiO2 (Palme and O’Neill, 2003) and the uncertainties on these values. The left-hand figure contains an insert that allows for a clearer view of the point at which the embryo masses reach 1 Earth Mass. -- astro-ph.EP

Astrogeology, Exoplanets, -moons, -comets, Meteorites & Asteroids, Press Release

Oxidation Constraints On Terrestrial Planet Formation From A Ring

by Keith CowingJune 2, 2026June 2, 2026

The present-day solar system comprises meteorites with varying oxidation levels, derived from different parent bodies.

Cartoon illustrating how the provenance of Earth’s building material evolved over time with a particular emphasis on how and when CC material was delivered to the terrestrial planets. a) Initial accretion in the terrestrial planets is of pure-NC material. b) Early giant planet growth/migration scatters a few large CC embryos into the inner disk while CC planetesimals are implanted into the asteroid belt. c) Earth accretes a few CC embryos as it grows, including one late in the accretionary sequence, but Mars does not. d) The Earth suffers one final NC-dominated, Moon-forming impact, after which it acquires ~0.5% of NC-dominated material (the late veneer). Timing given for each panel is not strict and mostly for illustrative purposes. -- astro-ph.EP

Astrochemistry, Astrogeology, Biogeochemical Cycles & Geobiology, Impact events, Meteorites & Asteroids, Status Report

Mechanisms and Timing of Carbonaceous Chondrite Delivery to Earth

by Keith CowingNovember 8, 2024November 8, 2024

The nucleosynthetic isotope signatures of meteorites and the bulk silicate Earth (BSE) indicate that Earth consists of a mixture of “carbonaceous” (CC) and “non-carbonaceous” (NC) materials.

Schematic overview of coupled redox-atmosphere-interior evolution model, PACMAN-P. The model is initialized with a completely molten mantle, and the solidification radius, rs, evolves from the core-mantle boundary to the surface, rp, as the planet cools. At each timestep, we calculate multiphase thermochemical equilibrium between C, H, O, and Fe-bearing species to find the mantle redox state and the partitioning of volatiles between the magma ocean and the atmosphere. Surface climate, Tsurf, is calculated using a radiative-convective model given atmospheric volatile inventories. Under highly reducing conditions created by large H2 envelopes, the reaction of H2 with the silicate magma ocean produces metallic iron, that is either sequestered in the core or remains in the mantle (two endmember assumptions). Atmospheric escape is either XUV-limited or diffusion limited depending on stratospheric composition, and under the former regime we calculate the hydrodynamic drag of O and CO. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report, TRAPPIST-1

The Erosion Of Large Primary Atmospheres Typically Leaves Behind Substantial Secondary Atmospheres On Temperate Rocky Planets

by Keith CowingOctober 1, 2024October 1, 2024

Exoplanet exploration has revealed that many–perhaps most–terrestrial exoplanets formed with substantial H2-rich envelopes, seemingly in contrast to solar system terrestrials, for which there is scant evidence of long-lived primary atmospheres. […]