Researchers build whole-earth simulation to distinguish abiotic exoplanets from inhabited worlds

A 5-billion-year computational simulation accurately models abiotic geochemical exchange across Earth’s core, mantle, crust, and atmosphere, establishing a non-living baseline to help astronomers identify true biosignatures on distant exoplanets

A research team led by the University of Washington has developed a comprehensive “whole-planet” computer simulation that models Earth’s chemical evolution over a 5-billion-year timeline, with one critical modification: the complete exclusion of biological life.

Published in The Planetary Science Journal, the model accurately predicts 19 fundamental planetary properties across Earth’s core, mantle, crust, surface, and atmosphere, establishing an abiotic geochemical baseline to help astronomers determine whether atmospheric gases on distant rocky exoplanets stem from non-biological processes or alien life.

Geochemical modelling and abiotic baselines

With more than 6,000 exoplanets catalogued to date, astrobiologists frequently analyse planetary atmospheres for chemical disequilibrium, such as the simultaneous presence of oxygen and methane, which neutralise each other unless continuously replenished by biological activity.

However, confirming whether an exoplanet is inhabited requires knowing what atmospheric states can arise purely through abiotic mechanisms:

• Whole-system coupling: The simulation links internal geodynamics (mantle heat flow, core cooling, and volcanic outgassing) with surface hydrology, atmospheric chemistry, and stellar radiation.
• 5-billion-year timeline: The model tracks chemical fluxes from Earth’s formation 4.5 billion years ago through 500 million years into the future, validating its accuracy against 19 physical and chemical parameters of the real Earth.
• Exoplanet customisation: Researchers can adjust the simulation’s initial parameters, such as planet mass, stellar irradiance, and interior composition, to model any rocky exoplanet and evaluate whether its observed atmosphere requires biological intervention.

Implications for astrobiology and mission design

By defining the chemical limits of non-living rocky worlds, the simulation provides an essential tool for evaluating data from current and next-generation space observatories:

1. Filtering false positives:

   • The tool allows scientists to test whether potential biosignatures (e.g., atmospheric methane or nitrous oxide) can be explained by interior outgassing or photochemistry alone.

2. Telescope instrument design:

   • Findings from the model will help refine science goals and instrument specifications for future NASA flagship missions, such as the proposed Habitable Worlds Observatory (HWO).