Scientists build whole-Earth simulation to help find life on other planets

Scientists built a complex virtual Earth simulation without life to help identify habitable planets that might host life. The simulation, published in The Planetary Science Journal, models Earth's geochemical systems for 5 billion years, from its formation through 500 million years in the future. It accurately predicts 19 planetary properties like heat flow through the mantle but excludes the influence of life. The model can be generalized to predict how an atmosphere might evolve on any rocky planet and help pinpoint evidence of life in atmospheres that don't fit the model. Lead author Samantha Gilbert-Janizek said the model can help determine the probability that what astronomers observe on an exoplanet indicates life on its surface.

The simulation was developed in the lab of Rory Barnes, a UW associate professor of astronomy. The model includes the core, mantle, crust, and surface, but not the atmosphere. The researchers added atmosphere modeling to the existing Earth simulation to connect the atmosphere to Earth's interior. The model can be tuned to study any rocky exoplanet that astrobiologists find interesting. Researchers can plug in basic details about that planet and run the simulation to see whether the model can reproduce the observed atmosphere without the influence of life. If they can't get a match, the planet in question gets even more interesting.

The simulation provides a planetary baseline for distinguishing between "habitable" and "inhabited" worlds. It can help identify planets with atmospheres that can only be explained by life's influence. The model can be used to study distant worlds and inform the design of future telescopes like the Habitable Worlds Observatory. Gilbert-Janizek said the new and improved model can also help inform the design of future telescopes built to study distant planets. The model is a significant step toward understanding where life can exist in the universe.

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