A Virtual Lifeless Earth Will Help Scientists Find Life on Exoplanets

A new research study titled "A Whole-planet Model of the Earth without Life for Terrestrial Exoplanet Studies" aims to help scientists distinguish between habitable and inhabited exoplanets. The study builds a virtual Earth model without life, reproducing key observations of the preindustrial Earth after 4.5 billion years. The model includes atmospheric CO2 and H2O, surface temperature and albedo, ocean mass, and other non-biological factors. The researchers used a code to compute synthetic HWO reflected-light spectra, including line absorptions for CO2, H2O, O2, O3, and CH4. This virtual Earth without life can serve as a benchmark to compare with detailed atmosphere observations of habitable worlds. The model successfully reproduces the properties of the Pre-Industrial Earth and predicts that a planet can maintain habitable conditions for a long time without requiring the presence of life. The model can help determine the probability that what we observe indicates life on the surface.

• The study is published in The Planetary Science Journal.
• The lead author is Samantha Gilbert-Janizek, a postdoctoral astronomy student at the University of Washington.
• The model reproduces 19 key observations of the preindustrial Earth after 4.5 Gyr.
• The model includes atmospheric CO2 and H2O, surface temperature and albedo, ocean mass, and other non-biological factors.
• The model uses a code to compute synthetic HWO reflected-light spectra for the true Earth and the abiotic Earth’s atmospheric state after 4.5 Gyr.
• The model can help determine the probability that what we observe indicates life on the surface.

The researchers built a coupled interior-atmosphere evolution model of the Earth without life from 50 Myr to 5 Gyr. The model initializes after Earth's magma ocean solidified and assumes that plate tectonics were active throughout Earth's history. The model reproduces the properties of the Pre-Industrial Earth and predicts that a planet can maintain habitable conditions for a long time without requiring the presence of life. The model can help determine the probability that what we observe indicates life on the surface. The model can serve as a benchmark to compare with detailed atmosphere observations of habitable worlds. The model can help scientists distinguish between habitable and inhabited exoplanets.

• The model is based on a coupled interior-atmosphere evolution model of the Earth without life from 50 Myr to 5 Gyr.
• The model initializes after Earth's magma ocean solidified and assumes that plate tectonics were active throughout Earth's history.
• The model reproduces the properties of the Pre-Industrial Earth and predicts that a planet can maintain habitable conditions for a long time without requiring the presence of life.
• The model can help determine the probability that what we observe indicates life on the surface.
• The model can serve as a benchmark to compare with detailed atmosphere observations of habitable worlds.

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