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The PEACH Model: Physiology, Exoclimatology, and Astroecology for Characterizing Habitability

Presentation #1217 in the session “Open Engagement Session C”.

Published onMar 17, 2021
The PEACH Model: Physiology, Exoclimatology, and Astroecology for Characterizing Habitability

A primary objective of the field of astrobiology is to identify worlds outside of our own that are capable of supporting life. Here, we apply an integrative approach between astrophysics, climate modeling, and ecophysiology to explore the relationship between alien environments and terrestrial life. I will discuss the development of a novel system that can be used as a tool to assess the habitable regions on exoplanet surfaces. In this model, simulated exoplanet environments are convolved with a real biological layer. Exoplanet environments are simulated using the climate model, Resolving Orbital and Climate Keys of Earth and Exoplanet Environments (ROCKE-3D, Way et. al. 2018). ROCKE-3D is a fully-coupled 3-dimensional oceanic-atmospheric general circulation model (GCM) featuring interactive atmospheric chemistry, aerosols, the carbon cycle, vegetation, and other tracers, as well as the standard ocean, sea ice, and land surface components. The GCM output is coupled in the astroecology model with empirically-derived thermal performance curves of 1,627 cell strains representing extremophiles from all six Kingdoms, termed the biokinetic spectrum for temperature (BKST, Corkrey et al. 2016). The BKST arises from a meta-analysis of cellular growth rate as a function of temperature. In this agent-based model, created with the software NetLogo, the survivability of a biological organism is determined by its thermal response to simulated local and global exoplanet temperature dynamics. This model can be applied to produce a list of exoplanets with the highest probability of having temperate surface conditions compatible with terrestrial-based thermophysiology, as well as surface maps highlighting potentially thermally habitable regions. Life, however, is dependent upon multiple variables including the presence of liquid water, nutrient content, and an energy source. Caveats of the methodology and application of our results are discussed with implications for extraterrestrial evolution and observable biosignatures.

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