Different is More: The Value of Finding an Inhabited Planet that is Far From Earth 2.0

Abstract

The search for an inhabited planet, other than our own, is a driver of planetary exploration in our solar system and beyond. Using information from our own planet to inform search strategies allows for a targeted search. It is, however, worth considering some span in the strategy and in a priori expectation. An inhabited Earth-like planet is one that would be similar to Earth in ways that extend beyond having biota. To facilitate analysis, we introduce a metric that extends from zero, for an inhabited planet that is like Earth in all other regards (i.e., zero differences), toward positive or negative values for planets that differ from Earth. The analysis shows how assessment of life potential in our galaxy changes more significantly if we find an inhabited planet that is less Earth-like (i.e., it quantifies how probability assessments improve with deviations from Earth-likeness). Discovering such planets could also provide a test of the strong form of the Gaia hypothesis - a test that has proved difficult using only the Earth as a laboratory. Lastly, we discuss how an Earth2.0 narrative, that has been presented to the public as a search strategy, comes with nostalgia-laden philosophical baggage that does not best serve exploration.

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• Tidal Limits to Planetary Habitability
• Habitability of Exoplanet Waterworlds
• Carbon cycling and habitability of Earth-size stagnant lid planets
• A Statistical Comparative Planetology Approach to the Hunt for Habitable Exoplanets and Life Beyond the Solar System
• Subsurface Exolife
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Cited by in corpus (5)

• On the Rate of Abiogenesis from a Bayesian Informatics Perspective
• Interior Controls on the Habitability of Rocky Planets
• Assessing the Intrinsic Uncertainty and Structural Stability of Planetary Models: 1) Parameterized Thermal-Tectonic History Models
• The Futility of Exoplanet Biosignatures
• Gaia as Solaris: An Alternative Default Evolutionary Trajectory