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

TL;DR

This paper explores the value of searching for inhabited planets that are significantly different from Earth, proposing a metric to evaluate their potential and discussing implications for planetary exploration strategies.

Contribution

It introduces a new metric for assessing how deviations from Earth-like conditions affect the likelihood of finding inhabited planets, challenging Earth-centric search narratives.

Findings

Assessment of life potential increases with less Earth-like planets.

Discovering diverse inhabited planets tests the Gaia hypothesis.

Earth2.0 focus may hinder exploration diversity.

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.