Searching for Life-As-We-Don't-Know-It: Mission-relevant Application of Assembly Theory for Exoplanet Life Detection

TL;DR

This paper proposes applying Assembly Theory to exoplanet atmospheres to quantify chemical complexity as a biosignature, enabling detection of unknown forms of life without relying on specific biochemistry.

Contribution

It introduces a novel framework using Assembly Theory for planetary atmospheres to assess potential biosignatures without assuming specific biological processes.

Findings

Framework quantifies minimum combinatorial complexity of atmospheric molecules.

Method can be validated against existing spectroscopic data.

Enables continuous measurement of planetary complexity for life detection.

Abstract

This white paper introduces a framework for applying Assembly Theory (AT) to planetary atmospheres as a biosignature framework suitable for the Habitable Worlds Observatory (HWO). AT quantifies the minimum combinatorial complexity required to co-construct an observed ensemble of molecular species, providing a measure of how much selection and evolution is encoded in a planetary atmosphere's chemical space, without assuming any specific biochemistry, kinetics nor metabolism. We outline some forthcoming results applying this framework and how it can be extended to population-level exoplanet studies, validated against existing spectroscopic data, and used to directly inform HWO instrumental requirements. Rather than imposing a binary alive/dead classification, AT-based atmospheric analysis would provide a continuous measure of planetary complexity, opening a path toward detecting life-as-we-don't-know-it.