Exoplanet Biosignatures: Future Directions

TL;DR

This paper proposes a Bayesian framework for exoplanet biosignature detection, aiming to guide future observations and interpret the data in a quantitative, flexible manner that accounts for uncertainties and diverse life signatures.

Contribution

It introduces a novel Bayesian methodology for assessing biosignatures, enabling generalized, probabilistic interpretation beyond known life signatures.

Findings

Framework allows quantitative confidence levels for life detection

Guides observational strategies including wavelength selection and survey scope

Integrates multidisciplinary insights to improve detection confidence

Abstract

Exoplanet science promises a continued rapid accumulation of new observations in the near future, energizing a drive to understand and interpret the forthcoming wealth of data to identify signs of life beyond our Solar System. The large statistics of exoplanet samples, combined with the ambiguity of our understanding of universal properties of life and its signatures, necessitate a quantitative framework for biosignature assessment Here, we introduce a Bayesian framework for guiding future directions in life detection, which permits the possibility of generalizing our search strategy beyond biosignatures of known life. The Bayesian methodology provides a language to define quantitatively the conditional probabilities and confidence levels of future life detection and, importantly, may constrain the prior probability of life with or without positive detection. We describe empirical and theoretical work necessary to place constraints on the relevant likelihoods, including those emerging from stellar and planetary context, the contingencies of evolutionary history and the universalities of physics and chemistry. We discuss how the Bayesian framework can guide our search strategies, including determining observational wavelengths or deciding between targeted searches or larger, lower resolution surveys. Our goal is to provide a quantitative framework not entrained to specific definitions of life or its signatures, which integrates the diverse disciplinary perspectives necessary to confidently detect alien life.