Revisiting Pigmentation as Biomarker and Biosignature for Extraterrestrial Life

Abstract:

Understanding what life may look like on other planets has long been an aim of astrobiology (DasSarma et al 2006). However, we have to date been hindered by our limited view of life constrained to our home planet, which serves as the basis for environmental and organismal analogues to extraterrestrial counterparts. Challenging this approach requires the use of novel techniques to expand the target ranges in the search for extraterrestrial life and biosignature detection. Recent research has proposed non-photosynthetic pigments often found in extremophiles as potential surface level biosignatures (Schweiterman et al. 2015), as well as outlined methods for the expansion of pigment families by structure and role, and rational design of pigments for optimized protective functionality (Schweitzer et al. 2009). We build upon these separate studies to propose an range of novel pigment structures that are similar to but distinct from pigments found in Earth-based extremophiles, expanding the library of pigments under consideration as aspects of non-Earth based life.

Utilizing molecular modeling tools, approaches from AI-based drug discovery, and structure-property prediction techniques, we present a method to discover novel pigments and simulate their associated spectra relevant for identifying new model extremophiles as well as new potential surface biosignatures for life on other planets. Unlike physical experimental design methods, computational models offer a path for rapid iteration and library creation relevant for exploratory search and validation. In this way, we recontextualize and expand the scope of extremophile and biosignature research by drawing from seemingly disparate fields to accelerate progress and challenge current methods in key areas of astrobiology.