AOPP Seminar - The changing colours of our planet as a tool for life detection on icy moons and exoplanets

We cannot predict life. We can, instead, learn from Earth’s biodiversity and their varied molecular catalogue of markers of adaptability. Biopigments are widespread biomolecules that serve as powerful surface biomarkers of adaptability to extreme conditions on our planet. These molecules have distinct and unique spectral signatures providing a promising avenue for detecting extraterrestrial life. However, current surface models for other planets overlook Earth’s broader biodiversity. In the Solar System, current models struggle to constrain non-icy mysterious spots on the surface of the Jovian icy moon Europa for lack of matching reference spectra. In parallel, exoplanet surface models tend to overemphasize chlorophyll-based landscapes, often constrained by the assumption that photosynthesis requires visible light. This introduces unnecessary restrictions on atmospheric opacity and composition. In reality, Earth's biosphere hosts a vast array of biopigments capable of harnessing energy across the UV to IR spectrum, driving diverse metabolisms, volatile byproducts, and environmental adaptations—many of which serve as analogues for targets to be studied with future telescopes and space missions. By integrating Earth’s biological and evolutionary diversity with astrophysical tools, I will present life-detection frameworks based on a broad spectral dataset. I will show how in situ reflectance data from Svalbard (Arctic) and Atacama Desert can help us correlate biosignatures with specific environments. These findings contribute to biologically informed planetary models, crucial for the next generation missions, including Extremely Large Telescopes (ELTs), the Habitable Worlds Observatory (HWO) and Large Interferometer For Exoplanets (LIFE), as well as NASA’s Europa Clipper, ESA’s Juice and Enceladus L4. These exciting new instruments will probe several planetary surfaces for a new biosphere where orange, yellow, or purple may be the new green.