Agnostic approaches to extant life detection on Ocean Worlds

Heather Graham, NASA Goddard Space Flight Center, Greenbelt, MD, United States, Sarah Johnson, Georgetown University, Washington, DC, United States, Eric Anslyn, University of Texas at Austin, Austin, United States, Pamela Gales Conrad, Carnegie Institution for Science, Washington, D.C., United States, Leroy Cronin, University of Glasgow, School of Chemistry, Glasgow, United Kingdom, Andrew Ellington, University of Texas at Austin, Austin, TX, United States, Cook, Jamie Elsila, NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, United States, Peter R Girguis, Harvard University, Organismic and Evolutionary Biology, Cambridge, MA, United States, Christopher H House, Pennsylvania State University, Geosciences and Environmental Systems Institute, University Park, United States, Chris Kempes, Santa Fe Institute, Santa Fe, United States, Eric Libby, Umea University, Umea, Sweden, Paul R Mahaffy, NASA Goddard Space Flight Center, Planetary Environments Laboratory, Greenbelt, United States, Barbara Sherwood Lollar, University of Toronto, Department of Earth Sciences, Toronto, ON, Canada and Andrew Steele, Carnegie Science, Earth and Planets Laboratory, Washington, United States
Abstract:
As we reach deeper into the Solar System, the likelihood of encountering organisms that do not share a common heritage with terrestrial life becomes much greater and life based on an unfamiliar biochemistry may exist Without presupposing a particular molecular framework the Laboratory for Agnostic Biosignatures (LAB) team pursues tools and techniques for life detection that could help us identify the unfamiliar features and chemistries that may represent processes of life as-yet unrecognized. These approaches can be tailored for applications on Ocean Worlds and are even being tested with instrumentation that is being flight-qualified for future missions to these destination. Members of LAB are working to understand the relationship between the chemical complexity patterns of organic molecules and the likelihood that these structures arise in the absence of biology. Analytical algorithms based on these results are being refined for a high-heritage mass spectrometer that will fly to Titan aboard Dragonfly. Another complexity-related method evaluates the variety of binding sites on the surface of an analyte, relying on the observation that at the molecular level biological surfaces represent a greater diversity of binding sites. This concept uses the various naturally-forming secondary and tertiary structures of oligonucleotides as probes for particular binding sites and uses novel sequencing technologies to then describe the nature and number of these binding aptamers. The LAB group is also exploring disequilibrium redox chemistries the possibility that redox couples that are inconsistent with abiotic reactions could be indicators of active metabolism. This could present as unexpected accumulations of chemical elements or isotopes or as patterns of energy transfer. The current density and other electrical signals produced by microbes are notable distinct from abiotic oxidation and could serve as an agnostic means of detecting metabolic activity via inert conductive electrodes. While it is necessary to broaden our scope and design inclusive life detection strategies, agnostic approaches are less definitive since they lack familiar analogs. The LAB data interpretation scheme considers expectations and likelihood and establishes critical thresholds for life detection based on probabilistic models.
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