title: Quantifying the origins of life on a planetary scale.
abstract: A simple, heuristic formula with parallels to the Drake Equation is introduced to help focus discussion on open questions for the origins of life in a planetary context. This approach indicates a number of areas where quantitative progress can be made on parameter estimation for determining origins of life probabilities, based on constraints from Bayesian approaches. We discuss a variety of "microscale" factors and their role in determining "macroscale" abiogenesis probabilities on suitable planets. We also propose that impact ejecta exchange between planets with parallel chemistries and chemical evolution could in principle amplify the development of molecular complexity and abiogenesis probabilities. This amplification could be very significant, and both bias our conclusions about abiogenesis probabilities based on the Earth and provide a major source of variance in the probability of life arising in planetary systems. We use our heuristic formula to suggest a number of observational routes for improving constraints on origins of life probabilities.
authors.affiliation: Columbia Astrobiology Center, Columbia Astrophysics Laboratory, New York, NY 10027; caleb@astro.columbia.edu lee.cronin@glasgow.ac.uk.
authors.forename: Caleb
authors.initials: C
authors.lastname: Scharf
authors.affiliation: School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, United Kingdom caleb@astro.columbia.edu lee.cronin@glasgow.ac.uk.
authors.forename: Leroy
authors.initials: L
authors.lastname: Cronin
mesh_terms: D001499:Bayes Theorem; D019369:Life; D016083:Planets
keywords: chemical search space; exoplanetary science; origin of life; planetary scale