Origins of life on exoplanets

Abstract

I show that exoplanets can be used to test origins scenarios. Origins scenarios start with certain initial conditions, proceed via a network of chemical reactions, and if successful result in a chemistry that is closer to a living system than the initial conditions. Exoplanet environments can be applied to test each of these three aspects of origins scenarios. I show what tests can be applied to the UV-driven cyanosulfidic scenario and how the application of some of these tests has already falsified certain versions of this scenario. Testing initial conditions replaces certain reactants with others and affects the overall chemical network underlying the cyanosulfidic scenario. The sequence of reactions the scenario invokes can provide a predicted upper limit on the ubiquity of life in the universe. The outcome of the experiments in different environments is part of a predicted distribution of biosignature detections that can be compared to future observed distributions.