Origins of Life on Exoplanets

TL;DR

This paper discusses how exoplanet environments can be used to test different origins of life scenarios, focusing on the UV-driven cyanosulfidic pathway, and how these tests can falsify or support certain hypotheses.

Contribution

It introduces a framework for testing origins of life scenarios on exoplanets and demonstrates how specific tests can falsify or refine these hypotheses.

Findings

Some versions of the cyanosulfidic scenario have been falsified by tests.

Testing initial conditions alters the predicted chemical networks.

Predicted biosignature distributions can be compared with future observations.

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 has replaced certain reactants with others and has affected the overall chemical network underlying the cyanosulfidic scenario. The sequence of reactions the scenario invokes provide a predicted upper limit on the ubiquity of life in the universe that has ample room for improvement. 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.