Galactic Distribution of Chirality Sources of Organic Molecules

TL;DR

This paper explores the galactic distribution of chiral organic molecules, examining processes influencing their origin and implications for planetary habitability and the emergence of life.

Contribution

It introduces a framework for estimating the distribution of chiral organic molecules across the galaxy and discusses mechanisms affecting their racemization in different cosmic environments.

Findings

Chirality influences the origin of life and is distributed throughout the galaxy.

Four processes can promote racemization of organic molecules in space.

A worksheet tool helps generate scenarios for organic molecule distribution.

Abstract

Conceptualizing planetary habitability depends on understanding how living organisms originated and what features of environments are essential to foster abiogenesis. Estimates of the abundance of life's building blocks are confounded by incomplete knowledge of the role of chirality and racemization in organic compounds in the origination of living organisms. Chirality is an essential feature of enzymes as well as many lock-and-key type structures. There are four known processes that can act on complex organic molecules to promote racemization for abiogenesis: quantum-tunneling effects; selection via interaction with circularly polarized light (CPL); templating processes; and interactions with electrical and magnetic (EM) fields. These occur in different places, respectively: cold interstellar space; regions of space with energetic photons, dust and/or magnetic fields; and mineral surfaces (for both templating and EM fields). Chirality as a feature of terrestrial life suggests neither a special place for local development of homochirality nor for extra-terrestrial enrichment and delivery. The presence of these molecules in three competing scenarios for life's origin - chemical gardens, geothermal fields, and ice substrates - relies on a framework of hypothesis and estimation. An easily-modified worksheet is included in the supplemental material that allows a user to generate different scenarios and data related to the distribution of chiral organic molecules as building blocks for living organisms within the galaxy. A simple hypothetical mechanism for planetary magnetic field reversals, based on a high-density plasma inner core, is also presented as a means to aid in estimating field polarity and hence the orientation of racemization processes based on planetary magnetic fields.