Galactic Distribution of Chirality Sources

Biochemical processes are known to utilize only one enantiomer, e.g. amino acids used by terrestrial life are generally the left-handed version. The concepts of chirality, optical activity and chiral enrichment are explored in the context of the origin of life in the universe before Earth. Chirality as a feature of terrestrial life suggests neither a special place for local development of homochirality nor for extra-terrestrial enrichment and delivery. Each seems to have some strengths. Chiral enrichment on asteroids or comets could have been promoted via photon polarization or preferential growth on ice mineral faces or both. Chiral enrichment in situ could have occurred via a variety of processes, including zeolite or sulfide surface templating. Stellar and planetary magnetic fields are discussed as well, and a novel mechanism for geomagnetic reversals is introduced based on analogy with stellar processes. Mineral classes and environments are also explored along with four hypothetical scenarios: asteroid/comet delivery; chemical gardens; geothermal fields; and icy worlds.