Volatile species in comet 67P/Churyumov-Gerasimenko -- investigating the link from the ISM to the terrestrial planets

TL;DR

This paper explores the chemical composition of comet 67P, highlighting the connection between interstellar medium molecules and those in comets, and discusses their potential role in delivering prebiotic molecules to Earth and implications for extraterrestrial life detection.

Contribution

It provides new insights into the link between cometary volatiles and interstellar molecules, emphasizing their inheritance and potential role in prebiotic chemistry on Earth.

Findings

Comets share many volatile molecules with the interstellar medium.

Comets may have delivered significant prebiotic molecules to Earth.

Comets contain molecules relevant to biological processes.

Abstract

Comets contain abundant amounts of organic and inorganic species. Many of the volatile molecules in comets have also been observed in the interstellar medium and some of them even with similar relative abundances, indicating formation under similar conditions or even sharing a common chemical pathway. There is a growing amount of evidence that suggests comets inherit and preserve substantial fractions of materials inherited from previous evolutionary phases, potentially indicating that commonplace processes occurred throughout comet-forming regions. Through impacts, part of this material has also been transported to the inner planetary system, including the terrestrial planets. While comets have been ruled out as a major contributor to terrestrial ocean water, substantial delivery of volatile species to the Earth's atmosphere, and as a consequence also organic molecules to its biomass, appears more likely. Comets contain many species of pre-biotic relevance and molecules that are related to biological processes on Earth, and have hence been proposed as potential indicators for the presence of biological processes in the search of extraterrestrial life. While the delivery of cometary material to Earth may have played a crucial role in the emergence of life, the presence of such alleged biosignature molecules in the abiotical environment of comets complicates the detection of life elsewhere in the universe.