Understanding the origin and diversity of water-soluble carboxylic acids in pristine meteorites

Fundamental questions related to the origin of life are long-standing, controversial, and multifaceted, but one critical answer we are capable to provide, is that the simple organic building blocks that all life require can be created by chemical processes that took place in space. However, 'Where did the chemical processes occur?', 'How were the molecules created?', 'How abundant are they?', 'What happened after they were created?', these related questions are equally crucial and yet they have not been answered to date.

The significance of answering these questions is addressed by STFC's Science Challenge "How do planetary systems support the existence of life?", and this proposal aims at tackling this challenge by studying the water-soluble organic material hosted in carbon-rich meteorites.

Meteorites, which are fragments of asteroids and "leftovers" of planetary formation, present an opportunity to evaluate the organic building blocks hosted within them. In this proposal, we will study the water-soluble carboxylic acids in the Winchcombe, Paris and Tagish Lake meteorites that are collected immediately after their fireballs streaked across the sky.

These samples provide a golden chance to analyse the organic content of pristine extraterrestrial samples largely unmodified by the terrestrial environment.

Carboxylic acids are a particularly intriguing class of organic molecules for many reasons. Most importantly, they play key roles in the biochemistry of life on Earth as they comprise cell membrane without which life cannot exist. Carboxylic acids are also the most abundant class of soluble organic compounds in meteorites, allowing the use of highly sensitive and selective analytical techniques to measure the abundances, distributions, structural and isotopic compositions of these prebiotic compounds.

We will extract carboxylic acids from the meteorite samples in a newly refurbished clean laboratory at Royal Holloway University of London, and will quantify their abundance and determine their structural diversity with the use of gas chromatography mass spectroscopy analysis at Imperial College London. The structural composition of these molecules is capable of reflecting the formational pathways of these biomolecules.

We will then interpret where these molecules were formed in space (within or beyond our solar system - on asteroids, or in the far cold interstellar medium) by referring to their isotopic compositions. The formational relationship between carboxylic acids and amino acids will also be explored in this study as they are both biologically essential and structurally related, and their relationship may shed light on their chemical formational pathways.

This study will deliver new data that allow us to properly determine the provenance of key water-soluble organic compounds in pristine meteoritic materials. Compound-specific stable isotopic analyses of both carboxylic acids and amino acids across various pristine meteorites will provide a step change in our understanding on how these important classes of prebiotic molecules were formed, the influence of asteroid processes, and how the presence of these biomolecules and availability of liquid water are connected.

The proposal will provide a timely impact as it build on the latest understanding of the extraterrestrial organic matter in asteroid Ryugu samples returned by JAXA's Hayabusa2 mission, and will inform imminent space exploration, sample return missions such as NASA's OSIRIS-REx mission. Our team has an ambition in leveraging our expertise in meteoritic study in igniting public interest in STEM research.