Organic Astrochemistry 101: Meteorites and the Origins of Life on Earth

Speaker: Dr. José Aponte, NASA Goddard

Host: Dr. Leah Dodson, UMCP

Abstract: Carbonaceous chondrites (carbon-rich meteorites) represent some the oldest and most primitive pieces of material formed in the Solar System; indeed, they could even be older than the Sun itself. These carbon-rich meteorites may have delivered an important concentration of organic compounds and water to the primitive Earth. Multiple organic classes, including those required for life (e.g. amino acids, carboxylic acids, nucleobases and polyols) have been identified from carbonaceous chondrites, providing valuable insights into the chemical inventory of the early Solar System, the primordial synthesis of organic matter, and the question of how life appeared on Earth.
                Amino acids constitute the basic building blocks of all protein-based living organisms on Earth and thus, they are among the most intriguing and studied meteoritic organic compounds found. Homochirality (predominance of the L enantiomer) in terrestrial biological proteins is a fundamental feature of life as we know it. L-enantiomeric excesses have been observed in some meteoritic amino acids, raising interesting questions about a potential link between meteorites and terrestrial homochirality. In addition, the stable isotopic compositions (D, 13C, 15N) of meteoritic organic compounds provide information on their formation mechanisms and histories. Contrasting the distribution, chirality and isotopic composition of meteoritic organic compounds in a wide range of carbonaceous chondrites provide important insights on the composition and environments of the protosolar nebula, the meteorite parent bodies, and may well provide clues about their synthesis and survival during the formation of our Solar System.
                 I will present results from our extensive investigation on the abundance and molecular distribution of amino acids, and other biologically relevant molecules extracted from meteorites. We will discuss their potential prebiotic origins and relevance to the emergence of life on Earth. We will also review the importance or sample return missions and our future findings after the analysis of asteroid samples brought to the Earth by JAXA’s Hayabusa2 (December 6, 2020) and NASA’s OSIRIS REx (September 24, 2023).

Physical Chemistry Seminar