Dr. John Eiler, Robert P. Sharp Professor of Geology and Geochemistry, and Ted and Ginger Jenkins Leadership Chair of Geological and Planetary Sciences, Caltech
Exploring the organic chemistry of the early solar system using molecular isotopic structure
Abstract
Organic chemistry is ubiquitous across all extraterrestrial environments — stellar envelopes, nebulae and protoplanetary disks, the diffuse interstellar medium (ISM) — and dominates the processing and delivery of volatiles to planetary bodies. Extraterrestrial settings and materials also present the most clearly revealed and diverse collection of constraints on the ways in which 'prebiotic' chemistry takes its first steps towards life.
This subject can be divided into several discrete stages and environments: the cold, diffuse settings of the ISM, nebula and outer protoplanetary discs; the warm, dense inner regions of disks; and the interiors of early solar system bodies, where water-rock reactions may guide a great range of 'prebiotic' chemistry. Extraterrestrial organics can be observed in these settings using a variety of astronomical approaches, but the most detailed and nuanced constraints come from the laboratory study of the thousands of organic compounds sampled by carbonaceous meteorites and returned samples of asteroids. Decades of study of these materials have revealed several first-order insights, but detailed explication has been challenging because these samples are intimate mixtures of materials formed across any of the settings and processes of interest — in fact, some compounds may be the end result of reactions occurring during all of them.
I will present a body of work that explores the origin and evolution of early solar system organic materials through application of molecular isotopic structure — the study of the distributions of naturally occurring rare isotopes (D, 13C, 15N, etc.) at scales of individual atomic positions and considering the very rare versions of molecules that contain two or more rare isotopes. These studies were enabled by more than two decades of technology invention, studies of the chemical physics of previously unexamined isotopic forms of molecules, and applications to meteorites, returned samples, ancient earth materials and their laboratory analogues. The results reveal the long, complex journey of carbon and other volatile materials from synthesis the ISM, through the early history of the disk and into the 'prebiotic cauldron' of early solar system bodies.
Biography
John Eiler is a geologist and geochemist specializing in the distribution of the stable isotopes among natural materials. His research group is best known for developing the study of natural molecules containing two or more rare isotopes – a rare but ubiquitous family of species that give rise to a variety of applied geochemical tools. Eiler was raised in Madison, Wisconsin, attended Beloit College before moving to the University of Iowa, where he earned a BS in Geology. He received his Ph.D. in Geology from the University of Wisconsin, Madison. He then worked as a postdoctoral fellow in stable isotope geochemistry at Caltech, where he joined the faculty in 1994. He is a recipient of the Day medal, Epstein medal, Macelwane medal, and Mineralogical Society of America young scientist award, and a member of the National Academy of Sciences.
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