What sets George Cody, acting director of the Geophysical Laboratory, apart from other geochemists is his pioneering use of sophisticated techniques such as enormous facilities for synchrotron radiation, and sample analysis with nuclear magnetic resonance (NMR) spectroscopy to characterize hydrocarbons. Today, Cody applies these techniques to analyzing the organic processes that alter sediments as they mature into rock inside the Earth and the molecular structure of extraterrestrial organics.
Wondering about where we came from has occupied the human imagination since the dawn of consciousness. Using samples from comets and meteorites, George Cody tracks the element carbon as it moves from the interstellar medium, through Solar System formation, ultimately to the origin of life.
Primitive meteorites, interplanetary dust particles, and comets are remnants of the early Solar System. The abundant organic matter contained in these primitive bodies records a long chemical history, beginning with reactions that occurred in the interstellar medium, and continuing with reactions that occurred during the formation and evolution of the early solar nebula, and in the formation and evolution of the parent bodies of meteorites. To untangling this record is a challenge: the vast majority of the organic carbon exists as an extremely complex polymer—large molecules with repeating units—that is insoluble by most means.
Cody and colleagues pioneered procedures applying solid-state nuclear magnetic resonance (NMR) spectroscopy to get around the insolubility problem. NMR spectroscopy reveals molecular information when nuclei of certain atoms are placed in an enormous magnetic field and then resonantly excited with radio-frequency pulses. The emission signal from the excited nuclei yield a spectral “fingerprint” characteristic of the electronic structure of the host molecule.
Cody also employs Carbon X-ray Absorption Edge Structure spectroscopy, which is essential to the analysis of comet particles. Results from both methods ultimately provide essential clues regarding the origin of extraterrestrial organic carbon and the history of chemical processing as the molecular cloud coalesced into the Solar System.
The retention of carbon in the inner Earth is a prerequisite to the origin of the global carbon cycle. Cody with colleagues have conducted NMR-based experiments that reveal how some carbon was retained even during the magma-ocean phase of Earth history. Such carbon may have been essential for the emergence of life.
The transition from a chemical world to a biological one remains a profound mystery. One promising area of this research is to investigate Earth’s natural catalysts and the environments in which they are found. Cody and colleagues study catalytic properties of so-called transition metal minerals that are abundant in deep-sea ore-bodies to help piece together the puzzle of life’s origins.
Cody received his B.S. from University of Massachusetts in geology in 1982. He then taught and conducted research there for two years. In then he joined Exxon Research and Engineering and studied the chemical structure of coal, work that inspired his Ph.D. thesis at Pennsylvania State University. After receiving his Ph. D., Cody was an Enrico Fermi Scholar at the Argonne National Laboratory. He joined Carnegie in 1995 and was made acting director of the Geophysical Laboratory in 2013. He is principal investigator in charge of W. M. Keck Solid State NMR Laboratory and principal investigator of the Carnegie's NASA Astrobiology Insititute.