Astrobiology Science and Technology for Exploring Planets (ASTEP)

PI: Glavin, Daniel

The origin of life on Earth, and possibly elsewhere, is expected to have required liquid water and a continuous supply of organic compounds. The delivery of organic matter by asteroids, comets, and carbonaceous meteorites could have significantly contributed to the early Earth’s prebiotic inventory with a continuous supply of biologically important organic compounds. A wide variety of organic compounds have been detected in the Murchison CM type carbonaceous chondrite including amino acids, purines and pyrimidines. These compounds are central to modern terrestrial biochemistry (as major components of proteins, nucleic acids, and coenzymes) and were probably pivotal in the origin of life. Although isotopic analyses of amino acids in Murchison indicate that these organic compounds are clearly distinct from terrestrial organic matter, an extraterrestrial source of purines and pyrimidines in CM type carbonaceous chondrites has remained unclear for over 25 years. We propose to isolate purines and pyrimidines from Murchison and other CM type carbonaceous chondrites collected in Antarctica using our recently developed sublimation extraction method to address this question. The meteorite extracts will then be analyzed for biological and non-biological purines and pyrimidines by the highly sensitive techniques of gas chromatography mass spectrometry (GCMS) and nanoflow liquid chromatography time of flight mass spectrometry (LC-ToF-MS) .We will furthermore compare their distribution in these meteorites with nucleobases extracted from soil and ice samples collected from the fall localities. In addition, nitrogen isotopic measurements of nucleobases and other N-heterocyclic compounds in meteorite extracts using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) will help establish their origin and may allow us to infer their nebular and/or parent body processes that lead to their formation. This work will provide crucial information to constrain the inventory of prebiotic organic compounds in the early solar system.