Cometary glycine detected in samples returned by Stardust

Abstract

Our previous analysis of cometary samples returned to Earth by NASAs Stardust spacecraft showed several amines and amino acids, but the origin of these compounds could not be firmly established. Here, we present the stable carbon isotopic ratios of glycine and -aminon- caproic acid (EACA), the two most abundant amino acids identified in Stardust-returned foil samples measured by gas chromatographymass spectrometry coupled with isotope ratio mass spectrometry. The delta-13C value for glycine of +29 +/- 6 ppm strongly suggests an extraterrestrial origin for glycine, while the delta-13C value for EACA of -25 +/- 2 ppm indicates terrestrial contamination by Nylon-6 during curation. This represents the first detection of a cometary amino acid.