Cometary Glycine Detected in Samples Returned by Stardust

Abstract

Our previous analysis of cometary samples returned to Earth by NASA's Stardust spacecraft showed several amines and amino acids, but the or igin of these compounds could not be firmly established. Here, we pre sent the stable carbon isotopic ratios of glycine and E-amino-n-caproic acid (EACA), the two most abundant amino acids identified in Stardu st-returned foil samples measured by gas chromatography-mass spectrom etry coupled with isotope ratio mass spectrometry. The Delta C-13 value for glycine of +29 +/- ? 6%: strongly suggests an extraterrestrial origin For glycine, while the Delta C-13 value for EACA of -25 +/-2 % indicates terrestrial contamination by Nylon-6 during curation. This represents the first detection of a cometary amino acid.