Extraterrestrial Amino Acids in the Almahata Sitta Meteorite


Danny Glavin, NASA Goddard Space Flight Center, Greenbelt, USA
Amino acid analyses of meteorite fragment#4 of asteroid 2008 TC3 called Almahata Sitta was carried out using high performance liquid chromatography coupled with UV fluorescence detection and time of flight mass spectrometry. Analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to six-carbon aliphatic amino acids and one- to three- carbon amines with abundances ranging from 0.5 to 149 parts-per-billion (ppb). The enantiomeric ratios of the amino acids alanine, isovaline, and norvaline in the meteorite were racemic (D/L ~ 1), indicating that these amino acids are indigenous to the meteorite and not terrestrial contaminants. The relative distribution of amino acids in Almahata Sitta is distinct from the distributions found in CV, CM, CI, and CR type carbonaceous meteorites that have been studied previously. The low abundances and unusual distribution of amino acids in Almahata Sitta may be due to extensive thermal alteration of amino acids in the carbonaceous precursor materials on the parent asteroid by partial melting during formation or impact shock heating.