Polycyclic aromatic hydrocarbons in asteroid 2008 TC3: Dispersion of organic compounds inside asteroids

• Published in: Meteoritics & planetary science Vol. 45; no. 10-11; pp. 1710 - 1717
• Main Authors: SABBAH, Hassan, MORROW, Amy L., JENNISKENS, Peter, SHADDAD, Muawia H., ZARE, Richard N.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2010; Wiley Subscription Services, Inc
• Subjects: Carbon; Meteors & meteorites; Polycyclic aromatic hydrocarbons
• ISSN: 1086-9379; 1945-5100
• DOI: 10.1111/j.1945-5100.2010.01103.x

– Ureilites are carbon‐bearing ultramafic rocks characterized by partial melt depletion and a violent disruption resulting in graphitic carbon and diamonds. Among the predominantly polymict ureilite meteorites collected from the impact of asteroid 2008 TC3 on October 7, 2008—the first time an asteroid was spotted in space and subsequently recovered in the form of meteorites—were many fresh‐looking chondrites. Four were classified as EH6 (#16), H5 (sample #25), EL6 (#41), and L4 (#A100) chondrites. All are called “Almahata Sitta,” named after the nearby inhabited outpost of Station 6. Six hundred meteorites were collected, which show a wide range of densities, textures, reflection properties, and elemental compositions. In this study, we employ laser desorption laser ionization mass spectrometry to analyze the polycyclic aromatic hydrocarbon (PAH) contents of six meteorites from 2008 TC3 that are ureilites (sample #1, #4, #7, #15, #27, and #47) and three anomalous fragments (sample #25, #16, and #41). Numerous organic compounds were detected with a PAH signature that has not been observed in the carbonaceous chondrites previously studied by our experimental apparatus. Specifically, the Almahata Sitta spectra lack the diversity of alkylation series of parent PAHs commonly observed in Murchison and other carbonaceous chondrites. Spatial mappings of aromatic species across the surface of a fragment of sample #4 are presented including detection of what appears to be the aromatic amino acid tyrosine. Potential sources of terrestrial organic contamination are discussed and ruled out as a source of our observations. Meteorites #25 and #16 are found to have the same distribution of PAHs as the Almahata Sitta meteorites. Other chondrites have much different organic fingerprints. We conclude that both an H5 and E chondrite were included in asteroid 2008 TC3 as foreign clasts and that organic compounds contained in ureilites can spread into other parts of an asteroid.