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Heterogeneous Distributions of Amino Acids Provide Evidence of Multiple Sources Within the Almahata Sitta Parent Body, Asteroid 2008 TC(sub 3)Two new fragments of the Almahata Sitta meteorite and a sample of sand from the related strewn field in the Nubian Desert, Sudan, were analyzed for two to six carbon aliphatic primary amino acids by ultrahigh performance liquid chromatography with UV-fluorescence detection and time-of-flight mass spectrometry (LC-FT/ToF-MS). The distribution of amino acids in fragment #25, an H5 ordinary chondrite, and fragment #27, a polymict ureilite, were compared with results from the previously analyzed fragment #4, also a polymict ureilite. All three meteorite fragments contain 180-270 parts-per-billion (ppb) of amino acids, roughly 1000-fold lower than the total amino acid abundance of the Murchison carbonaceous chondrite. All of the Almahata Sitta fragments analyzed have amino acid distributions that differ from the Nubian Desert sand, which primarily contains L-alpha-amino acids. In addition, the meteorites contain several amino acids that were not detected in the sand, indicating that many of the amino acids are extraterrestrial in origin. Despite their petrological differences, meteorite fragments #25 and #27 contain similar amino acid compositions; however, the distribution of amino acids in fragment #27 was distinct from those in fragment #4, even though both arc polymict ureilites from the same parent body. Unlike in CM2 and CR2/3 meteorites, there are low relative abundances of alpha-amino acids in the Almahata Sitta meteorite fragments, which suggest that Strecker-type chemistry was not a significant amino acid formation mechanism. Given the high temperatures that asteroid 2008 TC3 appears to have experienced and lack of evidence for aqueous alteration on the asteroid, it is possible that the extraterrestrial amino acids detected in Almahata Sitta were formed by Fischer-Tropsch/Haber-Bosch type gas-grain reactions at elevated temperatures.
Document ID
20110023539
Document Type
Reprint (Version printed in journal)
Authors
Burton, Aaron S. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Glavin, Daniel P. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Callahan, Michael P. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Dworkin, Jason P. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Jenniskens, Peter (Search for Extraterrestrial Intelligence Inst. Mountain View, CA, United States)
Shaddad, Muawia H. (Khartoum Univ. Sudan)
Date Acquired
August 25, 2013
Publication Date
October 7, 2011
Publication Information
Publication: Meteoricitcs and Planetary Science
Volume: 46
Issue: 11
Subject Category
Lunar and Planetary Science and Exploration
Report/Patent Number
GSFC.JA.5470.2011
Distribution Limits
Public
Copyright
Other