Extraterrestrial Amines and Amino Acids in Samples From Asteroid Bennu

NASA’s OSIRIS-REx mission collected regolith from the surface of Bennu, a B-type carbonaceous asteroid, and delivered it to Earth on September 24, 2023. These samples contain compounds from pristine solar system matter, which may provide insights into the origin of life. The current exploration addresses the following hypotheses of the OSIRIS-REx Sample Analysis Plan: Hypothesis 2.1—Bennu contains organic compounds important for life, including protein amino acids, and their precursors and side products; Hypothesis 2.2—enantiomeric excesses are present for some chiral amino acids and are of the same handedness as those found in life; and Hypothesis 2.3—Bennu contains soluble organic matter with abundances, distributions, isotopic, and enantiomeric compositions similar to those of aqueously altered CI and CM chondrites. Amines are organics analogous to amino acids as the two compound classes possess similar structural backbones. Therefore, simultaneously studying amines and amino acids can yield insights on the syntheses of both types of organics. Previous analyses of a 52 mg sample of aggregate (loose, unsorted) Bennu material, OREX-803001-0, detected 16 amines and 33 amino acids, including 14 protein amino acids. This Bennu sample contained a free amine abundance of 1,060 ± 89 nmol/g (lower by a factor of ~1.7x compared to CM2 Murchison) and a total amino acid abundance of 70 ± 2 nmol/g (lower by a factor of ~3.5x compared to CM2 Murchison). Additionally, all chiral unbound amino acids were racemic, which contrasts with observations of enantiomeric excesses in some meteorites. It is currently unknown if these reported observations are consistent across other Bennu samples or if organic heterogeneity exists that may reveal enantiomeric excesses, for example. In this work, we analyzed three additional Bennu samples to better understand the origin and distribution of extraterrestrial amines and amino acids.