Two-Dimensional Gas Chromatography Analysis of Samples Returned from Asteroid Bennu by OSIRIS-REx  

Extraterrestrial organic compounds are predominantly examined through the analysis of natural samples delivered to Earth via meteorites [1]. The focus has largely been on carbon-rich meteorites called carbonaceous chondrites. These meteorites are believed to be remnants of asteroids and are considered the oldest solid materials accessible for laboratory analysis within our solar system. The soluble organic compounds identified within carbonaceous chondrites serve as a comprehensive record of pre-solar chemical reactions, early solar system dynamics, and transformations arising from aqueous and thermal processes on the parent bodies [2]. Understanding the extraterrestrial origins of these compounds is crucial for unraveling the origins and evolution of our solar system and to determine if carbon-rich asteroids like Bennu could have delivered prebiotic molecules to the early Earth [3]. Due to the unavoidable interaction of carbonaceous chondrites with Earth’s biosphere, analyses of the organic content in meteorites discovered on Earth often reveal different degrees of terrestrial contamination. To address the potential issue of contamination in extraterrestrial materials and to provide a sample from a known extraterrestrial source, NASA’s Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) mission delivered samples from the near-Earth asteroid (101955) Bennu to Earth on 24 September 2023 [4]. Bennu materials will be extracted in dichloromethane at NASA Goddard Space Flight Center and will be analyzed by two-dimensional gas chromatography using a LECO GC-HRT+ 4D system (GC×GC high-resolution time of flight with mass spectrometry; GC×GC-HRMS). The use of GC×GC-HRMS offers the advantage of enabling an untargeted evaluation of the soluble organic contents in these samples. Through comparisons of data collected with the same technique from carbonaceous meteorites and from samples returned by JAXA’s Hayabusa2 mission from asteroid Ryugu, there is a potential to establish parent-daughter relationships between samples collected on Earth and asteroids [5]. Analyzing the organics of Bennu will contribute to understanding the intricate history and evolution of these compounds and their precursor molecules, spanning from the molecular cloud and protosolar nebulae to planetesimal formation and parent body processing. This study will center on the GC×GC-HRMS results obtained from solvent extracts of Bennu, which should reveal a diverse array of organic species.   Acknowledgments: Supported by NASA under Award NNH09ZDA007O & Contract NNM10AA11C.   References: [1] Simkus D. N. et al. (2019) Life 9, 47. [2] Glavin D. P. et al. (2018) Primitive Meteorites and Asteroids, pp. 205-271. [3] Chyba C. and Sagan C. (1992) Nature 355, 125-132. [4] Lauretta D. S. et al. (2022) Science 377, 285-291. [5] Aponte et al. (2023) Earth, Planets and Space 75, 28.